Oysters, a sustainable bluefood?

Oysters, a sustainable bluefood? | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Oysters, a sustainable bluefood? Paula Costa Domech, Ronan Cooney, Alexandre Tahar, Alan Kennedy, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4294313/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Sustainable food production that meets consumer demands while reducing environmental impacts is a critical societal challenge. The seafood industry, including shellfish aquaculture, is considered a key segment for future protein supplies. Like all food production sectors, environmental impacts of the "blue food” sector are a key consideration. The present study demonstrated that Irish Pacific oyster ( Magallana gigas ) farming has relatively low environmental impacts (i.e., 100-year global warming potential of 373.86 kg CO 2 eq. tonne -1 ; acidification potential of 1.33 kg SO 2 eq. tonne -1 ; and eutrophication potential of 0.39 kg PO 4 eq. tonne -1 ) compared to other seafood and terrestrial animal sectors. Using ecosystem services metrics, one tonne of fresh harvested oysters can remove, on average, 3.05 tonnes of nitrogen, 0.35 tonnes of phosphorus, and sequester 70.52 tonnes of carbon from the environment, thus potentially acting as a nutrient remediator and a potential short-term carbon sink. These findings show how oysters can offer a sustainable food source and provide local environmental benefits. The study also points to future work which could further improve ecosystem services modelling for this food source. Biological sciences/Biotechnology/Biologics Biological sciences/Biotechnology Earth and environmental sciences/Ecology Biological sciences/Ecology Biological sciences/Ecology/Agri ecology Biological sciences/Ecology/Climate change ecology Biological sciences/Ecology/Ecosystem services Earth and environmental sciences/Environmental sciences Earth and environmental sciences/Environmental sciences/Environmental impact Earth and environmental sciences/Environmental social sciences Earth and environmental sciences/Environmental social sciences/Climate change adaptation Earth and environmental sciences/Environmental social sciences/Climate change impacts Earth and environmental sciences/Environmental social sciences/Climate change mitigation Earth and environmental sciences/Environmental social sciences/Climate change policy Earth and environmental sciences/Environmental social sciences/Environmental impact Earth and environmental sciences/Environmental social sciences/Sustainability Earth and environmental sciences/Hydrology Biological sciences/Zoology Biological sciences/Zoology/Animal physiology Seafood Ecosystem services Sustainability Carbon capture Life Cycle Assessment Aquaculture. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Agriculture, including terrestrial livestock, has long been the principal protein source for many societies. While food production is an essential human activity, it does have significant environmental costs, including land degradation, climate change impacts, water consumption, deforestation, non-renewable fertilisers (inc. phosphorous), eutrophication, and chemotherapeutics. These challenges have driven innovation to change our food consumption habits and produce food using more sustainable systems [1]. The level of nutrient emissions to surface and coastal waters has increased dramatically over the past 50 years, impairing the quality of coastal waters due to eutrophication and nuisance algal blooms [2,3,4]. As a result, reducing nutrient loads such as nitrogen (N), phosphorous (P), and carbon (C) from anthropogenic activities (e.g., agriculture, wastewater treatment plants and industry emissions) is urgently required to address the overall deterioration of water bodies. In the context of climate change, there is also increasing urgency to reduce carbon emissions and promote carbon sequestration practices. Aquaculture is the activity of farming aquatic species such as finfish, crustaceans and bivalves. It has potential as a sustainable way to produce animal protein [5] and one of the food systems with a lower environmental burden supported by recent European policy, i.e., the European Green Deal [6] and the Farm to Fork Strategy [7]. Within the aquaculture sector, farming low trophic level species, such as bivalves, may be a more sustainable approach due to its lower environmental impact compared to current food production systems, such as terrestrial animal production [8]. From a farming perspective, bivalves have lower technical and labour requirements than other aquatic species, e.g., fish and crustaceans [9]. Bivalve farming doesn’t require feed inputs, as this group of animals are non-feeding organisms, i.e., they take up food particles from the water column or sediment (e.g., particulate organic matter, phytoplankton and zooplankton). In addition, bivalves contribute to carbon sequestration through the shell formation process (i.e., biomineralization), making them a potential net carbon dioxide sink. Bivalves can also provide wider ecosystem services (ES) to the aquatic environment, such as nutrient remediation and C sequestration [10,11]. Some of the most common cultured bivalve species include oysters, mussels, and clams. Several studies conducted on different shellfish species (e.g., blue mussel, Pacific oyster, clams, etc.) have highlighted the potential environmental benefits and the low impacts of bivalve farming (Supplementary Tables 1 and 2 provide an extensive summary of existing literature). For instance, a Danish mussel farm estimated a potential nutrient removal of 0.6-0.9 tonne N ha -1 year -1 and 0.03-0.04 tonne P ha -1 year -1 [12]. A life cycle assessment (LCA) conducted in Italy showed that Manila clam ( Venerupis philippinarum ) and Mediterranean mussel ( Mytilus galloprovincialis ) production resulted in relatively low greenhouse gas emissions of 0.022 and 0.055 kg CO 2- eq. kg harvested and packaged bivalves -1 , respectively. This study also showed that clams and mussels can sequester 254 and 146 g of CO 2 per kg of harvested and packaged bivalves, respectively [13]. However, there is currently limited information on the environmental impact, nutrient removal potential, and C sequestration potential of farmed oysters. A study estimated that Pacific oyster aquaculture could remove 0.02-0.14 tonnes N ha -1 year -1 from seawater [14]. Another study estimated that farmed produced eastern oyster( Crassostrea virginica ) releases a total of 0.13 kg CO 2- eq. kg protein -1 which, compared to other food sectors, was estimated to be less than 0.5% of the greenhouse gas emissions from beef, small ruminants, pork, and poultry [15]. Despite the wider potential benefits of bivalve aquaculture, European production of farmed mussels and oysters has been in a decline. Previous studies have pointed out disease prevalence, lack of mussel and oyster seed and low profitability as the main causes of the sector's decline in the European Union, EU [16,17]. To ensure the sustainable expansion of bivalve aquaculture, the current performance of the bivalve sector, in relation to nutrient emissions and carbon emissions requires further research to enable benchmark data and comparison to other sectors. Estimating the ES of bivalve species is still an emerging area of research, and considerable gaps remain in our understanding of biochemical processes and wider environmental interactions. Much of the published data have been generated in the United States where some species are not currently farmed in EU [18,19,20,21,22,23,24]. Overall, limited research has been undertaken within the EU, with variability in the methodology used [9,12,14,25,26,27]. In addition, most of the studies combining LCA and ES for shellfish only covered the net carbon capture potential of shellfish farming [13,28,29]. To better appraise the environmental performance, sustainability credentials and benefits of the Irish oyster-producing sector, this study evaluated the ES and environmental impacts of Pacific oyster farming by: 1 ) Assessing the nutrient remediation (i.e., N and P) and C sequestration potential ES of Pacific Oyster ( Magallana gigas ) through morphological and elemental analysis of representative samples; 2 ) Analysing the environmental impacts of oyster aquaculture by undertaking LCAs of regional Pacific oyster farms; and 3 ) Combining ES and LCAs results to determine the benefits of Pacific oyster culture in terms of eutrophication (i.e., N and P net remediation) and global warming potential (i.e., net C sink). The study combined ES and LCA approaches to provide a more holistic evaluation of the ecological potential of bivalve aquaculture and the environmental impact of their production. 2. Methods and materials 2.1. Site selection The oyster production sites (i.e., oyster producers or buyers for further processing) used in this study were located on a sheltered bay in the north-west of the Republic of Ireland. Samples from two Pacific oyster-producing sites (i.e., Site 1 and Site 2) were collected for morphological and elemental analysis, while the LCAs were modelled using operational data from three Pacific oyster farms located along the West coast (i.e., Site 1, Site 3 and Site 4), Site 1 providing samples for the morphological and elemental analysis (Figure 1). 2.2. Ecosystem services methodology 2.2.1. Morphological and elemental analysis For morphological and elemental analysis, farmers at each production site randomly harvested 15 individuals per market size category (i.e., small, 67.4-112.5 cm length; medium, 89.4-119.3 cm length; and large, 94.8-120.7 cm length) during different times of the winter season (i.e., February and March). Thus, there were a total of 45 samples per site. The following morphometric measurements were undertaken per oyster : 1. Total shell length, width, and depth; mm oyster -1 ; 2. Total wet weight; g oyster -1 ; 3. Shell wet weight and tissue wet weight; g oyster -1 , 4. Dry tissue and shell weights; g oyster -1 . Among the 15 individuals morphologically assessed per site and size category, sets of 6 individuals were randomly selected and pooled for the elemental analysis [30]. Thus, for each site, 18 individuals were selected for elemental analysis. Tissue and shells from pooled individuals were dried in a fan assisted oven at 80 °C until a constant weight is achieved. Dried tissue and shells from pooled individuals were crushed using a mortar and pestle for dried tissue and a mill for dried shells. The pooled tissue and shell samples were then analysed for N and C content through an elemental CHN analyser (Flash smart elemental analyser, Thermo Fisher, Waltham, Massachusetts, United States). P content was measured through Inductively Coupled Plasma Optical Emission Spectrometry (700 series ICP-OES, Agilent, Santa Clara, California, United States). The results obtained as %C, %N, and %P in the dried tissue and shell samples were used to calculate: (i) the average %C, %N and %P per individual oyster (and separately the tissue and shell for each oyster), size category and site investigated; (ii) the average mass of C, N, and P removed per fresh individual oyster; and (iii) the average mass of C, N, and P removed per tonne of oysters harvested. Differences in the elemental analysis (i.e., %C, %N, %P) of Pacific oyster between the three size classes and the sites investigated were analysed using two-way ANOVA tests. A post-hoc Tukey's test was conducted on each dataset to discern significant differences between sizes and sites. Statistical significance was assigned when P<0.05. Limitations of the approaches used are discussed in Section 4.1. 