How well do endemic wetland plant species perform in water purification?

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Philip Frenzel, Olivia Brunings, Karen J Esler, David C Le Maitre, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3860564/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 26 Nov, 2024 Read the published version in Wetlands → Version 1 posted 5 You are reading this latest preprint version Abstract Rising anthropogenic-induced nutrient enrichment of surface waters is of great concern globally as it jeopardizes the ecological integrity and functioning of freshwater ecosystems. Floating wetlands have been successfully used to treat nutrient enriched wastewater in developing nations, and provide additional co-benefits. We aimed to quantify the nutrient removal efficiency of high-potential, locally endemic wetland species on floating wetlands in different conditions and to understand whether the nutrient uptake process was characterised by key plant functional traits. Two experiments were run under Mediterranean-climate conditions of the Western Cape of South Africa: (1) a closed, oligotrophic mesocosm experiment representing local conditions and (2) a real-life ( in-situ ) eutrophic application. The mesocosm experiment conducted under oligotrophic local conditions yielded low nitrate, phosphate and ammonium removal rates (34.8-35.2 mgNO 3 -Nm -2 .d -1 , 10.4-10.7 mgPO 4 -Pm -2 .d -1 and 3.6-3.8 mgNH 4 -Nm - 2.d -1 ) in comparison to other floating wetland studies globally, yet high removal efficiencies (>90%). However the eutrophic in-situ experiment demonstrated the potential for these same locally endemic plants to remove up to 312 g.m -2 of nitrogen and 47 g.m -2 of phosphorus per year– which is relatively high compared to similar global research. Cyperus textilis had the highest daily nutrient uptake and content followed by Prionium serratum and Juncus lomatophyllus, while J. lomatophyllus had the greatest nutrient uptake efficiency. Two of the three species ( C. textilis and P. serratum ) stored significantly more total nutrients in their shoot tissue compared to their root tissue, suggesting that the permanent removal of nutrients from the system is possible through shoot harvesting. Floating wetlands planted with endemic plant species have the potential to remove nutrients effectively and sustainably from eutrophic water and can thus be implemented as low-cost nature-based solutions to mitigate pollution of lentic systems. floating treatment wetlands constructed wetlands nutrient removal plant uptake nature-based solution water treatment Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1 INTRODUCTION Increasing eutrophication of surface waters is of great concern globally as it jeopardizes freshwater ecosystems. This trend has necessitated the development of technologies for water purification. Typically, conventional wastewater treatment facilities are still widely used to improve water quality internationally, although they are costly to maintain and upgrade (Keizer-Vlek et al., 2014 ; Kivaisi, 2001 ; Wang et al., 2015 ). Due to increasing demand for wastewater treatment, there is a need for more innovative, affordable and sustainable decentralised technologies to treat wastewater – particularly for developing nations (Kivaisi, 2001 ). Extensive research into design considerations and optimization has resulted in various types of constructed wetlands being developed for different wastewater types (Babatunde et al., 2008 ; Batchelor and Loots, 1997 ; Jacklin et al., 2021b ; Wood and Pybus, 1992 ; Wu et al., 2015 ; S. Wu et al., 2014 ; Yeh et al., 2015 ). Floating wetlands, a type of constructed wetland, are manufactured buoyant structures designed to support emergent wetland plants. They are installed for the purpose of nutrient removal (Vymazal, 2007 ), with co-benefits such as aesthetic appeal, biodiversity enhancement (Biggs et al., 2006 ) and environmental education (Ahn, 2016 ). Floating wetlands also do not require highly qualified technicians to install and maintain, have no energy consumption, are able to fluctuate with water levels and require low capital costs (Abed et al., 2017 ; Pavlineri et al., 2017 ; Kivaisi, 2001 ). Studies have demonstrated that floating wetlands are capable of successfully removing nutrients and pollutants from various wastewater types (Headley and Tanner, 2008 ; Hubbard et al., 2004 ; Keizer-Vlek et al., 2014 ; Wang et al., 2015 ; White and Cousins, 2013 ). A study showed that floating wetlands planted with Typha latifolia removed 534 g. m − 2 Nitrogen (N), 79 g. m − 2 Phosphorus (P) and 563 g m − 2 Potassium (K) over a 16 month period from swine-polluted lagoon wastewater in the USA (Hubbard et al., 2004 ). Panicum hematomon removed 323 gN.m − 2 , 48 gP.m − 2 and 266 gK.m − 2 from the same. Urban wastewaters have been purified using floating wetlands planted with Iris pseudacorus and Typha angustifolia and which were found to remove 25 gN.m − 2 and 0.8 gP.m − 2 , and 2.5 gN.m − 2 and 0.006 gP.m − 2 respectively over a three month period in the Netherlands (Keizer-Vlek et al., 2014 ). Another study focussed on heavy metals found that Juncus effusus floating wetlands accumulated 0.023 mg. g − 1 Nickel and 0.080 mg.g − 1 Zinc in the shoots, and 0.131 mgNi.g − 1 and 0.21 mgZn.g − 1 in the roots over a four month period in France (Ladislas et al., 2015 ). In the same study, Carex riparia accumulated 0.031 mgNi.g − 1 and 0.045 mgZn.g − 1 in the shoots, compared to 0.113 mgNi.g − 1 and 0.045 mgZn.g − 1 in the roots over the same time period (Ladislas et al., 2015 ). Floating wetlands have also been found to be successful in remediating organic contaminants such as pesticides, pharmaceuticals, personal care products and per- and polyfluoroalkyl substances (Awad et al. 2022 ). Therefore, floating wetland technology demonstrates successful, non-specific application across various wastewater and pollutant types. Plant uptake is one pathway in which nutrients are removed in floating wetland systems. Plants facilitate the removal of nutrients through direct assimilation (absorption or adsorption), or indirectly by creating habitat for microbial communities on the root infrastructure – which assist in nutrient removal through processes such as denitrification (Lynch et al., 2015 ; Olguín et al., 2017 ). Various studies have highlighted the ability of plants to assist in phytoremediation of surface waters (Schachtschneider et al., 2017 , Jacklin et al 2021a , b , c , d ). The uptake capacity of plants varies considerably across species and is largely dependent on their anatomical and physiological properties, or their functional traits, which, in turn, allow different plants to have different tolerances to various nutrient thresholds (Moor et al., 2017 ; Pavlineri et al., 2017 ; Pérez-Harguindeguy et al., 2013 ; Wang et al., 2015 ; Wanielista et al., 2012 ). There is no universal trend as to where plants predominantly store their nutrients (i.e. disproportionally in their roots or shoots, or equally) (Wang et al., 2015 ; Wanielista et al., 2012 ). This potential for variation in uptake rates and storage location emphasises that plant selection is crucial in optimizing nutrient removal for specific use-cases and needs. If nutrient removal from the system via stem harvesting (e.g. mowing or cutting) is desired, then selecting plants with dominant storage in shoots is important. Species commonly selected for use in constructed wetlands tend to be ubiquitous generalists, for example Phragmites spp. and Typha spp. (Wu et al., 2015 ). Despite plant selection being a key element in designing constructed wetlands, very few wetland plant species have been thoroughly researched for this purpose globally (Vymazal, 2013 ). At the time of this research, very few wetland plant species had been investigated in the South African context, but more recently, a phyto-guide to species selection has been developed (Jacklin et al. 2021a ). Nevertheless, a large research gap remains to assess the potential of various indigenous plant species for nutrient removal (Wang and Sample, 2014 ). South Africa has no shortage of potentially useful wetland species, particularly in the Cape Region where there is high floral diversity (Hoveka et al., 2020 ). Moreover, in South Africa’s Cape region where this study took place, surface waters are typically oligotrophic (Ward & Winter, 2016 ) and thus native species are adapted to this typically low nutrient environment. However, large-scale landscape transformation in the Cape has resulted in significant nutrient enrichment of water bodies (Ward & Winter, 2016 ). Against this backdrop, the primary focus of this research was to investigate the nutrient removal capacities of local wetland plant species under near natural and nutrient enriched scenarios. In this study, we aimed to quantify the nutrient removal efficiency of high-potential, locally endemic wetland species on floating wetlands in a low nutrient mesocosm and high nutrient in-situ experiment. We investigated: (i) the nitrogen and phosphorus removal capacity of floating wetlands planted with three locally endemic species: Cyperus textilis , Juncus lomatophyllus and Prionium serratum , (ii) the contribution of plant nutrient uptake to the overall removal capacity of these floating wetlands, (iii) the dominant location of plant nutrient storage (roots or shoots), and (iv) the influence of plant functional traits in the process of nutrient uptake. We then reflect on the potential for practical implementation given the results of the experiments. 2 METHODS 2.1 Study species Plant selection has been identified as a crucial design consideration in constructed wetlands (Brisson and Chazarenc, 2009 ). Therefore, the criteria used to select species for experimentation is very important. Species selection for this study was based on the following criteria (adapted from Tanner 1996 ): “Ecological acceptability” i.e. no significant weed or disease risks or danger to the ecological or genetic integrity of surrounding natural ecosystems. Tolerance of local climatic conditions, pests and diseases. Tolerance of pollutants and hypertrophic waterlogged conditions. Ready propagation, and rapid establishment, spread and growth. Ability to co-exist with other wetland plants; not too large (i.e. should not sink the frame structure). Interesting/promising indigenous species that have not yet been studied in a wetland context. A short-list of eleven potential wetland species was compiled based on local industry experience (Table S1, Supplementary Material). From these, three high potential, locally endemic wetland species were selected for the experiment based on an evaluation using the six criteria outlined above (Table S2, Supplementary Material): Cyperus textilis , Juncus lomatophyllus , and Prionium serratum . These three species were used in both sets of experiments and the young plants were obtained from a local nursery. 2.2 Mesocosm experiment: oligotrophic conditions 2.2.1 Experimental set-up This mesocosm experiment was designed as a closed mass balance experiment with the aim to isolate the effects of floating wetlands on water quality. The experiment was conducted over one-month in a greenhouse (240 m 2 ) at Stellenbosch University from 27 January to 27 February 2017 i.e. during the summer season (Table S3, Supplementary Material). The experiment was performed in twenty-four 90 L plastic tanks (0.45 m x 0.75 m). The tanks were positioned in a randomised block design with six replicates each (Fig. 1 ). Each tank contained a standard floating wetland planted with ten plants of the same species (along with a small amount of their associated soil), except for the control which was without vegetation and soil (Keizer-Vlek et al., 2014 ). A standard floating wetland was constructed of high-density foam, mesh, hessian and a soil saver layer and was fastened together with cable ties. A set of four small garden fountain pumps were rotated daily between tanks, after being cleaned, to circulate the water. This was to avoid anoxia while keeping costs down. The seedlings were acquired four months prior, in September 2016, and the floating wetlands were constructed, and tanks filled with 70 L of municipal water (containing insignificant nutrient concentrations). The floating wetlands established over these four months whilst plant health, growth and survival were monitored closely using the framework of Brisson & Chazarenc ( 2009 ). Additions of Pokon (fertilizer for pot plants, Universeel plantenvoedsel, manufacturer: Pokon Naturado) were made during this period to ensure sufficient nutrients for growth as well as the presence of trace elements (B, Cu, Fe, Mn, Mo, Zn, and K). 2.2.2 Nutrient additions On 27 January 2017, the tanks were emptied and refilled with new municipal water. Three water samples were taken from the municipal water supply and tested, prior to any fertiliser additions, to establish baseline NH 4 -N, NO 3 -N and PO 4 -P concentrations. After this, 31.5 mL of NO 3 -N, 8.4 mL of NH 4 -N and 7.0 mL of PO 4 -P were added in 1000 mg.L − 1 concentrate forms to establish oligotrophic conditions relative to local ecosystems (Table S4 and Table S5, Supplementary Material). Three days later, a 100 mL water sample was taken for nutrient analysis from each tank to confirm the calculated concentrations of bioavailable nutrients (NH 4 –N, NO 3 –N, and PO 4 –P). During the experiment, concentrations of bioavailable nutrients were tested each week in two random tanks selected from each different plant species (Keizer-Vlek et al., 2014 ) as well as the control to determine whether more nutrients needed to be added in order to remain within the predetermined range. Only two tanks were sampled due to budget constraints; ideally each tank would have been tested. The water in the tanks was topped up weekly to 70 L using municipal water and the amount of water added was recorded for each tank. Two composite samples of the municipal water were tested for bioavailable nutrients each week. If the nutrient concentrations fell below minimum concentrations (0.16 mgNH 4 -N.L − 1 , 0.45 mgNO 3 -N.L − 1 , 0.10 mgPO 4 -P.L − 1 ), more nutrients were added to all the tanks and these amounts were recorded. All water quality tests were performed by AL Abbott & Associates Ltd, which are accredited to the ISO 17025:2005 standard (registration number 1982/004379/07). In addition, each week, various physico-chemical variables (dissolved oxygen, conductivity, temperature and pH) were recorded at a depth of 0.30 m using a handheld multi-parameter water quality meter in each tank (Model: YSI 556 Multi Probe System; YSI Environmental). Overall, water quality did not differ significantly among treatments except for pH, which was significantly lower in the J. lomatophyllus treatments, and significantly higher in the C. textilis treatments (Table S6, Supplementary Material). 2.2.3 Plant sampling and analysis At the start and end of the experiment, randomly chosen plant specimens were removed from each of the 18 planted floating wetlands for biomass measurements (wet and dry root and shoot biomass) and tissue nutrient analysis (for TN and TP concentrations). One plant per floating wetland (total of 18 plants) was removed at the start of the experiment, whilst two plants (total of 36 plants) were removed at the end of the experiment to increase the representativeness due to differential growth over the experiment. Before specimens were dried, several key plant functional traits were measured (10 measurements per plant), including plant height, root and shoot lengths, root surface area, leaf surface area, leaf and root mass. The surface areas were calculated using the method of Verschoren et al., ( 2017 ). Indices, such as specific root length, specific leaf area, root dry matter content and leaf dry matter content, were also calculated. Specimens were then dried to a constant mass at 70°C for a minimum of 48 hours. Root and shoot dry mass were determined for each specimen after which they were ground to 0.5 mm particle size using a Retsch Mill . Total nitrogen and phosphorus concentrations were measured in the roots and shoots of each specimen. All the plant tissue analyses were performed by BEMLAB Ltd , which are accredited to the ISO 17025:2005 standard (registration number 1996/006836/07). Total nitrogen content was determined using the Dumas Method and total phosphorus content was determined using a dry ash method whereby the sample was combusted in a muffle furnace at 480 o C for 8 hours, acidified, digested by heating, diluted, and analysed by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) (Spangler et al., 2019a ). Any floating algae were removed daily using a fish net, where necessary, from the tanks to establish a standard for nutrient removal with minimal interference of algae and therefore minimizing bias (e.g. between experiment and control). 2.2.4 Nutrient removal ability The nutrient removal ability of floating wetlands was calculated in three ways. Firstly, total removal of bioavailable nutrients (NO 3 -N, NH 4 -N and PO 4 -P) in the tanks was measured throughout the experiment through mass balance calculations following the water testing. Total removal was calculated by subtracting the bioavailable nutrients remaining in the tanks (NO 3 -N, NH 4 -N and PO 4 -P concentrations multiplied by the water volume) from the total nutrients added to the system throughout the experiment. Secondly, the removal rate was calculated, which used the total experiment duration to calculate a daily removal rate. Thirdly, removal efficiency was calculated, which is the total removal of bioavailable nutrients over the duration of the experiment relative to the total available nutrients in the system, expressed as a percentage. Data are made available in Table S7, Supplementary Material. 2.3 In-situ experiment: eutrophic conditions 2.3.1 Experimental set-up This experiment was designed to mimic the eutrophic conditions of many small farm dams in the region. This experiment was carried out in a large concrete wastewater retention pond at the Water Hub, located in Franschhoek in the Western Cape of South Africa; a remnant of the old Franschhoek Wastewater Treatment Works. The pond has a volume of 63.6 m 3 and measures 4.8 m (width) X 5 m (length) X 2.65 m (height) (Fig. 2 ). This experiment took place over three months from 12 March 2021 to 12 June 2021, in the austral autumn. Highly eutrophic water from the Stibeuel River, which flows past the Langrug informal settlement near Franschhoek before passing the Water Hub, was pumped into an old concrete wastewater retention pond in which the floating wetlands were established. The tank was filled to approximately 50% capacity. Eighteen floating wetlands of 0.5 m x 0.4 m (i.e. 0.2 m 2 ) in size were constructed (Fig. 2 ) using high-density foam, mesh, hessian, wooden dial sticks, and cable ties. Six replicates (wetlands) were used for each of the three treatments (plant species) and each floating wetland was planted with ten seedlings of the relevant species. The seedlings were carefully removed from their potting soil and as much soil as possible was detached without causing damage to the root system. Given that this was not a mesocosm experiment with individual wetlands in individual water bodies to investigate mass balance impacts on water quality, no control was necessary. Young seedlings were sourced from a local restoration nursery, Green Intaba, prior to the start of the experiment and were planted onto the constructed floating wetlands on 4 January 2021. The plants were allowed to establish over the following two months, during which plant health, growth, and survival were periodically monitored. Several J. lomatophyllus plants did not survive (plant health of these few seedlings was poor prior to being planted onto wetland structures, likely due to water stress during transport) and were replaced during the establishment phase. Due to the clonal growth of this species, plastic separators were placed between plants where necessary to distinguish the original individuals. The experiment commenced once the plants had successfully established. As there was a concrete bridge that cast a partial shadow over the retention pond, the position of each wetland (sun, shade, or mixed) was recorded during site visits (every two weeks during the establishment phase and weekly during the experiment) and the wetlands were moved to new locations on a rotational basis to ensure a randomised experimental design and prevent light exposure from becoming a bias. 2.3.2 Plant sampling and analysis The experiment commenced on 12 March 2021 and ran for a period of three months. At 28-day intervals during the experiment, three randomly selected plants were sampled (removed) from each floating wetland. Plant roots and shoots were separated for independent analysis, and the same method applied for grinding and drying as described for the mesocosm experiment was applied. The ground samples were thoroughly mixed, and a representative composite sample of root and shoot tissue of the three plants sampled from each wetland was sent to BEMLAB for tissue nutrient analysis of total nitrogen and total phosphorous. The same laboratory methods were used as described for the mesocosm experiment. The use of composite sampling was essential due to budget constraints; however, ANOVA power analyses indicated that the sample size was sufficient to detect significant differences if they are present (Table S8 and Table S9, Supplementary Material). The power analyses were based on the data from the mesocosm experiment, however, as the in-situ experiment was conducted under more eutrophic conditions, greater effect sizes were expected. Plant functional traits such as leaf dry matter content (LDMC), and root dry matter content (RDMC) were determined by dividing dry mass (mg) by wet mass (g) of leaves and roots respectively. Water quality samples were taken at the start of the experiment period as well as at monthly intervals during the experiment and sent to the laboratory at the South African Council for Scientific and Industrial Research (CSIR) for analysis of bioavailable nutrients (phosphates (PO 4 -P), nitrates (NO 3 -N), and ammonia + ammonium (NH 3 + NH 4 ). The CSIR are accredited to the ISO 17025:2017 standard (registration number T0093). This method cannot differentiate between the ammonium and ammonia. In addition to these samples, physicochemical variables (temperature, pH, total dissolved solids, and dissolved oxygen) were monitored weekly during the experiment using a handheld multi-parameter water quality meter to ensure nutrient levels did not reach toxic levels (Table S10, Supplementary Material). 2.3.3 Plant nutrient content and uptake capacity Plant uptake capacity , defined here as total nitrogen and total phosphorus uptake in plant tissues, was measured for both roots and shoots, by plant tissue analysis. Uptake was calculated by multiplying plant dry weight at the start and end of the experiment by the respective TN and TP concentrations, and subtracting the two (Keizer-Vlek et al., 2014 ). Plant nutrient concentration was used as an indication of nutrient storage efficiency (a measure of how well plants can store nutrients in their tissue). The ratio of the shoot to root nutrient content was used to test for differences in nutrient storage location among species. Nutrient uptake rates were estimated by calculating the mean nutrient uptake over 28-day periods and standardising these values to a daily rate (Table S11, Supplementary Material). To enable comparison with literature values, nutrient uptake values (mg.d − 1 ) per floating wetland (0.2 m 2 ) were standardised to values per square meter. The floating structures used in this experiment were 0.2 m 2 in size and were planted with 10 plants each, thus 5 wetlands and 50 plants would be needed to cover 1m 2 of surface water. To estimate the uptake of each species in terms of mg.m − 2 .d − 1 , the mean daily uptake rate was multiplied by 50. To get an estimate of the nutrient uptake ability of these systems over a longer period, the daily values (mg.m − 2 .d − 1 ) were also converted to an annual estimate (g.m − 2 .y − 1 ); this estimate does however not take the plant growth cycle into account. This experiment was in the austral autumn and therefore during the spring and summer it is possible that uptake rates may be higher, and in winter slightly lower. It is important to emphasize that these plants are evergreen and that there are still high levels of solar radiation in the autumn in South Africa. Despite this, it is likely that the results from this experiment provide a slightly lower estimate than the plants full potential. It is important to note that three plants were removed from each wetland monthly, thus the remaining plants had more space to grow and less competition. Consequently, the uptake rates (mg.m − 2 .d − 1 ) in this experiment represent values that would be obtained at relatively high planting densities (50 plants per m 2 ) accompanied by regular biomass harvesting. 