Characterisation of microplastics in an isolated mangrove island using multiple ecosystem components including brachyuran crabs

Characterisation of microplastics in an isolated mangrove island using multiple ecosystem components including brachyuran crabs | 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 Research Article Characterisation of microplastics in an isolated mangrove island using multiple ecosystem components including brachyuran crabs Gopika Sivan, Jestin M.S, Apreshgi K.P, Priyaja P This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4285631/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 16 Jul, 2025 Read the published version in Wetlands → Version 1 posted 5 You are reading this latest preprint version Abstract Mangroves serving as interfaces between land and sea, function as significant filtration and interception systems for environmental microplastics (MPs). The structural complexity of mangrove roots enhances their trapping potential, making them prospective sinks for plastics. MPs have a strong affinity for mangrove leaves due to their lipophilic surface, temporarily accumulating MPs from both air and water. Brachyuran crabs, the core processors of mangrove litter can ingest MPs bound to leaves, potentially transferring them through the food chain to apex predators. Currently, studies from isolated mangrove islands are lacking. So, we conducted a holistic study examining MPs within multiple ecosystem components of an isolated mangrove island including water, sediment, leaves, stilt root and fallen leaves of mangrove as well as body parts of three species of mangrove crabs along southwest coast of India. Scanning electron microscopy with energy-dispersive X-ray spectroscopy was carried out to confirm the suspected MPs in root and leaf. MPs were detected in water, sediment, fallen leaves and crabs. Abundance of MPs in water and sediment was 5.42 ± 0.2 particles/L and 400 ± 86 particles/Kg respectively, with the size range > 350 µ. Fallen leaves showed an abundance of 0.062 ± 0.054 particles/cm 2 . A higher abundance of MPs was observed in the gastro-intestinal tract of mangrove crabs. Fibre was the dominant morphotype in all components, revealing trophic transfer from water and sediment to crabs via fallen leaves and direct ingestion. The findings indicate that even isolated mangrove islands serve as repositories for MPs, affecting the mangrove food chain. Plastics leaf litter pollution bioindicator Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Introduction Mangroves are vital intertidal ecosystems renowned for their high biological productivity, serving as primary feeding and breeding grounds for a diverse array of organisms (Arceo-Carranza et al. 2021 ; Das et al. 2022 ; Bacar et al. 2023 ). These ecosystems are highly susceptible to microplastic (MP) accumulation due to their distinct geography, high primary productivity, complex hydrodynamic and topographical factors. Mangroves are recognized as prospective sinks for plastics due to the structural complexity of roots with high trapping potential (Martin et al. 2019 ; Deng et al. 2021 ; Paduani et al. 2024 ). They tend to accumulate more MPs compared to neighbouring ecosystems, regardless of whether the MPs are suspended in water, buried in sediment, ingested by organisms or attached to leaves or plants (Wang et al. 2023 ). Mangroves intercept MPs from various sources, including riverine sources, atmospheric deposition and marine origin (Li et al. 2022 ). This interception trend raises concern, as the build-up of MPs could endanger mangrove ecosystems over time, as these particles have the potential to persist for decades and the accumulation of MPs in these habitats is increasing at an exponential rate (Jiao et al. 2022 ; Wang et al. 2023 ). Crabs, particularly brachyuran crabs, dominate the benthic fauna of the mangrove ecosystems, primarily consuming leaves and organic debris on the forest floor (Shanij et al. 2016 ). Among them, sesarmid crabs ( Parasesarma plicatum ) are significant initial processors of mangrove leaf litter (Rani et al. 2023 ). Grapsid crabs like Metopograpsus latifrons exhibit opportunistic feeding habits, consuming leaves, molluscs and crustaceans (Vannini et al. 1997 ) and while Metopograpsus thukuhar feeds on macroalgae and mangrove leaves (Fratini et al. 2000 ). Despite being non-edible, these three crab species play a vital role in linking lower-level consumers