2.2.2. National ecological impact The morphological and elemental analysis results were then extrapolated to farm and national scale to obtain: a) the quantities of nutrients and carbon removed annually on each production site using the average annual production for the period 2015-2020 i.e., average annual production (tonne year -1 ) x N, P or C removed per tonne of fresh product (kg tonne -1 ); and b) national extrapolation of nutrients and carbon removed using the most recent estimated total annual production of Irish Pacific oysters [31], i.e., N, P or C removed per tonne of fresh product (kg tonne -1 ) x national production of Pacific oysters (tonne year -1 ). An ecosystem services analysis of Pacific oyster farming was carried out to associate a monetary value with the nutrient remediation potential. This valuation of nutrient removal ES was calculated using the following median values for the removal of N (€18.9 kg -1 ) and P (€33.9 kg -1 ) [25]. These monetary values represent the theoretical cost of upgrading a wastewater treatment plant to remove one kg of N and P. Obviously, such values can vary between treatment plants depending on existing load, plant technology, discharge limits, plant size, etc. Nutrient valuation was also extrapolated nationally by applying the national production of Pacific oyster for 2022 [31]. Results were also equated to wastewater treatment plant performance in terms of population equivalent for N removal. A wastewater treatment plant, with secondary treatment, was estimated to remove, on average, 3.3 kg N person -1 year -1 [21]. This figure was applied to calculate the population equivalent where a wastewater treatment plant would remove the amount of N remediated (extrapolated as per the above) by pacific oyster farming in Ireland. 2.3. Life cycle assessment methodology 2.3.1. Goal and scope LCA studies were undertaken on three Pacific oyster sites along Ireland’s West coast. A cradle-to-gate system boundary was used for the farming and on-site processing activities at each site. The systems boundaries included aquaculture infrastructure, seed procurement, consumable materials, energy production (electric and diesel), culture and harvesting, processing, and packaging. Waste management and treatment of waste materials and packaging are also included within the system boundaries. The functional units applied were one tonne of live oyster product (meat and shell), i.e., farm-to-gate. Each studied site produced, on average, 111 tonnes of oysters for the market annually. All sites used bags and trestles to grow their oysters, and oyster seed was purchased domestically (Figure 2). 2.3.2. Life cycle inventory The life cycle inventory used primary data from the partner farms. Primary data was collected through questionnaires, interviews, and site visits. Energy, fuel, and consumables values were validated against bills and invoices where possible. Secondary data was collected from established life cycle databases such as Ecoinvent v3.10, Agri-footprint 6.3, and Agribalyse 3.0.1 to populate the life cycle inventories. The life cycle inventory of the present study covers all farm-based activities, infrastructures, and use of resources (Supplementary Table 5). The main transport vehicles used for daily farming activities at each site were a fleet of tractors and trailers. The trestles at each site were manufactured from 25 mm reinforced steel bars and weighed 18 kg per segment. The service life of the trestles was estimated to be 15 years. Oyster bags were made of high-density polyethene and weighed approximately 800 g per bag, with an average service life of 8 years. 2.3.3. Life cycle assessment The life cycle impact assessment methodology was undertaken through the CML method [32] (Guinée, 2002). The following impact assessment categories were included: 100-year global warming potential (GWP, kg CO 2 eq.), Acidification potential (AP, kg SO 2 eq.), Eutrophication potential (EP, kg PO 4 eq.), and Cumulative energy demand (CED,MJ), which assesses the degree of energy consumption associated with a production system [33]. These impact categories are the most concerning for aquaculture and shellfish production systems, as cited in many studies [34,35,36]. 2.4. Life cycle assessment and ecosystem services In this study, the elemental analysis results (i.e., N, P and C content in Pacific oyster shells) were adapted to LCA impact categories to estimate the ES provided by Pacific oyster aquaculture in Ireland. N and P content in the shell were converted to PO 4 eq., a compatible form under the EP impact category. Characterisation factors of 0.42 and 3.07 were applied to convert N and P to PO 4 eq., respectively [37]. To determine the net GWP of Pacific oyster farming, C content in oyster shells (i.e., amount of CO 2 sequestered in the shell during biocalcification) was converted to CO 2 eq [28]. The N, C, and P contained in the soft tissue were not included within the ES calculations as they are considered a short stage of the biogenic carbon cycle. On the contrary, shells can sequester nutrients for extended periods [13,15]. 3. Results 3.1. Ecosystem services Results of the nutrient (i.e., %N and %P) and carbon content (i.e., %C) analysis for each site and size investigated, did not show significant differences in %N and %C values between sites and sizes (Supplementary Table 4). %P values followed a similar trend as %C and %N, with homogeneous values between sites and sizes. Results to farm scale were extrapolated in terms of fresh product to compare them across the entire Irish sector for Pacific oyster farming. Since no significant differences in nutrient and carbon % were observed between size categories for a given site (Supplementary Table 4), nutrient and carbon content values were averaged per site to express the kg of N, P and C removed from the sea per tonne of fresh product per site (Figure 3). The results showed increased removal of nutrients (73% more N removed per tonne) and carbon (13% more C removed per tonne) in Site 2 compared to Site 1 (Figures 3A & 3C). In terms of P removed, Site 2 removed 51% more P per tonne of fresh product than Site 1 (Figure 3B). 3.2. Life Cycle Assessment The LCA results for 1 tonne of Pacific oysters produced in 2019 (Supplementary Table 6; Figure 4A) showed an estimated GWP of 373.86 kg CO 2 eq. The single most significant contributor to GWP was grading and packing at 38%. This was driven by the use of electricity to operate the various grading machines, hoppers and shaking tables for processing and grading the oysters. The second largest contributor to GWP was diesel production and combustion at 18% of GWP. Electricity data was provided as an annual figure for the whole farming site but was not measured for individual equipment. Therefore, it was not possible to differentiate between activities such as grading, processing, or stock deployment. Trestles accounted for 17% of GWP, followed by depuration at 14% of GWP. The remaining inputs (i.e., bags and seed production) contributed 8% to GWP. The AP for 1 tonne of oysters were estimated to be 1.33 kg SO 2 eq. Diesel combustion and production accounted for 42% of the AP. The steel that was used in the production of the trestles contributed to 18% of AP. The remaining contributors were those relying on the use of energy. Grading, packing, and depuration combined accounted for 31% of AP. The remaining 13% of AP arose from oyster bag production (6%) and seed production (4%). The EP for a tonne of oysters was estimated to be 0.4 kg PO 4 eq. Trestle production accounted for 33% of the EP. The combustion of diesel was the second largest contributor at 27%, followed by depuration at 13%. CED was 4,757.5 MJ tonne -1 of oysters. The contribution of each process followed a similar pattern to the other impact categories, except for diesel production, which accounted for 22% of energy demand. In contrast with other impact categories, the contribution from oyster bag production was higher, accounting for 16% of CED. When assessed across the different energy categories, the primary energy source for oyster production comes from non-renewable fossil fuels (Figure 4B). 3.3. Life cycle assessment and ecosystem services The quantification of oyster ES (i.e., nutrient remediation and carbon sequestration) resulted in improved EP and GWP emissions. When characterised to PO 4 eq., oyster shells were able to sequester 2.92 kg PO 4 eq. tonne -1 (Figure 5A). When compared to the EP of oyster production at this site (0.39 kg PO 4 eq. tonne -1 , Supplementary Table 6), the results indicate that Pacific oyster production has a high nutrient remediation potential, sequestering 630% more PO 4 eq. tonne -1 than their EP, resulting in a negative EP (-2.52 PO 4 eq. tonne -1 ). When C was characterised as CO 2 eq., results show that 259.77 kg CO 2 eq. tonne -1 was bound in the shell (Figure 5B). When compared to the estimated GWP for Pacific oyster production to farmgate (373.86 kg CO2 eq. tonne-1, Supplementary Table 6), carbon emissions from P. oyster farming are reduced by 31%, resulting in a net emission of 114.09 kg CO 2 eq. tonne -1 . 4. Discussion 4.1. Ecosystem services The present study appraised Ireland’s Pacific oyster production system, its contribution to ES, and its environmental impact through LCA. The designed experimental protocol produced data on the nutrients and C sequestration potential of one of the most farmed shellfish species in the country and globally [38]. The results obtained in the present study showed similar %C, %N, and %P in P. oyster shells and tissues compared to other shellfish species [11]. In terms of C sequestration and nutrient removal ES, the current Irish oyster sector may have a C sequestration potential of 825.2 tonnes year -1 and N and P removal potential of 33.6 and 3.9 tonnes year -1 , respectively. Comparison with other ES studies in shellfish species is difficult due to differences in the metrics used. Compared to the present results for Pacific oyster farming (i.e., 3.05 kg N tonne P.oyster -1 , 0.95 kg P tonne P.oyster -1 and 75.02 kg C tonne P.oyster -1 ), a study conducted on blue mussels showed higher nutrient removal potential (i.e., 5.0 – 8.5 kg N tonne mussel -1 and 0.43 – 0.95 kg P tonne mussel -1 ) and similar C sequestration potential (i.e., 74.7-77.5 kg C tonne mussel -1 ) [30]. Due to resource limitations, only nutrient removal, and C sequestration processes associated with oyster farming were investigated in this study. Hence, the net nutrient removal and C sequestration potential of oyster farming could be lower if nutrient and C emissions from shellfish (i.e., pseudo-faeces excretion) were assessed within the experimental boundaries. The accumulation of faeces and pseudo-faeces under the oyster trestles results in bio-deposition, a process where seabed sediments are enriched with organic N and P bio-deposits. Consequently, enriched sediments could be used as a potential energy and food source for consumer invertebrates, thus stimulating primary productivity and creating geological modifications of the underlying sediment [39]. A deeper understanding of the impact and interaction of shellfish pseudo-faeces on long-term net carbon and shellfish nutrient uptake is needed. This would include the frequent analysis of nutrients and carbon in water and shellfish, as well as a mass balance approach under laboratory conditions in order to accurately gauge the impact and interaction effect. Due to limited data, several assumptions were made for the extrapolation of results. To extrapolate the shellfish individual results to farm level, it was assumed that shellfish from across the farm uptake carbon and nutrients the same way as the average performance obtained from the sampled individuals. This assumption is justified since the most affecting parameters (i.e., shellfish species, cultivating condition and water quality) on nutrients and C sequestration potential were considered constant at the farm level [40,41]. In the national extrapolation, it was assumed that shellfish from all farming sites across Ireland would perform at the same level as the ones investigated. The investigated farms in this study were located on the west coast of Ireland, where water quality, environmental conditions, and cultivation practices differ from the southern and eastern Irish coasts. Therefore, future