2.4 Data analysis For the mesocosm and in-situ experiment, most statistical analyses were performed in Statistica and R version 3.6.2 (R Core Team, 2019 ). For the mesocosm experiment, one-way ANOVAs were performed to investigate significant difference in total removal, removal rates and removal efficiencies of NO 3 -N, NH 4 -N and PO 4 -P between all the floating wetland treatments because the data were found to be normally distributed and variances were homoscedastic. For significant differences, the Fisher least significant difference (LSD) post hoc test was used. To investigate significant differences in traits LDMC, RDMC, SLA and SRL, a one-way ANOVA was run. For SRL and RDMC data, a Welch test was run because the variances were heteroscedastic and the data were normally distributed. For significant differences, a Games-Howel post hoc was run. For the SLA and LDMC, the data were normally distributed, and the variances were homoscedastic. For significant differences, a LSD post hoc test was run. For the in-situ experiment, differences in dry mass, nutrient content, and nutrient storage efficiency, linear mixed models were fitted using the ‘lmer’ function within the ‘lme4’ package (Bates et al., 2015 ). The “wetland” and “plant” sampled were entered as random effects to account for dependence between observations from the same wetland. “Species”, “sampling day”, and the interaction between species and sampling day were entered as fixed effects. First, the effect of the interaction between species and sampling day was tested by comparing the fit of the model to a reduced model that only contained the two main effects. Where the interaction term was significant, separate models were run to test the significance of species on each sampling day individually. If a significant difference was not detected, the interaction term was excluded from the model and the significance of the main effects were tested. The significance was tested by running a Kenward-Roger F-test using the “pbkrtest” package in R (Halekoh and Højsgaard, 2014 ). Where a significant influence of species or sampling day was detected, a post hoc test was performed on the relevant model using the ‘emmeans’ function from the ‘emmeans’ package in R (Lenth, 2021 ). Correlation analyses were performed to determine if the physicochemical variables were correlated with the water quality data as well as to determine whether there was an association between plant growth (dry matter at the three timesteps) and nutrient content. Pearson’s correlation analysis was used for parametric data while Spearman’s Rank correlation analysis was used for non-parametric data. To investigate significant differences between shoot:root ratios across both experiments, a generalised linear mixed model (with binomial distribution) was used. A multiple comparison Tukey test was used to test for significant differences. 3 RESULTS 3.1 Nutrient uptake ability under oligotrophic conditions The total removal (mg) of NO 3 -N, PO 4 -P and NH 4 -N from the water was very low across planted and unplanted floating wetland treatments. The total NO 3 -N and NH 4 -N removal of floating wetlands did not differ significantly among treatments (Fig. 3 A). However, the floating wetlands planted with Cyperus textilis, Juncus lomatophyllus and Prionium serratum had significantly higher total PO 4 -P removal relative to the control (F (3,20) = 6.52; df = 20; p < 0.01) (Fig. 3 A). Low removal rates (mg.m 2 .d − 1 ) from the water were observed for all parameters and treatments (Fig. 3 B). No significant difference was observed between treatments for NO 3 -N and NH 4 -N removal rates, however there was a significant difference in the PO 4 -P removal rate between floating wetlands planted with C. textilis, J. lomatophyllus and P. serratum relative to the control (F (3,20) = 6.52; df = 20; p 90%) were observed across all treatments (Fig. 3 C). This was also occasionally the case for the control; however, results were more variable. There was a significant difference in PO 4 -P removal efficiency between floating wetlands planted with C. textilis, J. lomatophyllus and P. serratum relative to the control (F (3,20) = 6.42; df = 20; p < 0.01) (Fig. 3 C). 3.2 Nutrient uptake potential under eutrophic conditions Cyperus textilis accumulated a mean total of 477.9 ± 254.45 mg TN and 72.3 ± 40.36 mg TP over a one-month period under eutrophic conditions – which is signficiantly higher than P. serratum and J. lomatophyllus which accumulated a mean total of 175.3 ± 43.60 mg TN and 14.5 ± 6.42 mg TP, and 30.9 ± 80.99 mg TN and 6.7 ± 14.27 mg TP respectively over the same period (Fig. 4 ). Two species, namely C. textilis and P. serratum , stored significantly more nutrients (both nitrogen and phosphorus) in their shoot tissue compared to their root tissue (Nitrogen: F (4,30) = 19.44; df = 30; p < 0.01) (Phosphorus: F (4,30) = 17.65; df = 30; p < 0.01) (Fig. 4 ). Specifically, C. textilis stored significantly more TN and TP in its shoots than both J. lomatophyllus and P. serratum . Cyperus textilis also had the highest nutrient uptake and content per day followed by P. serratum and J. lomatophyllus (Fig S 1, Fig S 2, Fig S 3, Supplementary Material), while J. lomatophyllus had the greatest nutrient uptake efficiency (Fig S 4, Supplementary Material). 3.3 What is the role of plant functional traits in the process of nutrient uptake? 3.3.1 Dominant location of plant nutrient storage The nitrogen shoot:root ratio for all treatments was significantly higher in the in-situ experiment compared to the mesocosm experiment (F (5,36.3) = 83.35;p < 0.01). However, this differed to the phosphorus shoot:root ratios for C. textilis and P. serratum which were significantly higher in the in-situ experiment (Fig. 5 ). For both Total Nitrogen and Total Phosphorus shoot:root ratios, C. textilis was significantly higher than the other treatments within the in-situ experiment (Fig. 5 ). Interestingly, these trends did not concur with the concentrations of nutrient storage within the roots and shoots of the study species under different nutrient environments. Juncus lomatophyllus stored a significantly higher concentration of nitrogen and phosphorus when compared to the other two plant species (Fig. 6 ). Generally, J. lomatophyllus had significantly higher concentrations of both Nitrogen and Phosphorus stored within the shoots in comparison to the roots – expect for the in-situ experiment, where the roots stored significantly more Phosphorus than the shoots (Fig. 6 ). Also, most plants species, regardless of the experiment type, stored a significantly higher concentration of nutrients in the shoots than their roots – particularly J. lomatophyllus and C. textilis (Fig. 6 ). 3.3.2 Plant functional traits When comparing traits of the three endemic wetland plant species, the LDMC of C. textilis was significantly higher across all species, while J. lomatophyllus was significantly lower (F (2,33) = 166.88; df = 33; p < 0.01) (Fig. 7 ). The RDMC was significantly higher for P. serratum and significantly lower for J. lomatophyllus (F (2,33) = 143.51; df = 33; p < 0.01) (Fig. 7 ). The mean SRL and mean SLA of J. lomatophyllus was significantly higher than that of P. serratum and C. textilis (Fig. 7 ). The traits measured in the in situ experiment were very similar and are not presented here (Table S15, Supplementary Material). 3.3.3 Relationship between plant growth and nutrient content Relatively similar significantly positive relationships between nutrient content (both nitrogen and phosphorus) and plant growth (i.e. an increase in dry matter) were observed for all three species for both roots and shoots in the in-situ experiment (Fig. 8 ). However, J. lomatophyllus appeared to store slightly higher concentrations of TN and TP per unit dry matter in both shoots and roots, but especially roots, relative to the other two species. However, J. lomatophyllus remains relatively small over the three months relative to the other two species, leading to lower overall TN and TP contents. The mean ratio of plant dry matter (g) to nitrogen content (g) for all three species was 55:1, while that of phosphorus was 421:1 (Fig. 8 ). 4 DISCUSSION 4.1 Nutrient uptake ability In the mesocosm experiment, the total removal amount and removal rates of bioavailable nutrients across treatments were very low overall due to the naturally oligotrophic conditions applied. Oligotrophic Cape freshwater systems are nutrient poor primarily due to the nutrient deficient parent geology (Lamont 1983 ). Other floating wetland studies are found to have high removal rates – ranging between removal rates as high as Headley and Tanner ( 2012 ) and as low as Saeed et al., ( 2016 ) i.e. from 210 to 114 000 mgNO 3 -N.m − 2 .d − 1 , 559 to 4600 mgPO 4 -P.m − 2 .d − 1 and, 1480 to 36000 mgNH 4 -N.m − 2 .d − 1 (Headley and Tanner, 2012 ; Saeed et al., 2016 ; Stewart et al., 2008 ). This range of removal rates is still high in comparison to the low removal rates found in this mesocosm experiment. The high removal efficiencies (> 90%) observed for all nutrient parameters (NO 3 -N, PO 4 -P and NH 4 -N) across planted floating wetland treatments in the mesocosm experiment is likely due to the adaptation of these species to naturally oligotrophic conditions. These efficiencies were not significantly different for the control (except for PO 4 -P), but the controls exhibited much higher variability and greater ranges for NH 4 -N. These removal efficiencies are very high in comparison to other studies, such as Van De Moortel et al. ( 2010 ) who observed that the presence of plants (i.e. Carex sp.) on floating wetlands resulted in a significantly higher NH 4 -N removal efficiency (35%) than the control (3%), which consisted of an unplanted mat. Keizer-Vlek et al. ( 2014 ) also showed this trend where an Iris -planted floating wetland had a much higher TN removal efficiency of 98%, in comparison to the unplanted control of only 14%. Nevertheless, Keizer-Vlek et al. ( 2014 ) and Van De Moortel et al. ( 2010 ) emphasised the large variability of removal efficiencies between studies. The low nutrient removal amounts, but high removal efficiencies observed in our experiment suggests that most nutrients added to the treatments were removed by the floating wetlands. The similar removal efficiencies and amounts observed between floating wetlands treatments and the control suggest that microbes assosciated with the surface area provided by the wetland infrastructure may be performing nutrient uptake in the absence of plants, or may play an important role even in the presence of plants (Stewart et al., 2008 ; Wu et al., 2016 ). However, where plants were present on floating wetlands, it is likely that the nutrients were accumulated within the plant matter as evidenced by an increase in plant biomass. Whilst additional nutrient removal pathways (i.e. other than the role of plants) are not the focus of this paper, various other pathways could explain the trends observed in the mesocosm experiment (Stewart et al., 2008 ; Wu et al., 2016 ). This experiment suggested that these floating wetlands and endemic plants had high potential that required testing in a real-life eutrophic application. 4.2 Nutrient uptake potential Testing the potential for these endemic plant species for water purification in a eutrophic in-situ experiment revealed high nutrient uptake capacities across all species. However, Cyperus textilis outperformed both Juncus lomatophyllus and Prionium serratum in terms of nutrient uptake, storing most of this in its shoots, largely due to its greater size and faster growth rates. Therefore, considering water quality alone (i.e. not other factors, such as biodiversity), C. textilis had the highest benefit out of the three study species. All species grew well and appeared to tolerate and thrive in the eutrophic conditions despite being adapted to oligotrophic conditions. Clearly no thresholds were exceeded, but a follow-up study on the tolerance levels and ranges of optimal performance of these endemic species to eutrophic conditions would be useful. A review of eight studies, conducted mainly in humid subtropical and sub-humid continental climates, found that nitrogen uptake abilities for plant species, including common species such as Phragmites australis, Juncus effusus and Typha species, varied between 13.2 and 390 mgN.m − 2 .d − 1 (Choudhury et al., 2019 ). A review of another eight studies, conducted mainly in China, found that the water purification abilities of species such as Canna indica, P. australis, J. effusus and Typha species varied between 17 and 912 mgN.m − 2 .d − 1 with mean uptake rates of 430 ± 350 mgN.m − 2 .d − 1 (Wang et al., 2020 ). Compared to these studies, both C. textilis , with nitrogen uptake of 853 mgN.m − 2 .d − 1 , and P. serratum with nitrogen uptake of 313 mgN.m − 2 .d − 1 performed comparatively well. Temperature plays an important role in plant growth and thus nutrient uptake. A study looking at the applicability of P. australis and Zizania caduciflora floating wetlands to treat agricultural runoff in China found that nitrogen uptake ranged between 206.5 and 628.5 mgN.m − 2 .d − 1 with the highest uptake rates occurring during the summer months (Lu et al., 2009 ). The water temperatures of the current study were similar to those observed during winter, autumn and spring in Lu et al., ( 2009 ), yet the nitrogen uptake rate for C. textilis outperformed the maximum uptake rates found in this study, perhaps indicating that at higher water temperatures, such as in summer, maximum potential uptake may occur. Under the low temperatures found in northern Sweden (mean summer temperature of 10°C), floating wetlands had a nitrogen uptake rate of between 7.56–24.75 mgN.m − 2 .d − 1 (Choudhury et al., 2019 ). Thus, all three plant species outperformed species grown in colder climates, highlighting the potential value of floating treatment wetlands particularly in warmer regions with longer growing seasons such as South Africa. The phosphorus uptake rates of J. lomatophyllus and P. serratum in our study were also higher than several other species studied (Wang et al., 2020 ). A study conducted in south Australia on the use of Paspalum paspalodes, Myriophyllum aquaticum , and Ranunculus repens planted floating mats found that these three species had mean phosphorus uptake rates ranging between 43 and 86 mgP.m − 2 .d − 1 (Wen and Recknagel, 2002 ), and in our study C. textilis performed comparatively well with 129 mgP.m − 2 .d − 1 unlike J. lomatophyllus and P. serratum . Likewise C. textilis performed well relative to results of a review of eight studies, conducted mainly in China, which found that phosphorus uptake rates for numerous plant species, including Canna indica, P. australis, J. effusus and Typha species, varied between 2 and 163 mgP.m − 2 .d − 1 (Wang et al., 2020 ). A study conducted after ours, investigating the use of nine South African endemic plant species for use in biofilters, also confirmed that C. textilis and P. serratum consistently showed some of the best results in terms of nutrient removal relative to the other seven species (Jacklin et al., 2021b ). The nitrogen removal ability of C. textilis was similar to that of C. indica measured at varying ratios of ammonium and nitrate concentrations in China while P. serratum had slightly lower nutrient removal abilities (Zhang et al., 2018 ). Canna indica, Thalia dealbata , and Lythrum salicaria were found to have accumulated a mean of 1523 mg, 1619 mg, and 908 mg of nitrogen per plant and 144 mg, 102 mg, and 71 mg of phosphorus per plant respectively over 84 days in an experiment in China (Ge et al., 2016 ). Over the same time in our in situ experiment, C. textilis accumulated a mean of 1855 mg of nitrogen and 262 mg of phosphorus per plant, thus performing better than all three species. The review of eight studies, conducted mostly in China, found that the nutrient content measured for several species ranged between 32 and 5803 mg of nitrogen per plant, and between 2 and 437 mg of phosphorus per plant (Wang et al., 2020 ). Cyperus textilis and P. serratum performed better in the in-situ experiment than the majority of the species in the review (Wang et al., 2020 ). In contrast, the nutrient storage of P. cordata and J. effusus plants surpassed the nutrient storage measured in our study, likely due to the greater plant biomass production (Spangler et al., 2019b ). Nitrogen and phosphorus removal of floating wetlands planted with Carex stricta, Agrostis alba, Iris ensata, Panicum virgatum , and Canna generalis together with a generalist species after eight weeks were all greater than the nutrient removal measured in our study, however, the nutrient concentrations used were higher than that in the current study (Spangler et al., 2019a ). 4.3 Role of key plant functional traits in nutrient removal Cyperus textilis performed best in terms of nutrient uptake under eutrophic conditions, followed by Prionium serratum and then Juncus lomatophyllus . The traits that seemed to characterise this high nutrient uptake were biomass, leaf dry matter content (LDMC) and specific leaf areas (SLA). Both biomass and LDMC were higher for the two species that performed better at nutrient uptake, whereas SLA was lower. This may indicate that wetland species with high LDMC, low SLA and that are able to grow relatively large, may be highly suitable for floating treatment wetlands. Juncus lomatophyllus had the highest nutrient uptake efficiency, i.e. highest N and P concentrations in its tissues, which was concomitant with higher SLA. Although higher SLA in turn suggests a higher relative growth rate and a more acquisitive strategy in terms of the plant economic spectrum (Garnier et al., 2001 ; Grassein et al., 2015 ; Moor et al., 2017 ; Pérez-Harguindeguy et al., 2013 ), J. lomatophyllus is a small wetland plant, which does not attain high biomass, but rather spreads laterally via vegetative growth. Therefore its potential for nutrient uptake is lower in eutrophic conditions compared to the other two species. The other two species were more conservative in terms of their resource use, but able to attain greater size and biomass and therefore take up more nutrients overall. The life history strategies of C. textilis and P. serratum are likely to be more that of competitors (Rebelo et al. 2022 ), whereas J. lomatophyllus appears to me more of a ruderal or stress tolerant wetland species (Grime, 1977 ). Species that are more competitive and amass more biomass would need to be frequently harvested to keep biomass down and avoid self-shading and senescence on floating treatment wetlands. 4.4 Caveats There were several limitations to this study due to budget or logistical constraints, since this research was conducted in a resource constrained country: (1) less water quality sampling of bio-available nutrients than would be desired in the mesocosm experiment, (2) the taking of composite samples in both experiments, and (3) relatively small sample sizes in both experiments. The relatively small sample sizes meant that if in some cases larger plants were randomly sampled at the start of the experiment (e.g. in the mesocosm experiment), and smaller plants at the end, and vice versa , the attempts to quantify nutrient uptake would be biased. The only way to overcome this, since sampling is destructive, would be to have a much larger sample size, which would be much more costly. Lastly, the role of plants in nutrient uptake relative to microbes is debated (Brix, 1993 ; Pavlineri et al., 2017 ; Shutes, 2001 ). In the mesocosm experiment, overall nutrient uptake was similar to the control, which may suggest that microbial activity plays an important role, or alternatively that it can compensate for the absence of plants when a substrate with large surface area (e.g. floating wetland frame) is provided. No conclusions can be made without directly studying the contribution of microbes, and this is an interesting avenue for future research. 4.5 Practical considerations and conservation implications Biomass was found to increase over the experiment period, indicating that plants continued to grow and accumulate nutrients, however, the growth and nutrient removal rates were found to decrease over time. Two primary factors may have contributed to the decreased growth and nutrient uptake rate, namely competition and/or self-shading and temperature decline towards winter. While competition for space between plants could have reduced the rate of biomass accumulation, the impact thereof was likely minimal, as plants were removed at intervals for sampling, providing room for growth. Self-shading could have played a role in reducing the rate of biomass production for C. textilis , as this species had prolific shoot growth (Suding et al., 2005 ). However, plants also have intrinsic growth limitations, meaning that they are able to grow rapidly and take up nutrients until a certain size is reached whereafter growth rate decreases (Lasfar et al., 2007 ). Competition, self-shading and intrinsic growth limitations all suggest that biomass harvesting could be a good solution to maintain the system in a state that allows for optimal growth and nutrient removal (Sun et al., 2019 ). Similar to other studies, our results for both experiments indicate that shoots are generally the dominant nutrient storage location for these three species, thus shoot harvesting and disposal is recommended to maximise nutrient uptake, and permanently remove nutrients from the system (Barco et al., 2021 ; Garcia Chanc et al., 2019 ; Huth et al., 2021 ; Schwammberger et al., 2020 ; White and Cousins, 2013 . Harvesting shoot biomass stimulates new, accelerated growth, reduces internal nutrient cycling, and thus increases nutrient removal (Colares et al., 2020 ; Ng and Chan, 2021 ; Zhou et al., 2017 ). With high temperatures positively influencing plant growth (typically more rapid growth), nutrient removal is accelerated during summer months (Bi et al., 2019 ). Furthermore, actively growing shoots can have higher nutrient concentrations than mature shoots (Sun et al., 2019 ). If plants slow uptake as winter approaches, this would suggest that having floating wetlands installed and established before the austral summer would be important for best results. To understand the potential impact of these uptake rates at a farm-scale, a quick calculation using floating wetlands theoretically planted with C. textilis was performed. This calculation was based on a similarly polluted farm dam with 10 floating wetlands, each with 10 C. textilis plants on each wetland. The potential uptake was estimated at 0.6 kg of nitrogen and 0.1 kg of phosphorus per year (Table S17, Supplementary Material). 4.6 Additional benefits of floating wetlands This study has demonstrated that certain endemic South African wetland plant species show potential to remove excess nutrients from eutrophic water and thrive in these conditions. In addition to their nutrient uptake abilities, floating treatment wetlands offer numerous co-benefits, such as biodiversity, aesthetic and educational benefits (Stefanakis, 2019 ). Floating wetlands provide habitats for fauna, act as refugia for aquatic species in urban and agricultural areas, could potentially act as steppingstone habitats, and provide aesthetic benefits to people (Stefanakis, 2019 ). In the current study, the floating wetlands were found to be home to at least two frog species, Strongylopus grayil and Sclerophrys capensis , a snake, Lycodonomorphus rufulus , and numerous dragonfly species were seen in the vicinity of the wetlands. Artificial ponds have been found to have great conservation value for aquatic insect diversity by forming part of a diverse pondscape and conservation corridors in degraded or transformed landscapes (Deacon et al., 2018 ). As such, the use of native wetland species in artificial ponds to improve water quality will benefit the overall ecosystem health and biodiversity of the region. 