with those higher in the food chain. MPs have a strong affinity for mangrove leaves due to their lipophilic surface and so they act as temporary sinks of MPs from both air and water (Bi et al. 2020 ; Yin et al. 2021 ; Wei et al. 2024 ). Crabs are the initial processors of mangrove leaf litter and their bioturbation activity causes MPs to enter their bodies directly (Capparelli et al. 2022 ). These crabs become prey for large carnivorous crabs, fishes and herons (Brennecke et al. 2015 ; Shanij et al. 2016 ), thereby facilitating the transfer of MPs across higher trophic levels. As mangroves are transition zones between land and sea, most of the plastics are intercepted among the roots and so there is a high chance of trophic transfer of these particles through the food chain. In an isolated mangrove island, direct input from the land is absent. So, in this study, we characterised the status of MPs in an isolated mangrove ecosystem along the south west coast of India. Assessment of MPs was done in multiple ecosystem components of the mangrove island including water, sediment, leaves, stilt root and fallen leaf of dominating mangrove species ( Rhizophora mucronata ) along with three species of mangrove crabs ( Metopograpsus latifrons, Metopograpsus thukuhar and Parasesarma plicatum ). There is a lack of information about the bioavailability of MPs that adhere to mangrove leaves and their trophic transfer (Fang et al. 2023 ). Also, holistic studies on MPs from the mangrove ecosystems are relatively scarce (Batel et al. 2016 ; Miller et al. 2020 ; Sarker et al. 2022 ). Materials and methods Sampling Samples were collected from a remote mangrove island of Chettuva, along the southwest coast of India (10° 53ꞌ 74 N, 76° 04ꞌ 98 E) during March 2022 (Fig. 1 ). Chettuva is known for one of the biggest mangrove forests in Kerala, situated at the confluence of the Chettuva river and the Arabian Sea and a site of migratory birds including herons, egrets and kingfishers. This remote mangrove island is devoid of human habitation, but serves as a popular destination for ecotourism activities. This mangrove forest is dominated by the species, Rhizophora mucronata . Surface water temperature was measured using a mercury-in-glass thermometer, pH and salinity was measured using portable water analyser. Dissolved oxygen was determined by Winkler method (APHA 2000 ). Water and sediment samples were collected and transferred to sample containers. Crabs were collected using scoop nets and hand-picking. The leaves (n = 12) and stilt roots of mangroves were also collected and all the samples were brought to the laboratory in ice-freezed conditions. Sediment texture analysis Sediment texture analysis was carried out using wet sieving (Krumbein and Pettijohn 1938 ). 100g of wet sediment samples were treated with 30% H 2 O 2 and rinsed with distilled water to remove organic components. 1N HCl was added to remove the CaCO 3 and washed with distilled water to remove residual HCl. The sediment was dried in a hot air oven at 60°C for 3 hours. About 10g of the dried sediment sample was weighed out. A suspension of 20 ml of 20% sodium hexametaphosphate was added, diluted with distilled water and it was sieved through a 63 µm mesh. The sand retained was transferred to a pre-weighed Petri dish, dried at 60°C, and weighed. The filtered sample was made up to 1000 ml, well agitated, and allowed to settle. From this, about 10 ml was pipetted out from a height of 10-20cm after 51 minutes and 39 seconds. It was also transferred to a small pre-weighed beaker, dried, and weighed to quantify silt and clay fractions. Identification of mangrove Field identification of mangrove was done following Reddy ( 2008 ). Length, width and surface area of leaves were measured using ImageJ software. Identification of mangrove crabs Crabs of approximately equal length were selected for the study and morphometric measurements (carapace length, carapace width and weight) were taken. Crabs were morphologically identified using taxonomic keys (Tweedie 1949 ; Al-Ghais and Cooper 1996 ; Rahayu and Ng 2010 ). Analysis of MPs in water 50L of water was collected and sieved through stacked sieves (500µ, 350µ and 180µ) and the filtrate was washed using pre-filtered distilled water and transferred to respective sample containers. The filtrate obtained after passing 50L of water through stacked sieves of different mesh sizes were pre-treated by density