research should investigate other shellfish-producing areas to confirm the present results and expand the number of oyster samples assessed to increase the resolution of N, P, and C bioaccumulation datasets. In terms of value, if a nutrient credit programme were implemented at the national and international level, nutrient removal from oyster production would represent a potential benefit of €1.8 million annually to the Irish shellfish sector. Due to the lack of European derived data sets, the monetary benefit of the present study was estimated based on the nutrient removal valuation methodology of a previous U.S. study [25]. Therefore, to accurately reflect the current European and Irish oyster farming status, more studies are needed on the valuation of ecosystem services in Europe. It is now recognised that bivalve production provides not only ecosystem services but also cultural and economic services. The high amounts of C, N and P in oyster shells give them great potential for use in various applications. A study conducted in Korea found that oyster shell meal used as a liming agent for agricultural fields significantly increased soil pH and improved soil nutritional status, i.e., available phosphate and organic matter mass [42]. Shellfish shells could also be used as calcium supplements for livestock. The addition of shells ( Venus gallina ) to a limestone supplement significantly improved the egg production performance of laying hens [43]. Oyster shells could also be a sustainable alternative to traditional building materials (e.g., mortar sand). A study conducted in South Korea showed that small oyster shell particles (2–0.074 mm) were a potential substitute for conventional mortar sands in terms of compressive strength [44]. Additionally, waste oyster shells are a potential hard substrate for preparing artificial reefs for coral and oyster reef restoration [45,46,47,48]. Hence, the reuse of oyster shells and their variety of applications could represent a new income stream for the oyster industry, while allowing its transition towards a blue circular economy. 4.2. Life cycle assessment In the Irish Pacific oyster farming sector, fuel use (i.e., use of tractors for oyster harvesting) and energy use (i.e., grading and packaging) were the main drivers of the environmental burden. Infrastructure and equipment played a secondary role in environmental impact. The low service life of the oyster bags and trestles influenced all impact categories. Recent LCA studies on shellfish aquaculture have also reported similar findings, with 39% of GWP for mussels farmed in Italy arising from equipment and infrastructure [13]. To reduce the operation associated impacts, operators could apply alternative approaches to lower the fuel and energy use, such as the use of renewable energy sources, biofuels or investment in more efficient engines. According to the Renewable Energy Directive, by 2030, EU countries must ensure that the share of renewables in final energy consumption in transport is at least 14%, including a minimum share of 3.5% of advanced biofuels [49]. On the other hand, extending the service life of the farming equipment could reduce infrastructure-associated impacts in oyster farming. Oyster farming has shown relatively low global impacts on the environment compared to other seafood production sectors (e.g., wild catch fisheries and aquaculture) or livestock farming. The GWP to produce 1 tonne of rainbow trout (flow-through system), seabass (sea cages) and turbot (recirculating aquaculture system) was estimated at 2,753 kg CO 2 eq., 3,601 kg CO 2 eq. and 6,017 kg CO 2 eq., respectively [50]. The GWP for the capture of 1 tonne of horse mackerel by purse seiners and bottom trawlers in Galicia was estimated at 796 kg CO 2 eq. and 2,278 kg CO 2 eq., respectively [51]. The estimated GWP to produce a tonne of liveweight pig meat and liveweight broiler are 4,268.8 CO 2 eq. and 1,389.85 CO 2 eq., respectively [52,53]. The main environmental drivers in producing animal proteins from aquaculture, fisheries, and terrestrial farming are feed production, energy use, and fuel use. Furthermore, these food production systems are more complex in their life cycle stages, requiring sophisticated infrastructure, more labour, complex technologies (e.g., recirculating aquaculture systems, flow-through aquaculture systems), and additional processing steps (e.g., feed production, slaughtering, meat processing). In contrast, oyster farming is less technical and is done with traditional techniques (i.e., non-fed rack-and-bag culture in intertidal areas) that do not require feed input and complex infrastructures. There may be opportunities in the bivalve sector for value-added or novel food products targeted at environmentally conscious consumers. These strategic prospects may exist in high-growth food sectors, such as sports nutrition and snacks, for marketing it as a proteinous and nutritious food. Additional opportunities exist in pairing bivalves’ nutritional density and environmental performance to inform consumers better how they can meet their nutritional requirements while limiting their environmental impact [54]. While the present study demonstrates a low ecological impact, future LCAs should aim to increase the sample size of farms to obtain more solid results. In addition, there is a need to expand the scope of the study higher up the value chain and look at value-added products and the valorisation of circular economy opportunities for bivalve waste and shells in particular. 4.3. Environmental strategies of bivalve farming Given the strong results of bivalve farming as an EP remediator, there are opportunities to use or include bivalve aquaculture as part of integrated catchment management. With many Irish rivers failing to meet the requirements of the Water Framework Directive (2000/60/EC) [55] and the national herd increasing, the pairing or co-location of these food production systems as complementary activities may allow for the mitigation of the excessive nutrients in coastal and transitional waters, while also producing a low carbon food product. This integrated approach may be limited regarding suitable sites, but novel and emerging bivalve culture systems may address this. In addition, uncertainty exists regarding the net nutrient remediation potential results presented in this study, as they may vary if more recent EP characterisation factors are used to convert N and P to PO 4 eq. The present study also shows the potential of oyster production as a carbon sink, with higher carbon sequestration potential (260 kg CO 2 eq. tonne harvested oysters – 1 ) compared to clams (254 kg CO 2 eq. tonne harvested clams -1 ) and mussel (146 kg tonne harvested mussels -1 ) farming [13]. With carbon farming being included in the EU’s new Common Agriculture Policy Strategic Plan 2023-2027 , there is also an opportunity for bivalve aquaculture to aid and play an active role in this form of environmental management [56]. The seafood sector, including aquaculture producers, processors, wholesalers, retailers and food certification bodies, is facing a growing demand for information on the environmental footprint of their products from customers, investors and government agencies [57]. The present study provides a scientific basis to meet these informational demands and contribute to the imminent introduction of a science-based metric such as the Product Environmental Footprint [58]. This study brings an innovative and valuable approach with positive results, thus serving as a reference point for future research on the sustainable potential of the shellfish sector. Declarations Acknowledgement The present study was part of the ShellAqua project (BIM-21/KGS/001) funded under the Bord Iascaigh Mhara’s Knowledge Gateway Scheme, which is co-financed by the national exchequer: Ireland’s EU structure funds programme (ESIF) 2014-2020 & the European Maritime and Fisheries Fund (EMFF). The authors would also like to acknowledge funding from InterReg Atlantic Areas ERDF (NEPTUNUS – EAPA_576/2018). The authors would like to thank the commercial Irish oyster farms contributing to the data collection for this study. Author contributions PCD: Investigation; Formal analysis; Validation; Visualisation; Roles/Writing – original draft; Writing – review & editing. AT: Conceptualisation; Data curation; Formal analysis; Funding acquisition; Investigation; Methodology; Project administration; Resources; Software; Validation; Visualisation; Roles/Writing – original draft; Writing – review & editing. RC: Conceptualisation; Data curation; Formal analysis; Funding acquisition; Investigation; Methodology; Project administration; Resources; Software; Supervision; Validation; Visualisation; Roles/Writing – original draft; Writing – review & editing. AK: Formal analysis; Project administration; Supervision; Validation; Visualisation; Roles/Writing – original draft; Writing – review & editing. AHLW: Formal analysis; Supervision; Validation; Visualisation; Roles/Writing – original draft; Writing – review & editing. EC: Conceptualisation; Formal analysis; Funding acquisition; Investigation; Methodology; Project administration; Resources; Software; Supervision; Validation; Visualisation; Roles/Writing – original draft; Writing – review & editing. Competing interests All authors declare no financial or non-financial competing interests. Data availability The datasets presented in the current study are available from the corresponding author upon reasonable request. References Ilea, R. C. Intensive livestock farming: Global trends, increased environmental concerns, and ethical solutions. J. Agr and Env Eth . 22(2), 153–167. https://doi.org/10.1007/s10806-008-9136-3 (2009) Maúre, E.d.R., Terauchi, G., Ishizaka, J., Clinton, N. & DeWitt, M. Globally consistent assessment of coastal eutrophication. Nat Commun . 12, 6142. https://doi.org/10.1038/s41467-021-26391-9 (2021) EPA, Environmental Protection Agency. Water Quality in 2020: An indicators Report. Prepared by W. Trodd and S. O’Boyle. ISBN: 978-1-84095-965-9 (2020). Available online at https://www.epa.ie/pubs/reports/water/waterqua/Water%20Quality%20in%202019%20-%20an%20indicators%20report.pdf. Wan, A.H., et al. 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Aubin, J., Fontaine C., Callier, M. & Roque d’orbcastel E. Blue mussel ( Mytilus edulis ) bouchot culture in Mont-St Michel Bay: potential mitigation effects on climate change and eutrophication Intern J of Life Cycle Assess . 23, 1030-1041 (2018). Tamburini, E., Fano, E. A., Castaldelli, G. & Turolla, E. Life Cycle Assessment of oyster farming in the Po delta, northern Italy, Resources. 8(4), 170. https://doi.org/10.3390/resources8040170 (2019). Tamburini, E., Turolla, E., Fano E. A. & Castaldelli, G. Sustainability of mussel farming in the Po river delta, northern Italy, based on a Life Cycle Assessment approach. Sustainability. 