5 CONCLUSION Floating wetlands, a cost-effective green technology, present an opportunity to purify agricultural wastewater in lentic systems, like small farm dams, in South Africa. Using endemic South African wetland plant species, especially those with fast growth rates such as Cyperus textilis , has high potential to effectively remove nutrients as well as provide other co-benefits. This research fills a gap in the literature in terms of using endemic wetland species for floating treatment wetlands in the Global South, and specifically Africa. Declarations Competing interests The authors have no relevant financial or non-financial interests to disclose. Funding This work was supported by NCC Environmental Services, the South African National Research Foundation, the Daniel Booysen Memorial Fund, the South African Association of Botanists, the South African National Research Foundation (Grant #: 76861), the Water Research Commission South Africa (Grant #: 2019-2020-00034), and a Council for Scientific and Industrial Research Parliamentary Grant. Author contributions AJR, PF, OB contributed to the study conception and design. Material preparation, data collection and analysis were performed by PF, OB, AJR. The first draft of the manuscript was written by AJR, PF, OB and PF, OB, AJR, KJE, DLM commented on previous versions of the manuscript. PF, OB, AJR, KJE, and DLM read and approved the final manuscript. ACKNOWLEDGEMENTS We thank NCC Environmental Services (Sean Altern, Andrew Purnell and Quinton van Wyk), the South African National Research Foundation, the Daniel Booysen memorial fund and the South African Association of Botanists 2021 for funding. Prof Karen Esler acknowledges funding through NRF grant 76861 and Water Research Commission (WRC) in South Africa (Project: 2019/2020-00034) in the frame of the collaborative international consortium NATWIP (Nature-Based Solutions for Water Management in the Peri-Urban) financed under the 2018 Joint Call of theWaterWorks2017 ERA-NET Cofund. Prof David Le Maitre acknowledged the support of the CSIR through its Parliamentary Grant funding. We acknowledge the South African Weather Service and the Engineering Department at Stellenbosch University for climatological data, and BirdLife as well as Johann van Biljon of Green Intaba for the provision of all plants for the mesocosm and in-situ experiment respectively. We thank Dr Kevin Winter from The Water Hub for hosting the in-situ experiment and assistance with logistics, as well as Mr. Simphiwe Madyibi, site manager at the Water Hub. We also thank Prof Martin Kidd from Stellenbosch University for statistical support. A special thanks to Ronell Frenzel, Alta Saunders, Cindy Anger, Ron Brunings, Tracy Brunings, Wim Brunings, Marianne de Kock, Lauren Searle, Seonaid Streydom, Keagan Stubs, and Rubin Venter for practical assistance. Data availability The datasets generated during and/or analysed during the current study are available in the supplementary material. References Abbaspour, S., 2011. Water quality in developing countries, South Asia, South Africa: Water quality management and activities that cause water pollution. Int. Conf. Environ. Agric. Eng. 15, 94–102. Abed, S., Almuktar, S., Scholz, M., 2017. Remediation of synthetic greywater in mesocosm — Scale floating treatment wetlands. Ecol. Eng. 102, 303–319. https://doi.org/10.1016/j.ecoleng.2017.01.043 Abou-Elela, S.I., 2017. Constructed Wetlands: The green technology for municipal wastewater wreatment and reuse in agriculture, Handbook of Environmental Chemistry. Springer International Publishing. https://doi.org/10.1007/698_2017_69 Adelana, S., Xu, Y, 2006. Contamination and protection of the Cape Flats Aquifer, South Africa, in: Xu, Yongxin, Usher, B. (Eds.), Groundwater Pollution in Africa. Taylor and Francis Group, London, pp. 265–277. Ahn, C., 2016. A creative collaboration between the science of ecosystem restoration and art for sustainable stormwater management on an urban college campus. Restor. Ecol. 24, 291–297. https://doi.org/10.1111/rec.12341 Amano, Y., Sakai, Y., Sekiya, T., Takeya, K., Taki, K., Machida, M., 2010. Effect of phosphorus fluctuation caused by river water dilution in eutrophic lake on competition between blue-green alga Microcystis aeruginosa and diatom Cyclotella sp. J. Environ. Sci. 22, 1666–1673. https://doi.org/10.1016/S1001-0742(09)60304-1 Apinda-Legnouo, E., Samways, M., Simaika, J., 2014. Value of artificial ponds for aquatic beetle and bug conservation in the Cape Floristic Region biodiversity hotspot. Aquat. Conserv. Mar. Freshw. Ecosyst. 24, 522–535. https://doi.org/10.1002/aqc.2413 Awad, J., Brunetti, G., Juhasz, A., Williams, M., Navarro, D., Drigo, B., Bougoure, J., Vanderzalm, J., Beecham, S. 2022. Application of native plants in constructed floating wetlands as a passive remediation approach for PFAS-impacted surface water. J. Hazard. Mater. 429, 128326. https://doi.org/10.1016/j.jhazmat.2022.128326. Babatunde, A., Zhao, Y., O’Neill, M., O’Sullivan, B., 2008. Constructed wetlands for environmental pollution control: A review of developments, research and practice in Ireland. Environ. Int. 34, 116–126. https://doi.org/10.1016/j.envint.2007.06.013 Barco, A., Bona, S., Borin, M., 2021. Plant species for floating treatment wetlands: A decade of experiments in North Italy. Sci. Total Environ. 751. https://doi.org/10.1016/j.scitotenv.2020.141666 Batchelor, A., Loots, P., 1997. A critical evaluation of a pilot scale subsurface flow wetland: 10 years after commissioning. Water Sci. Technol. 35, 337–343. Bates, D., Mächler, M., Bolker, B.M., Walker, S.C., 2015. Fitting linear mixed-effects models using lme4. J. Stat. Softw. 67. https://doi.org/10.18637/jss.v067.i01 Bi, R., Zhou, C., Jia, Y., Wang, S., Li, P., Reichwaldt, E.S., Liu, W., 2019. Giving waterbodies the treatment they need: A critical review of the application of constructed floating wetlands. J. Environ. Manage. 238, 484–498. https://doi.org/10.1016/j.jenvman.2019.02.064 Biggs, D., Turpie, J., Fabricius, C., 2006. The Economics, Institutions and Conservation Benefits of Community-Based Avitourism in South Africa. Borne, K.E., Fassman, E.A., Tanner, C.C., 2013. Floating treatment wetland retrofit to improve stormwater pond performance for suspended solids, copper and zinc. Ecol. Eng. 54, 173–182. https://doi.org/10.1016/j.ecoleng.2013.01.031 Boucher, C., Withers, M., 2004. Palmiet: Prionium serratum, a Cape river plant. Veld Flora 26–28. Brisson, J., Chazarenc, F., 2009. Maximizing pollutant removal in constructed wetlands: Should we pay more attention to macrophyte species selection? Sci. Total Environ. 407, 3923–3930. https://doi.org/10.1016/j.scitotenv.2008.05.047 Brix, H., 1993. Wastewater treatment in constructed wetlands: System design, removal processes and treatment performance, in: Moshiri, A. (Ed.), Constructed Wetlands for Water Quality Improvement. Lewis Publishers, Boca Raton, Florida, pp. 9–22. Choudhury, M.I., Segersten, J., Hellman, M., Mckie, B.G., Hallin, S., Ecke, F., 2019. Importance of plant species for nitrogen removal using constructed floating wetlands in a cold climate. Ecol. Eng. 138, 126–132. https://doi.org/10.1016/j.ecoleng.2019.07.012 Colares, G.S., Dell’Osbel, N., Wiesel, P.G., Oliveira, G.A., Lemos, P.H.Z., da Silva, F.P., Lutterbeck, C.A., Kist, L.T., Machado, Ê.L., 2020. Floating treatment wetlands: A review and bibliometric analysis. Sci. Total Environ. 714. https://doi.org/10.1016/j.scitotenv.2020.136776 De La Rey, P.A., Taylor, J.C., Laas, A., Van Rensburg, L., Vosloo, A., 2004. Determining the possible application value of diatoms as indicators of general water quality: A comparison with SASS 5. Water SA 30, 325–332. https://doi.org/10.4314/wsa.v30i3.5080 De Villiers, S., Thiart, C., 2007. The nutrient status of South African rivers: Concentrations, trends and fluxes from the 1970s to 2005. S. Afr. J. Sci. 103, 343–349. Deacon, C., Samways, M.J., Pryke, J.S., 2018. Artificial reservoirs complement natural ponds to improve pondscape resilience in conservation corridors in a biodiversity hotspot. PLoS One 13, 1–17. https://doi.org/10.1371/journal.pone.0204148 Donnenfeld, Z., Crookes, C., Hedden, S., 2018. A delicate balance: Water scarcity in South Africa. South. Africa Rep. 13, 1–24. DWAF, 1996. South African water quality guidelines, in: Aquatic Ecosystems. Emmerson, W.D., 1989. The Nutrient Status of the Sundays River Estuary South Africa. Water Res. 23, 1059–1067. Feng, X.Y., Raitt, L.M., Jonker, L., 2005. A Survey of Inorganic Chemical Pollution in the Bottelary River, Cape Town. Frenzel, P., 2018. Investigating the potential of floating wetlands in small farm dams in the Western Cape, South Africa (Masters dissertation). Stellenbosch University. Garcia Chanc, L.M., Van Brunt, S.C., Majsztrik, J.C., White, S.A., 2019. Short- and long-term dynamics of nutrient removal in floating treatment wetlands. Water Res. 159, 153–163. https://doi.org/10.1016/j.watres.2019.05.012 Garnier, E., Laurent, G., Bellmann, A., Debain, S., Berthelier, P., Ducout, B., Roumet, C., Navas, M., 2001. Consistency leaf traits species ranking based on functional leaf traits. New Phytol. 152, 69–83. https://doi.org/10.1046/j.0028-646x.2001.00239.x Ge, Z., Feng, C., Wang, X., Zhang, J., 2016. Seasonal applicability of three vegetation constructed floating treatment wetlands for nutrient removal and harvesting strategy in urban stormwater retention ponds. Int. Biodeterior. Biodegrad. 112, 80–87. https://doi.org/10.1016/j.ibiod.2016.05.007 González-Alcaraz, M.N., Egea, C., María-Cervantes, A., Jiménez-Cárceles, F.J., Álvarez-Rogel, J., 2011. Effects of eutrophic water flooding on nitrate concentrations in mine wastes. Ecol. Eng. 37, 693–702. https://doi.org/10.1016/j.ecoleng.2010.02.009 Gordon, N., Adams, J.B., Garcia-Rodriguez, F., 2011. Water quality status and phytoplankton composition in Soetendalvlei, Voëlvlei and Waskraalsvlei, three shallow wetlands on the Agulhas Plain, South Africa. African J. Aquat. Sci. 36, 19–33. https://doi.org/10.2989/16085914.2011.559709 Grassein, F., Lemauviel-Lavenant, S., Lavorel, S., Bahn, M., Bardgett, R.D., Desclos-Theveniau, M., Laine, P., 2015. Relationships between functional traits and inorganic nitrogen acquisition among eight contrasting European grass species. Ann. Bot. 115, 107–115. https://doi.org/10.1093/aob/mcu233 Griffin, N.J., 2017. The rise and fall of dissolved phosphate in South African rivers. S. Afr. J. Sci. 113, 1–7. https://doi.org/10.17159/sajs.2017/20170020 Grime, J.P, 1977. Evidence for the Existence of Three Primary Strategies in Plants and Its Relevance to Ecological and Evolutionary Theory. Am Natur. 111, 1169–1194. Guittonny-Philippe, A., Masotti, V., Höhener, P., Boudenne, J.-L., Viglione, J., Laffont-Schwob, I., 2014. Constructed wetlands to reduce metal pollution from industrial catchments in aquatic Mediterranean ecosystems: A review to overcome obstacles and suggest potential solutions. Environ. Int. 64, 1–16. https://doi.org/10.1016/j.envint.2013.11.016 Halekoh, U., Højsgaard, S., 2014. A kenward-Roger approximation and parametric bootstrap methods for tests in linear mixed models-the R package pbkrtest. J. Stat. Softw. 59, 1–32. https://doi.org/10.18637/jss.v059.i09 Harding, W.R., 2015. Living with eutrophication in South Africa: A review of realities and challenges. Trans. R. Soc. South Africa 70, 155–171. https://doi.org/10.1080/0035919X.2015.1014878 Headley, T.R., Tanner, C.C., 2008. Floating Treatment Wetlands: an Innovative Option for Stormwater Quality Applications, in: 11th International Conference on Wetland Systems for Water Pollution Control. pp. 1101–1106. Headley, T.R., Tanner, C.C., 2012. Constructed wetlands with floating emergent macrophytes: An innovative stormwater treatment technology. Crit. Rev. Environ. Sci. Technol. 42, 2261–2310. https://doi.org/10.1080/10643389.2011.574108 Hoveka, L.N., van der Bank, M., Davies, T.J., 2020. Evaluating the performance of a protected area network in South Africa and its implications for megadiverse countries. Biol. Conserv. 248, 108577. https://doi.org/10.1016/j.biocon.2020.108577 Hu, M.H., Ao, Y.S., Yang, X.E., Li, T.Q., 2008. Treating eutrophic water for nutrient reduction using an aquatic macrophyte (Ipomoea aquatica Forsskal) in a deep flow technique system. Agric. Water Manag. 95, 607–615. https://doi.org/10.1016/j.agwat.2008.01.001 Hubbard, R.K., Gascho, G.J., Newton, G.L., 2004. Use of floating vegetation to remove nutrients from swine lagoon wastewater. Trans. Am. Soc. Agric. Eng. 47, 1963–1972. https://doi.org/10.13031/2013.17809 Huth, I., Walker, C., Kulkarni, R., Lucke, T., 2021. Using constructed floating wetlands to remove nutrients from a waste stabilization pond. Water 13. https://doi.org/10.3390/w13131746 IRIS, 2021. Effluent Discharge Into South African Rivers: Integrated Regulatory Information System (IRIS) Dashboard [WWW Document]. Dep. Water Sanit. URL http://ws.dwa.gov.za/IRIS/myriver.aspx?c2VvcD0xJnNob3dfYWxsPTE= (accessed 11.1.21). Jacklin, D.M., Brink, I.C., Jacobs, S.M., 2021a. A phyto-guide to species selection for optimised South African green infrastructure. Water SA 47, 515-522. https://doi.org/10.17159/wsa/2021.v47.i4.3875 Jacklin, D.M., Brink, I.C., Jacobs, S.M., 2021b. Efficiencies of indigenous South African plant biofilters for urban stormwater runoff water quality improvement with a focus on nutrients and metals. AQUA — Water Infrastructure, Ecosyst. Soc. https://doi.org/10.2166/aqua.2021.187 Jacklin, D.M., Brink, I.C., Jacobs, S.M., 2021c. Exploring the use of indigenous Western Cape plants as potential water and soil pollutant phytoremediators with a focus on green infrastructure. Water SA 47, 317-325. https://doi.org/10.17159/wsa/2021.v47.i3.11860 Jacklin, D.M., Brink, I.C., Jacobs, S.M., 2021d. Urban stormwater nutrient and metal removal in small-scale green infrastructure: exploring engineered plant biofilter media optimisation. Water Sci Tech 84, 1715-1731. https://doi.org/10.2166/wst.2021.353 Keizer-Vlek, H.E., Verdonschot, P.F.M., Verdonschot, R.C.M., Dekkers, D., 2014. The contribution of plant uptake to nutrient removal by floating treatment wetlands. Ecol. Eng. 73, 684–690. https://doi.org/10.1016/j.ecoleng.2014.09.081 Kivaisi, A.K., 2001. The potential for constructed wetlands for wastewater treatment and reuse in developing countries: a review. Ecol. Eng. 16, 545–560. https://doi.org/10.1016/S0925-8574(00)00113-0 Kyambadde, J., Kansiime, F., Gumaelius, L., Dalhammar, G., 2004. A comparative study of Cyperus papyrus and Miscanthidium violaceum-based constructed wetlands for wastewater treatment in a tropical climate. Water Res. 38, 475–485. https://doi.org/10.1016/j.watres.2003.10.008 Ladislas, S., Gérente, C., Chazarenc, F., Brisson, J., Andrès, Y., 2015. Floating treatment wetlands for heavy metal removal in highway stormwater ponds. Ecol. Eng. 80, 85–91. https://doi.org/10.1016/j.ecoleng.2014.09.115 Lamont, B.B., 1983. Strategies for Maximizing Nutrient Uptake in Two Mediterranean Ecosystems of Low Nutrient Status, in: Kruger, F.J., Mitchell, D.T., Jarvis, J.U.M. (Eds.), Mediterranean-Type Ecosystems: The Role of Nutrients. Springer, Berlin, Heidelberg, pp. 246–273. Lasfar, S., Monette, F., Millette, L., Azzouz, A., 2007. Intrinsic growth rate: A new approach to evaluate the effects of temperature, photoperiod and phosphorus-nitrogen concentrations on duckweed growth under controlled eutrophication. Water Res. 41, 2333–2340. https://doi.org/10.1016/j.watres.2007.01.059 Lenth, R. V., 2021. emmeans: Estimated Marginal Means, aka Least-Squares Means. R Packag. version 1.6.3. Li, M., Wu, Y.-J., Yu, Z.-L., Sheng, G.-P., Yu, H.-Q., 2009. Enhanced nitrogen and phosphorus removal from eutrophic lake water by Ipomoea aquatica with low-energy ion implantation. Water Res. 43, 1247–1256. https://doi.org/10.1016/j.watres.2008.12.013 Li, X.N., Song, H.L., Li, W., Lu, X.W., Nishimura, O., 2010. An integrated ecological floating-bed employing plant, freshwater clam and biofilm carrier for purification of eutrophic water. Ecol. Eng. 36, 382–390. https://doi.org/10.1016/j.ecoleng.2009.11.004 Lu, S., Zhang, P., Jin, X., Xiang, C., Gui, M., Zhang, J., Li, F., 2009. Nitrogen removal from agricultural runoff by full-scale constructed wetland in China. Hydrobiologia 621, 115–126. https://doi.org/10.1007/s10750-008-9636-1 Lynch, J., Fox, L.J., Owen, J.S., Sample, D.J., 2015. Evaluation of commercial floating treatment wetland technologies for nutrient remediation of stormwater. Ecol. Eng. 75, 61–69. https://doi.org/10.1016/j.ecoleng.2014.11.001 Moor, H., Rydin, H., Hylander, K., Nilsson, M.B., Lindborg, R., Norberg, J., 2017. Towards a trait-based ecology of wetland vegetation. J. Ecol. 1, 1–13. https://doi.org/10.1111/1365-2745.12734 Morrison, G., Fatoki, O.S., Persson, L., Ekberg, A., 2001. Assessment of the impact of point source pollution from the Keiskammahoek Sewage Treatment Plant on the Keiskamma River - pH, electrical conductivity, oxygen- demanding substance (COD) and nutrients. Water SA 27, 475–480. https://doi.org/10.4314/wsa.v27i4.4960 Müller, I., Schmid, B., Weiner, J., 2000. The effect of nutrient availability on biomass allocation patterns in 27 species of herbaceous plants. Perspect. Plant Ecol. Evol. Syst. 3, 115–127. https://doi.org/10.1078/1433-8319-00007 Musingafi, M.C.C., Tom, T., 2014. Fresh water sources pollution: A human related threat to fresh water security in South Africa. J. Public Policy Gov. 1, 72–81. Ng, Y.S., Chan, D.J.C., 2021. The enhancement of treatment capacity and the performance of phytoremediation system by fed batch and periodic harvesting. RSC Adv. 11, 6049–6059. https://doi.org/10.1039/d0ra08088h Nowlin, W.H., Evarts, J.L., Vanni, M.J., 2005. Release rates and potential fates of nitrogen and phosphorus from sediments in a eutrophic reservoir. Freshw. Biol. 50, 301–322. https://doi.org/10.1111/j.1365-2427.2004.01316.x Oberholster, P.J., Ashton, P.J., 2008. State of the nation report: An overview of the current status of water quality and eutrophication in South African rivers and reservoirs, Parliamentary Grant Deliverable. Olguín, E.J., Sánchez-Galván, G., Melo, F.J., Hernández, V.J., González-Portela, R.E., 2017. Long-term assessment at field scale of Floating Treatment Wetlands for improvement of water quality and provision of ecosystem services in a eutrophic urban pond. Sci. Total Environ. 584–585, 561–571. https://doi.org/10.1016/j.scitotenv.2017.01.072 Oliveira, G.A., Colares, G.S., Lutterbeck, C.A., Dell’Osbel, N., Machado, Ê.L., Rodrigues, L.R., 2021. Floating treatment wetlands in domestic wastewater treatment as a decentralized sanitation alternative. Sci. Total Environ. 773, 145609. https://doi.org/10.1016/j.scitotenv.2021.145609 Padedda, B.M., Sechi, N., Lai, G.G., Mariani, M.A., Pulina, S., Satta, C.T., Bazzoni, A.M., Virdis, T., Buscarinu, P., Lugliè, A., 2015. A fast-response methodological approach to assessing and managing nutrient loads in eutrophic Mediterranean reservoirs. Ecol. Eng. 85, 47–55. https://doi.org/10.1016/j.ecoleng.2015.09.062 Pavlineri, N., Skoulikidis, N.T., Tsihrintzis, V.A., 2017. Constructed Floating Wetlands: A review of research, design, operation and management aspects, and data meta-analysis. Chem. Eng. J. 308, 1120–1132. https://doi.org/10.1016/j.cej.2016.09.140 Pérez-Harguindeguy, N., Diaz, S., Garnier, E., Lavorel, S., Poorter, H., Jaureguiberry, P., Bret-Harte, M.S.S., Cornwell, W.K.K., Craine, J.M.M., Gurvich, D.E.E., Urcelay, C., Veneklaas, E.J.J., Reich, P.B.B., Poorter, L., Wright, I.J.J., Etc., Ray, P., Etc., Díaz, S., Lavorel, S., Poorter, H., Jaureguiberry, P., Bret-Harte, M.S.S., Cornwell, W.K.K., Craine, J.M.M., Gurvich, D.E.E., Urcelay, C., Veneklaas, E.J.J., Reich, P.B.B., Poorter, L., Wright, I.J.J., Ray, P., Enrico, L., Pausas, J.G., Vos, A.C. de, Buchmann, N., Funes, G., Quétier, F., Hodgson, J.G., Thompson, K., Morgan, H.D., Steege, H. ter, Heijden, M.G.A. van der, Sack, L., Blonder, B., Poschlod, P., Vaieretti, M. V., Conti, G., Staver, A.C., Aquino, S., Cornelissen, J.H.C., 2013. New Handbook for standardized measurment of plant functional traits worldwide. Aust. J. Bot. 61, 167–234. https://doi.org/http://dx.doi.org/10.1071/BT12225 Polomski, R.F., Taylor, M.D., Bielenberg, D.G., Bridges, W.C., Klaine, S.J., Whitwell, T., 2009. Nitrogen and phosphorus remediation by three floating aquatic macrophytes in greenhouse-based laboratory-scale subsurface constructed wetlands. Water. Air. Soil Pollut. 197, 223–232. https://doi.org/10.1007/s11270-008-9805-x R Core Team, 2019. R: A language and environment for statistical computing. Rebelo, A.J., Jarmain, C., Esler, K.J., Cowling, R.M., Le Maitre, D.C., 2020. Water-use characteristics of Palmiet (Prionium serratum), an endemic south African wetland plant. Water SA 46, 558–572. https://doi.org/10.17159/wsa/2020.v46.i4.9069 Rebelo, A. J., Sieben, E. Meire, P., Esler, K.J. 2022. at drives patchiness in palmiet wetlands? Wetlands Ecol. Manage. 30:785–811. https://doi.org/10.1007/s11273-021-09853-1 Rehman, K., Ijaz, A., Arslan, M., Afzal, M., 2019. Floating treatment wetlands as biological buoyant filters for wastewater reclamation. Int. J. Phytoremediation 21, 1273–1289. https://doi.org/10.1080/15226514.2019.1633253 Rezazada, F.A., 2020. Constructed floating wetlands mediated nutrient management of eutrophic lakes. World J. Adv. Res. Rev. 7, 212–221. https://doi.org/10.30574/wjarr Richardson, C., Vaithiyanathan, P., 2009. Biogeochemical Dynamics II: Cycling and Storage of Phosphorus in Wetlands, in: Maltby, E., Barker, T. (Eds.), The Wetlands Handbook. Wiley-Blackwell, Oxford, UK, pp. 228–248. Rommens, W., Maes, J., Dekeza, N., Inghelbrecht, P., Nhiwatiwa, T., Holsters, E., Ollevier, F., Marshall, B., Brendonck, L., 2003. The impact of water hyacinth (Eichhornia crassipes) in a eutrophic subtropical impoundment (Lake Chivero, Zimbabwe). I. Water quality. Arch. für Hydrobiol. 158, 373–388. https://doi.org/10.1127/0003-9136/2003/0158-0373 Saeed, T., Paul, B., Afrin, R., Al-muyeed, A., Sun, G., 2016. Floating constructed wetland for the treatment of polluted river water : A pilot scale study on seasonal variation and shock load. Chem. Eng. J. 287, 62–73. https://doi.org/10.1016/j.cej.2015.10.118 Samal, K., Kar, S., Trivedi, S., 2019. Ecological floating bed (EFB) for decontamination of polluted water bodies: Design, mechanism and performance. J. Environ. Manage. 251. https://doi.org/10.1016/j.jenvman.2019.109550 Schachtschneider, K., Chamier, J., Somerset, V., 2017. Phytostabilization of metals by indigenous riparian vegetation. Water SA 43, 177–185. https://doi.org/10.4314/wsa.v43i2.01 Schulz, R., Peall, S., 2001. Effectiveness of a Constructed Wetland for Retention of Nonpoint-Source Pesticide Pollution in the Lourens River Catchment, South Africa. Environ. Sci. Technol. 35, 422–426. Schwammberger, P.F., Yule, C.M., Tindale, N.W., 2020. Rapid plant responses following relocation of a constructed floating wetland from a construction site into an urban stormwater retention pond. Sci. Total Environ. 699. https://doi.org/10.1016/j.scitotenv.2019.134372 Shahid, M.J., Arslan, M., Ali, S., Siddique, M., Afzal, M., 2018. Floating Wetlands: A sustainable tool for wastewater treatment. Clean - Soil, Air, Water 46. https://doi.org/10.1002/clen.201800120 Shahid, M.J., Arslan, M., Siddique, M., Ali, S., Tahseen, R., Afzal, M., 2019. Potentialities of floating wetlands for the treatment of polluted water of river Ravi, Pakistan. Ecol. Eng. 133, 167–176. https://doi.org/10.1016/j.ecoleng.2019.04.022 Shutes, R.B.E., 2001. Artificial wetlands and water quality improvement. Environ. Int. 26, 441–447. https://doi.org/10.1016/S0160-4120(01)00025-3 Simaika, J.P., Samways, M.J., Frenzel, P.P., 2016. Artificial ponds increase local dragonfly diversity in a global biodiversity hotspot. Biodivers. Conserv. 25, 1–15. https://doi.org/10.1007/s10531-016-1168-9 Spangler, J.T., Sample, D.J., Fox, L.J., Albano, J.P., White, S.A., 2019a. Assessing nitrogen and phosphorus removal potential of five plant species in floating treatment wetlands receiving simulated nursery runoff. Environ. Sci. Pollut. Res. 26, 5751–5768. https://doi.org/10.1007/s11356-018-3964-0 Spangler, J.T., Sample, D.J., Fox, L.J., Owen, J.S., White, S.A., 2019b. Floating treatment wetland aided nutrient removal from agricultural runoff using two wetland species. Ecol. Eng. 127, 468–479. https://doi.org/10.1016/j.ecoleng.2018.12.017 Stefanakis, A.I., 2019. The role of constructed wetlands as green infrastructure for sustainable urban water management. Sustainability 11. https://doi.org/10.3390/su11246981 Stewart, F.M., Mulholland, T., Cunningham, A.B., Kania, B.G., Osterlund, M.T., 2008. Floating islands as an alternative to constructed wetlands for treatment of excess nutrients from agricultural and municipal wastes-results of laboratory-scale tests. L. Contam. Reclam. 16, 25–33. https://doi.org/10.2462/09670513.874 Suding, K.N., Collins, S.L., Gough, L., Clark, C., Cleland, E.E., Gross, K.L., Milchunas, D.G., Pennings, S., 2005. Functional- and abundance-based mechanisms explain diversity loss due to N fertilization. Proc. Natl. Acad. Sci. U. S. A. 102, 4387–4392. https://doi.org/10.1073/pnas.0408648102 Sugiyama, S., Hama, T., 2013. Effects of water temperature on phosphate adsorption onto sediments in an agricultural drainage canal in a paddy-field district. Ecol. Eng. 61, 94–99. https://doi.org/10.1016/j.ecoleng.2013.09.053 Sun, L., Liu, Y., Jin, H., 2009. Nitrogen removal from polluted river by enhanced floating bed grown canna. Ecol. Eng. 35, 135–140. https://doi.org/10.1016/j.ecoleng.2008.09.016 Sun, S., Gao, L., He, S., Huang, J., Zhou, W., 2019. Nitrogen removal in response to plants harvesting in two kinds of enhanced hydroponic root mats treating secondary effluent. Sci. Total Environ. 670, 200–209. https://doi.org/10.1016/j.scitotenv.2019.03.182 Tanner, C.C., 1996. Plants for constructed wetland treatment systems - A comparison of the growth and nutrient uptake of eight emergent species. Ecol. Eng. 7, 59–83. https://doi.org/10.1016/0925-8574(95)00066-6 Tanner, C.C., Headley, T.R., 2011. Components of floating emergent macrophyte treatment wetlands influencing removal of stormwater pollutants. Ecol. Eng. 37, 474–486. https://doi.org/10.1016/j.ecoleng.2010.12.012 Temmink, R.J.M., Fritz, C., van Dijk, G., Hensgens, G., Lamers, L.P.M., Krebs, M., Gaudig, G., Joosten, H., 2017. Sphagnum farming in a eutrophic world: The importance of optimal nutrient stoichiometry. Ecol. Eng. 98, 196–205. https://doi.org/10.1016/j.ecoleng.2016.10.069 Teng, C.J., Leu, S.Y., Ko, C.H., Fan, C., Sheu, Y.S., Hu, H.Y., 2012. Economic and environmental analysis of using constructed riparian wetlands to support urbanized municipal wastewater treatment. Ecol. Eng. 44, 249–258. https://doi.org/10.1016/j.ecoleng.2012.03.009 Tharp, R., Westhelle, K., Hurley, S., 2019. Macrophyte performance in floating treatment wetlands on a suburban stormwater pond: Implications for cold climate conditions. Ecol. Eng. 136, 152–159. https://doi.org/10.1016/j.ecoleng.2019.06.011 Van De Moortel, A.M.K., Meers, E., De Pauw, N., Tack, F.M.G., 2010. Effects of vegetation, season and temperature on the removal of pollutants in experimental floating treatment wetlands. Water. Air. Soil Pollut. 