separation (using concentrated NaCl solution), hydrogen peroxide treatment (30% H 2 O 2 ), and vacuum filtration (1.2µm GF/C glass microfiber filter, Whatman™) followed by visual sorting under a stereomicroscope. Analysis of MPs in sediment MPs in sediment samples were extracted following modified floatation method (Thompson et al. 2004 ; Nor and Obbard 2014 ; Falahudin et al. 2020 ). About 1 Kg of sediment was weighed and transferred to a glass beaker and allowed to suspend in concentrated NaCl solution (3 L). The same is stirred vigorously for 5–10 minutes and allowed to settle for 2 hrs. 30% H 2 O 2 was added to the sediment to digest organic material and the mixture was allowed to stand for 24 hrs (Cordova et al. 2021 ). The supernatant was concentrated by passing through a stacked arranged sieve of 500µ, 350µ, and 180µ respectively. The sieves were carefully washed so as to transfer the particles including MPs into the labelled container for vacuum filtration. Pre-treated sediment samples were filtered through a 1.2µm glass microfiber filter (GF/C, 47 mm diameter, Whatman™) to isolate the MPs followed by visual sorting under a stereomicroscope. Analysis of MPs in the leaf and stilt root of mangrove For isolating MPs, the leaves and roots of mangrove tree were washed with Milli-Q® water and cut in to small pieces followed by treatment with 10% KOH at 40˚C for 48 hrs (Fang et al. 2018 ). When the solution became clear and yellow, digestion was considered as complete and the solution was diluted with warm Milli-Q® water in 1:10 ratio. The supernatant was filtered through 1.2 µm glass microfiber filter (Whatman GF/C). MPs on the fallen leaves (N = 12) was extracted following Fang et al. ( 2023 ). Each glass bottle with four fallen mangrove leaves was filled with Milli-Q water and was placed in ultrasonic bath for 5 minutes to promote the MPs from falling off the leaves. Water was then transferred to a pre-cleaned glass beaker and the process was repeated three times. All the water collected in glass beaker was then filtered through a GF/C membrane filter (1.2 µm pore size, 47 mm diameter, Whatman™) followed by visual sorting. Analysis of MPs in mangrove crabs Body parts of the crab such as the carapace, gastro-intestinal tract (GIT) and claw muscle (CM) were dissected out using forceps and scalpel and were weighed. 25 crabs of each species were pooled together for MPs analysis. NaCl and H 2 O 2 were pre-filtered through 1.2µm filter prior to use. For isolating MPs, the carapace was washed thoroughly with Milli-Q® water and cut into small pieces followed by treatment with 10% KOH at 40˚C for 48 hrs (Fang et al. 2018 ). When the solution became clear and yellow, digestion was considered as complete and the solution was diluted with warm Milli-Q® water in 1:10 ratio. The supernatant was filtered through 1.2 µm filter (Whatman GF/C). For isolating MPs, the GIT and CM were put in to 1L glass beaker and digested separately. About 200–400 ml of 30% H 2 O 2 was added to the beakers to digest the organic matter. Beakers were covered with lid immediately and were placed in oscillation incubator at 65˚C with 80 rpm for 24–72 hrs depending upon the digestion level (Jabeen et al. 2017 ). About 800 ml of saturated NaCl was added to the beakers to separate MPs from dissolved solution of samples via floatation. The solution was mixed by stirring and kept overnight to observe the clearance level. Then the overlying water was directly filtered through 1.2 µm microfiber filters (Whatman GF/C), using a vacuum pump. After the filtration, filters were placed in cleaned Petri dishes with lids for microscopic observation of plastic items. The abundance, morphotype and the colour of the MPs were recorded. Fourier-transform infrared spectroscopy (FTIR) analysis To identify the polymer, representative samples of MPs (N = 20) were selected randomly and analysed by FT-IR spectrometer (PerkinElmer Spectrum 100 FT-IR). Scanning electron microscope (SEM) and Energy dispersive X-ray (EDAX) analysis To determine the surface morphology and elemental composition of suspected microplastics, we carried out SEM/EDAX (Zeiss Microsystems EVO 18) analysis on the stilt root and leaf of the mangrove. Quality control All the sampling equipment’s was washed with Milli-Q water to prevent contamination. All the samples were collected in glass containers. Reagents were also filtered through 1.2µm filter prior to use. Lab coats and