12, 3814 . https://doi.org/10.3390/su12093814 (2020). Table Table 1: Extrapolated results on quantities of carbon, nitrogen, and phosphorous removed annually per site from average annual production and estimated nutrient removal values. Unit Site 1 Site 2 Average National extrapolation*** Annual production Tonne year -1 75 196 n.a. 11,000 C sequestered kg tonne -1 fresh product 70.33 79.71 70.52 n.a. kg year -1 5,296.86 15,622.36 10,459.11 825,198.06 N removed kg tonne -1 fresh product 2.24 3.87 3.05 n.a. kg year -1 168.53 757.73 463.13 33,572.32 Value N removal* € tonne -1 fresh product 42.2 72.0 57.5 n.a. € year -1 3,176.9 14,283.9 8,730.4 1,931,543.5 P removed kg tonne -1 fresh product 0.28 0.42 0.35 n.a. kg year -1 21.10 82.93 52.02 3,868.42 Value P removal* € tonne -1 fresh product 9.51 14.40 11.93 n.a. € year -1 716.0 2,814.1 1,798.5 46,161.7 Total value nutrient removal € year -1 3,892.9 17,098.0 10,495.5 1,977,705.2 Population equivalent (N)** individuals 53 230 140 10,173 C, carbon; N, nitrogen; P, phosphorous; n.a., not applicable; *Value per tonne of N and P removed taken from Carss et al., 2020; ** Nitrogen population equivalent is based on a value of 3.3 kg N treated per person per year [21]; *** based on BIM 2022 figures [31], i.e., total Irish annual Pacific oyster production of 11,000 tonnes. Additional Declarations No competing interests reported. Supplementary Files Supplementaryinformation.Oystersasustaianblebluefood.docx Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 06 Jun, 2024 Reviews received at journal 29 May, 2024 Reviews received at journal 14 May, 2024 Reviewers agreed at journal 09 May, 2024 Reviewers agreed at journal 25 Apr, 2024 Reviewers invited by journal 24 Apr, 2024 Editor assigned by journal 23 Apr, 2024 Submission checks completed at journal 22 Apr, 2024 First submitted to journal 19 Apr, 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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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-4294313","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":295175711,"identity":"c02615f0-84db-4454-afde-e5997752429d","order_by":0,"name":"Paula Costa Domech","email":"data:image/png;base64,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","orcid":"","institution":"University of Galway","correspondingAuthor":true,"prefix":"","firstName":"Paula","middleName":"Costa","lastName":"Domech","suffix":""},{"id":295175713,"identity":"27814855-b3bb-4f0d-aa55-d5fd6e775472","order_by":1,"name":"Ronan Cooney","email":"","orcid":"","institution":"University of Galway","correspondingAuthor":false,"prefix":"","firstName":"Ronan","middleName":"","lastName":"Cooney","suffix":""},{"id":295175715,"identity":"034eeb5d-5f3a-43a4-8491-8b9fd10887a1","order_by":2,"name":"Alexandre Tahar","email":"","orcid":"","institution":"University of Galway","correspondingAuthor":false,"prefix":"","firstName":"Alexandre","middleName":"","lastName":"Tahar","suffix":""},{"id":295175716,"identity":"9f75b306-3362-466b-a21c-46200e1a8113","order_by":3,"name":"Alan Kennedy","email":"","orcid":"","institution":"University of Galway","correspondingAuthor":false,"prefix":"","firstName":"Alan","middleName":"","lastName":"Kennedy","suffix":""},{"id":295175717,"identity":"1e7c2c86-973c-40da-b8b1-8c911cfcdfb2","order_by":4,"name":"Alex H L Wan","email":"","orcid":"","institution":"University of Galway","correspondingAuthor":false,"prefix":"","firstName":"Alex","middleName":"H L","lastName":"Wan","suffix":""},{"id":295175718,"identity":"3a0a9dee-00bf-45aa-a7ee-a72fbeb01d80","order_by":5,"name":"Eoghan Clifford","email":"","orcid":"","institution":"University of Galway","correspondingAuthor":false,"prefix":"","firstName":"Eoghan","middleName":"","lastName":"Clifford","suffix":""}],"badges":[],"createdAt":"2024-04-19 16:35:07","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4294313/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4294313/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":55296499,"identity":"c7b07271-24d8-4b36-b980-45218bf7c273","added_by":"auto","created_at":"2024-04-25 10:45:12","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":150826,"visible":true,"origin":"","legend":"\u003cp\u003eStudy overview for the data collection on life cycle assessment and ecosystem models. Solid boxes represent procedures. Dashed boxes represent outcomes. L: large size; M: medium size; S: small size; N: nitrogen; P: phosphorus; C: carbon; LCA: Life Cycle Assessment; GWP: Global warming potential; EP: eutrophication potential; AP: acidification potential; CED: cumulative energy demand.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4294313/v1/0503aa942bedd0c55d76486b.png"},{"id":55296502,"identity":"4a8a08da-6067-4eb3-82e3-63b764416360","added_by":"auto","created_at":"2024-04-25 10:45:12","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":166632,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e) System boundaries used in the Life Cycle Assessment (LCA) of Pacific oyster production in the north-west of Ireland. The solid boxes represent processes (foreground and background). The dot-dashed box indicates the system boundaries. Solid arrows depict direct mass flows, and dashed arrows indicate indirect mass flows; \u003cstrong\u003eb\u003c/strong\u003e) Plan and longitudinal overview of the layout and dimensions of oyster trestles; \u003cstrong\u003ec\u003c/strong\u003e) Typical trestle setup and oyster bags used on the farming sites.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4294313/v1/73910e9c1852c1397ca71dd7.png"},{"id":55296498,"identity":"2f6eae43-8a33-4d19-8c3c-fda1e968c05b","added_by":"auto","created_at":"2024-04-25 10:45:12","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":34703,"visible":true,"origin":"","legend":"\u003cp\u003eNitrogen (a), phosphorous (b) and carbon (c) removed per tonne of fresh Pacific oyster (\u003cem\u003eMagallana gigas\u003c/em\u003e) product harvested per site investigated ± standard deviation, n= 3.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Extrapolating the oyster data to a national scale showed that 825.2 tonnes of C, 33.6 tonnes of N and 3.9 tonnes of P could be annually removed from the coastal waters (Table 2). While the economic equivalent value of such nutrient removal amounted to be €1.9 million year \u003csup\u003e-1\u003c/sup\u003e, of which N removal accounts for the largest share. In terms of population equivalent, the amounts of N removed annually from the investigated sites are equivalent to the N emitted by populations of 53 (Site 1) and 230 (Site 2). Based on the national extrapolation, the Irish Pacific oyster sector could nitrogen equivalent to that in wastewater generated from a population of 10,173 people.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4294313/v1/e6cd96c95bbc93879b2ad86d.png"},{"id":55296497,"identity":"7175c0d1-0850-45b6-b908-adce6f95cb10","added_by":"auto","created_at":"2024-04-25 10:45:12","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":70292,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea)\u003c/strong\u003e The contribution of the environmental burden from the farming processes to produce a tonne of fresh Pacific oysters (\u003cem\u003eMagallana gigas\u003c/em\u003e) to market; \u003cstrong\u003eb)\u003c/strong\u003e Impact assessment of the Cumulative Energy Demand for a tonne of fresh Pacific oysters.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4294313/v1/93e3f39eb5d202e22ef88678.png"},{"id":55296501,"identity":"d9ab48af-42d0-4d8b-9549-9bd82507320d","added_by":"auto","created_at":"2024-04-25 10:45:12","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":29925,"visible":true,"origin":"","legend":"\u003cp\u003eQuantification of ecosystem services (i.e., nutrient remediation and carbon sequestration) and its effects on \u003cstrong\u003ea\u003c/strong\u003e) eutrophication potential (EP); and\u003cstrong\u003e b\u003c/strong\u003e) global warming potential (GWP) from Pacific oyster farming.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4294313/v1/da2797d49f208a7f6df84882.png"},{"id":55296864,"identity":"100757dd-bee9-47f9-bb2b-d382354f5cec","added_by":"auto","created_at":"2024-04-25 10:53:12","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":809328,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4294313/v1/5c137526-f284-4d2d-8d74-affc944f5363.pdf"},{"id":55296500,"identity":"80df895e-0d13-41cf-938e-e3292439c8e7","added_by":"auto","created_at":"2024-04-25 10:45:12","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":50594,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementaryinformation.Oystersasustaianblebluefood.docx","url":"https://assets-eu.researchsquare.com/files/rs-4294313/v1/297ca56844cb3c0286f5f1ac.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Oysters, a sustainable bluefood?","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAgriculture, including terrestrial livestock, has long been the principal protein source for many societies. While food production is an essential human activity, it does have significant environmental costs, including land degradation, climate change impacts, water consumption, deforestation, non-renewable fertilisers (inc. phosphorous), eutrophication, and chemotherapeutics. These challenges have driven innovation to change our food consumption habits and produce food using more sustainable systems [1].\u0026nbsp;The level of nutrient emissions to surface and coastal waters has increased dramatically over the past 50 years, impairing the quality of coastal waters due to eutrophication and nuisance algal blooms [2,3,4]. As a result, reducing nutrient loads such as nitrogen (N), phosphorous (P), and carbon (C) from anthropogenic activities (e.g., agriculture, wastewater treatment plants and industry emissions) is urgently required to address the overall deterioration of water bodies.\u0026nbsp;In the context of climate change, there is also increasing urgency to reduce carbon emissions and promote carbon sequestration practices.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAquaculture is the activity of farming aquatic species such as finfish, crustaceans and bivalves. It has potential as a sustainable way to produce animal protein [5] and one of the food systems with a lower environmental burden supported by recent European policy, i.e., the European Green Deal [6] and the Farm to Fork Strategy [7].\u0026nbsp;Within the aquaculture sector, farming low trophic level species, such as bivalves, may\u0026nbsp;be\u0026nbsp;a more sustainable approach due to its lower environmental impact compared to current food production systems, such as terrestrial animal production [8].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFrom a farming perspective, bivalves have\u0026nbsp;lower technical and labour requirements than other aquatic species, e.g., fish and crustaceans [9].\u0026nbsp;Bivalve farming doesn’t require feed inputs, as this group of animals are non-feeding organisms, i.e., they take up food particles from the water column or sediment (e.g., particulate organic matter, phytoplankton and zooplankton).\u0026nbsp;In addition, bivalves contribute to carbon sequestration through the shell formation process (i.e., biomineralization), making them a potential net carbon dioxide sink.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eBivalves can also provide wider ecosystem services (ES) to the aquatic environment, such as nutrient remediation and C sequestration [10,11].\u0026nbsp;Some of the most common cultured bivalve species include oysters, mussels, and clams.\u0026nbsp;Several studies conducted on different shellfish species (e.g., blue mussel, Pacific oyster, clams, etc.) have highlighted the potential environmental benefits and the low impacts of bivalve farming (Supplementary Tables 1 and 2 provide an extensive summary of existing literature).\u0026nbsp;For instance, a Danish mussel farm estimated a potential nutrient removal of 0.6-0.9 tonne N ha\u003csup\u003e-1\u003c/sup\u003e year\u003csup\u003e-1\u003c/sup\u003e and 0.03-0.04 tonne P ha\u003csup\u003e-1\u003c/sup\u003e year\u003csup\u003e-1\u003c/sup\u003e [12]. A\u0026nbsp;life\u0026nbsp;cycle\u0026nbsp;assessment (LCA) conducted in Italy showed that Manila clam (\u003cem\u003eVenerupis philippinarum\u003c/em\u003e) and Mediterranean mussel (\u003cem\u003eMytilus galloprovincialis\u003c/em\u003e) production resulted in\u0026nbsp;relatively\u0026nbsp;low greenhouse gas emissions of 0.022 and 0.055 kg CO\u003csub\u003e2-\u003c/sub\u003eeq. kg harvested and packaged bivalves \u003csup\u003e-1\u003c/sup\u003e, respectively. This study also showed that clams and mussels can sequester 254 and 146 g of CO\u003csub\u003e2\u0026nbsp;\u003c/sub\u003eper kg of harvested and packaged bivalves, respectively [13].