212, 281–297. https://doi.org/10.1007/s11270-010-0342-z Van Ginkel, C.E., 2011. Eutrophication: Present reality and future challenges for South Africa. Water SA 37, 693–702. https://doi.org/10.4314/wsa.v37i5.6 Van Ginkel, C.E., Glen, R.P., Gordon-Gray, K.D., Cilliers, C.J., Muasya, M., van Deventer, P.P., 2011. Easy identification of some South African wetland plants (Grasses, Restios, Sedges, Rushes, Bulrushes, Eriocaulons and Yellow-eyed grasses), Water Research Commission. Van Rensburg, S.J., Barnard, S., Krüger, M., 2016. Challenges in the potable water industry due to changes in source water quality: Case study of Midvaal Water Company, South Africa. Water SA 42, 633–640. https://doi.org/10.4314/wsa.v42i4.14 Verschoren, V., Schoelynck, J., Buis, K., Visser, F., Meire, P., Temmerman, S., 2017. Mapping the spatio-temporal distribution of key vegetation cover properties in lowland river reaches, using digital photography. Environ. Monit. Assess. 189. https://doi.org/10.1007/s10661-017-6004-5 Vymazal, J., 2007. Removal of nutrients in various types of constructed wetlands. Sci. Total Environ. 380, 48–65. https://doi.org/10.1016/j.scitotenv.2006.09.014 Vymazal, J., 2013. The use of hybrid constructed wetlands for wastewater treatment with special attention to nitrogen removal: A review of a recent development. Water Res. 47, 4795–4811. https://doi.org/10.1016/j.watres.2013.05.029 Wang, C.Y., Sample, D.J., 2014. Assessment of the nutrient removal effectiveness of floating treatment wetlands applied to urban retention ponds. J. Environ. Manage. 137, 23–35. https://doi.org/10.1016/j.jenvman.2014.02.008 Wang, C., Sample, D.J., Day, S.D., Grizzard, T.J., 2015. Floating treatment wetland nutrient removal through vegetation harvest and observations from a field study. Ecol. Eng. 78, 15–26. https://doi.org/10.1016/j.ecoleng.2014.05.018 Wang, W.H., Wang, Y., Sun, L.Q., Zheng, Y.C., Zhao, J.C., 2020. Research and application status of ecological floating bed in eutrophic landscape water restoration. Sci. Total Environ. 704, 135434. https://doi.org/10.1016/j.scitotenv.2019.135434 Wanielista, M., Chang, N.-B., Chopra, M., Xuan, Z., Islam, K., Marimon, Z., 2012. Floating Wetland Systems for Nutrient Removal in Stormwater Ponds. Orlando. Ward, E.W., Winter, K., 2016. Missing the link: Urban stormwater quality and resident behaviour. Water SA 42, 571–576. https://doi.org/10.4314/wsa.v42i4.07 Wen, L., Recknagel, F., 2002. In situ removal of dissolved phosphorus in irrigation drainage water by planted floats: Preliminary results from growth chamber experiment. Agric. Ecosyst. Environ. 90, 9–15. https://doi.org/10.1016/S0167-8809(01)00292-4 West, S., Cairns, R., Schultz, L., 2016. What constitutes a successful biodiversity corridor? A Q-study in the Cape Floristic Region, South Africa. Biol. Conserv. 198, 183–192. https://doi.org/10.1016/j.biocon.2016.04.019 White, S.A., Cousins, M.M., 2013. Floating treatment wetland aided remediation of nitrogen and phosphorus from simulated stormwater runoff. Ecol. Eng. 61, 207–215. https://doi.org/10.1016/j.ecoleng.2013.09.020 Winston, R.J., Hunt, W.F., Kennedy, S.G., Merriman, L.S., Chandler, J., Brown, D., 2013. Evaluation of floating treatment wetlands as retrofits to existing stormwater retention ponds. Ecol. Eng. 54, 254–265. https://doi.org/10.1016/j.ecoleng.2013.01.023 Wood, A., Pybus, P., 1992. Artificial wetland use for wastewater treatment theory, practice and economic review. Pretoria. Wu, H., Zhang, J., Ngo, H.H., Guo, W., Hu, Z., Liang, S., Fan, J., Liu, H., 2015. A review on the sustainability of constructed wetlands for wastewater treatment: Design and operation. Bioresour. Technol. 175, 594–601. https://doi.org/10.1016/j.biortech.2014.10.068 Wu, Q., Hu, Y., Li, S., Peng, S., Zhao, H., 2016. Microbial mechanisms of using enhanced ecological floating beds for eutrophic water improvement. Bioresour. Technol. 211, 451–456. https://doi.org/10.1016/j.biortech.2016.03.113 Wu, S., Kuschk, P., Brix, H., Vymazal, J., Dong, R., 2014. Development of constructed wetlands in performance intensifications for wastewater treatment: A nitrogen and organic matter targeted review. Water Res. 57, 40–55. https://doi.org/10.1016/j.watres.2014.03.020 Wu, Y., Li, L., Gan, N., Zheng, L., Ma, H., Shan, K., Liu, J., Xiao, B., Song, L., 2014. Seasonal dynamics of water bloom-forming Microcystis morphospecies and the associated extracellular microcystin concentrations in large, shallow, eutrophic Dianchi Lake. J. Environ. Sci. 26, 1921–1929. https://doi.org/10.1016/j.jes.2014.06.031 Yang, Z., Wang, Q., Zhang, J., Xie, H., Feng, S., 2016. Effect of Plant Harvesting on the Performance of Constructed Wetlands during Summer. Water 8, 4–13. https://doi.org/10.3390/w8010024 Yeh, N., Yeh, P., Chang, Y.H., 2015. Artificial floating islands for environmental improvement. Renew. Sustain. Energy Rev. 47, 616–622. https://doi.org/10.1016/j.rser.2015.03.090 Zhang, L., Sun, Z., Xie, J., Wu, J., Cheng, S., 2018. Nutrient removal, biomass accumulation and nitrogen-transformation functional gene response to different nitrogen forms in enhanced floating treatment wetlands. Ecol. Eng. 112, 21–25. https://doi.org/10.1016/j.ecoleng.2017.12.021 Zhao, F., Xi, S., Yang, X., Yang, W., Li, J., Gu, B., He, Z., 2012. Purifying eutrophic river waters with integrated floating island systems. Ecol. Eng. 40, 53–60. https://doi.org/10.1016/j.ecoleng.2011.12.012 Zhao, F., Zhan, X., Xu, H., Zhu, G., Zou, W., Zhu, M., Kang, L., Guo, Y., Zhao, X., Wang, Z., Tang, W., 2021. New insights into eutrophication management: Importance of temperature and water residence time. J. Environ. Sci. (China) 111, 229–239. https://doi.org/10.1016/j.jes.2021.02.033 Zheng, L., Cardenas, M.B., Wang, L., 2016. Temperature effects on nitrogen cycling and nitrate removal-production efficiency in bed form-induced hyporheic zones. J. Geophys. Res. G Biogeosciences 121, 1086–1103. https://doi.org/10.1002/2015JG003162 Zhou, X., He, Z., Jones, K.D., Li, L., Stoffella, P.J., 2017. Dominating aquatic macrophytes for the removal of nutrients from waterways of the Indian River Lagoon basin, South Florida, USA. Ecol. Eng. 101, 107–119. https://doi.org/10.1016/j.ecoleng.2017.01.006 Supplementary Files SUPPLEMENTARYMATERIAL.docx Cite Share Download PDF Status: Published Journal Publication published 26 Nov, 2024 Read the published version in Wetlands → Version 1 posted Reviewers agreed at journal 26 Jan, 2024 Reviewers invited by journal 25 Jan, 2024 Editor invited by journal 25 Jan, 2024 Editor assigned by journal 23 Jan, 2024 First submitted to journal 23 Jan, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3860564","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":269534963,"identity":"80a594ef-59ff-4777-be63-a5691b6bd44e","order_by":0,"name":"Philip Frenzel","email":"","orcid":"","institution":"Stellenbosch University Department of Conservation Ecology and Entomology","correspondingAuthor":false,"prefix":"","firstName":"Philip","middleName":"","lastName":"Frenzel","suffix":""},{"id":269534964,"identity":"ec7f9b64-8123-4e44-95ef-ba5a69c6d0af","order_by":1,"name":"Olivia Brunings","email":"","orcid":"","institution":"Stellenbosch University Department of Conservation Ecology and Entomology","correspondingAuthor":false,"prefix":"","firstName":"Olivia","middleName":"","lastName":"Brunings","suffix":""},{"id":269534965,"identity":"30c1e9a8-e232-49f3-81c7-feea80f0e052","order_by":2,"name":"Karen J Esler","email":"","orcid":"","institution":"Stellenbosch University Department of Conservation Ecology and Entomology","correspondingAuthor":false,"prefix":"","firstName":"Karen","middleName":"J","lastName":"Esler","suffix":""},{"id":269534966,"identity":"2dcc4307-ee57-4d74-b2dc-9eb827a88865","order_by":3,"name":"David C Le Maitre","email":"","orcid":"","institution":"Stellenbosch University Department of Conservation Ecology and Entomology","correspondingAuthor":false,"prefix":"","firstName":"David","middleName":"C Le","lastName":"Maitre","suffix":""},{"id":269534967,"identity":"58785aeb-da7a-4641-a975-f7dc96db6e7f","order_by":4,"name":"Alanna J. Rebelo","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/0lEQVRIiWNgGAWjYDACdhhDgoHxAEMFkMHM3IBfCzNCC8MBhjMgEUZStDC2gVgEtPA3Mz97XFDDkM8v3XzgwMd5tdH87UAtPyq24dQicZjN3HjGMQbLmXOOJRycue147ozDjA2MPWdu47bmMIOZNA8bg4HBjRyDw7zbjuU2ALUwM7bh1iJ/mP2bNM8/BgP7G/kfDvPOOZY7n5AWg8M8ZtK8bUBbJHIYDvM21ORuIKTF8DBPmTRvn4SBxJ1jBgdnHDuQuxGo5SA+v8gdb98mzfPNxoB/dvPDBx9q6nLnnT988MGPCjzehwAJRGiAwAFC6pFBHSmKR8EoGAWjYIQAAGVHWIYQqRASAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-7544-9895","institution":"Agricultural Research Council Soil Climate and Water","correspondingAuthor":true,"prefix":"","firstName":"Alanna","middleName":"J.","lastName":"Rebelo","suffix":""}],"badges":[],"createdAt":"2024-01-13 15:39:18","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3860564/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3860564/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s13157-024-01871-y","type":"published","date":"2024-11-26T15:57:14+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":50384291,"identity":"7f8377c6-e7db-4f0f-8f28-76b3cbd2a42e","added_by":"auto","created_at":"2024-01-30 17:28:48","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":99794,"visible":true,"origin":"","legend":"\u003cp\u003eDesign of the mesocosm experiment in the greenhouse (a), showing the floating wetlands: “P” is \u003cem\u003ePrionium serratum\u003c/em\u003e, “J” is \u003cem\u003eJuncus lomatophyllus\u003c/em\u003e, and “C” is \u003cem\u003eCyperus textilis\u003c/em\u003e, (b) and the configuration (c), in Stellenbosch, South Africa (n=24)\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3860564/v1/c1638da55465f4e43ad4ac45.jpg"},{"id":50386625,"identity":"820a5d43-560b-44b9-b220-731d5f8f9306","added_by":"auto","created_at":"2024-01-30 17:44:47","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":69532,"visible":true,"origin":"","legend":"\u003cp\u003eDesign of the \u003cem\u003ein-situ\u003c/em\u003e experiment in the treatment pond (a), showing the treatments: “P” is \u003cem\u003ePrionium serratum\u003c/em\u003e, “J” is \u003cem\u003eJuncus lomatophyllus\u003c/em\u003e, and “C” is \u003cem\u003eCyperus textilis\u003c/em\u003e (b) and the rough configuration (c) in Franschhoek, South Africa (n=18)\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3860564/v1/1b21301968d72ebe6bcfda46.jpg"},{"id":50384281,"identity":"df6220be-d1d7-49b2-a125-5f8cd0e5163b","added_by":"auto","created_at":"2024-01-30 17:28:47","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":100984,"visible":true,"origin":"","legend":"\u003cp\u003eBox and whisker plots showing (A) Total removal (mg), (B) Removal rate (mg.m\u003csup\u003e2\u003c/sup\u003e.d\u003csup\u003e-1\u003c/sup\u003e), and (C) Removal efficiency (%) from water during the mesocosm experiment (n=6, N=24) under low nutrient conditions (1 month, from 27 January 2017 to 27 February 2017) for three endemic wetland species from South Africa. The solid black lines indicate median values, while the black crosses indicate the mean value per treatment. The solid black dots represent the outliers in the data. Letters denote significance differences at p\u0026lt;0.05. Values can be found in in Table S7, Supplementary Material\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3860564/v1/181cb8e26e2ac758f3672a87.jpg"},{"id":50384284,"identity":"64b9e77b-2b1e-4bb7-81e7-0cb0d35ed790","added_by":"auto","created_at":"2024-01-30 17:28:47","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":58098,"visible":true,"origin":"","legend":"\u003cp\u003eMean monthly Total Nitrogen and Total Phosphorus plant uptake (mg) by \u003cem\u003eCyperus textilis, Juncus lomatophyllus and Prionium serratum \u003c/em\u003efor the \u003cem\u003ein-situ\u003c/em\u003e experiment (3 months, from 12 March 2021 to 12 June 2021), South Africa. The solid black lines indicate median values, while the black crosses indicate the mean value per treatment. The solid black dots represent outliers. The boxes indicate the 25% and 75% percentiles. Letters denote significant differences between roots, shoots and total across species at p\u0026lt;0.05. Values can be found in in Table S12, Supplementary Material\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3860564/v1/021ddde73b851bfd4f151a35.jpg"},{"id":50384287,"identity":"9bb598ed-8532-486a-83c2-0d045aeee9a3","added_by":"auto","created_at":"2024-01-30 17:28:47","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":48166,"visible":true,"origin":"","legend":"\u003cp\u003eRatios of dominant location of plant nutrient storage for both experiments – i.e. low (mesocosm experiment, 1 month in 2017) compared to high (\u003cem\u003ein-situ\u003c/em\u003e experiment, 3 months in 2021) nutrient conditions in South Africa. The solid black lines indicate median values, while the black crosses indicate the mean value per treatment. The solid black dots represent outliers. Letters denote significance at p\u0026lt;0.05. Values can be found in Table S13, Supplementary Material\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3860564/v1/98a4e5e88d06cad3a4f2d1fa.jpg"},{"id":50385739,"identity":"a5e911e8-e2df-47d4-b809-f88e0f3e8d5f","added_by":"auto","created_at":"2024-01-30 17:36:47","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":83548,"visible":true,"origin":"","legend":"\u003cp\u003eGraph showing difference in Total Nitrogen and Total Phosphorus concentrations between roots and shoots as well as between both experiments \u0026nbsp;– i.e. low (mesocosm experiment, 1 month in 2017) compared to high (\u003cem\u003ein-situ\u003c/em\u003e experiment, 3 months in 2021) nutrient conditions in South Africa. The solid black lines indicate median values, while the black crosses indicate the mean value per treatment. The solid black dots represent outliers. Letters denote significance at p\u0026lt;0.05. Values can be found in Table S14, Supplementary Material\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3860564/v1/c5e61f209474d4f8ac055a37.jpg"},{"id":50384289,"identity":"3a6a4e97-6fcf-4f9e-a4eb-91b6fa2c8695","added_by":"auto","created_at":"2024-01-30 17:28:48","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":66738,"visible":true,"origin":"","legend":"\u003cp\u003eIndices derived from key plant functional traits for the three species measured within the one-month mesocosm experiment in the summer of 2017 in South Africa. LDMC = Leaf Dry Matter Content; RDMC = Root Dry Matter Content; SLA = Specific Leaf Area; and SRL = Specific Root Length. The solid black lines indicate median values, while the black crosses indicate the mean value per treatment. The solid black dots represent outliers. Letters denote signficiant differences at p\u0026lt;0.05. Values for the other key plant function traits can be found in Table S16, Supplementary Material\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3860564/v1/b8480b01956e5d4312290528.jpg"},{"id":50384285,"identity":"95c83cf6-8cc4-41e7-b910-0b3a9ceb18cf","added_by":"auto","created_at":"2024-01-30 17:28:47","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":108107,"visible":true,"origin":"","legend":"\u003cp\u003eRelationship between plant growth (i.e. increase in root and shoot dry matter) and nutrient uptake for the three species measured for the three-month \u003cem\u003ein-situ\u003c/em\u003eexperiment (12 March 2021 to 12 June 2021) in South Africa. (A) Correlation between shoot dry matter (g) and shoot nitrogen content (g), (B) shoot dry matter (g) and shoot phosphorus content (g), (C) root dry matter (g) and root nitrogen content (g), (D) root dry matter (g) and root phosphorus content (g), (E) total dry matter (g) and total nitrogen content (g), (F) and total dry matter (g) and total phosphorus content (g). The dashed lines represent linear trendlines and the associated Spearman’s correlation coefficient and p-value for each species is indicated in the relevant colour on each graph\u003c/p\u003e","description":"","filename":"8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3860564/v1/1a47e8267cfa70726272e0c5.jpg"},{"id":70382369,"identity":"e4e8a79e-1aa0-4829-a57c-66ecb4e11e86","added_by":"auto","created_at":"2024-12-02 16:26:10","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1592391,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3860564/v1/d8439d48-7650-48fa-8d46-cb4df94d8cc9.pdf"},{"id":50384283,"identity":"8045a44c-6633-492d-acbd-e88f098839fd","added_by":"auto","created_at":"2024-01-30 17:28:47","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":767256,"visible":true,"origin":"","legend":"","description":"","filename":"SUPPLEMENTARYMATERIAL.docx","url":"https://assets-eu.researchsquare.com/files/rs-3860564/v1/38153a03d06d34262a8ff358.docx"}],"financialInterests":"","formattedTitle":"How well do endemic wetland plant species perform in water purification?","fulltext":[{"header":"1 INTRODUCTION","content":"\u003cp\u003eIncreasing eutrophication of surface waters is of great concern globally as it jeopardizes freshwater ecosystems. This trend has necessitated the development of technologies for water purification. Typically, conventional wastewater treatment facilities are still widely used to improve water quality internationally, although they are costly to maintain and upgrade (Keizer-Vlek et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Kivaisi, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Wang et al., \u003cspan citationid=\"CR112\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Due to increasing demand for wastewater treatment, there is a need for more innovative, affordable and sustainable decentralised technologies to treat wastewater \u0026ndash; particularly for developing nations (Kivaisi, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). Extensive research into design considerations and optimization has resulted in various types of constructed wetlands being developed for different wastewater types (Babatunde et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Batchelor and Loots, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1997\u003c/span\u003e; Jacklin et al., \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2021b\u003c/span\u003e; Wood and Pybus, \u003cspan citationid=\"CR120\" class=\"CitationRef\"\u003e1992\u003c/span\u003e; Wu et al., \u003cspan citationid=\"CR121\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; S. Wu et al., \u003cspan citationid=\"CR124\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Yeh et al., \u003cspan citationid=\"CR126\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Floating wetlands, a type of constructed wetland, are manufactured buoyant structures designed to support emergent wetland plants. They are installed for the purpose of nutrient removal (Vymazal, \u003cspan citationid=\"CR109\" class=\"CitationRef\"\u003e2007\u003c/span\u003e), with co-benefits such as aesthetic appeal, biodiversity enhancement (Biggs et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2006\u003c/span\u003e) and environmental education (Ahn, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Floating wetlands also do not require highly qualified technicians to install and maintain, have no energy consumption, are able to fluctuate with water levels and require low capital costs (Abed et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Pavlineri et al., \u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Kivaisi, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2001\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eStudies have demonstrated that floating wetlands are capable of successfully removing nutrients and pollutants from various wastewater types (Headley and Tanner, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Hubbard et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Keizer-Vlek et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Wang et al., \u003cspan citationid=\"CR112\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; White and Cousins, \u003cspan citationid=\"CR118\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). A study showed that floating wetlands planted with \u003cem\u003eTypha latifolia\u003c/em\u003e removed 534 g. m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e Nitrogen (N), 79 g. m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e Phosphorus (P) and 563 g m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e Potassium (K) over a 16 month period from swine-polluted lagoon wastewater in the USA (Hubbard et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). \u003cem\u003ePanicum hematomon\u003c/em\u003e removed 323 gN.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e, 48 gP.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e and 266 gK.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e from the same. Urban wastewaters have been purified using floating wetlands planted with \u003cem\u003eIris pseudacorus\u003c/em\u003e and \u003cem\u003eTypha angustifolia\u003c/em\u003e and which were found to remove 25 gN.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e and 0.8 gP.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e, and 2.5 gN.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e and 0.006 gP.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e respectively over a three month period in the Netherlands (Keizer-Vlek et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Another study focussed on heavy metals found that \u003cem\u003eJuncus effusus\u003c/em\u003e floating wetlands accumulated 0.023 mg. g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e Nickel and 0.080 mg.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e Zinc in the shoots, and 0.131 mgNi.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 0.21 mgZn.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in the roots over a four month period in France (Ladislas et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). In the same study, \u003cem\u003eCarex riparia\u003c/em\u003e accumulated 0.031 mgNi.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 0.045 mgZn.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in the shoots, compared to 0.113 mgNi.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 0.045 mgZn.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in the roots over the same time period (Ladislas et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Floating wetlands have also been found to be successful in remediating organic contaminants such as pesticides, pharmaceuticals, personal care products and per- and polyfluoroalkyl substances (Awad et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Therefore, floating wetland technology demonstrates successful, non-specific application across various wastewater and pollutant types.\u003c/p\u003e \u003cp\u003ePlant uptake is one pathway in which nutrients are removed in floating wetland systems. Plants facilitate the removal of nutrients through direct assimilation (absorption or adsorption), or indirectly by creating habitat for microbial communities on the root infrastructure \u0026ndash; which assist in nutrient removal through processes such as denitrification (Lynch et al., \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Olgu\u0026iacute;n et al., \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Various studies have highlighted the ability of plants to assist in phytoremediation of surface waters (Schachtschneider et al., \u003cspan citationid=\"CR84\" class=\"CitationRef\"\u003e2017\u003c/span\u003e, Jacklin et al \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2021a\u003c/span\u003e,\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003eb\u003c/span\u003e,\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003ec\u003c/span\u003e,\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003ed\u003c/span\u003e). The uptake capacity of plants varies considerably across species and is largely dependent on their anatomical and physiological properties, or their functional traits, which, in turn, allow different plants to have different tolerances to various nutrient thresholds (Moor et al., \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Pavlineri et al., \u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; P\u0026eacute;rez-Harguindeguy et al., \u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Wang et al., \u003cspan citationid=\"CR112\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Wanielista et al., \u003cspan citationid=\"CR114\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). There is no universal trend as to where plants predominantly store their nutrients (i.e. disproportionally in their roots or shoots, or equally) (Wang et al., \u003cspan citationid=\"CR112\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Wanielista et al., \u003cspan citationid=\"CR114\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). This potential for variation in uptake rates and storage location emphasises that plant selection is crucial in optimizing nutrient removal for specific use-cases and needs. If nutrient removal from the system via stem harvesting (e.g. mowing or cutting) is desired, then selecting plants with dominant storage in shoots is important.