gloves were worn during sample preparation and processing. After filtration, the filter papers were kept in pre-cleaned glass Petri dishes until identification and characterization. Statistical analysis One-way ANOVA was used to determine the variation of MP abundance in three crab species and fallen leaves. Results were considered with a significance level of 0.05 and the data were analysed using IBM-SPSS Statistics for Windows (Version 26.0). Results Physico-chemical parameters Temperature of the water was 33.7º C. Salinity and pH were 25 psu and 8.3 respectively and dissolved oxygen was 7.25 mg/L. Sediment texture analysis According to the sediment texture analysis, sediment constituted 92.6% of sand followed by silt (6.8%) and clay (0.6%). Identification of mangrove Mangrove was identified as Rhizophora mucronata . Tall-sized tree, stilt roots emerging from the lower trunk, woody, slender and cylindrical. Leaves were simple and opposite, dark glossy green, mucronate. Morphometrics of leaves (mean value ± SE) are presented in Table 1 . Table 1 Morphometrics of leaves (mean value ± SE) Length (cm) Width (cm) Weight (g) Area (sq.cm) 12.47 ± 2.10 6.54 ± 1.37 1.91 ± 0.32 54.58 ± 16.31 Identification of mangrove crabs A total of 25 crabs of each species were collected from the study area and identified. They belonged to 3 species namely Metopograpsus latifrons (White 1847 ), Metopograpsus thukuhar (Owen 1839 ) and Parasesarma plicatum (Latreille 1803 ) (Fig. 2 , 3 ). Mean values for carapace length, carapace width and weight of crabs are given in Table 2 . Table 2 Morphometrics of the mangrove crabs with their standard deviation Parameters Metopograpsus latifrons Metopograpsus thukuhar Parasesarma plicatum Carapace width (cm) 2.9–3.3 ± 0.20 2.7–3.1 ± 0.22 2.5–3.1 ± 0.19 Carapace length (cm) 2.5–2.9 ± 0.25 2.2–2.6 ± 0.18 2.2–2.9 ± 0.18 Weight (g) 2.9–3.62 ± 0.78 4.0-7.5 ± 0.95 2.8-4.0 ± 0.87 Analysis of MPs in water In water, abundance of MPs was found to be 5.42 ± 0.2 particles/L, and the morphotype of MPs was dominated by fibres (89.5%) followed by fragment (10.5%) (Fig. 4 ). Foams were absent in water samples. Based on mesh sizes used for sieving, MPs were classified in to > 500µ, > 350µ, and > 180µ respectively. In water samples, 500µ mesh retained 2 ± 0.6 particles/L followed by 350µ (1.2 ± 0.6 particles/L) and 180µ (0.06 ± 0.02 particles/L) (Fig. 5 A). MPs obtained from the water samples were grouped into four major colours (transparent, red, blue and black) (Fig. 5 B). In water, transparent MPs constituted 63% followed by blue (21%) and red colour (15.7%). Black-coloured MPs were absent in water samples. Analysis of MPs in sediment Abundance of MPs was relatively high in sediment (400 ± 86 particles/Kg), dominated by fibres (61.6%), films (21.2%), fragments (16.2%) and foams (1%). In sediment, 500µ mesh retained a greater number of 165 ± 37 particles/Kg. 350µ and 180µ mesh retained 155 ± 18 particles/Kg and 80 ± 9 particles/Kg respectively (Fig. 5 A). MPs with transparent colour (47%) was dominated followed by red (26%), blue (18.7) and black (7.5%) (Fig. 5 B). Analysis of MPs in the leaf and stilt root MPs were not observed in the digested leaf and root samples, but was detected in the fallen leaves. MP abundance on the fallen leaves were (0.062 ± 0.054 particles/cm 2 ). Fibre was the only morphotype found on the fallen leaves and were dominated by black colour (41.6%) followed by blue (33.3%) and red (25%). SEM/EDAX analysis SEM/EDAX analysis provided high-resolution images and the elemental composition of stilt root and leaf to screen whether the suspected particles are microplastics or not. SEM/EDAX analysis of particles that were identified as non-plastics are shown in Fig. 6 and Fig. 7 . Carbon EDAX peak which is characteristic of commonly found plastics like polyethylene and polypropylene was not detected. Analysis of MPs in mangrove crabs Fibres were detected in the CM and GIT of three crab species (Fig. 8 , 9 ). In CM, relatively higher abundance of MPs (1.75 particles/g) was found in both P. plicatum and M. latifrons followed by M. thukuhar (1 particle/g) (Table 3 ). The CM of M. latifrons was dominated by transparent colour (60%), M. thukuhar by red colour (50%) and P. plicatum by blue colour (60%) (Fig. 10 ). In the GIT, highest ingestion of MPs was found in P. plicatum with 6 particles/g. M. thukuhar and M. latifrons ingested 5 particles/g and 2.5 particles/g respectively (Table 3 ). MPs with blue colour dominated in the GIT of P. plicatum (58.4%) and M. thukuhar (40%) (Fig. 11 ). Gut contents of three crab species are represented in Fig. 8 D-F. No significant difference was observed in the abundance and the colour of the MPs between the tissues of three crab species (p > 0.05). MPs were absent in the carapace of the three crab species. Figure 11 Colour combination of MPs in the gastrointestinal tract of Parasesarma plicatum, Metopograpsus thukuhar and Metopograpsus latifrons . Table 3 Abundance of MPs in the claw muscle (CM) and gastro-intestinal tract (GIT) of three crab species ( Metopograpsus latifrons , Metopograpsus thukuhar , Parasesarma plicatum ). Body parts M. latifrons M. thukuhar P. plicatum CM 1.75 particles/g 1 particle/g 1.75 particles/g GIT 5 particles/g 2.5 particles/g 6 particles/g Fourier-transform infrared spectroscopy (FTIR) analysis Among the different MPs (N = 25) analysed, different spectral peaks were obtained (Fig. 12 ). The comparison of the spectral peaks with the spectral libraries revealed the identity of the polymer. The most abundant polymers in the analysed samples were high-density polyethylene-HDPE (55%), followed by low-density polyethylene-LDPE (30%), polypropylene-PP (5%), and polystyrene-PS (5%). Discussion Mangrove ecosystems have become a focal point for the accumulation of MPs, which can be attributed to the elevated productivity and biomass of mangroves, coupled with hydrodynamic conditions (Wang et al. 2023 ; Prarat et al. 2024 ). The fate of MPs intercepted within mangroves encompasses various pathways including sediment deposition, suspension in water, biological deposition (ingestion by organisms) and attachment to leaves and other structures within the mangrove environment (Wang et al. 2023 ). In this study, we made an assessment of MPs within multiple ecosystem components including water, sediment, leaves, stilt root and fallen leaves of R. mucronata , and mangrove crabs ( M. latifrons, M. thukuhar and P. plicatum ), within an isolated mangrove island. The study location is a remote mangrove island along the southwest coast of India, devoid of human habitation, but serving as a popular destination for ecotourism activities with efficient management of discarded plastics. Despite these efforts, MPs were detected in all components of the island’s ecosystem, except fresh leaves and stilt roots. The island receives wastewater discharges from residential areas, with the Kecheeri River serving as a major input into the Arabian Sea at Chettuva Lake, potentially acting as a carrier of MPs. The abundance of MPs in sediment (400 ± 86 particles/Kg) far exceeded that of water (5.42 ± 0.2 particles/L). Owing to high organic matter, mangrove sediment can absorb MPs through a range of physical, chemical, and biological processes (Martin et al. 2020 ). Despite the thick mangrove cover along the southwest coast of India, studies on MPs from mangroves remain scarce. Kannankai et al. ( 2022 ) reported higher concentrations of MPs (1275 ± 532 particles/Kg in the sediment and 101.6 particles/L in the surface waters) in an urban mangrove ecosystem along the southwest coast compared to the island ecosystem. Fibres were the most abundant morphotype in both water and sediment, consistent with previous findings in various mangrove ecosystems (Rahmawati and Patria, 2019 ; Duan et al. 2021 ; Kannankai et al. 2022 ). Fibres are derived presumably from synthetic clothing, fragmentation of MPs, fibrous fishing gears and atmospheric fallout (Dris et al. 2016 ; Hu et al. 2020). Fragments, primarily formed through photooxidation of larger plastic debris or mechanical abrasion of packaging and clothing wastes were also prevalent (Song et al. 2015). Mangrove ecosystems play a crucial role in intercepting a substantial portion of riverine MPs, with the interception rates influenced by MPs characteristics, sediment properties and hydrodynamic factors (Jiao et al. 2022 ). The dominant crab taxa in mangrove ecosystems include sesarmids and grapsid crabs (Apreshgi and Abraham 2019 ). Fibres were detected in both the CM and the GIT of the three crab species, indicating their transfer from water and sediment. The abundance of MPs in mangrove crabs can be attributed to the availability of plastics within the mangrove environment and their feeding behaviour (Not et al. 2020 ; Abd Rahim et al. 2023 ). This study is the first to report MPs in