\u003c/p\u003e\n\u003cp\u003eHowever, there is currently limited information on the environmental impact, nutrient removal potential, and C sequestration potential of farmed oysters. A study estimated that Pacific oyster aquaculture could remove 0.02-0.14 tonnes N ha\u003csup\u003e-1\u003c/sup\u003e year\u003csup\u003e-1\u003c/sup\u003e from seawater [14]. Another study estimated that farmed produced eastern oyster(\u003cem\u003eCrassostrea virginica\u003c/em\u003e)\u0026nbsp;releases a total of 0.13 kg CO\u003csub\u003e2-\u003c/sub\u003eeq. kg protein \u003csup\u003e-1\u003c/sup\u003e which, compared to other food sectors, was estimated to be less than 0.5% of the greenhouse gas emissions from beef, small ruminants, pork, and poultry [15].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDespite the wider potential benefits of bivalve aquaculture, European production of farmed mussels and oysters has been in a decline. Previous studies have pointed out disease prevalence, lack of mussel and oyster seed and low profitability as the main causes of the sector's decline in the European Union, EU [16,17]. To ensure the sustainable expansion of bivalve aquaculture,\u0026nbsp;the current performance of the bivalve sector, in relation to nutrient emissions and carbon emissions requires further research to enable benchmark data and comparison to other sectors.\u0026nbsp;Estimating the\u0026nbsp;ES of bivalve species is still an emerging area of research, and considerable gaps remain in our understanding of biochemical processes and wider environmental interactions. Much of the published\u0026nbsp;data have been generated in the United States\u0026nbsp;where some\u0026nbsp;species\u0026nbsp;are not currently farmed in EU\u0026nbsp;[18,19,20,21,22,23,24]. Overall, limited research has been undertaken within the EU, with variability in the methodology used [9,12,14,25,26,27]. In addition, most of the studies combining LCA and ES for shellfish only covered the net carbon capture potential of shellfish farming [13,28,29].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTo better appraise the environmental performance, sustainability credentials and benefits of the Irish oyster-producing sector, this study evaluated the ES and environmental impacts of Pacific oyster farming by:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1\u003c/strong\u003e) Assessing the nutrient remediation (i.e., N and P) and C sequestration potential ES of Pacific Oyster (\u003cem\u003eMagallana gigas\u003c/em\u003e) through morphological and elemental analysis of representative samples;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2\u003c/strong\u003e) Analysing the environmental impacts of oyster aquaculture by undertaking LCAs of regional Pacific oyster farms; and\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3\u003c/strong\u003e) Combining ES and LCAs results to determine the benefits of Pacific oyster culture in terms of eutrophication (i.e., N and P net remediation) and global warming potential (i.e., net C sink).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe study combined\u0026nbsp;ES and LCA approaches to provide a more holistic evaluation of the ecological potential of bivalve aquaculture and the environmental impact of their production.\u003c/p\u003e"},{"header":"2.\tMethods and materials ","content":"\u003cp\u003e\u003cstrong\u003e2.1.\u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp; Site selection\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe oyster production sites (i.e., oyster producers or buyers for further processing) used in this study were located on a sheltered bay in the north-west of the Republic of Ireland. Samples from two Pacific oyster-producing sites (i.e., Site 1 and Site 2) were collected for morphological and elemental analysis, while the LCAs were modelled using operational data from three Pacific oyster farms located along the West coast (i.e., Site 1, Site 3 and Site 4), Site 1 providing samples for the morphological and elemental analysis (Figure 1).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2.\u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/strong\u003e \u003cstrong\u003eEcosystem services methodology\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2.1.\u0026nbsp; \u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eMorphological and elemental analysis\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFor morphological and elemental analysis, farmers at each production site randomly harvested 15 individuals per market size category (i.e., small, 67.4-112.5 cm length; medium, 89.4-119.3 cm length; and large, 94.8-120.7 cm length) during different times of the winter season (i.e., February and March). Thus, there were a total of 45 samples per site. The following morphometric measurements were undertaken per oyster\u003cstrong\u003e:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e1.\u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/strong\u003eTotal shell length, width, and depth; mm oyster\u003csup\u003e-1\u003c/sup\u003e;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.\u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/strong\u003eTotal wet weight; g oyster\u003csup\u003e-1\u003c/sup\u003e;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.\u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/strong\u003eShell wet weight and tissue wet weight; g oyster\u003csup\u003e-1\u003c/sup\u003e,\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.\u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/strong\u003eDry tissue and shell weights; g oyster\u003csup\u003e-1\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAmong the 15 individuals morphologically assessed per site and size category, sets of 6 individuals were randomly selected and pooled for the elemental analysis [30]. Thus, for each site, 18 individuals were selected for elemental analysis. Tissue and shells from pooled individuals were dried in a fan assisted oven at 80 °C until a constant weight is achieved. Dried tissue and shells from pooled individuals were crushed using a mortar and pestle for dried tissue and a mill for dried shells. The pooled tissue and shell samples were then analysed for N and C content through an elemental CHN analyser (Flash smart elemental analyser, Thermo Fisher, Waltham, Massachusetts, United States). P content was measured through Inductively Coupled Plasma Optical Emission Spectrometry (700 series ICP-OES, Agilent,\u0026nbsp;Santa Clara, California, United States). The results obtained as %C, %N, and %P in the dried tissue and shell samples were used to calculate: (i) the\u0026nbsp;average %C, %N and %P per individual oyster (and separately the tissue and shell for each oyster), size category and site investigated; (ii) the average mass of C, N, and P removed per fresh individual oyster; and (iii) the average mass of C, N, and P removed per tonne of oysters harvested.\u0026nbsp;Differences in the\u0026nbsp;elemental analysis (i.e., %C, %N, %P) of Pacific oyster between the three size classes and the sites investigated were analysed using two-way ANOVA tests. A post-hoc Tukey's test was conducted on each dataset to discern significant differences between sizes and sites. Statistical significance was assigned when P\u0026lt;0.05. Limitations of the approaches used are discussed in Section 4.1.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2.2.\u0026nbsp; \u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eNational ecological impact\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe morphological and elemental analysis results were then extrapolated to farm and national scale to obtain: a) the quantities of nutrients and carbon removed annually on each production site using the average annual production for the period 2015-2020 i.e., average annual production (tonne year \u003csup\u003e-1\u003c/sup\u003e) x N, P or C removed per tonne of fresh product (kg tonne \u003csup\u003e-1\u003c/sup\u003e); and b) national extrapolation of nutrients and carbon removed using the most recent estimated total annual production of Irish Pacific oysters [31], i.e., \u0026nbsp;N, P or C removed per tonne of fresh product (kg tonne \u003csup\u003e-1\u003c/sup\u003e) x national production of Pacific oysters (tonne year\u003csup\u003e-1\u003c/sup\u003e).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAn ecosystem services analysis of Pacific oyster farming was carried out to associate a monetary value with the nutrient remediation potential. This valuation of nutrient removal ES was calculated using the following median values for the removal of N (€18.9 kg\u003csup\u003e-1\u003c/sup\u003e) and P (€33.9 kg\u003csup\u003e-1\u003c/sup\u003e) [25]. These monetary values represent the theoretical cost of upgrading a\u0026nbsp;wastewater treatment plant to remove one kg of N and P. Obviously, such values can vary between treatment plants depending on existing load, plant technology, discharge limits, plant size, etc.\u0026nbsp;Nutrient valuation was also extrapolated nationally by applying the national production of Pacific oyster for 2022 [31]. Results were also equated to wastewater treatment plant performance in terms of population equivalent for N removal. A wastewater treatment plant, with secondary treatment, was estimated to remove, on average, 3.3 kg N person\u003csup\u003e-1\u003c/sup\u003e year\u003csup\u003e\u0026nbsp;-1\u0026nbsp;\u003c/sup\u003e[21]. This figure was applied to calculate the population equivalent where a wastewater treatment plant would remove the amount of N remediated (extrapolated as per the above) by pacific oyster farming in Ireland.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3.\u0026nbsp; \u0026nbsp;Life cycle assessment methodology\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3.1.\u0026nbsp; \u0026nbsp;Goal and scope\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLCA studies were undertaken on three Pacific oyster sites along Ireland’s West coast. A cradle-to-gate system boundary was used for the farming and on-site processing activities at each site. The systems boundaries included aquaculture infrastructure, seed procurement, consumable materials, energy production (electric and diesel), culture and harvesting, processing, and packaging. Waste management and treatment of waste materials and packaging are also included within the system boundaries. The functional units applied were one tonne of live oyster product (meat and shell), i.e., farm-to-gate. Each studied site produced, on average, 111 tonnes of oysters for the market annually. All sites used bags and trestles to grow their oysters, and oyster seed was purchased domestically (Figure 2).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3.2.\u0026nbsp; \u0026nbsp; Life cycle inventory\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe life cycle inventory used primary data from the partner farms. Primary data was collected through questionnaires, interviews, and site visits. Energy, fuel, and consumables values were validated against bills and invoices where possible.\u0026nbsp;Secondary data was collected from established life cycle databases such as Ecoinvent v3.10, Agri-footprint 6.3, and Agribalyse 3.0.1 to populate the life cycle inventories.\u0026nbsp;The life cycle inventory of the present study covers all farm-based activities, infrastructures, and use of resources (Supplementary Table 5).\u0026nbsp;The main transport vehicles used for daily farming activities at each site were a fleet of tractors and trailers.\u0026nbsp;The trestles at each site were manufactured from 25 mm reinforced steel bars and weighed 18 kg per segment. The service life of the trestles was estimated to be 15 years. Oyster bags were made of high-density polyethene and weighed approximately 800 g per bag, with an average service life of\u0026nbsp;8 years.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3.3.\u0026nbsp; \u0026nbsp;Life cycle assessment\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe life cycle impact assessment methodology was undertaken through the CML method [32] (Guinée, 2002).