\u003c/p\u003e \u003cp\u003eSpecies commonly selected for use in constructed wetlands tend to be ubiquitous generalists, for example \u003cem\u003ePhragmites\u003c/em\u003e spp. and \u003cem\u003eTypha\u003c/em\u003e spp. (Wu et al., \u003cspan citationid=\"CR121\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Despite plant selection being a key element in designing constructed wetlands, very few wetland plant species have been thoroughly researched for this purpose globally (Vymazal, \u003cspan citationid=\"CR110\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). At the time of this research, very few wetland plant species had been investigated in the South African context, but more recently, a phyto-guide to species selection has been developed (Jacklin et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2021a\u003c/span\u003e). Nevertheless, a large research gap remains to assess the potential of various indigenous plant species for nutrient removal (Wang and Sample, \u003cspan citationid=\"CR111\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). South Africa has no shortage of potentially useful wetland species, particularly in the Cape Region where there is high floral diversity (Hoveka et al., \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Moreover, in South Africa\u0026rsquo;s Cape region where this study took place, surface waters are typically oligotrophic (Ward \u0026amp; Winter, \u003cspan citationid=\"CR115\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) and thus native species are adapted to this typically low nutrient environment. However, large-scale landscape transformation in the Cape has resulted in significant nutrient enrichment of water bodies (Ward \u0026amp; Winter, \u003cspan citationid=\"CR115\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Against this backdrop, the primary focus of this research was to investigate the nutrient removal capacities of local wetland plant species under near natural and nutrient enriched scenarios.\u003c/p\u003e \u003cp\u003eIn this study, we aimed to quantify the nutrient removal efficiency of high-potential, locally endemic wetland species on floating wetlands in a low nutrient mesocosm and high nutrient \u003cem\u003ein-situ\u003c/em\u003e experiment. We investigated: (i) the nitrogen and phosphorus removal capacity of floating wetlands planted with three locally endemic species: \u003cem\u003eCyperus textilis\u003c/em\u003e, \u003cem\u003eJuncus lomatophyllus\u003c/em\u003e and \u003cem\u003ePrionium serratum\u003c/em\u003e, (ii) the contribution of plant nutrient uptake to the overall removal capacity of these floating wetlands, (iii) the dominant location of plant nutrient storage (roots or shoots), and (iv) the influence of plant functional traits in the process of nutrient uptake. We then reflect on the potential for practical implementation given the results of the experiments.\u003c/p\u003e"},{"header":"2 METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Study species\u003c/h2\u003e \u003cp\u003ePlant selection has been identified as a crucial design consideration in constructed wetlands (Brisson and Chazarenc, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Therefore, the criteria used to select species for experimentation is very important. Species selection for this study was based on the following criteria (adapted from Tanner \u003cspan citationid=\"CR99\" class=\"CitationRef\"\u003e1996\u003c/span\u003e):\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003e\u0026ldquo;Ecological acceptability\u0026rdquo; i.e. no significant weed or disease risks or danger to the ecological or genetic integrity of surrounding natural ecosystems.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eTolerance of local climatic conditions, pests and diseases.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eTolerance of pollutants and hypertrophic waterlogged conditions.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eReady propagation, and rapid establishment, spread and growth.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eAbility to co-exist with other wetland plants; not too large (i.e. should not sink the frame structure).\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eInteresting/promising indigenous species that have not yet been studied in a wetland context.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e \u003cp\u003eA short-list of eleven potential wetland species was compiled based on local industry experience (Table S1, Supplementary Material). From these, three high potential, locally endemic wetland species were selected for the experiment based on an evaluation using the six criteria outlined above (Table S2, Supplementary Material): \u003cem\u003eCyperus textilis\u003c/em\u003e, \u003cem\u003eJuncus lomatophyllus\u003c/em\u003e, and \u003cem\u003ePrionium serratum\u003c/em\u003e. These three species were used in both sets of experiments and the young plants were obtained from a local nursery.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Mesocosm experiment: oligotrophic conditions\u003c/h2\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.2.1 Experimental set-up\u003c/h2\u003e \u003cp\u003eThis mesocosm experiment was designed as a closed mass balance experiment with the aim to isolate the effects of floating wetlands on water quality. The experiment was conducted over one-month in a greenhouse (240 m\u003csup\u003e2\u003c/sup\u003e) at Stellenbosch University from 27 January to 27 February 2017 i.e. during the summer season (Table S3, Supplementary Material). The experiment was performed in twenty-four 90 L plastic tanks (0.45 m x 0.75 m). The tanks were positioned in a randomised block design with six replicates each (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Each tank contained a standard floating wetland planted with ten plants of the same species (along with a small amount of their associated soil), except for the control which was without vegetation and soil (Keizer-Vlek et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). A standard floating wetland was constructed of high-density foam, mesh, hessian and a soil saver layer and was fastened together with cable ties. A set of four small garden fountain pumps were rotated daily between tanks, after being cleaned, to circulate the water. This was to avoid anoxia while keeping costs down.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe seedlings were acquired four months prior, in September 2016, and the floating wetlands were constructed, and tanks filled with 70 L of municipal water (containing insignificant nutrient concentrations). The floating wetlands established over these four months whilst plant health, growth and survival were monitored closely using the framework of Brisson \u0026amp; Chazarenc (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Additions of Pokon (fertilizer for pot plants, Universeel plantenvoedsel, manufacturer: Pokon Naturado) were made during this period to ensure sufficient nutrients for growth as well as the presence of trace elements (B, Cu, Fe, Mn, Mo, Zn, and K).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.2.2 Nutrient additions\u003c/h2\u003e \u003cp\u003eOn 27 January 2017, the tanks were emptied and refilled with new municipal water. Three water samples were taken from the municipal water supply and tested, prior to any fertiliser additions, to establish baseline NH\u003csub\u003e4\u003c/sub\u003e-N, NO\u003csub\u003e3\u003c/sub\u003e-N and PO\u003csub\u003e4\u003c/sub\u003e-P concentrations. After this, 31.5 mL of NO\u003csub\u003e3\u003c/sub\u003e-N, 8.4 mL of NH\u003csub\u003e4\u003c/sub\u003e-N and 7.0 mL of PO\u003csub\u003e4\u003c/sub\u003e-P were added in 1000 mg.L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e concentrate forms to establish oligotrophic conditions relative to local ecosystems (Table S4 and Table S5, Supplementary Material). Three days later, a 100 mL water sample was taken for nutrient analysis from each tank to confirm the calculated concentrations of bioavailable nutrients (NH\u003csub\u003e4\u003c/sub\u003e\u0026ndash;N, NO\u003csub\u003e3\u003c/sub\u003e\u0026ndash;N, and PO\u003csub\u003e4\u003c/sub\u003e\u0026ndash;P).\u003c/p\u003e \u003cp\u003eDuring the experiment, concentrations of bioavailable nutrients were tested each week in two random tanks selected from each different plant species (Keizer-Vlek et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) as well as the control to determine whether more nutrients needed to be added in order to remain within the predetermined range. Only two tanks were sampled due to budget constraints; ideally each tank would have been tested. The water in the tanks was topped up weekly to 70 L using municipal water and the amount of water added was recorded for each tank. Two composite samples of the municipal water were tested for bioavailable nutrients each week. If the nutrient concentrations fell below minimum concentrations (0.16 mgNH\u003csub\u003e4\u003c/sub\u003e-N.L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 0.45 mgNO\u003csub\u003e3\u003c/sub\u003e-N.L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 0.10 mgPO\u003csub\u003e4\u003c/sub\u003e-P.L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), more nutrients were added to all the tanks and these amounts were recorded. All water quality tests were performed by AL Abbott \u0026amp; Associates Ltd, which are accredited to the ISO 17025:2005 standard (registration number 1982/004379/07).\u003c/p\u003e \u003cp\u003eIn addition, each week, various physico-chemical variables (dissolved oxygen, conductivity, temperature and pH) were recorded at a depth of 0.30 m using a handheld multi-parameter water quality meter in each tank (Model: YSI 556 Multi Probe System; YSI Environmental). Overall, water quality did not differ significantly among treatments except for pH, which was significantly lower in the \u003cem\u003eJ. lomatophyllus\u003c/em\u003e treatments, and significantly higher in the \u003cem\u003eC. textilis\u003c/em\u003e treatments (Table S6, Supplementary Material).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.2.3 Plant sampling and analysis\u003c/h2\u003e \u003cp\u003eAt the start and end of the experiment, randomly chosen plant specimens were removed from each of the 18 planted floating wetlands for biomass measurements (wet and dry root and shoot biomass) and tissue nutrient analysis (for TN and TP concentrations). One plant per floating wetland (total of 18 plants) was removed at the start of the experiment, whilst two plants (total of 36 plants) were removed at the end of the experiment to increase the representativeness due to differential growth over the experiment. Before specimens were dried, several key plant functional traits were measured (10 measurements per plant), including plant height, root and shoot lengths, root surface area, leaf surface area, leaf and root mass. The surface areas were calculated using the method of Verschoren et al., (\u003cspan citationid=\"CR108\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Indices, such as specific root length, specific leaf area, root dry matter content and leaf dry matter content, were also calculated. Specimens were then dried to a constant mass at 70\u0026deg;C for a minimum of 48 hours. Root and shoot dry mass were determined for each specimen after which they were ground to 0.5 mm particle size using a \u003cem\u003eRetsch Mill\u003c/em\u003e. Total nitrogen and phosphorus concentrations were measured in the roots and shoots of each specimen. All the plant tissue analyses were performed by \u003cem\u003eBEMLAB Ltd\u003c/em\u003e, which are accredited to the ISO 17025:2005 standard (registration number 1996/006836/07). Total nitrogen content was determined using the Dumas Method and total phosphorus content was determined using a dry ash method whereby the sample was combusted in a muffle furnace at 480\u003csup\u003eo\u003c/sup\u003eC for 8 hours, acidified, digested by heating, diluted, and analysed by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) (Spangler et al., \u003cspan citationid=\"CR91\" class=\"CitationRef\"\u003e2019a\u003c/span\u003e). Any floating algae were removed daily using a fish net, where necessary, from the tanks to establish a standard for nutrient removal with minimal interference of algae and therefore minimizing bias (e.g. between experiment and control).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e2.2.4 Nutrient removal ability\u003c/h2\u003e \u003cp\u003eThe nutrient removal ability of floating wetlands was calculated in three ways. Firstly, \u003cb\u003etotal removal\u003c/b\u003e of bioavailable nutrients (NO\u003csub\u003e3\u003c/sub\u003e-N, NH\u003csub\u003e4\u003c/sub\u003e-N and PO\u003csub\u003e4\u003c/sub\u003e-P) in the tanks was measured throughout the experiment through mass balance calculations following the water testing. Total removal was calculated by subtracting the bioavailable nutrients remaining in the tanks (NO\u003csub\u003e3\u003c/sub\u003e-N, NH\u003csub\u003e4\u003c/sub\u003e-N and PO\u003csub\u003e4\u003c/sub\u003e-P concentrations multiplied by the water volume) from the total nutrients added to the system throughout the experiment. Secondly, the \u003cb\u003eremoval rate\u003c/b\u003e was calculated, which used the total experiment duration to calculate a daily removal rate. Thirdly, \u003cb\u003eremoval efficiency\u003c/b\u003e was calculated, which is the total removal of bioavailable nutrients over the duration of the experiment relative to the total available nutrients in the system, expressed as a percentage. Data are made available in Table S7, Supplementary Material.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.3 In-situ experiment: eutrophic conditions\u003c/h2\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e2.3.1 Experimental set-up\u003c/h2\u003e \u003cp\u003eThis experiment was designed to mimic the eutrophic conditions of many small farm dams in the region. This experiment was carried out in a large concrete wastewater retention pond at the Water Hub, located in Franschhoek in the Western Cape of South Africa; a remnant of the old Franschhoek Wastewater Treatment Works. The pond has a volume of 63.6 m\u003csup\u003e3\u003c/sup\u003e and measures 4.8 m (width) X 5 m (length) X 2.65 m (height) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThis experiment took place over three months from 12 March 2021 to 12 June 2021, in the austral autumn. Highly eutrophic water from the Stibeuel River, which flows past the Langrug informal settlement near Franschhoek before passing the Water Hub, was pumped into an old concrete wastewater retention pond in which the floating wetlands were established. The tank was filled to approximately 50% capacity. Eighteen floating wetlands of 0.5 m x 0.4 m (i.e. 0.2 m\u003csup\u003e2\u003c/sup\u003e) in size were constructed (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) using high-density foam, mesh, hessian, wooden dial sticks, and cable ties. Six replicates (wetlands) were used for each of the three treatments (plant species) and each floating wetland was planted with ten seedlings of the relevant species. The seedlings were carefully removed from their potting soil and as much soil as possible was detached without causing damage to the root system. Given that this was not a mesocosm experiment with individual wetlands in individual water bodies to investigate mass balance impacts on water quality, no control was necessary.\u003c/p\u003e \u003cp\u003eYoung seedlings were sourced from a local restoration nursery, Green Intaba, prior to the start of the experiment and were planted onto the constructed floating wetlands on 4 January 2021. The plants were allowed to establish over the following two months, during which plant health, growth, and survival were periodically monitored. Several \u003cem\u003eJ. lomatophyllus\u003c/em\u003e plants did not survive (plant health of these few seedlings was poor prior to being planted onto wetland structures, likely due to water stress during transport) and were replaced during the establishment phase. Due to the clonal growth of this species, plastic separators were placed between plants where necessary to distinguish the original individuals. The experiment commenced once the plants had successfully established. As there was a concrete bridge that cast a partial shadow over the retention pond, the position of each wetland (sun, shade, or mixed) was recorded during site visits (every two weeks during the establishment phase and weekly during the experiment) and the wetlands were moved to new locations on a rotational basis to ensure a randomised experimental design and prevent light exposure from becoming a bias.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e2.3.2 Plant sampling and analysis\u003c/h2\u003e \u003cp\u003eThe experiment commenced on 12 March 2021 and ran for a period of three months. At 28-day intervals during the experiment, three randomly selected plants were sampled (removed) from each floating wetland. Plant roots and shoots were separated for independent analysis, and the same method applied for grinding and drying as described for the mesocosm experiment was applied. The ground samples were thoroughly mixed, and a representative composite sample of root and shoot tissue of the three plants sampled from each wetland was sent to BEMLAB for tissue nutrient analysis of total nitrogen and total phosphorous. The same laboratory methods were used as described for the mesocosm experiment. The use of composite sampling was essential due to budget constraints; however, ANOVA power analyses indicated that the sample size was sufficient to detect significant differences if they are present (Table S8 and Table S9, Supplementary Material). The power analyses were based on the data from the mesocosm experiment, however, as the \u003cem\u003ein-situ\u003c/em\u003e experiment was conducted under more eutrophic conditions, greater effect sizes were expected. Plant functional traits such as leaf dry matter content (LDMC), and root dry matter content (RDMC) were determined by dividing dry mass (mg) by wet mass (g) of leaves and roots respectively.\u003c/p\u003e \u003cp\u003eWater quality samples were taken at the start of the experiment period as well as at monthly intervals during the experiment and sent to the laboratory at the South African Council for Scientific and Industrial Research (CSIR) for analysis of bioavailable nutrients (phosphates (PO\u003csub\u003e4\u003c/sub\u003e-P), nitrates (NO\u003csub\u003e3\u003c/sub\u003e-N), and ammonia\u0026thinsp;+\u0026thinsp;ammonium (NH\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;NH\u003csub\u003e4\u003c/sub\u003e). The CSIR are accredited to the ISO 17025:2017 standard (registration number T0093). This method cannot differentiate between the ammonium and ammonia. In addition to these samples, physicochemical variables (temperature, pH, total dissolved solids, and dissolved oxygen) were monitored weekly during the experiment using a handheld multi-parameter water quality meter to ensure nutrient levels did not reach toxic levels (Table S10, Supplementary Material).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003e2.3.3 Plant nutrient content and uptake capacity\u003c/h2\u003e \u003cp\u003e \u003cb\u003ePlant uptake capacity\u003c/b\u003e, defined here as total nitrogen and total phosphorus uptake in plant tissues, was measured for both roots and shoots, by plant tissue analysis. Uptake was calculated by multiplying plant dry weight at the start and end of the experiment by the respective TN and TP concentrations, and subtracting the two (Keizer-Vlek et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Plant nutrient concentration was used as an indication of \u003cb\u003enutrient storage efficiency\u003c/b\u003e (a measure of how well plants can store nutrients in their tissue). The ratio of the \u003cb\u003eshoot to root nutrient content\u003c/b\u003e was used to test for differences in nutrient storage location among species.\u003c/p\u003e \u003cp\u003e \u003cb\u003eNutrient uptake rates\u003c/b\u003e were estimated by calculating the mean nutrient uptake over 28-day periods and standardising these values to a daily rate (Table S11, Supplementary Material). To enable comparison with literature values, nutrient uptake values (mg.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) per floating wetland (0.2 m\u003csup\u003e2\u003c/sup\u003e) were standardised to values per square meter. The floating structures used in this experiment were 0.2 m\u003csup\u003e2\u003c/sup\u003e in size and were planted with 10 plants each, thus 5 wetlands and 50 plants would be needed to cover 1m\u003csup\u003e2\u003c/sup\u003e of surface water. To estimate the uptake of each species in terms of mg.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, the mean daily uptake rate was multiplied by 50. To get an estimate of the nutrient uptake ability of these systems over a longer period, the daily values (mg.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) were also converted to an annual estimate (g.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.y\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e); this estimate does however not take the plant growth cycle into account. This experiment was in the austral autumn and therefore during the spring and summer it is possible that uptake rates may be higher, and in winter slightly lower. It is important to emphasize that these plants are evergreen and that there are still high levels of solar radiation in the autumn in South Africa. Despite this, it is likely that the results from this experiment provide a slightly lower estimate than the plants full potential. It is important to note that three plants were removed from each wetland monthly, thus the remaining plants had more space to grow and less competition. Consequently, the uptake rates (mg.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) in this experiment represent values that would be obtained at relatively high planting densities (50 plants per m\u003csup\u003e2\u003c/sup\u003e) accompanied by regular biomass harvesting.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Data analysis\u003c/h2\u003e \u003cp\u003eFor the mesocosm and \u003cem\u003ein-situ\u003c/em\u003e experiment, most statistical analyses were performed in Statistica and R version 3.6.2 (R Core Team, \u003cspan citationid=\"CR75\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFor the mesocosm experiment, \u003cb\u003eone-way ANOVAs\u003c/b\u003e were performed to investigate significant difference in total removal, removal rates and removal efficiencies of NO\u003csub\u003e3\u003c/sub\u003e-N, NH\u003csub\u003e4\u003c/sub\u003e-N and PO\u003csub\u003e4\u003c/sub\u003e-P between all the floating wetland treatments because the data were found to be normally distributed and variances were homoscedastic. For significant differences, the \u003cb\u003eFisher least significant difference (LSD) post hoc\u003c/b\u003e test was used. To investigate significant differences in traits LDMC, RDMC, SLA and SRL, a \u003cb\u003eone-way ANOVA\u003c/b\u003e was run. For SRL and RDMC data, a \u003cb\u003eWelch\u003c/b\u003e test was run because the variances were heteroscedastic and the data were normally distributed. For significant differences, a \u003cb\u003eGames-Howel\u003c/b\u003e post hoc was run. For the SLA and LDMC, the data were normally distributed, and the variances were homoscedastic. For significant differences, a \u003cb\u003eLSD post hoc\u003c/b\u003e test was run.\u003c/p\u003e \u003cp\u003eFor the \u003cem\u003ein-situ\u003c/em\u003e experiment, differences in dry mass, nutrient content, and nutrient storage efficiency, \u003cb\u003elinear mixed models\u003c/b\u003e were fitted using the \u0026lsquo;lmer\u0026rsquo; function within the \u0026lsquo;lme4\u0026rsquo; package (Bates et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). The \u0026ldquo;wetland\u0026rdquo; and \u0026ldquo;plant\u0026rdquo; sampled were entered as random effects to account for dependence between observations from the same wetland. \u0026ldquo;Species\u0026rdquo;, \u0026ldquo;sampling day\u0026rdquo;, and the interaction between species and sampling day were entered as fixed effects. First, the effect of the interaction between species and sampling day was tested by comparing the fit of the model to a reduced model that only contained the two main effects. Where the interaction term was significant, separate models were run to test the significance of species on each sampling day individually. If a significant difference was not detected, the interaction term was excluded from the model and the significance of the main effects were tested. The significance was tested by running a \u003cb\u003eKenward-Roger F-test\u003c/b\u003e using the \u0026ldquo;pbkrtest\u0026rdquo; package in R (Halekoh and H\u0026oslash;jsgaard, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Where a significant influence of species or sampling day was detected, a \u003cb\u003epost hoc\u003c/b\u003e test was performed on the relevant model using the \u0026lsquo;emmeans\u0026rsquo; function from the \u0026lsquo;emmeans\u0026rsquo; package in R (Lenth, \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). \u003cb\u003eCorrelation analyses\u003c/b\u003e were performed to determine if the physicochemical variables were correlated with the water quality data as well as to determine whether there was an association between plant growth (dry matter at the three timesteps) and nutrient content. Pearson\u0026rsquo;s correlation analysis was used for parametric data while Spearman\u0026rsquo;s Rank correlation analysis was used for non-parametric data. To investigate significant differences between shoot:root ratios across both experiments, a \u003cb\u003egeneralised linear mixed model\u003c/b\u003e (with binomial distribution) was used. A multiple comparison \u003cb\u003eTukey test\u003c/b\u003e was used to test for significant differences.