the CM and GIT of P. plicatum , M. thukuhar and M. latifrons from southwest coast of India. Among the three crab species, sesarmid crab P. plicatum exhibited the highest abundance of MPs in the GIT, likely due to its preference for mangrove leaf litter as a primary food source. The presence of MPs in brachyuran crabs makes them ideal indicators of MPs contamination (Abd Rahim et al. 2023 ). Hence, the crab P. plicatum can be used as an indicator of MP pollution in tropical mangrove ecosystems. The presence of MPs in CM of crabs is not reported in earlier studies. Translocation of MPs into different organs including gills, stomach and hepatopancreas of the fiddler-crab Uca rapax has been documented (Brennecke et al. 2015 ). Fibres were the only morphotype found on fallen mangrove leaves, potentially serving as a pathway for MPs to enter the crab’s body, as they feed on leaf litter. Fallen mangrove leaf as a potential pathway for MPs to enter the snails with opportunistic feeding behaviour has been reported by Fang et al. ( 2023 ). A previous study has reported an abundance of 1.9 ± 0.9 particles/g in the mangrove crab Ucides occidentalis of Tumbes mangroves (Aguirre-Sanchez et al. 2024 ). Water and sediment were dominated by transparent MPs. Studies in mangrove ecosystems have reported transparent and white as the main colours in water and sediment of mangroves (Aliabad et al. 2019 ; Li et al. 2020 , Duan et al. 2021 ). Fallen mangrove leaves were dominated by black, blue and red coloured MPs. Fang et al. ( 2023 ) reported black, blue, transparent and white coloured mesoplastics and MPs in mangrove leaves and herbivorous snails. Colour of MPs is considered crucial as it influences species ingesting behaviour (Cverenkárová et al. 2021 ). Blue-coloured MPs dominated in the GIT of M. thukuhar and P. plicatum , and transparent MPs in M. latifrons . A striking variation in the MPs colouration was observed in the CM of three crab species, with M. latifrons dominated by transparent colour, M. thukuhar by red colour and P. plicatum by blue colour. The polymers identified in the samples predominantly included HDPE, LDPE, PP and PS. LDPE and PP were reported as dominant polymers in urban mangrove ecosystems along the southwest coast (Kannankai et al. 2022 ). An increase in the MP abundance and trophic level transfer could pose significant hazards to both inhabitants and ecosystem functioning (Daniel et al. 2022 ). Conclusion This study provides insights into the distribution of MPs within various components of an isolated mangrove island ecosystem. The mangrove island serves as a focal point for the interception of MPs due to its geographical location near the river mouth, facilitating the accumulation of plastic debris carried by freshwater runoff from inland areas. The prevalence of the fibre morphotype across different environmental compartments such as water, sediment, fallen mangrove leaves, claw muscle (CM) and gastrointestinal tract (GIT) of crabs underlines the pervasive nature of MPs in the mangrove ecosystem. The detection of MPs in the fallen leaves suggests a potential pathway for trophic transfer directly through the food chain. The relatively high abundance of MPs in the GIT of sesarmid crab P. plicatum highlights the susceptibility of certain species to MPs uptake and accumulation. Understanding the presence of MPs at different trophic levels is crucial for comprehending their transport and transformation mechanisms within the mangrove ecosystem. An upsurge in the MPs abundance poses a threat to benthic biota and higher trophic levels, potentially impacting the health and resilience of the mangrove ecosystem. Declarations Acknowledgements The first author is grateful to the Cochin University of Science and Technology, Kerala for the award of University Senior Research Fellowship. We express our gratitude to the Head of the Department of Chemical Oceanography, Cochin University of Science and Technology for their invaluable assistance with FT-IR analysis. We thank Mr. Usman and Ms. Chandramathy A.K for their assistance during field work. Author contributions All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Gopika Sivan, Jestin M.S, Apreshgi K.P and Priyaja P. The first draft of the manuscript was written by Gopika Sivan and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Funding The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. Code availability Not applicable