\u0026nbsp;The following impact assessment categories were included: 100-year global warming potential (GWP, kg CO\u003csub\u003e2\u003c/sub\u003e eq.), Acidification potential (AP, kg SO\u003csub\u003e2\u003c/sub\u003e eq.), Eutrophication potential (EP, kg PO\u003csub\u003e4\u003c/sub\u003e eq.), and Cumulative energy demand (CED,MJ), which assesses the degree of energy consumption associated with a production system [33]. These impact categories are the most concerning for aquaculture and shellfish production systems, as cited in many studies [34,35,36].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.4.\u0026nbsp; \u0026nbsp; Life cycle assessment and ecosystem services\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn this study, the elemental analysis results (i.e., N, P and C content in Pacific oyster shells) were adapted to LCA impact categories to estimate the ES provided by Pacific oyster aquaculture in Ireland. N and P content in the shell were converted to PO\u003csub\u003e4\u003c/sub\u003e eq., a compatible form under the EP impact category. Characterisation factors of 0.42 and 3.07 were applied to convert N and P to PO\u003csub\u003e4\u003c/sub\u003e eq., respectively [37]. To determine the net GWP of Pacific oyster farming, C content in oyster shells (i.e., amount of CO\u003csub\u003e2\u003c/sub\u003e sequestered in the shell during biocalcification) was converted to CO\u003csub\u003e2\u003c/sub\u003e eq [28]. The N, C, and P contained in the soft tissue were not included within the ES calculations as they are considered a short stage of the biogenic carbon cycle. On the contrary, shells can sequester nutrients for extended periods [13,15].\u003c/p\u003e"},{"header":"3.\tResults ","content":"\u003cp\u003e\u003cstrong\u003e3.1.\u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp; Ecosystem services\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eResults of the nutrient (i.e., %N and %P) and carbon content (i.e., %C) analysis for each site and size investigated, did not show significant differences in %N and %C values between sites and sizes (Supplementary Table 4). %P values followed a similar trend as %C and %N, with homogeneous values between sites and sizes.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eResults to farm scale were extrapolated in terms of fresh product to compare them across the entire Irish sector for Pacific oyster farming. Since no significant differences in nutrient and carbon % were observed between size categories for a given site (Supplementary Table 4), nutrient and carbon content values were averaged per site to express the kg of N, P and C removed from the sea per tonne of fresh product per site (Figure 3). The results showed increased removal of nutrients (73% more N removed per tonne) and carbon (13% more C removed per tonne) in Site 2 compared to Site 1 (Figures 3A \u0026amp; 3C). In terms of P removed, Site 2 removed 51% more P per tonne of fresh product than Site 1 (Figure 3B).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.\u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Life Cycle Assessment\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe LCA results for 1 tonne of Pacific oysters produced in 2019 (Supplementary Table 6; Figure 4A) showed an estimated GWP of 373.86 kg CO\u003csub\u003e2\u003c/sub\u003e eq. The single most significant contributor to GWP was grading and packing at 38%. This was driven by the use of electricity to operate the various grading machines, hoppers and shaking tables for processing and grading the oysters. The second largest contributor to GWP was diesel production and combustion at 18% of GWP. Electricity data was provided as an annual figure for the whole farming site but was not measured for individual equipment. Therefore, it was not possible to differentiate between activities such as grading, processing, or stock deployment. Trestles accounted for 17% of GWP, followed by depuration at 14% of GWP. The remaining inputs (i.e., bags and seed production) contributed 8% to GWP.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe AP for 1 tonne of oysters were estimated to be 1.33 kg SO\u003csub\u003e2\u003c/sub\u003e eq. Diesel combustion and production accounted for 42% of the AP. The steel that was used in the production of the trestles contributed to 18% of AP. The remaining contributors were those relying on the use of energy. Grading, packing, and depuration combined accounted for 31% of AP. The remaining 13% of AP arose from oyster bag production (6%) and seed production (4%). The EP for a tonne of oysters was estimated to be 0.4 kg PO\u003csub\u003e4\u003c/sub\u003e eq. Trestle production accounted for 33% of the EP. The combustion of diesel was the second largest contributor at 27%, followed by depuration at 13%. CED was 4,757.5 MJ tonne\u003csup\u003e-1\u003c/sup\u003e of oysters. The contribution of each process followed a similar pattern to the other impact categories, except for diesel production, which accounted for 22% of energy demand. In contrast with other impact categories, the contribution from oyster bag production was higher, accounting for 16% of CED. When assessed across the different energy categories, the primary energy source for oyster production comes from non-renewable fossil fuels (Figure 4B).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.3. \u0026nbsp; \u0026nbsp; \u0026nbsp; Life cycle assessment and ecosystem services\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe quantification of oyster ES (i.e., nutrient remediation and carbon sequestration) resulted in improved EP and GWP emissions. When characterised to PO\u003csub\u003e4\u003c/sub\u003e eq., oyster shells were able to sequester 2.92 kg PO\u003csub\u003e4\u003c/sub\u003e eq. tonne\u003csup\u003e-1\u003c/sup\u003e (Figure 5A). When compared to the EP of oyster production at this site (0.39 kg PO\u003csub\u003e4\u003c/sub\u003e eq. tonne\u003csup\u003e-1\u003c/sup\u003e, Supplementary Table 6), the results indicate that Pacific oyster production has a high nutrient remediation potential, sequestering 630% more PO\u003csub\u003e4\u003c/sub\u003e eq. tonne\u003csup\u003e-1\u003c/sup\u003e than their EP, resulting in a negative EP (-2.52 PO\u003csub\u003e4\u003c/sub\u003e eq. tonne\u003csup\u003e-1\u003c/sup\u003e). When C was characterised as CO\u003csub\u003e2\u003c/sub\u003e eq., results show that 259.77 kg CO\u003csub\u003e2\u003c/sub\u003e eq. tonne\u003csup\u003e-1\u003c/sup\u003e was bound in the shell (Figure 5B). When compared to the estimated GWP for Pacific oyster production to farmgate (373.86 kg CO2 eq. tonne-1, Supplementary Table 6), carbon emissions from P. oyster farming are reduced by 31%, resulting in a net emission of 114.09 kg CO\u003csub\u003e2\u003c/sub\u003e eq. tonne\u003csup\u003e-1\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e"},{"header":"4.\tDiscussion ","content":"\u003cp\u003e\u003cstrong\u003e4.1.\u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u0026nbsp;Ecosystem services\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe present study appraised Ireland’s Pacific oyster production system, its contribution to ES, and its environmental impact through LCA. The designed experimental protocol produced data on the nutrients and C sequestration potential of one of the most farmed shellfish species in the country and globally [38].\u0026nbsp;The results obtained in the present study showed similar %C, %N, and %P in P. oyster shells and tissues compared to other shellfish species [11].\u0026nbsp;In terms of C sequestration and nutrient removal\u0026nbsp;ES, the current Irish oyster sector may have a C sequestration potential of 825.2 tonnes year \u003csup\u003e-1\u003c/sup\u003e and N and P removal potential of 33.6 and 3.9 tonnes year \u003csup\u003e-1\u003c/sup\u003e, respectively. Comparison with other ES studies in shellfish species is difficult due to differences in the metrics used. Compared to the present results for Pacific oyster farming (i.e., 3.05 kg N tonne P.oyster\u003csup\u003e-1\u003c/sup\u003e, 0.95 kg P tonne P.oyster\u003csup\u003e-1\u0026nbsp;\u003c/sup\u003eand 75.02 kg C tonne P.oyster\u003csup\u003e-1\u003c/sup\u003e), a study conducted on blue mussels showed higher nutrient removal potential (i.e., 5.0 – 8.5 kg N tonne mussel\u003csup\u003e-1\u003c/sup\u003e and 0.43 – 0.95 kg P tonne mussel\u003csup\u003e-1\u003c/sup\u003e) and similar C sequestration potential (i.e., 74.7-77.5 kg C tonne mussel\u003csup\u003e-1\u003c/sup\u003e) [30]. Due to resource limitations, only nutrient removal, and C sequestration processes associated with oyster farming were investigated in this study. Hence, the net nutrient removal and C sequestration potential of oyster farming could be lower if nutrient and C emissions from shellfish (i.e., pseudo-faeces excretion) were assessed within the experimental boundaries.\u0026nbsp;The accumulation of faeces and pseudo-faeces under the oyster trestles results in bio-deposition, a process where seabed sediments are enriched with organic N and P bio-deposits. Consequently, enriched sediments could be used as a potential energy and food source for consumer invertebrates, thus stimulating primary productivity and creating geological modifications of the underlying sediment [39]. A deeper understanding of the impact and interaction of shellfish pseudo-faeces on long-term net carbon and shellfish nutrient uptake is needed. This would include the frequent analysis of nutrients and carbon in water and shellfish, as well as a mass balance approach under laboratory conditions in order to accurately gauge the impact and interaction effect.\u003c/p\u003e\n\u003cp\u003eDue to limited data, several assumptions were made for the extrapolation of results. To extrapolate the shellfish individual results to farm level, it was assumed that shellfish from across the farm uptake carbon and nutrients the same way as the average performance obtained from the sampled individuals. This assumption is justified since\u0026nbsp;the most affecting parameters (i.e., shellfish species, cultivating condition and water quality)\u0026nbsp;on nutrients and C sequestration potential\u0026nbsp;were\u0026nbsp;considered constant at the farm level [40,41]. In the national extrapolation, it was assumed that shellfish from all farming sites across Ireland would perform at the same level as the ones investigated. The investigated farms in this study were located on the west coast of Ireland, where water quality, environmental conditions, and cultivation practices differ from the southern and eastern Irish coasts. Therefore, future research should investigate other shellfish-producing areas to confirm the present results and expand the number of oyster samples assessed to increase the resolution of N, P, and C bioaccumulation datasets.\u003c/p\u003e\n\u003cp\u003eIn terms of value, if a nutrient credit programme were implemented at the national and international level, nutrient removal from oyster production would represent a potential benefit of €1.8 million annually to the Irish shellfish sector. Due to the lack of European derived data sets, the monetary benefit of the present study was estimated based on the nutrient removal valuation methodology of a previous U.S. study [25]. Therefore, to accurately reflect the current European and Irish oyster farming status, more studies are needed on the valuation of ecosystem services in Europe. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIt is now recognised that bivalve production provides not only ecosystem services but also cultural and economic services. The high amounts of C, N and P in oyster shells give them great potential for use in various applications. A study conducted in Korea found that oyster shell meal used as a liming agent for agricultural fields significantly increased soil pH and improved soil nutritional status, i.e., available phosphate and organic matter mass [42].