\u003c/p\u003e \u003c/div\u003e"},{"header":"3 RESULTS","content":"\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Nutrient uptake ability under oligotrophic conditions\u003c/h2\u003e \u003cp\u003eThe total removal (mg) of NO\u003csub\u003e3\u003c/sub\u003e-N, PO\u003csub\u003e4\u003c/sub\u003e-P and NH\u003csub\u003e4\u003c/sub\u003e-N from the water was very low across planted and unplanted floating wetland treatments. The total NO\u003csub\u003e3\u003c/sub\u003e-N and NH\u003csub\u003e4\u003c/sub\u003e-N removal of floating wetlands did not differ significantly among treatments (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA). However, the floating wetlands planted with \u003cem\u003eCyperus textilis, Juncus lomatophyllus\u003c/em\u003e and \u003cem\u003ePrionium serratum\u003c/em\u003e had significantly higher total PO\u003csub\u003e4\u003c/sub\u003e-P removal relative to the control (F\u003csub\u003e(3,20)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.52; df\u0026thinsp;=\u0026thinsp;20; p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA).\u003c/p\u003e \u003cp\u003eLow removal rates (mg.m\u003csup\u003e2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) from the water were observed for all parameters and treatments (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB). No significant difference was observed between treatments for NO\u003csub\u003e3\u003c/sub\u003e-N and NH\u003csub\u003e4\u003c/sub\u003e-N removal rates, however there was a significant difference in the PO\u003csub\u003e4\u003c/sub\u003e-P removal rate between floating wetlands planted with \u003cem\u003eC. textilis, J. lomatophyllus\u003c/em\u003e and \u003cem\u003eP. serratum\u003c/em\u003e relative to the control (F\u003csub\u003e(3,20)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.52; df\u0026thinsp;=\u0026thinsp;20; p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003eWhen comparing nutrient removal efficiencies, high removal efficiencies (\u0026gt;\u0026thinsp;90%) were observed across all treatments (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eC). This was also occasionally the case for the control; however, results were more variable. There was a significant difference in PO\u003csub\u003e4\u003c/sub\u003e-P removal efficiency between floating wetlands planted with \u003cem\u003eC. textilis, J. lomatophyllus\u003c/em\u003e and \u003cem\u003eP. serratum\u003c/em\u003e relative to the control (F\u003csub\u003e(3,20)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.42; df\u0026thinsp;=\u0026thinsp;20; p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eC).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Nutrient uptake potential under eutrophic conditions\u003c/h2\u003e \u003cp\u003e \u003cem\u003eCyperus textilis\u003c/em\u003e accumulated a mean total of 477.9\u0026thinsp;\u0026plusmn;\u0026thinsp;254.45 mg TN and 72.3\u0026thinsp;\u0026plusmn;\u0026thinsp;40.36 mg TP over a one-month period under eutrophic conditions \u0026ndash; which is signficiantly higher than \u003cem\u003eP. serratum\u003c/em\u003e and \u003cem\u003eJ. lomatophyllus\u003c/em\u003e which accumulated a mean total of 175.3\u0026thinsp;\u0026plusmn;\u0026thinsp;43.60 mg TN and 14.5\u0026thinsp;\u0026plusmn;\u0026thinsp;6.42 mg TP, and 30.9\u0026thinsp;\u0026plusmn;\u0026thinsp;80.99 mg TN and 6.7\u0026thinsp;\u0026plusmn;\u0026thinsp;14.27 mg TP respectively over the same period (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Two species, namely \u003cem\u003eC. textilis\u003c/em\u003e and \u003cem\u003eP. serratum\u003c/em\u003e, stored significantly more nutrients (both nitrogen and phosphorus) in their shoot tissue compared to their root tissue (Nitrogen: F\u003csub\u003e(4,30)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;19.44; df\u0026thinsp;=\u0026thinsp;30; p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) (Phosphorus: F\u003csub\u003e(4,30)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;17.65; df\u0026thinsp;=\u0026thinsp;30; p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Specifically, \u003cem\u003eC. textilis\u003c/em\u003e stored significantly more TN and TP in its shoots than both \u003cem\u003eJ. lomatophyllus\u003c/em\u003e and \u003cem\u003eP. serratum\u003c/em\u003e. \u003cem\u003eCyperus textilis\u003c/em\u003e also had the highest nutrient uptake and content per day followed by \u003cem\u003eP. serratum\u003c/em\u003e and \u003cem\u003eJ. lomatophyllus\u003c/em\u003e (Fig S 1, Fig S 2, Fig S 3, Supplementary Material), while \u003cem\u003eJ. lomatophyllus\u003c/em\u003e had the greatest nutrient uptake efficiency (Fig S 4, Supplementary Material).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e3.3 What is the role of plant functional traits in the process of nutrient uptake?\u003c/h2\u003e \u003cdiv id=\"Sec18\" class=\"Section3\"\u003e \u003ch2\u003e3.3.1 Dominant location of plant nutrient storage\u003c/h2\u003e \u003cp\u003eThe nitrogen shoot:root ratio for all treatments was significantly higher in the \u003cem\u003ein-situ\u003c/em\u003e experiment compared to the mesocosm experiment (F\u003csub\u003e(5,36.3)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;83.35;p\u0026thinsp;\u0026lt;\u0026thinsp;0.01). However, this differed to the phosphorus shoot:root ratios for \u003cem\u003eC. textilis\u003c/em\u003e and \u003cem\u003eP. serratum\u003c/em\u003e which were significantly higher in the \u003cem\u003ein-situ\u003c/em\u003e experiment (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). For both Total Nitrogen and Total Phosphorus shoot:root ratios, \u003cem\u003eC. textilis\u003c/em\u003e was significantly higher than the other treatments within the \u003cem\u003ein-situ\u003c/em\u003e experiment (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eInterestingly, these trends did not concur with the concentrations of nutrient storage within the roots and shoots of the study species under different nutrient environments. \u003cem\u003eJuncus lomatophyllus\u003c/em\u003e stored a significantly higher concentration of nitrogen and phosphorus when compared to the other two plant species (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Generally, \u003cem\u003eJ. lomatophyllus\u003c/em\u003e had significantly higher concentrations of both Nitrogen and Phosphorus stored within the shoots in comparison to the roots \u0026ndash; expect for the \u003cem\u003ein-situ\u003c/em\u003e experiment, where the roots stored significantly more Phosphorus than the shoots (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Also, most plants species, regardless of the experiment type, stored a significantly higher concentration of nutrients in the shoots than their roots \u0026ndash; particularly \u003cem\u003eJ. lomatophyllus and C. textilis\u003c/em\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section3\"\u003e \u003ch2\u003e3.3.2 Plant functional traits\u003c/h2\u003e \u003cp\u003eWhen comparing traits of the three endemic wetland plant species, the LDMC of \u003cem\u003eC. textilis\u003c/em\u003e was significantly higher across all species, while \u003cem\u003eJ. lomatophyllus\u003c/em\u003e was significantly lower (F\u003csub\u003e(2,33)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;166.88; df\u0026thinsp;=\u0026thinsp;33; p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). The RDMC was significantly higher for \u003cem\u003eP. serratum\u003c/em\u003e and significantly lower for \u003cem\u003eJ. lomatophyllus\u003c/em\u003e (F\u003csub\u003e(2,33)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;143.51; df\u0026thinsp;=\u0026thinsp;33; p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). The mean SRL and mean SLA of \u003cem\u003eJ. lomatophyllus\u003c/em\u003e was significantly higher than that of \u003cem\u003eP. serratum\u003c/em\u003e and \u003cem\u003eC. textilis\u003c/em\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). The traits measured in the \u003cem\u003ein situ\u003c/em\u003e experiment were very similar and are not presented here (Table S15, Supplementary Material).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section3\"\u003e \u003ch2\u003e3.3.3 Relationship between plant growth and nutrient content\u003c/h2\u003e \u003cp\u003eRelatively similar significantly positive relationships between nutrient content (both nitrogen and phosphorus) and plant growth (i.e. an increase in dry matter) were observed for all three species for both roots and shoots in the \u003cem\u003ein-situ\u003c/em\u003e experiment (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e). However, \u003cem\u003eJ. lomatophyllus\u003c/em\u003e appeared to store slightly higher concentrations of TN and TP per unit dry matter in both shoots and roots, but especially roots, relative to the other two species. However, \u003cem\u003eJ. lomatophyllus\u003c/em\u003e remains relatively small over the three months relative to the other two species, leading to lower overall TN and TP contents. The mean ratio of plant dry matter (g) to nitrogen content (g) for all three species was 55:1, while that of phosphorus was 421:1 (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"4 DISCUSSION","content":"\u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003e4.1 Nutrient uptake ability\u003c/h2\u003e \u003cp\u003eIn the mesocosm experiment, the total removal amount and removal rates of bioavailable nutrients across treatments were very low overall due to the naturally oligotrophic conditions applied. Oligotrophic Cape freshwater systems are nutrient poor primarily due to the nutrient deficient parent geology (Lamont \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e1983\u003c/span\u003e). Other floating wetland studies are found to have high removal rates \u0026ndash; ranging between removal rates as high as Headley and Tanner (\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2012\u003c/span\u003e) and as low as Saeed et al., (\u003cspan citationid=\"CR82\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) i.e. from 210 to 114 000 mgNO\u003csub\u003e3\u003c/sub\u003e-N.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 559 to 4600 mgPO\u003csub\u003e4\u003c/sub\u003e-P.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and, 1480 to 36000 mgNH\u003csub\u003e4\u003c/sub\u003e-N.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Headley and Tanner, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Saeed et al., \u003cspan citationid=\"CR82\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Stewart et al., \u003cspan citationid=\"CR94\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). This range of removal rates is still high in comparison to the low removal rates found in this mesocosm experiment.\u003c/p\u003e \u003cp\u003eThe high removal efficiencies (\u0026gt;\u0026thinsp;90%) observed for all nutrient parameters (NO\u003csub\u003e3\u003c/sub\u003e-N, PO\u003csub\u003e4\u003c/sub\u003e-P and NH\u003csub\u003e4\u003c/sub\u003e-N) across planted floating wetland treatments in the mesocosm experiment is likely due to the adaptation of these species to naturally oligotrophic conditions. These efficiencies were not significantly different for the control (except for PO\u003csub\u003e4\u003c/sub\u003e-P), but the controls exhibited much higher variability and greater ranges for NH\u003csub\u003e4\u003c/sub\u003e-N. These removal efficiencies are very high in comparison to other studies, such as Van De Moortel et al. (\u003cspan citationid=\"CR104\" class=\"CitationRef\"\u003e2010\u003c/span\u003e) who observed that the presence of plants (i.e. \u003cem\u003eCarex\u003c/em\u003e sp.) on floating wetlands resulted in a significantly higher NH\u003csub\u003e4\u003c/sub\u003e-N removal efficiency (35%) than the control (3%), which consisted of an unplanted mat. Keizer-Vlek et al. (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) also showed this trend where an \u003cem\u003eIris\u003c/em\u003e-planted floating wetland had a much higher TN removal efficiency of 98%, in comparison to the unplanted control of only 14%. Nevertheless, Keizer-Vlek et al. (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) and Van De Moortel et al. (\u003cspan citationid=\"CR104\" class=\"CitationRef\"\u003e2010\u003c/span\u003e) emphasised the large variability of removal efficiencies between studies. The low nutrient removal amounts, but high removal efficiencies observed in our experiment suggests that most nutrients added to the treatments were removed by the floating wetlands.\u003c/p\u003e \u003cp\u003eThe similar removal efficiencies and amounts observed between floating wetlands treatments and the control suggest that microbes assosciated with the surface area provided by the wetland infrastructure may be performing nutrient uptake in the absence of plants, or may play an important role even in the presence of plants (Stewart et al., \u003cspan citationid=\"CR94\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Wu et al., \u003cspan citationid=\"CR122\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). However, where plants were present on floating wetlands, it is likely that the nutrients were accumulated within the plant matter as evidenced by an increase in plant biomass. Whilst additional nutrient removal pathways (i.e. other than the role of plants) are not the focus of this paper, various other pathways could explain the trends observed in the mesocosm experiment (Stewart et al., \u003cspan citationid=\"CR94\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Wu et al., \u003cspan citationid=\"CR122\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). This experiment suggested that these floating wetlands and endemic plants had high potential that required testing in a real-life eutrophic application.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section2\"\u003e \u003ch2\u003e4.2 Nutrient uptake potential\u003c/h2\u003e \u003cp\u003eTesting the potential for these endemic plant species for water purification in a eutrophic \u003cem\u003ein-situ\u003c/em\u003e experiment revealed high nutrient uptake capacities across all species. However, \u003cem\u003eCyperus textilis\u003c/em\u003e outperformed both \u003cem\u003eJuncus lomatophyllus\u003c/em\u003e and \u003cem\u003ePrionium serratum\u003c/em\u003e in terms of nutrient uptake, storing most of this in its shoots, largely due to its greater size and faster growth rates. Therefore, considering water quality alone (i.e. not other factors, such as biodiversity), \u003cem\u003eC. textilis\u003c/em\u003e had the highest benefit out of the three study species. All species grew well and appeared to tolerate and thrive in the eutrophic conditions despite being adapted to oligotrophic conditions. Clearly no thresholds were exceeded, but a follow-up study on the tolerance levels and ranges of optimal performance of these endemic species to eutrophic conditions would be useful.\u003c/p\u003e \u003cp\u003eA review of eight studies, conducted mainly in humid subtropical and sub-humid continental climates, found that nitrogen uptake abilities for plant species, including common species such as \u003cem\u003ePhragmites australis, Juncus effusus\u003c/em\u003e and \u003cem\u003eTypha\u003c/em\u003e species, varied between 13.2 and 390 mgN.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Choudhury et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). A review of another eight studies, conducted mainly in China, found that the water purification abilities of species such as \u003cem\u003eCanna indica, P. australis, J. effusus\u003c/em\u003e and \u003cem\u003eTypha\u003c/em\u003e species varied between 17 and 912 mgN.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e with mean uptake rates of 430\u0026thinsp;\u0026plusmn;\u0026thinsp;350 mgN.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Wang et al., \u003cspan citationid=\"CR113\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Compared to these studies, both \u003cem\u003eC. textilis\u003c/em\u003e, with nitrogen uptake of 853 mgN.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and \u003cem\u003eP. serratum\u003c/em\u003e with nitrogen uptake of 313 mgN.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e performed comparatively well.\u003c/p\u003e \u003cp\u003eTemperature plays an important role in plant growth and thus nutrient uptake. A study looking at the applicability of \u003cem\u003eP. australis\u003c/em\u003e and \u003cem\u003eZizania caduciflora\u003c/em\u003e floating wetlands to treat agricultural runoff in China found that nitrogen uptake ranged between 206.5 and 628.5 mgN.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e with the highest uptake rates occurring during the summer months (Lu et al., \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). The water temperatures of the current study were similar to those observed during winter, autumn and spring in Lu et al., (\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), yet the nitrogen uptake rate for \u003cem\u003eC. textilis\u003c/em\u003e outperformed the maximum uptake rates found in this study, perhaps indicating that at higher water temperatures, such as in summer, maximum potential uptake may occur. Under the low temperatures found in northern Sweden (mean summer temperature of 10\u0026deg;C), floating wetlands had a nitrogen uptake rate of between 7.56\u0026ndash;24.75 mgN.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Choudhury et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Thus, all three plant species outperformed species grown in colder climates, highlighting the potential value of floating treatment wetlands particularly in warmer regions with longer growing seasons such as South Africa.\u003c/p\u003e \u003cp\u003eThe phosphorus uptake rates of \u003cem\u003eJ. lomatophyllus\u003c/em\u003e and \u003cem\u003eP. serratum\u003c/em\u003e in our study were also higher than several other species studied (Wang et al., \u003cspan citationid=\"CR113\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). A study conducted in south Australia on the use of \u003cem\u003ePaspalum paspalodes, Myriophyllum aquaticum\u003c/em\u003e, and \u003cem\u003eRanunculus repens\u003c/em\u003e planted floating mats found that these three species had mean phosphorus uptake rates ranging between 43 and 86 mgP.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Wen and Recknagel, \u003cspan citationid=\"CR116\" class=\"CitationRef\"\u003e2002\u003c/span\u003e), and in our study \u003cem\u003eC. textilis\u003c/em\u003e performed comparatively well with 129 mgP.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e unlike \u003cem\u003eJ. lomatophyllus\u003c/em\u003e and \u003cem\u003eP. serratum\u003c/em\u003e. Likewise \u003cem\u003eC. textilis\u003c/em\u003e performed well relative to results of a review of eight studies, conducted mainly in China, which found that phosphorus uptake rates for numerous plant species, including \u003cem\u003eCanna indica, P. australis, J. effusus\u003c/em\u003e and \u003cem\u003eTypha\u003c/em\u003e species, varied between 2 and 163 mgP.m\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e.d\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Wang et al., \u003cspan citationid=\"CR113\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). A study conducted after ours, investigating the use of nine South African endemic plant species for use in biofilters, also confirmed that \u003cem\u003eC. textilis\u003c/em\u003e and \u003cem\u003eP. serratum\u003c/em\u003e consistently showed some of the best results in terms of nutrient removal relative to the other seven species (Jacklin et al., \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2021b\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe nitrogen removal ability of \u003cem\u003eC. textilis\u003c/em\u003e was similar to that of \u003cem\u003eC. indica\u003c/em\u003e measured at varying ratios of ammonium and nitrate concentrations in China while \u003cem\u003eP. serratum\u003c/em\u003e had slightly lower nutrient removal abilities (Zhang et al., \u003cspan citationid=\"CR127\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). \u003cem\u003eCanna indica, Thalia dealbata\u003c/em\u003e, and \u003cem\u003eLythrum salicaria\u003c/em\u003e were found to have accumulated a mean of 1523 mg, 1619 mg, and 908 mg of nitrogen per plant and 144 mg, 102 mg, and 71 mg of phosphorus per plant respectively over 84 days in an experiment in China (Ge et al., \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Over the same time in our \u003cem\u003ein situ\u003c/em\u003e experiment, \u003cem\u003eC. textilis\u003c/em\u003e accumulated a mean of 1855 mg of nitrogen and 262 mg of phosphorus per plant, thus performing better than all three species. The review of eight studies, conducted mostly in China, found that the nutrient content measured for several species ranged between 32 and 5803 mg of nitrogen per plant, and between 2 and 437 mg of phosphorus per plant (Wang et al., \u003cspan citationid=\"CR113\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). \u003cem\u003eCyperus textilis\u003c/em\u003e and \u003cem\u003eP. serratum\u003c/em\u003e performed better in the \u003cem\u003ein-situ\u003c/em\u003e experiment than the majority of the species in the review (Wang et al., \u003cspan citationid=\"CR113\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). In contrast, the nutrient storage of \u003cem\u003eP. cordata\u003c/em\u003e and \u003cem\u003eJ. effusus\u003c/em\u003e plants surpassed the nutrient storage measured in our study, likely due to the greater plant biomass production (Spangler et al., \u003cspan citationid=\"CR92\" class=\"CitationRef\"\u003e2019b\u003c/span\u003e). Nitrogen and phosphorus removal of floating wetlands planted with \u003cem\u003eCarex stricta, Agrostis alba, Iris ensata, Panicum virgatum\u003c/em\u003e, and \u003cem\u003eCanna generalis\u003c/em\u003e together with a generalist species after eight weeks were all greater than the nutrient removal measured in our study, however, the nutrient concentrations used were higher than that in the current study (Spangler et al., \u003cspan citationid=\"CR91\" class=\"CitationRef\"\u003e2019a\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec24\" class=\"Section2\"\u003e \u003ch2\u003e4.3 Role of key plant functional traits in nutrient removal\u003c/h2\u003e \u003cp\u003e \u003cem\u003eCyperus textilis\u003c/em\u003e performed best in terms of nutrient uptake under eutrophic conditions, followed by \u003cem\u003ePrionium serratum\u003c/em\u003e and then \u003cem\u003eJuncus lomatophyllus\u003c/em\u003e. The traits that seemed to characterise this high nutrient uptake were biomass, leaf dry matter content (LDMC) and specific leaf areas (SLA). Both biomass and LDMC were higher for the two species that performed better at nutrient uptake, whereas SLA was lower. This may indicate that wetland species with high LDMC, low SLA and that are able to grow relatively large, may be highly suitable for floating treatment wetlands.\u003c/p\u003e \u003cp\u003e \u003cem\u003eJuncus lomatophyllus\u003c/em\u003e had the highest nutrient uptake efficiency, i.e. highest N and P concentrations in its tissues, which was concomitant with higher SLA. Although higher SLA in turn suggests a higher relative growth rate and a more acquisitive strategy in terms of the plant economic spectrum (Garnier et al., \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Grassein et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Moor et al., \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; P\u0026eacute;rez-Harguindeguy et al., \u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), J. \u003cem\u003elomatophyllus\u003c/em\u003e is a small wetland plant, which does not attain high biomass, but rather spreads laterally via vegetative growth. Therefore its potential for nutrient uptake is lower in eutrophic conditions compared to the other two species. The other two species were more conservative in terms of their resource use, but able to attain greater size and biomass and therefore take up more nutrients overall. The life history strategies of \u003cem\u003eC. textilis\u003c/em\u003e and \u003cem\u003eP. serratum\u003c/em\u003e are likely to be more that of competitors (Rebelo et al. \u003cspan citationid=\"CR77\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), whereas \u003cem\u003eJ. lomatophyllus\u003c/em\u003e appears to me more of a ruderal or stress tolerant wetland species (Grime, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e1977\u003c/span\u003e). Species that are more competitive and amass more biomass would need to be frequently harvested to keep biomass down and avoid self-shading and senescence on floating treatment wetlands.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec25\" class=\"Section2\"\u003e \u003ch2\u003e4.4 Caveats\u003c/h2\u003e \u003cp\u003eThere were several limitations to this study due to budget or logistical constraints, since this research was conducted in a resource constrained country: (1) less water quality sampling of bio-available nutrients than would be desired in the mesocosm experiment, (2) the taking of composite samples in both experiments, and (3) relatively small sample sizes in both experiments. The relatively small sample sizes meant that if in some cases larger plants were randomly sampled at the start of the experiment (e.g. in the mesocosm experiment), and smaller plants at the end, and \u003cem\u003evice versa\u003c/em\u003e, the attempts to quantify nutrient uptake would be biased. The only way to overcome this, since sampling is destructive, would be to have a much larger sample size, which would be much more costly. Lastly, the role of plants in nutrient uptake relative to microbes is debated (Brix, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1993\u003c/span\u003e; Pavlineri et al., \u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Shutes, \u003cspan citationid=\"CR89\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). In the mesocosm experiment, overall nutrient uptake was similar to the control, which may suggest that microbial activity plays an important role, or alternatively that it can compensate for the absence of plants when a substrate with large surface area (e.g. floating wetland frame) is provided. No conclusions can be made without directly studying the contribution of microbes, and this is an interesting avenue for future research.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec26\" class=\"Section2\"\u003e \u003ch2\u003e4.5 Practical considerations and conservation implications\u003c/h2\u003e \u003cp\u003eBiomass was found to increase over the experiment period, indicating that plants continued to grow and accumulate nutrients, however, the growth and nutrient removal rates were found to decrease over time. Two primary factors may have contributed to the decreased growth and nutrient uptake rate, namely competition and/or self-shading and temperature decline towards winter.\u003c/p\u003e \u003cp\u003eWhile competition for space between plants could have reduced the rate of biomass accumulation, the impact thereof was likely minimal, as plants were removed at intervals for sampling, providing room for growth. Self-shading could have played a role in reducing the rate of biomass production for \u003cem\u003eC. textilis\u003c/em\u003e, as this species had prolific shoot growth (Suding et al., \u003cspan citationid=\"CR95\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). However, plants also have intrinsic growth limitations, meaning that they are able to grow rapidly and take up nutrients until a certain size is reached whereafter growth rate decreases (Lasfar et al., \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). Competition, self-shading and intrinsic growth limitations all suggest that biomass harvesting could be a good solution to maintain the system in a state that allows for optimal growth and nutrient removal (Sun et al., \u003cspan citationid=\"CR98\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Similar to other studies, our results for both experiments indicate that shoots are generally the dominant nutrient storage location for these three species, thus shoot harvesting and disposal is recommended to maximise nutrient uptake, and permanently remove nutrients from the system (Barco et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Garcia Chanc et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Huth et al., \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Schwammberger et al., \u003cspan citationid=\"CR86\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; White and Cousins, \u003cspan citationid=\"CR118\" class=\"CitationRef\"\u003e2013\u003c/span\u003e. Harvesting shoot biomass stimulates new, accelerated growth, reduces internal nutrient cycling, and thus increases nutrient removal (Colares et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Ng and Chan, \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Zhou et al., \u003cspan citationid=\"CR131\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eWith high temperatures positively influencing plant growth (typically more rapid growth), nutrient removal is accelerated during summer months (Bi et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Furthermore, actively growing shoots can have higher nutrient concentrations than mature shoots (Sun et al., \u003cspan citationid=\"CR98\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). If plants slow uptake as winter approaches, this would suggest that having floating wetlands installed and established before the austral summer would be important for best results.\u003c/p\u003e \u003cp\u003eTo understand the potential impact of these uptake rates at a farm-scale, a quick calculation using floating wetlands theoretically planted with \u003cem\u003eC. textilis\u003c/em\u003e was performed. This calculation was based on a similarly polluted farm dam with 10 floating wetlands, each with 10 \u003cem\u003eC. textilis\u003c/em\u003e plants on each wetland. The potential uptake was estimated at 0.6 kg of nitrogen and 0.1 kg of phosphorus per year (Table S17, Supplementary Material).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec27\" class=\"Section2\"\u003e \u003ch2\u003e4.6 Additional benefits of floating wetlands\u003c/h2\u003e \u003cp\u003eThis study has demonstrated that certain endemic South African wetland plant species show potential to remove excess nutrients from eutrophic water and thrive in these conditions. In addition to their nutrient uptake abilities, floating treatment wetlands offer numerous co-benefits, such as biodiversity, aesthetic and educational benefits (Stefanakis, \u003cspan citationid=\"CR93\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Floating wetlands provide habitats for fauna, act as refugia for aquatic species in urban and agricultural areas, could potentially act as steppingstone habitats, and provide aesthetic benefits to people (Stefanakis, \u003cspan citationid=\"CR93\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). In the current study, the floating wetlands were found to be home to at least two frog species, \u003cem\u003eStrongylopus grayil\u003c/em\u003e and \u003cem\u003eSclerophrys capensis\u003c/em\u003e, a snake, \u003cem\u003eLycodonomorphus rufulus\u003c/em\u003e, and numerous dragonfly species were seen in the vicinity of the wetlands. Artificial ponds have been found to have great conservation value for aquatic insect diversity by forming part of a diverse pondscape and conservation corridors in degraded or transformed landscapes (Deacon et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). As such, the use of native wetland species in artificial ponds to improve water quality will benefit the overall ecosystem health and biodiversity of the region.\u003c/p\u003e \u003c/div\u003e"},{"header":"5 CONCLUSION","content":"\u003cp\u003eFloating wetlands, a cost-effective green technology, present an opportunity to purify agricultural wastewater in lentic systems, like small farm dams, in South Africa. Using endemic South African wetland plant species, especially those with fast growth rates such as \u003cem\u003eCyperus textilis\u003c/em\u003e, has high potential to effectively remove nutrients as well as provide other co-benefits. This research fills a gap in the literature in terms of using endemic wetland species for floating treatment wetlands in the Global South, and specifically Africa.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis work was supported by NCC Environmental Services, the South African National Research Foundation, the Daniel Booysen Memorial Fund, the South African Association of Botanists, the South African National Research Foundation (Grant #: 76861), the Water Research Commission South Africa (Grant #: 2019-2020-00034), and a Council for Scientific and Industrial Research Parliamentary Grant.\u003c/p\u003e\u003ch2\u003eAuthor contributions\u003c/h2\u003e \u003cp\u003eAJR, PF, OB contributed to the study conception and design. Material preparation, data collection and analysis were performed by PF, OB, AJR. The first draft of the manuscript was written by AJR, PF, OB and PF, OB, AJR, KJE, DLM commented on previous versions of the manuscript. PF, OB, AJR, KJE, and DLM read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eACKNOWLEDGEMENTS\u003c/h2\u003e \u003cp\u003eWe thank NCC Environmental Services (Sean Altern, Andrew Purnell and Quinton van Wyk), the South African National Research Foundation, the Daniel Booysen memorial fund and the South African Association of Botanists 2021 for funding. Prof Karen Esler acknowledges funding through NRF grant 76861 and Water Research Commission (WRC) in South Africa (Project: 2019/2020-00034) in the frame of the collaborative international consortium NATWIP (Nature-Based Solutions for Water Management in the Peri-Urban) financed under the 2018 Joint Call of theWaterWorks2017 ERA-NET Cofund. Prof David Le Maitre acknowledged the support of the CSIR through its Parliamentary Grant funding. We acknowledge the South African Weather Service and the Engineering Department at Stellenbosch University for climatological data, and BirdLife as well as Johann van Biljon of Green Intaba for the provision of all plants for the mesocosm and \u003cem\u003ein-situ\u003c/em\u003e experiment respectively. We thank Dr Kevin Winter from The Water Hub for hosting the \u003cem\u003ein-situ\u003c/em\u003e experiment and assistance with logistics, as well as Mr. Simphiwe Madyibi, site manager at the Water Hub. We also thank Prof Martin Kidd from Stellenbosch University for statistical support. A special thanks to Ronell Frenzel, Alta Saunders, Cindy Anger, Ron Brunings, Tracy Brunings, Wim Brunings, Marianne de Kock, Lauren Searle, Seonaid Streydom, Keagan Stubs, and Rubin Venter for practical assistance.\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e \u003cp\u003eThe datasets generated during and/or analysed during the current study are available in the supplementary material.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbbaspour, S., 2011. Water quality in developing countries, South Asia, South Africa: Water quality management and activities that cause water pollution. Int. Conf. Environ. Agric. Eng. 15, 94\u0026ndash;102.\u003c/li\u003e\n\u003cli\u003eAbed, S., Almuktar, S., Scholz, M., 2017. Remediation of synthetic greywater in mesocosm \u0026mdash; Scale floating treatment wetlands. Ecol. Eng. 102, 303\u0026ndash;319. https://doi.org/10.1016/j.ecoleng.2017.01.043\u003c/li\u003e\n\u003cli\u003eAbou-Elela, S.I., 2017. Constructed Wetlands: The green technology for municipal wastewater wreatment and reuse in agriculture, Handbook of Environmental Chemistry. Springer International Publishing. https://doi.org/10.1007/698_2017_69\u003c/li\u003e\n\u003cli\u003eAdelana, S., Xu, Y, 2006. Contamination and protection of the Cape Flats Aquifer, South Africa, in: Xu, Yongxin, Usher, B. (Eds.), Groundwater Pollution in Africa. Taylor and Francis Group, London, pp. 265\u0026ndash;277.\u003c/li\u003e\n\u003cli\u003eAhn, C., 2016. A creative collaboration between the science of ecosystem restoration and art for sustainable stormwater management on an urban college campus. Restor. Ecol. 24, 291\u0026ndash;297. https://doi.org/10.1111/rec.12341\u003c/li\u003e\n\u003cli\u003eAmano, Y., Sakai, Y., Sekiya, T., Takeya, K., Taki, K., Machida, M., 2010. Effect of phosphorus fluctuation caused by river water dilution in eutrophic lake on competition between blue-green alga Microcystis aeruginosa and diatom Cyclotella sp. J. Environ. Sci. 22, 1666\u0026ndash;1673. https://doi.org/10.1016/S1001-0742(09)60304-1\u003c/li\u003e\n\u003cli\u003eApinda-Legnouo, E., Samways, M., Simaika, J., 2014. Value of artificial ponds for aquatic beetle and bug conservation in the Cape Floristic Region biodiversity hotspot. Aquat. Conserv. Mar. Freshw. Ecosyst. 24, 522\u0026ndash;535. https://doi.org/10.1002/aqc.2413\u003c/li\u003e\n\u003cli\u003eAwad, J., Brunetti, G., Juhasz, A., Williams, M., Navarro, D., Drigo, B., Bougoure, J., Vanderzalm, J., Beecham, S. 2022. Application of native plants in constructed floating wetlands as a passive remediation approach for PFAS-impacted surface water. J. Hazard. Mater. 429, 128326. https://doi.org/10.1016/j.jhazmat.2022.128326.\u003c/li\u003e\n\u003cli\u003eBabatunde, A., Zhao, Y., O\u0026rsquo;Neill, M., O\u0026rsquo;Sullivan, B., 2008. Constructed wetlands for environmental pollution control: A review of developments, research and practice in Ireland. Environ. Int. 34, 116\u0026ndash;126. https://doi.org/10.1016/j.envint.2007.06.013\u003c/li\u003e\n\u003cli\u003eBarco, A., Bona, S., Borin, M., 2021. Plant species for floating treatment wetlands: A decade of experiments in North Italy. Sci. Total Environ. 751. https://doi.org/10.1016/j.scitotenv.2020.141666\u003c/li\u003e\n\u003cli\u003eBatchelor, A., Loots, P., 1997. A critical evaluation of a pilot scale subsurface flow wetland: 10 years after commissioning. Water Sci. Technol. 35, 337\u0026ndash;343.\u003c/li\u003e\n\u003cli\u003eBates, D., M\u0026auml;chler, M., Bolker, B.M., Walker, S.C., 2015. Fitting linear mixed-effects models using lme4. J. Stat. Softw. 67. https://doi.org/10.18637/jss.v067.i01\u003c/li\u003e\n\u003cli\u003eBi, R., Zhou, C., Jia, Y., Wang, S., Li, P., Reichwaldt, E.S., Liu, W., 2019. Giving waterbodies the treatment they need: A critical review of the application of constructed floating wetlands. J. Environ. Manage. 238, 484\u0026ndash;498. https://doi.org/10.1016/j.jenvman.2019.02.064\u003c/li\u003e\n\u003cli\u003eBiggs, D., Turpie, J., Fabricius, C., 2006. The Economics, Institutions and Conservation Benefits of Community-Based Avitourism in South Africa.\u003c/li\u003e\n\u003cli\u003eBorne, K.E., Fassman, E.A., Tanner, C.C., 2013. Floating treatment wetland retrofit to improve stormwater pond performance for suspended solids, copper and zinc. Ecol. Eng. 54, 173\u0026ndash;182. https://doi.org/10.1016/j.ecoleng.2013.01.031\u003c/li\u003e\n\u003cli\u003eBoucher, C., Withers, M., 2004. Palmiet: Prionium serratum, a Cape river plant. Veld Flora 26\u0026ndash;28.\u003c/li\u003e\n\u003cli\u003eBrisson, J., Chazarenc, F., 2009. Maximizing pollutant removal in constructed wetlands: Should we pay more attention to macrophyte species selection? Sci. Total Environ. 407, 3923\u0026ndash;3930. https://doi.org/10.1016/j.scitotenv.2008.05.047\u003c/li\u003e\n\u003cli\u003eBrix, H., 1993. Wastewater treatment in constructed wetlands: System design, removal processes and treatment performance, in: Moshiri, A. (Ed.), Constructed Wetlands for Water Quality Improvement. Lewis Publishers, Boca Raton, Florida, pp. 9\u0026ndash;22.\u003c/li\u003e\n\u003cli\u003eChoudhury, M.I., Segersten, J., Hellman, M., Mckie, B.G., Hallin, S., Ecke, F., 2019. Importance of plant species for nitrogen removal using constructed floating wetlands in a cold climate. Ecol. Eng. 138, 126\u0026ndash;132. https://doi.org/10.1016/j.ecoleng.2019.07.012\u003c/li\u003e\n\u003cli\u003eColares, G.S., Dell\u0026rsquo;Osbel, N., Wiesel, P.G., Oliveira, G.A., Lemos, P.H.Z., da Silva, F.P., Lutterbeck, C.A., Kist, L.T., Machado, \u0026Ecirc;.L., 2020. Floating treatment wetlands: A review and bibliometric analysis. Sci. Total Environ. 714. https://doi.org/10.1016/j.scitotenv.2020.136776\u003c/li\u003e\n\u003cli\u003eDe La Rey, P.A., Taylor, J.C., Laas, A., Van Rensburg, L., Vosloo, A., 2004. Determining the possible application value of diatoms as indicators of general water quality: A comparison with SASS 5. Water SA 30, 325\u0026ndash;332. https://doi.org/10.4314/wsa.v30i3.5080\u003c/li\u003e\n\u003cli\u003eDe Villiers, S., Thiart, C., 2007. The nutrient status of South African rivers: Concentrations, trends and fluxes from the 1970s to 2005. S. Afr. J. Sci. 103, 343\u0026ndash;349.\u003c/li\u003e\n\u003cli\u003eDeacon, C., Samways, M.J., Pryke, J.S., 2018. Artificial reservoirs complement natural ponds to improve pondscape resilience in conservation corridors in a biodiversity hotspot. PLoS One 13, 1\u0026ndash;17. https://doi.org/10.1371/journal.pone.0204148\u003c/li\u003e\n\u003cli\u003eDonnenfeld, Z., Crookes, C., Hedden, S., 2018. A delicate balance: Water scarcity in South Africa. South. Africa Rep. 13, 1\u0026ndash;24.\u003c/li\u003e\n\u003cli\u003eDWAF, 1996. South African water quality guidelines, in: Aquatic Ecosystems.\u003c/li\u003e\n\u003cli\u003eEmmerson, W.D., 1989. The Nutrient Status of the Sundays River Estuary South Africa. Water Res. 23, 1059\u0026ndash;1067.\u003c/li\u003e\n\u003cli\u003eFeng, X.Y., Raitt, L.M., Jonker, L., 2005. A Survey of Inorganic Chemical Pollution in the Bottelary River, Cape Town.\u003c/li\u003e\n\u003cli\u003eFrenzel, P., 2018. Investigating the potential of floating wetlands in small farm dams in the Western Cape, South Africa (Masters dissertation). Stellenbosch University.\u003c/li\u003e\n\u003cli\u003eGarcia Chanc, L.M., Van Brunt, S.C., Majsztrik, J.C., White, S.A., 2019. Short- and long-term dynamics of nutrient removal in floating treatment wetlands. Water Res. 159, 153\u0026ndash;163. https://doi.org/10.1016/j.watres.2019.05.012\u003c/li\u003e\n\u003cli\u003eGarnier, E., Laurent, G., Bellmann, A., Debain, S., Berthelier, P., Ducout, B., Roumet, C., Navas, M., 2001. Consistency leaf traits species ranking based on functional leaf traits. New Phytol. 152, 69\u0026ndash;83. https://doi.org/10.1046/j.0028-646x.2001.00239.x\u003c/li\u003e\n\u003cli\u003eGe, Z., Feng, C., Wang, X., Zhang, J., 2016. Seasonal applicability of three vegetation constructed floating treatment wetlands for nutrient removal and harvesting strategy in urban stormwater retention ponds. Int. Biodeterior. Biodegrad. 112, 80\u0026ndash;87. https://doi.org/10.1016/j.ibiod.2016.05.007\u003c/li\u003e\n\u003cli\u003eGonz\u0026aacute;lez-Alcaraz, M.N., Egea, C., Mar\u0026iacute;a-Cervantes, A., Jim\u0026eacute;nez-C\u0026aacute;rceles, F.J., \u0026Aacute;lvarez-Rogel, J., 2011. Effects of eutrophic water flooding on nitrate concentrations in mine wastes. Ecol. Eng. 37, 693\u0026ndash;702. https://doi.org/10.1016/j.ecoleng.2010.02.009\u003c/li\u003e\n\u003cli\u003eGordon, N., Adams, J.B., Garcia-Rodriguez, F., 2011. Water quality status and phytoplankton composition in Soetendalvlei, Vo\u0026euml;lvlei and Waskraalsvlei, three shallow wetlands on the Agulhas Plain, South Africa. African J. Aquat. Sci. 36, 19\u0026ndash;33. https://doi.org/10.2989/16085914.2011.559709\u003c/li\u003e\n\u003cli\u003eGrassein, F., Lemauviel-Lavenant, S., Lavorel, S., Bahn, M., Bardgett, R.D., Desclos-Theveniau, M., Laine, P., 2015. Relationships between functional traits and inorganic nitrogen acquisition among eight contrasting European grass species. Ann. Bot. 115, 107\u0026ndash;115. https://doi.org/10.1093/aob/mcu233\u003c/li\u003e\n\u003cli\u003eGriffin, N.J., 2017. The rise and fall of dissolved phosphate in South African rivers. S. Afr. J. Sci. 113, 1\u0026ndash;7. https://doi.org/10.17159/sajs.2017/20170020\u003c/li\u003e\n\u003cli\u003eGrime, J.P, 1977. Evidence for the Existence of Three Primary Strategies in Plants and Its Relevance to Ecological and Evolutionary Theory. Am Natur. 111, 1169\u0026ndash;1194. \u003c/li\u003e\n\u003cli\u003eGuittonny-Philippe, A., Masotti, V., H\u0026ouml;hener, P., Boudenne, J.-L., Viglione, J., Laffont-Schwob, I., 2014. Constructed wetlands to reduce metal pollution from industrial catchments in aquatic Mediterranean ecosystems: A review to overcome obstacles and suggest potential solutions. Environ. Int. 64, 1\u0026ndash;16. https://doi.org/10.1016/j.envint.2013.11.016\u003c/li\u003e\n\u003cli\u003eHalekoh, U., H\u0026oslash;jsgaard, S., 2014. A kenward-Roger approximation and parametric bootstrap methods for tests in linear mixed models-the R package pbkrtest. J. Stat. Softw. 59, 1\u0026ndash;32. https://doi.org/10.18637/jss.v059.i09\u003c/li\u003e\n\u003cli\u003eHarding, W.R., 2015. Living with eutrophication in South Africa: A review of realities and challenges. Trans. R. Soc. South Africa 70, 155\u0026ndash;171. https://doi.org/10.1080/0035919X.2015.1014878\u003c/li\u003e\n\u003cli\u003eHeadley, T.R., Tanner, C.C., 2008. Floating Treatment Wetlands: an Innovative Option for Stormwater Quality Applications, in: 11th International Conference on Wetland Systems for Water Pollution Control. pp. 1101\u0026ndash;1106.\u003c/li\u003e\n\u003cli\u003eHeadley, T.R., Tanner, C.C., 2012. Constructed wetlands with floating emergent macrophytes: An innovative stormwater treatment technology. Crit. Rev. Environ. Sci. Technol. 42, 2261\u0026ndash;2310. https://doi.org/10.1080/10643389.2011.574108\u003c/li\u003e\n\u003cli\u003eHoveka, L.N., van der Bank, M., Davies, T.J., 2020. Evaluating the performance of a protected area network in South Africa and its implications for megadiverse countries. Biol. Conserv. 248, 108577. https://doi.org/10.1016/j.biocon.2020.108577\u003c/li\u003e\n\u003cli\u003eHu, M.H., Ao, Y.S., Yang, X.E., Li, T.Q., 2008. Treating eutrophic water for nutrient reduction using an aquatic macrophyte (Ipomoea aquatica Forsskal) in a deep flow technique system. Agric. Water Manag. 95, 607\u0026ndash;615. https://doi.org/10.1016/j.agwat.2008.01.001\u003c/li\u003e\n\u003cli\u003eHubbard, R.K., Gascho, G.J., Newton, G.L., 2004. Use of floating vegetation to remove nutrients from swine lagoon wastewater. Trans. Am. Soc. Agric. Eng. 47, 1963\u0026ndash;1972. https://doi.org/10.13031/2013.17809\u003c/li\u003e\n\u003cli\u003eHuth, I., Walker, C., Kulkarni, R., Lucke, T., 2021. Using constructed floating wetlands to remove nutrients from a waste stabilization pond. Water 13. https://doi.org/10.3390/w13131746\u003c/li\u003e\n\u003cli\u003eIRIS, 2021. Effluent Discharge Into South African Rivers: Integrated Regulatory Information System (IRIS) Dashboard [WWW Document]. Dep. Water Sanit. URL http://ws.dwa.gov.za/IRIS/myriver.aspx?c2VvcD0xJnNob3dfYWxsPTE= (accessed 11.1.21).\u003c/li\u003e\n\u003cli\u003eJacklin, D.M., Brink, I.C., Jacobs, S.M., 2021a. A phyto-guide to species selection for optimised South African green infrastructure. Water SA 47, 515-522. https://doi.org/10.17159/wsa/2021.v47.i4.3875\u003c/li\u003e\n\u003cli\u003eJacklin, D.M., Brink, I.C., Jacobs, S.M., 2021b. Efficiencies of indigenous South African plant biofilters for urban stormwater runoff water quality improvement with a focus on nutrients and metals. AQUA \u0026mdash; Water Infrastructure, Ecosyst. Soc. https://doi.org/10.2166/aqua.2021.187\u003c/li\u003e\n\u003cli\u003eJacklin, D.M., Brink, I.C., Jacobs, S.M., 2021c. Exploring the use of indigenous Western Cape plants as potential water and soil pollutant phytoremediators with a focus on green infrastructure. Water SA 47, 317-325. https://doi.org/10.17159/wsa/2021.v47.i3.11860\u003c/li\u003e\n\u003cli\u003eJacklin, D.M., Brink, I.C., Jacobs, S.M., 2021d. Urban stormwater nutrient and metal removal in small-scale green infrastructure: exploring engineered plant biofilter media optimisation. Water Sci Tech 84, 1715-1731. https://doi.org/10.2166/wst.2021.353\u003c/li\u003e\n\u003cli\u003eKeizer-Vlek, H.E., Verdonschot, P.F.M., Verdonschot, R.C.M., Dekkers, D., 2014. The contribution of plant uptake to nutrient removal by floating treatment wetlands. Ecol. Eng. 73, 684\u0026ndash;690. https://doi.org/10.1016/j.ecoleng.2014.09.081\u003c/li\u003e\n\u003cli\u003eKivaisi, A.K., 2001. The potential for constructed wetlands for wastewater treatment and reuse in developing countries: a review. Ecol. Eng. 16, 545\u0026ndash;560. https://doi.org/10.1016/S0925-8574(00)00113-0\u003c/li\u003e\n\u003cli\u003eKyambadde, J., Kansiime, F., Gumaelius, L., Dalhammar, G., 2004. A comparative study of Cyperus papyrus and Miscanthidium violaceum-based constructed wetlands for wastewater treatment in a tropical climate. Water Res. 38, 475\u0026ndash;485. https://doi.org/10.1016/j.watres.2003.10.008\u003c/li\u003e\n\u003cli\u003eLadislas, S., G\u0026eacute;rente, C., Chazarenc, F., Brisson, J., Andr\u0026egrave;s, Y., 2015. Floating treatment wetlands for heavy metal removal in highway stormwater ponds. Ecol. Eng. 80, 85\u0026ndash;91. https://doi.org/10.1016/j.ecoleng.2014.09.115\u003c/li\u003e\n\u003cli\u003eLamont, B.B., 1983. Strategies for Maximizing Nutrient Uptake in Two Mediterranean Ecosystems of Low Nutrient Status, in: Kruger, F.J., Mitchell, D.T., Jarvis, J.U.M. (Eds.), Mediterranean-Type Ecosystems: The Role of Nutrients. Springer, Berlin, Heidelberg, pp. 246\u0026ndash;273.\u003c/li\u003e\n\u003cli\u003eLasfar, S., Monette, F., Millette, L., Azzouz, A., 2007. Intrinsic growth rate: A new approach to evaluate the effects of temperature, photoperiod and phosphorus-nitrogen concentrations on duckweed growth under controlled eutrophication. Water Res. 41, 2333\u0026ndash;2340. https://doi.org/10.1016/j.watres.2007.01.059\u003c/li\u003e\n\u003cli\u003eLenth, R. V., 2021. emmeans: Estimated Marginal Means, aka Least-Squares Means. R Packag. version 1.6.3.\u003c/li\u003e\n\u003cli\u003eLi, M., Wu, Y.-J., Yu, Z.-L., Sheng, G.-P., Yu, H.