\u0026nbsp;Shellfish shells could also be used as calcium supplements for livestock. The addition of shells (\u003cem\u003eVenus gallina\u003c/em\u003e) to a limestone supplement significantly improved the egg production performance of laying hens [43]. Oyster shells could also be a sustainable alternative to traditional building materials (e.g., mortar sand). A\u0026nbsp;study conducted in South Korea showed that small oyster shell particles (2–0.074 mm) were a potential substitute for conventional mortar sands in terms of compressive strength [44]. Additionally, waste oyster shells are a potential hard substrate for preparing artificial reefs for coral and oyster reef restoration [45,46,47,48]. Hence, the reuse of oyster shells and their variety of applications could represent a new income stream for the oyster industry, while allowing its transition towards a blue circular economy.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.2.\u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;Life cycle assessment\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn the Irish Pacific oyster farming sector, fuel use (i.e., use of tractors for oyster harvesting) and energy use (i.e., grading and packaging) were the main drivers of the environmental burden. Infrastructure and equipment played a secondary role in environmental impact.\u0026nbsp;The low service life of the oyster bags and trestles influenced all impact categories. Recent LCA studies on shellfish aquaculture have also reported similar findings, with 39% of GWP for mussels farmed in Italy arising from equipment and infrastructure [13]. To reduce the operation associated impacts, operators could apply alternative approaches to lower the fuel and energy use, such as the use of renewable energy sources, biofuels or investment in more efficient engines. According to the Renewable Energy Directive, by 2030, EU countries must ensure that the share of renewables in final energy consumption in transport is at least 14%, including a minimum share of 3.5% of advanced biofuels [49]. On the other hand, extending the service life of the farming equipment could reduce infrastructure-associated impacts in oyster farming.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOyster farming has shown relatively low global impacts on the environment compared to other seafood production sectors (e.g., wild catch fisheries and aquaculture) or livestock farming. The GWP to produce 1 tonne of rainbow trout (flow-through system), seabass (sea cages) and turbot (recirculating aquaculture system) was estimated at 2,753 kg CO\u003csub\u003e2\u003c/sub\u003e eq., 3,601 kg CO\u003csub\u003e2\u003c/sub\u003e eq. and 6,017 kg CO\u003csub\u003e2\u003c/sub\u003e eq., respectively [50]. The GWP for the capture of 1 tonne of horse mackerel by purse seiners and bottom trawlers in Galicia was estimated at 796 kg CO\u003csub\u003e2\u003c/sub\u003e eq. and 2,278 kg CO\u003csub\u003e2\u003c/sub\u003e eq., respectively [51]. The estimated GWP to produce a tonne of liveweight pig meat and liveweight broiler are 4,268.8 CO\u003csub\u003e2\u003c/sub\u003e eq. and 1,389.85 CO\u003csub\u003e2\u003c/sub\u003e eq., respectively [52,53]. The main environmental drivers in producing animal proteins from aquaculture, fisheries, and terrestrial farming are feed production, energy use, and fuel use. Furthermore, these food production systems are more complex in their life cycle stages, requiring sophisticated infrastructure, more labour, complex technologies (e.g., recirculating aquaculture systems, flow-through aquaculture systems), and additional processing steps (e.g., feed production, slaughtering, meat processing). In contrast, oyster farming is less technical and is done with traditional techniques (i.e., non-fed rack-and-bag culture in intertidal areas) that do not require feed input and complex infrastructures. There may be opportunities in the bivalve sector for value-added or novel food products targeted at environmentally conscious consumers. These strategic prospects may exist in high-growth food sectors, such as sports nutrition and snacks, for marketing it as a proteinous and nutritious food. Additional opportunities exist in pairing bivalves’ nutritional density and environmental performance to inform consumers better how they can meet their nutritional requirements while limiting their environmental impact [54]. While the present study demonstrates a low ecological impact, future LCAs should aim to increase the sample size of farms to obtain more solid results. In addition, there is a need to expand the scope of the study higher up the value chain and look at value-added products and the valorisation of circular economy opportunities for bivalve waste and shells in particular.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4.3.\u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp; Environmental strategies of bivalve farming \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eGiven the strong results of bivalve farming as an EP remediator, there are opportunities to use or include bivalve aquaculture as part of integrated catchment management. With many Irish rivers failing to meet the requirements of the Water Framework Directive (2000/60/EC) [55] and the national herd increasing, the pairing or co-location of these food production systems as complementary activities may allow for the mitigation of the excessive nutrients in coastal and transitional waters, while also producing a low carbon food product. This integrated approach may be limited regarding suitable sites, but novel and emerging bivalve culture systems may address this. In addition, uncertainty exists regarding the net nutrient remediation potential results presented in this study, as they may vary if more recent EP characterisation factors are used to convert N and P to\u0026nbsp;PO\u003csub\u003e4\u003c/sub\u003e eq.\u0026nbsp;The present study also shows the potential of oyster production as a carbon sink, with higher carbon sequestration potential (260 kg CO\u003csub\u003e2\u003c/sub\u003e eq. tonne harvested oysters \u003csup\u003e– 1\u003c/sup\u003e) compared to clams (254 kg CO\u003csub\u003e2\u003c/sub\u003e eq. tonne harvested clams \u003csup\u003e-1\u003c/sup\u003e) and mussel (146 kg tonne harvested mussels \u003csup\u003e-1\u003c/sup\u003e) farming [13]. With carbon farming being included in the EU’s new Common Agriculture Policy Strategic Plan\u0026nbsp;\u003cem\u003e2023-2027\u003c/em\u003e, there is also an opportunity for bivalve aquaculture to aid and play an active role in this form of environmental management [56].\u003c/p\u003e\n\u003cp\u003eThe seafood sector, including aquaculture producers, processors, wholesalers, retailers and food certification bodies, is facing a growing demand for information on the environmental footprint of their products from customers, investors and government agencies [57]. The present study provides a scientific basis to meet these informational demands and contribute to the imminent introduction of a science-based metric such as the Product Environmental Footprint [58]. This study brings an innovative and valuable approach with positive results, thus serving as a reference point for future research on the sustainable potential of the shellfish sector.\u0026nbsp;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgement\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe present study was part of the ShellAqua project (BIM-21/KGS/001) funded under the Bord Iascaigh Mhara’s\u0026nbsp;Knowledge Gateway Scheme, which is co-financed by the national exchequer: Ireland’s EU structure funds programme (ESIF) 2014-2020 \u0026amp; the European Maritime and Fisheries Fund (EMFF). The authors would also like to acknowledge funding from InterReg Atlantic Areas ERDF (NEPTUNUS – EAPA_576/2018). The authors would like to thank the commercial Irish oyster farms contributing to the data collection for this study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003cbr\u003e\u0026nbsp;PCD:\u0026nbsp;\u003c/strong\u003eInvestigation;\u0026nbsp;Formal analysis; Validation; Visualisation;\u0026nbsp;Roles/Writing – original draft; Writing – review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAT:\u0026nbsp;\u003c/strong\u003eConceptualisation; Data curation; Formal analysis; Funding acquisition; Investigation; Methodology; Project administration; Resources; Software; Validation; Visualisation; Roles/Writing – original draft; Writing – review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRC:\u0026nbsp;\u003c/strong\u003eConceptualisation; Data curation; Formal analysis; Funding acquisition; Investigation; Methodology; Project administration; Resources; Software; Supervision; Validation; Visualisation; Roles/Writing – original draft; Writing – review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAK:\u0026nbsp;\u003c/strong\u003eFormal analysis; Project administration; Supervision; Validation; Visualisation; Roles/Writing – original draft; Writing – review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAHLW:\u003c/strong\u003e Formal analysis; Supervision;\u0026nbsp;Validation; Visualisation; Roles/Writing – original draft; Writing – review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEC:\u003c/strong\u003e Conceptualisation; Formal analysis; Funding acquisition; Investigation; Methodology; Project administration; Resources; Software; Supervision; Validation; Visualisation; Roles/Writing – original draft; Writing – review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors declare no financial or non-financial competing interests.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets presented in the current study are available from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References ","content":"\u003col\u003e\n\u003cli\u003eIlea, R. 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Sustainability of mussel farming in the Po river delta, northern Italy, based on a Life Cycle Assessment approach. \u003cem\u003eSustainability.\u003c/em\u003e 12, 3814\u003cem\u003e. \u003c/em\u003ehttps://doi.org/10.3390/su12093814 (2020). \u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Table","content":"\u003cp\u003e\u003cstrong\u003eTable 1:\u003c/strong\u003e Extrapolated results on quantities of carbon, nitrogen, and phosphorous removed annually per site from average annual production and estimated nutrient removal values. \u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"929\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.285252960172228%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.38966630785791%\"\u003e\n \u003cp\u003e\u003cstrong\u003eUnit\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e\u003cstrong\u003eSite 1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e\u003cstrong\u003eSite 2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.240043057050592%\"\u003e\n \u003cp\u003e\u003cstrong\u003eAverage\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.667384284176535%\"\u003e\n \u003cp\u003e\u003cstrong\u003eNational extrapolation***\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.285252960172228%\"\u003e\n \u003cp\u003e\u003cstrong\u003eAnnual production\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.38966630785791%\"\u003e\n \u003cp\u003eTonne year\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e196\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.240043057050592%\"\u003e\n \u003cp\u003en.a.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.667384284176535%\"\u003e\n \u003cp\u003e11,000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.285252960172228%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eC sequestered\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.38966630785791%\"\u003e\n \u003cp\u003ekg tonne \u003csup\u003e-1\u003c/sup\u003e fresh product\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e70.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e79.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.240043057050592%\"\u003e\n \u003cp\u003e70.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.667384284176535%\"\u003e\n \u003cp\u003en.a.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.429479034307498%\"\u003e\n \u003cp\u003ekg year\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.772554002541295%\"\u003e\n \u003cp\u003e5,296.