-Q., 2009. Enhanced nitrogen and phosphorus removal from eutrophic lake water by Ipomoea aquatica with low-energy ion implantation. Water Res. 43, 1247\u0026ndash;1256. https://doi.org/10.1016/j.watres.2008.12.013\u003c/li\u003e\n\u003cli\u003eLi, X.N., Song, H.L., Li, W., Lu, X.W., Nishimura, O., 2010. An integrated ecological floating-bed employing plant, freshwater clam and biofilm carrier for purification of eutrophic water. Ecol. Eng. 36, 382\u0026ndash;390. https://doi.org/10.1016/j.ecoleng.2009.11.004\u003c/li\u003e\n\u003cli\u003eLu, S., Zhang, P., Jin, X., Xiang, C., Gui, M., Zhang, J., Li, F., 2009. Nitrogen removal from agricultural runoff by full-scale constructed wetland in China. Hydrobiologia 621, 115\u0026ndash;126. https://doi.org/10.1007/s10750-008-9636-1\u003c/li\u003e\n\u003cli\u003eLynch, J., Fox, L.J., Owen, J.S., Sample, D.J., 2015. Evaluation of commercial floating treatment wetland technologies for nutrient remediation of stormwater. Ecol. Eng. 75, 61\u0026ndash;69. https://doi.org/10.1016/j.ecoleng.2014.11.001\u003c/li\u003e\n\u003cli\u003eMoor, H., Rydin, H., Hylander, K., Nilsson, M.B., Lindborg, R., Norberg, J., 2017. Towards a trait-based ecology of wetland vegetation. J. Ecol. 1, 1\u0026ndash;13. https://doi.org/10.1111/1365-2745.12734\u003c/li\u003e\n\u003cli\u003eMorrison, G., Fatoki, O.S., Persson, L., Ekberg, A., 2001. Assessment of the impact of point source pollution from the Keiskammahoek Sewage Treatment Plant on the Keiskamma River - pH, electrical conductivity, oxygen- demanding substance (COD) and nutrients. Water SA 27, 475\u0026ndash;480. https://doi.org/10.4314/wsa.v27i4.4960\u003c/li\u003e\n\u003cli\u003eM\u0026uuml;ller, I., Schmid, B., Weiner, J., 2000. The effect of nutrient availability on biomass allocation patterns in 27 species of herbaceous plants. Perspect. Plant Ecol. Evol. Syst. 3, 115\u0026ndash;127. https://doi.org/10.1078/1433-8319-00007\u003c/li\u003e\n\u003cli\u003eMusingafi, M.C.C., Tom, T., 2014. Fresh water sources pollution: A human related threat to fresh water security in South Africa. J. Public Policy Gov. 1, 72\u0026ndash;81.\u003c/li\u003e\n\u003cli\u003eNg, Y.S., Chan, D.J.C., 2021. The enhancement of treatment capacity and the performance of phytoremediation system by fed batch and periodic harvesting. RSC Adv. 11, 6049\u0026ndash;6059. https://doi.org/10.1039/d0ra08088h\u003c/li\u003e\n\u003cli\u003eNowlin, W.H., Evarts, J.L., Vanni, M.J., 2005. Release rates and potential fates of nitrogen and phosphorus from sediments in a eutrophic reservoir. Freshw. Biol. 50, 301\u0026ndash;322. https://doi.org/10.1111/j.1365-2427.2004.01316.x\u003c/li\u003e\n\u003cli\u003eOberholster, P.J., Ashton, P.J., 2008. State of the nation report: An overview of the current status of water quality and eutrophication in South African rivers and reservoirs, Parliamentary Grant Deliverable.\u003c/li\u003e\n\u003cli\u003eOlgu\u0026iacute;n, E.J., S\u0026aacute;nchez-Galv\u0026aacute;n, G., Melo, F.J., Hern\u0026aacute;ndez, V.J., Gonz\u0026aacute;lez-Portela, R.E., 2017. Long-term assessment at field scale of Floating Treatment Wetlands for improvement of water quality and provision of ecosystem services in a eutrophic urban pond. Sci. Total Environ. 584\u0026ndash;585, 561\u0026ndash;571. https://doi.org/10.1016/j.scitotenv.2017.01.072\u003c/li\u003e\n\u003cli\u003eOliveira, G.A., Colares, G.S., Lutterbeck, C.A., Dell\u0026rsquo;Osbel, N., Machado, \u0026Ecirc;.L., Rodrigues, L.R., 2021. Floating treatment wetlands in domestic wastewater treatment as a decentralized sanitation alternative. Sci. Total Environ. 773, 145609. https://doi.org/10.1016/j.scitotenv.2021.145609\u003c/li\u003e\n\u003cli\u003ePadedda, B.M., Sechi, N., Lai, G.G., Mariani, M.A., Pulina, S., Satta, C.T., Bazzoni, A.M., Virdis, T., Buscarinu, P., Lugli\u0026egrave;, A., 2015. A fast-response methodological approach to assessing and managing nutrient loads in eutrophic Mediterranean reservoirs. Ecol. Eng. 85, 47\u0026ndash;55. https://doi.org/10.1016/j.ecoleng.2015.09.062\u003c/li\u003e\n\u003cli\u003ePavlineri, N., Skoulikidis, N.T., Tsihrintzis, V.A., 2017. Constructed Floating Wetlands: A review of research, design, operation and management aspects, and data meta-analysis. Chem. Eng. J. 308, 1120\u0026ndash;1132. https://doi.org/10.1016/j.cej.2016.09.140\u003c/li\u003e\n\u003cli\u003eP\u0026eacute;rez-Harguindeguy, N., Diaz, S., Garnier, E., Lavorel, S., Poorter, H., Jaureguiberry, P., Bret-Harte, M.S.S., Cornwell, W.K.K., Craine, J.M.M., Gurvich, D.E.E., Urcelay, C., Veneklaas, E.J.J., Reich, P.B.B., Poorter, L., Wright, I.J.J., Etc., Ray, P., Etc., D\u0026iacute;az, S., Lavorel, S., Poorter, H., Jaureguiberry, P., Bret-Harte, M.S.S., Cornwell, W.K.K., Craine, J.M.M., Gurvich, D.E.E., Urcelay, C., Veneklaas, E.J.J., Reich, P.B.B., Poorter, L., Wright, I.J.J., Ray, P., Enrico, L., Pausas, J.G., Vos, A.C. de, Buchmann, N., Funes, G., Qu\u0026eacute;tier, F., Hodgson, J.G., Thompson, K., Morgan, H.D., Steege, H. ter, Heijden, M.G.A. van der, Sack, L., Blonder, B., Poschlod, P., Vaieretti, M. V., Conti, G., Staver, A.C., Aquino, S., Cornelissen, J.H.C., 2013. New Handbook for standardized measurment of plant functional traits worldwide. Aust. J. Bot. 61, 167\u0026ndash;234. https://doi.org/http://dx.doi.org/10.1071/BT12225\u003c/li\u003e\n\u003cli\u003ePolomski, R.F., Taylor, M.D., Bielenberg, D.G., Bridges, W.C., Klaine, S.J., Whitwell, T., 2009. Nitrogen and phosphorus remediation by three floating aquatic macrophytes in greenhouse-based laboratory-scale subsurface constructed wetlands. Water. Air. Soil Pollut. 197, 223\u0026ndash;232. https://doi.org/10.1007/s11270-008-9805-x\u003c/li\u003e\n\u003cli\u003eR Core Team, 2019. R: A language and environment for statistical computing.\u003c/li\u003e\n\u003cli\u003eRebelo, A.J., Jarmain, C., Esler, K.J., Cowling, R.M., Le Maitre, D.C., 2020. Water-use characteristics of Palmiet (Prionium serratum), an endemic south African wetland plant. Water SA 46, 558\u0026ndash;572. https://doi.org/10.17159/wsa/2020.v46.i4.9069\u003c/li\u003e\n\u003cli\u003eRebelo, A. J., Sieben, E. Meire, P., Esler, K.J. 2022. at drives patchiness in palmiet wetlands? Wetlands Ecol. Manage. 30:785\u0026ndash;811. https://doi.org/10.1007/s11273-021-09853-1\u003c/li\u003e\n\u003cli\u003eRehman, K., Ijaz, A., Arslan, M., Afzal, M., 2019. Floating treatment wetlands as biological buoyant filters for wastewater reclamation. Int. J. Phytoremediation 21, 1273\u0026ndash;1289. https://doi.org/10.1080/15226514.2019.1633253\u003c/li\u003e\n\u003cli\u003eRezazada, F.A., 2020. Constructed floating wetlands mediated nutrient management of eutrophic lakes. World J. Adv. Res. Rev. 7, 212\u0026ndash;221. https://doi.org/10.30574/wjarr\u003c/li\u003e\n\u003cli\u003eRichardson, C., Vaithiyanathan, P., 2009. Biogeochemical Dynamics II: Cycling and Storage of Phosphorus in Wetlands, in: Maltby, E., Barker, T. (Eds.), The Wetlands Handbook. Wiley-Blackwell, Oxford, UK, pp. 228\u0026ndash;248.\u003c/li\u003e\n\u003cli\u003eRommens, W., Maes, J., Dekeza, N., Inghelbrecht, P., Nhiwatiwa, T., Holsters, E., Ollevier, F., Marshall, B., Brendonck, L., 2003. The impact of water hyacinth (Eichhornia crassipes) in a eutrophic subtropical impoundment (Lake Chivero, Zimbabwe). I. Water quality. Arch. f\u0026uuml;r Hydrobiol. 158, 373\u0026ndash;388. https://doi.org/10.1127/0003-9136/2003/0158-0373\u003c/li\u003e\n\u003cli\u003eSaeed, T., Paul, B., Afrin, R., Al-muyeed, A., Sun, G., 2016. Floating constructed wetland for the treatment of polluted river water : A pilot scale study on seasonal variation and shock load. Chem. Eng. J. 287, 62\u0026ndash;73. https://doi.org/10.1016/j.cej.2015.10.118\u003c/li\u003e\n\u003cli\u003eSamal, K., Kar, S., Trivedi, S., 2019. Ecological floating bed (EFB) for decontamination of polluted water bodies: Design, mechanism and performance. J. Environ. Manage. 251. https://doi.org/10.1016/j.jenvman.2019.109550\u003c/li\u003e\n\u003cli\u003eSchachtschneider, K., Chamier, J., Somerset, V., 2017. Phytostabilization of metals by indigenous riparian vegetation. Water SA 43, 177\u0026ndash;185. https://doi.org/10.4314/wsa.v43i2.01\u003c/li\u003e\n\u003cli\u003eSchulz, R., Peall, S., 2001. Effectiveness of a Constructed Wetland for Retention of Nonpoint-Source Pesticide Pollution in the Lourens River Catchment, South Africa. Environ. Sci. Technol. 35, 422\u0026ndash;426.\u003c/li\u003e\n\u003cli\u003eSchwammberger, P.F., Yule, C.M., Tindale, N.W., 2020. Rapid plant responses following relocation of a constructed floating wetland from a construction site into an urban stormwater retention pond. Sci. Total Environ. 699. https://doi.org/10.1016/j.scitotenv.2019.134372\u003c/li\u003e\n\u003cli\u003eShahid, M.J., Arslan, M., Ali, S., Siddique, M., Afzal, M., 2018. Floating Wetlands: A sustainable tool for wastewater treatment. Clean - Soil, Air, Water 46. https://doi.org/10.1002/clen.201800120\u003c/li\u003e\n\u003cli\u003eShahid, M.J., Arslan, M., Siddique, M., Ali, S., Tahseen, R., Afzal, M., 2019. Potentialities of floating wetlands for the treatment of polluted water of river Ravi, Pakistan. Ecol. Eng. 133, 167\u0026ndash;176. https://doi.org/10.1016/j.ecoleng.2019.04.022\u003c/li\u003e\n\u003cli\u003eShutes, R.B.E., 2001. Artificial wetlands and water quality improvement. Environ. Int. 26, 441\u0026ndash;447. https://doi.org/10.1016/S0160-4120(01)00025-3\u003c/li\u003e\n\u003cli\u003eSimaika, J.P., Samways, M.J., Frenzel, P.P., 2016. Artificial ponds increase local dragonfly diversity in a global biodiversity hotspot. Biodivers. Conserv. 25, 1\u0026ndash;15. https://doi.org/10.1007/s10531-016-1168-9\u003c/li\u003e\n\u003cli\u003eSpangler, J.T., Sample, D.J., Fox, L.J., Albano, J.P., White, S.A., 2019a. Assessing nitrogen and phosphorus removal potential of five plant species in floating treatment wetlands receiving simulated nursery runoff. Environ. Sci. Pollut. Res. 26, 5751\u0026ndash;5768. https://doi.org/10.1007/s11356-018-3964-0\u003c/li\u003e\n\u003cli\u003eSpangler, J.T., Sample, D.J., Fox, L.J., Owen, J.S., White, S.A., 2019b. Floating treatment wetland aided nutrient removal from agricultural runoff using two wetland species. Ecol. Eng. 127, 468\u0026ndash;479. https://doi.org/10.1016/j.ecoleng.2018.12.017\u003c/li\u003e\n\u003cli\u003eStefanakis, A.I., 2019. The role of constructed wetlands as green infrastructure for sustainable urban water management. Sustainability 11. https://doi.org/10.3390/su11246981\u003c/li\u003e\n\u003cli\u003eStewart, F.M., Mulholland, T., Cunningham, A.B., Kania, B.G., Osterlund, M.T., 2008. Floating islands as an alternative to constructed wetlands for treatment of excess nutrients from agricultural and municipal wastes-results of laboratory-scale tests. L. Contam. Reclam. 16, 25\u0026ndash;33. https://doi.org/10.2462/09670513.874\u003c/li\u003e\n\u003cli\u003eSuding, K.N., Collins, S.L., Gough, L., Clark, C., Cleland, E.E., Gross, K.L., Milchunas, D.G., Pennings, S., 2005. Functional- and abundance-based mechanisms explain diversity loss due to N fertilization. Proc. Natl. Acad. Sci. U. S. A. 102, 4387\u0026ndash;4392. https://doi.org/10.1073/pnas.0408648102\u003c/li\u003e\n\u003cli\u003eSugiyama, S., Hama, T., 2013. Effects of water temperature on phosphate adsorption onto sediments in an agricultural drainage canal in a paddy-field district. Ecol. Eng. 61, 94\u0026ndash;99. https://doi.org/10.1016/j.ecoleng.2013.09.053\u003c/li\u003e\n\u003cli\u003eSun, L., Liu, Y., Jin, H., 2009. Nitrogen removal from polluted river by enhanced floating bed grown canna. Ecol. Eng. 35, 135\u0026ndash;140. https://doi.org/10.1016/j.ecoleng.2008.09.016\u003c/li\u003e\n\u003cli\u003eSun, S., Gao, L., He, S., Huang, J., Zhou, W., 2019. Nitrogen removal in response to plants harvesting in two kinds of enhanced hydroponic root mats treating secondary effluent. Sci. Total Environ. 670, 200\u0026ndash;209. https://doi.org/10.1016/j.scitotenv.2019.03.182\u003c/li\u003e\n\u003cli\u003eTanner, C.C., 1996. Plants for constructed wetland treatment systems - A comparison of the growth and nutrient uptake of eight emergent species. Ecol. Eng. 7, 59\u0026ndash;83. https://doi.org/10.1016/0925-8574(95)00066-6\u003c/li\u003e\n\u003cli\u003eTanner, C.C., Headley, T.R., 2011. Components of floating emergent macrophyte treatment wetlands influencing removal of stormwater pollutants. Ecol. Eng. 37, 474\u0026ndash;486. https://doi.org/10.1016/j.ecoleng.2010.12.012\u003c/li\u003e\n\u003cli\u003eTemmink, R.J.M., Fritz, C., van Dijk, G., Hensgens, G., Lamers, L.P.M., Krebs, M., Gaudig, G., Joosten, H., 2017. Sphagnum farming in a eutrophic world: The importance of optimal nutrient stoichiometry. Ecol. Eng. 98, 196\u0026ndash;205. https://doi.org/10.1016/j.ecoleng.2016.10.069\u003c/li\u003e\n\u003cli\u003eTeng, C.J., Leu, S.Y., Ko, C.H., Fan, C., Sheu, Y.S., Hu, H.Y., 2012. Economic and environmental analysis of using constructed riparian wetlands to support urbanized municipal wastewater treatment. Ecol. Eng. 44, 249\u0026ndash;258. https://doi.org/10.1016/j.ecoleng.2012.03.009\u003c/li\u003e\n\u003cli\u003eTharp, R., Westhelle, K., Hurley, S., 2019. Macrophyte performance in floating treatment wetlands on a suburban stormwater pond: Implications for cold climate conditions. Ecol. Eng. 136, 152\u0026ndash;159. https://doi.org/10.1016/j.ecoleng.2019.06.011\u003c/li\u003e\n\u003cli\u003eVan De Moortel, A.M.K., Meers, E., De Pauw, N., Tack, F.M.G., 2010. Effects of vegetation, season and temperature on the removal of pollutants in experimental floating treatment wetlands. Water. Air. Soil Pollut. 212, 281\u0026ndash;297. https://doi.org/10.1007/s11270-010-0342-z\u003c/li\u003e\n\u003cli\u003eVan Ginkel, C.E., 2011. Eutrophication: Present reality and future challenges for South Africa. Water SA 37, 693\u0026ndash;702. https://doi.org/10.4314/wsa.v37i5.6\u003c/li\u003e\n\u003cli\u003eVan Ginkel, C.E., Glen, R.P., Gordon-Gray, K.D., Cilliers, C.J., Muasya, M., van Deventer, P.P., 2011. Easy identification of some South African wetland plants (Grasses, Restios, Sedges, Rushes, Bulrushes, Eriocaulons and Yellow-eyed grasses), Water Research Commission.\u003c/li\u003e\n\u003cli\u003eVan Rensburg, S.J., Barnard, S., Kr\u0026uuml;ger, M., 2016. Challenges in the potable water industry due to changes in source water quality: Case study of Midvaal Water Company, South Africa. Water SA 42, 633\u0026ndash;640. https://doi.org/10.4314/wsa.v42i4.14\u003c/li\u003e\n\u003cli\u003eVerschoren, V., Schoelynck, J., Buis, K., Visser, F., Meire, P., Temmerman, S., 2017. Mapping the spatio-temporal distribution of key vegetation cover properties in lowland river reaches, using digital photography. Environ. Monit. Assess. 189. https://doi.org/10.1007/s10661-017-6004-5\u003c/li\u003e\n\u003cli\u003eVymazal, J., 2007. Removal of nutrients in various types of constructed wetlands. Sci. Total Environ. 380, 48\u0026ndash;65. https://doi.org/10.1016/j.scitotenv.2006.09.014\u003c/li\u003e\n\u003cli\u003eVymazal, J., 2013. The use of hybrid constructed wetlands for wastewater treatment with special attention to nitrogen removal: A review of a recent development. Water Res. 47, 4795\u0026ndash;4811. https://doi.org/10.1016/j.watres.2013.05.029\u003c/li\u003e\n\u003cli\u003eWang, C.Y., Sample, D.J., 2014. Assessment of the nutrient removal effectiveness of floating treatment wetlands applied to urban retention ponds. J. Environ. Manage. 137, 23\u0026ndash;35. https://doi.org/10.1016/j.jenvman.2014.02.008\u003c/li\u003e\n\u003cli\u003eWang, C., Sample, D.J., Day, S.D., Grizzard, T.J., 2015. Floating treatment wetland nutrient removal through vegetation harvest and observations from a field study. Ecol. Eng. 78, 15\u0026ndash;26. https://doi.org/10.1016/j.ecoleng.2014.05.018\u003c/li\u003e\n\u003cli\u003eWang, W.H., Wang, Y., Sun, L.Q., Zheng, Y.C., Zhao, J.C., 2020. Research and application status of ecological floating bed in eutrophic landscape water restoration. Sci. Total Environ. 704, 135434. https://doi.org/10.1016/j.scitotenv.2019.135434\u003c/li\u003e\n\u003cli\u003eWanielista, M., Chang, N.-B., Chopra, M., Xuan, Z., Islam, K., Marimon, Z., 2012. Floating Wetland Systems for Nutrient Removal in Stormwater Ponds. Orlando.\u003c/li\u003e\n\u003cli\u003eWard, E.W., Winter, K., 2016. Missing the link: Urban stormwater quality and resident behaviour. Water SA 42, 571\u0026ndash;576. https://doi.org/10.4314/wsa.v42i4.07\u003c/li\u003e\n\u003cli\u003eWen, L., Recknagel, F., 2002. In situ removal of dissolved phosphorus in irrigation drainage water by planted floats: Preliminary results from growth chamber experiment. Agric. Ecosyst. Environ. 90, 9\u0026ndash;15. https://doi.org/10.1016/S0167-8809(01)00292-4\u003c/li\u003e\n\u003cli\u003eWest, S., Cairns, R., Schultz, L., 2016. What constitutes a successful biodiversity corridor? A Q-study in the Cape Floristic Region, South Africa. Biol. Conserv. 198, 183\u0026ndash;192. https://doi.org/10.1016/j.biocon.2016.04.019\u003c/li\u003e\n\u003cli\u003eWhite, S.A., Cousins, M.M., 2013. Floating treatment wetland aided remediation of nitrogen and phosphorus from simulated stormwater runoff. Ecol. Eng. 61, 207\u0026ndash;215. https://doi.org/10.1016/j.ecoleng.2013.09.020\u003c/li\u003e\n\u003cli\u003eWinston, R.J., Hunt, W.F., Kennedy, S.G., Merriman, L.S., Chandler, J., Brown, D., 2013. Evaluation of floating treatment wetlands as retrofits to existing stormwater retention ponds. Ecol. Eng. 54, 254\u0026ndash;265. https://doi.org/10.1016/j.ecoleng.2013.01.023\u003c/li\u003e\n\u003cli\u003eWood, A., Pybus, P., 1992. Artificial wetland use for wastewater treatment theory, practice and economic review. Pretoria.\u003c/li\u003e\n\u003cli\u003eWu, H., Zhang, J., Ngo, H.H., Guo, W., Hu, Z., Liang, S., Fan, J., Liu, H., 2015. A review on the sustainability of constructed wetlands for wastewater treatment: Design and operation. Bioresour. Technol. 175, 594\u0026ndash;601. https://doi.org/10.1016/j.biortech.2014.10.068\u003c/li\u003e\n\u003cli\u003eWu, Q., Hu, Y., Li, S., Peng, S., Zhao, H., 2016. Microbial mechanisms of using enhanced ecological floating beds for eutrophic water improvement. Bioresour. Technol. 211, 451\u0026ndash;456. https://doi.org/10.1016/j.biortech.2016.03.113\u003c/li\u003e\n\u003cli\u003eWu, S., Kuschk, P., Brix, H., Vymazal, J., Dong, R., 2014. Development of constructed wetlands in performance intensifications for wastewater treatment: A nitrogen and organic matter targeted review. Water Res. 57, 40\u0026ndash;55. https://doi.org/10.1016/j.watres.2014.03.020\u003c/li\u003e\n\u003cli\u003eWu, Y., Li, L., Gan, N., Zheng, L., Ma, H., Shan, K., Liu, J., Xiao, B., Song, L., 2014. Seasonal dynamics of water bloom-forming Microcystis morphospecies and the associated extracellular microcystin concentrations in large, shallow, eutrophic Dianchi Lake. J. Environ. Sci. 26, 1921\u0026ndash;1929. https://doi.org/10.1016/j.jes.2014.06.031\u003c/li\u003e\n\u003cli\u003eYang, Z., Wang, Q., Zhang, J., Xie, H., Feng, S., 2016. Effect of Plant Harvesting on the Performance of Constructed Wetlands during Summer. Water 8, 4\u0026ndash;13. https://doi.org/10.3390/w8010024\u003c/li\u003e\n\u003cli\u003eYeh, N., Yeh, P., Chang, Y.H., 2015. Artificial floating islands for environmental improvement. Renew. Sustain. Energy Rev. 47, 616\u0026ndash;622. https://doi.org/10.1016/j.rser.2015.03.090\u003c/li\u003e\n\u003cli\u003eZhang, L., Sun, Z., Xie, J., Wu, J., Cheng, S., 2018. Nutrient removal, biomass accumulation and nitrogen-transformation functional gene response to different nitrogen forms in enhanced floating treatment wetlands. Ecol. Eng. 112, 21\u0026ndash;25. https://doi.org/10.1016/j.ecoleng.2017.12.021\u003c/li\u003e\n\u003cli\u003eZhao, F., Xi, S., Yang, X., Yang, W., Li, J., Gu, B., He, Z., 2012. Purifying eutrophic river waters with integrated floating island systems. Ecol. Eng. 40, 53\u0026ndash;60. https://doi.org/10.1016/j.ecoleng.2011.12.012\u003c/li\u003e\n\u003cli\u003eZhao, F., Zhan, X., Xu, H., Zhu, G., Zou, W., Zhu, M., Kang, L., Guo, Y., Zhao, X., Wang, Z., Tang, W., 2021. New insights into eutrophication management: Importance of temperature and water residence time. J. Environ. Sci. (China) 111, 229\u0026ndash;239. https://doi.org/10.1016/j.jes.2021.02.033\u003c/li\u003e\n\u003cli\u003eZheng, L., Cardenas, M.B., Wang, L., 2016. Temperature effects on nitrogen cycling and nitrate removal-production efficiency in bed form-induced hyporheic zones. J. Geophys. Res. G Biogeosciences 121, 1086\u0026ndash;1103. https://doi.org/10.1002/2015JG003162\u003c/li\u003e\n\u003cli\u003eZhou, X., He, Z., Jones, K.D., Li, L., Stoffella, P.J., 2017. Dominating aquatic macrophytes for the removal of nutrients from waterways of the Indian River Lagoon basin, South Florida, USA. Ecol. Eng. 101, 107\u0026ndash;119. https://doi.org/10.1016/j.ecoleng.2017.01.006\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"wetlands","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wela","sideBox":"Learn more about [Wetlands](https://www.springer.com/journal/13157)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/wela/default.aspx","title":"Wetlands","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"floating treatment wetlands, constructed wetlands, nutrient removal, plant uptake, nature-based solution, water treatment","lastPublishedDoi":"10.21203/rs.3.rs-3860564/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3860564/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eRising anthropogenic-induced nutrient enrichment of surface waters is of great concern globally as it jeopardizes the ecological integrity and functioning of freshwater ecosystems. Floating wetlands have been successfully used to treat nutrient enriched wastewater in developing nations, and provide additional co-benefits. We aimed to quantify the nutrient removal efficiency of high-potential, locally endemic wetland species on floating wetlands in different conditions and to understand whether the nutrient uptake process was characterised by key plant functional traits. Two experiments were run under Mediterranean-climate conditions of the Western Cape of South Africa: (1) a closed, oligotrophic mesocosm experiment representing local conditions and (2) a real-life (\u003cem\u003ein-situ\u003c/em\u003e) eutrophic application. The mesocosm experiment conducted under oligotrophic local conditions yielded low nitrate, phosphate and ammonium removal rates (34.8-35.2\u0026nbsp;mgNO\u003csub\u003e3\u003c/sub\u003e-Nm\u003csup\u003e-2\u003c/sup\u003e.d\u003csup\u003e-1\u003c/sup\u003e, 10.4-10.7\u0026nbsp;mgPO\u003csub\u003e4\u003c/sub\u003e-Pm\u003csup\u003e-2\u003c/sup\u003e.d\u003csup\u003e-1\u003c/sup\u003e and 3.6-3.8\u0026nbsp;mgNH\u003csub\u003e4\u003c/sub\u003e-Nm\u003csup\u003e-\u003c/sup\u003e2.d\u003csup\u003e-1\u003c/sup\u003e) in comparison to other floating wetland studies globally, yet high removal efficiencies (\u0026gt;90%). However the eutrophic \u003cem\u003ein-situ\u003c/em\u003e experiment demonstrated the potential for these same locally endemic plants to remove up to 312\u0026nbsp;g.m\u003csup\u003e-2\u003c/sup\u003e of nitrogen and 47\u0026nbsp;g.m\u003csup\u003e-2\u003c/sup\u003e of phosphorus per year– which is relatively high compared to similar global research. \u003cem\u003eCyperus\u0026nbsp;textilis \u003c/em\u003ehad the highest daily nutrient uptake and content followed by \u003cem\u003ePrionium\u0026nbsp;serratum \u003c/em\u003eand \u003cem\u003eJuncus\u0026nbsp;lomatophyllus, \u003c/em\u003ewhile \u003cem\u003eJ.\u0026nbsp;lomatophyllus \u003c/em\u003ehad the greatest nutrient uptake efficiency. Two of the three species (\u003cem\u003eC.\u0026nbsp;textilis\u003c/em\u003e and \u003cem\u003eP.\u0026nbsp;serratum\u003c/em\u003e) stored significantly more total nutrients in their shoot tissue compared to their root tissue, suggesting that the permanent removal of nutrients from the system is possible through shoot harvesting. Floating wetlands planted with endemic plant species have the potential to remove nutrients effectively and sustainably from eutrophic water and can thus be implemented as low-cost nature-based solutions to mitigate pollution of lentic systems.\u003c/p\u003e","manuscriptTitle":"How well do endemic wetland plant species perform in water purification?","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-30 17:28:42","doi":"10.21203/rs.3.rs-3860564/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2024-01-26T07:02:27+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-01-26T02:24:00+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Wetlands","date":"2024-01-25T21:56:13+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-01-24T03:06:17+00:00","index":"","fulltext":""},{"type":"submitted","content":"Wetlands","date":"2024-01-23T14:04:32+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"wetlands","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wela","sideBox":"Learn more about [Wetlands](https://www.springer.com/journal/13157)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/wela/default.aspx","title":"Wetlands","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"4d55d6f6-67ea-4687-b1d0-02596e1980b7","owner":[],"postedDate":"January 30th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-12-02T16:00:31+00:00","versionOfRecord":{"articleIdentity":"rs-3860564","link":"https://doi.org/10.1007/s13157-024-01871-y","journal":{"identity":"wetlands","isVorOnly":false,"title":"Wetlands"},"publishedOn":"2024-11-26 15:57:14","publishedOnDateReadable":"November 26th, 2024"},"versionCreatedAt":"2024-01-30 17:28:42","video":"","vorDoi":"10.1007/s13157-024-01871-y","vorDoiUrl":"https://doi.org/10.1007/s13157-024-01871-y","workflowStages":[]},"version":"v1","identity":"rs-3860564","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3860564","identity":"rs-3860564","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}