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.772554002541295%\"\u003e\n \u003cp\u003e15,622.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.628970775095299%\"\u003e\n \u003cp\u003e10,459.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.396442185514612%\"\u003e\n \u003cp\u003e825,198.06\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.285252960172228%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eN removed\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.38966630785791%\"\u003e\n \u003cp\u003ekg tonne -1 fresh product\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e2.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e3.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.240043057050592%\"\u003e\n \u003cp\u003e3.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.667384284176535%\"\u003e\n \u003cp\u003en.a.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.429479034307498%\"\u003e\n \u003cp\u003ekg year\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.772554002541295%\"\u003e\n \u003cp\u003e168.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.772554002541295%\"\u003e\n \u003cp\u003e757.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.628970775095299%\"\u003e\n \u003cp\u003e463.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.396442185514612%\"\u003e\n \u003cp\u003e33,572.32\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.285252960172228%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eValue N removal*\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.38966630785791%\"\u003e\n \u003cp\u003e\u0026euro; tonne\u003csup\u003e-1\u003c/sup\u003e fresh product\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e42.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e72.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.240043057050592%\"\u003e\n \u003cp\u003e57.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.667384284176535%\"\u003e\n \u003cp\u003en.a.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.429479034307498%\"\u003e\n \u003cp\u003e\u0026euro; year\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.772554002541295%\"\u003e\n \u003cp\u003e3,176.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.772554002541295%\"\u003e\n \u003cp\u003e14,283.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.628970775095299%\"\u003e\n \u003cp\u003e8,730.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.396442185514612%\"\u003e\n \u003cp\u003e1,931,543.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.285252960172228%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eP removed\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.38966630785791%\"\u003e\n \u003cp\u003ekg tonne\u003csup\u003e\u0026nbsp;-1\u003c/sup\u003e fresh product\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e0.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e0.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.240043057050592%\"\u003e\n \u003cp\u003e0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.667384284176535%\"\u003e\n \u003cp\u003en.a.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.429479034307498%\"\u003e\n \u003cp\u003ekg year\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.772554002541295%\"\u003e\n \u003cp\u003e21.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.772554002541295%\"\u003e\n \u003cp\u003e82.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.628970775095299%\"\u003e\n \u003cp\u003e52.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.396442185514612%\"\u003e\n \u003cp\u003e3,868.42\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.285252960172228%\" rowspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003eValue P removal*\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.38966630785791%\"\u003e\n \u003cp\u003e\u0026euro; tonne\u003csup\u003e-1\u003c/sup\u003e fresh product\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e9.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e14.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.240043057050592%\"\u003e\n \u003cp\u003e11.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.667384284176535%\"\u003e\n \u003cp\u003en.a.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"26.429479034307498%\"\u003e\n \u003cp\u003e\u0026euro; year\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.772554002541295%\"\u003e\n \u003cp\u003e716.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.772554002541295%\"\u003e\n \u003cp\u003e2,814.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.628970775095299%\"\u003e\n \u003cp\u003e1,798.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.396442185514612%\"\u003e\n \u003cp\u003e46,161.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.285252960172228%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTotal value nutrient removal\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.38966630785791%\"\u003e\n \u003cp\u003e\u0026euro; year\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e3,892.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e17,098.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.240043057050592%\"\u003e\n \u003cp\u003e10,495.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.667384284176535%\"\u003e\n \u003cp\u003e1,977,705.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.285252960172228%\"\u003e\n \u003cp\u003e\u003cstrong\u003ePopulation equivalent (N)**\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.38966630785791%\"\u003e\n \u003cp\u003eindividuals\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.208826695371368%\"\u003e\n \u003cp\u003e230\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.240043057050592%\"\u003e\n \u003cp\u003e140\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.667384284176535%\"\u003e\n \u003cp\u003e10,173\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eC, carbon; N, nitrogen; P, phosphorous; n.a., not applicable;\u0026nbsp;*Value per tonne of N and P removed taken from Carss et al., 2020; **\u0026nbsp;Nitrogen population equivalent is\u0026nbsp;based on a value of 3.3 kg N treated per person per year [21];\u0026nbsp;*** based on BIM 2022 figures [31], i.e., total Irish annual Pacific oyster production of 11,000 tonnes.\u003c/p\u003e\n"}],"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":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"npj-sustainable-agriculture","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [npj Sustainable Agriculture](https://www.nature.com/npjsustainagric/)","snPcode":"44264","submissionUrl":"https://submission.springernature.com/new-submission/44264/3","title":"npj Sustainable Agriculture","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"NPJ","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Seafood, Ecosystem services, Sustainability, Carbon capture, Life Cycle Assessment, Aquaculture. ","lastPublishedDoi":"10.21203/rs.3.rs-4294313/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4294313/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eSustainable food production that meets consumer demands while reducing environmental impacts is a critical societal challenge. The seafood industry, including shellfish aquaculture, is considered a key segment for future protein supplies. Like all food production sectors, environmental impacts of the \"blue food” sector are a key consideration. The present study demonstrated that Irish Pacific oyster (\u003cem\u003eMagallana gigas\u003c/em\u003e) farming has relatively low environmental impacts (i.e., 100-year global warming potential of 373.86 kg CO\u003csub\u003e2\u003c/sub\u003e eq. tonne\u003csup\u003e-1\u003c/sup\u003e; acidification potential of 1.33 kg SO\u003csub\u003e2\u003c/sub\u003e eq. tonne\u003csup\u003e-1\u003c/sup\u003e;\u003csup\u003e \u003c/sup\u003eand eutrophication potential of 0.39 kg PO\u003csub\u003e4\u003c/sub\u003e eq. tonne\u003csup\u003e-1\u003c/sup\u003e) compared to other seafood and terrestrial animal sectors. Using ecosystem services metrics, one tonne of fresh harvested oysters can remove, on average, 3.05 tonnes of nitrogen, 0.35 tonnes of phosphorus, and sequester 70.52 tonnes of carbon from the environment, thus potentially acting as a nutrient remediator and a potential short-term carbon sink. These findings show how oysters can offer a sustainable food source and provide local environmental benefits. The study also points to future work which could further improve ecosystem services modelling for this food source.\u003c/p\u003e","manuscriptTitle":"Oysters, a sustainable bluefood?","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-25 10:45:07","doi":"10.21203/rs.3.rs-4294313/v1","editorialEvents":[{"type":"communityComments","content":1},{"type":"decision","content":"Revision requested","date":"2024-06-07T00:15:46+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-05-30T03:17:39+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-05-14T16:37:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"127076581891317833568867493788673741530","date":"2024-05-09T18:26:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"96967729176906250895347939937033219926","date":"2024-04-25T11:18:01+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-04-25T00:06:21+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-04-23T06:08:24+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-04-22T06:01:34+00:00","index":"","fulltext":""},{"type":"submitted","content":"npj Sustainable Agriculture","date":"2024-04-19T16:33:05+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"npj-sustainable-agriculture","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [npj Sustainable Agriculture](https://www.nature.com/npjsustainagric/)","snPcode":"44264","submissionUrl":"https://submission.springernature.com/new-submission/44264/3","title":"npj Sustainable Agriculture","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"NPJ","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"f7214a2e-e322-4592-b6c3-edb58ae59c83","owner":[],"postedDate":"April 25th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":31123727,"name":"Biological sciences/Biotechnology/Biologics"},{"id":31123728,"name":"Biological sciences/Biotechnology"},{"id":31123729,"name":"Earth and environmental sciences/Ecology"},{"id":31123730,"name":"Biological sciences/Ecology"},{"id":31123731,"name":"Biological sciences/Ecology/Agri ecology"},{"id":31123732,"name":"Biological sciences/Ecology/Climate change ecology"},{"id":31123733,"name":"Biological sciences/Ecology/Ecosystem services"},{"id":31123734,"name":"Earth and environmental sciences/Environmental sciences"},{"id":31123735,"name":"Earth and environmental sciences/Environmental sciences/Environmental impact"},{"id":31123736,"name":"Earth and environmental sciences/Environmental social sciences"},{"id":31123737,"name":"Earth and environmental sciences/Environmental social sciences/Climate change adaptation"},{"id":31123738,"name":"Earth and environmental sciences/Environmental social sciences/Climate change impacts"},{"id":31123739,"name":"Earth and environmental sciences/Environmental social sciences/Climate change mitigation"},{"id":31123740,"name":"Earth and environmental sciences/Environmental social sciences/Climate change policy"},{"id":31123743,"name":"Earth and environmental sciences/Environmental social sciences/Environmental impact"},{"id":31123744,"name":"Earth and environmental sciences/Environmental social sciences/Sustainability"},{"id":31123745,"name":"Earth and environmental sciences/Hydrology"},{"id":31123746,"name":"Biological sciences/Zoology"},{"id":31123747,"name":"Biological sciences/Zoology/Animal physiology"}],"tags":[],"updatedAt":"2025-03-28T04:23:16+00:00","versionOfRecord":[],"versionCreatedAt":"2024-04-25 10:45:07","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4294313","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4294313","identity":"rs-4294313","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}