Data availability All data generated or analysed during this study are included in this manuscript. Ethics approval Not applicable Conflicts of interest The authors have no relevant financial or non-financial interests to disclose. References Abd Rahim NH, Cannicci S, Ibrahim YS, et al (2023) Commercially important mangrove crabs are more susceptible to microplastic contamination than other brachyuran species. Sci Total Environ 903:166271. doi: 10.1016/j.scitotenv.2023.166271 Aguirre-Sanchez A, Purca S, Cole M, et al (2024) Prevalence of microplastics in Peruvian mangrove sediments and edible mangrove species. Mar Pollut Bull 200:116075. doi: 10.1016/j.marpolbul.2024.116075 Al-Ghais SM, Cooper RT (1996) Brachyura (Grapsidae, Ocypodidae, Portunidae, Xanthidae and Leucosiidae) of Umm Al Quwain mangal, United Arab Emirates. Trop Zool 9:409–430. Aliabad MK, Nassiri M, Kor K (2019) Microplastics in the surface seawaters of Chabahar Bay, Gulf of Oman (Makran Coasts). Mar Pollut Bull 143:125–133. doi: 10.1016/j.marpolbul.2019.04.037 APHA (2000) Standard methods for the examination of water and wastewater, 18th ed. American Public Health Association (APHA), American Water Works Association (AWWA) and Water Pollution Control Federation (WPCF), Washington, DC. Apreshgi KP, Abraham KM (2019) Brachyuran crab diversity in an isolated mangrove patch of the Cochin backwater, central Kerala, India. J Aquat Biol Fish 7(1&2):8-14. Arceo-Carranza D, Chiappa-Carrara X, Chávez López R, Yáñez Arenas C (2021) Mangroves as Feeding and Breeding Grounds. In: Rastogi RP, Phulwaria M, Gupta DK (eds) Mangroves: Ecology, Biodiversity and Management. Springer Singapore, Singapore, pp 63–95 Bacar FF, Lisboa SN, Sitoe A (2023) The Mangrove Forest of Quirimbas National Park Reveals High Carbon Stock Than Previously Estimated in Southern Africa. Wetlands 43:60. doi: 10.1007/s13157-023-01707-1 Batel A, Linti F, Scherer M, et al (2016) Transfer of benzo [ a ] pyrene from microplastics to Artemia nauplii and further to zebrafish via a trophic food web experiment: CYP1A induction and visual tracking of persistent organic pollutants. Environ Toxicol Chem 35:1656–1666. doi: 10.1002/etc.3361 Bi M, He Q, Chen Y (2020) What Roles Are Terrestrial Plants Playing in Global Microplastic Cycling?. Environ Sci Technol 54:5325–5327. doi: 10.1021/acs.est.0c01009 Brennecke D, Ferreira EC, Costa TMM, et al (2015) Ingested microplastics (>100μm) are translocated to organs of the tropical fiddler crab Uca rapax . Mar Pollut Bull 96:491–495. doi: 10.1016/j.marpolbul.2015.05.001 Capparelli MV, Martínez-Colón M, Lucas-Solis O, et al (2022) Can the bioturbation activity of the fiddler crab Minuca rapax modify the distribution of microplastics in sediments? Mar Pollut Bull 180:113798. doi: 10.1016/j.marpolbul.2022.113798 Cordova MR, Ulumuddin YI, Purbonegoro T, Shiomoto A (2021) Characterization of microplastics in mangrove sediment of Muara Angke Wildlife Reserve, Indonesia. Mar Pollut Bull 163:112012. doi: 10.1016/j.marpolbul.2021.112012 Cverenkárová K, Valachovičová M, Mackuľak T, et al (2021) Microplastics in the Food Chain. Life 11:1349. doi: 10.3390/life11121349 Daniel DB, Ashraf PM, Thomas SN (2022) Impact of 2018 Kerala flood on the abundance and distribution of microplastics in marine environment off Cochin, Southeastern Arabian Sea, India. Reg Stud Mar Sci 53:102367. doi: 10.1016/j.rsma.2022.102367 Das SC, Das S, Tah J (2022) Mangrove Forests and People’s Livelihoods. In: Das SC, Pullaiah, Ashton EC (eds) Mangroves: Biodiversity, Livelihoods and Conservation. Springer Nature Singapore, Singapore, pp 153–173 Deng H, He J, Feng D, et al (2021) Microplastics pollution in mangrove ecosystems: A critical review of current knowledge and future directions. Sci Total Environ 753:142041. doi: 10.1016/j.scitotenv.2020.142041 Dris R, Gasperi J, Saad M, et al (2016) Synthetic fibers in atmospheric fallout: A source of microplastics in the environment? Mar Pollut Bull 104:290–293. doi: 10.1016/j.marpolbul.2016.01.006 Duan J, Han J, Cheung SG, et al (2021) How mangrove plants affect microplastic distribution in sediments of coastal wetlands: Case study in Shenzhen Bay, South China. Sci Total Environ 767:144695. doi: 10.1016/j.scitotenv.2020.144695 Falahudin D, Cordova MR, Sun X, et al (2020) The first occurrence, spatial distribution and characteristics of microplastic particles in sediments from Banten Bay, Indonesia. Sci Total Environ 705:135304. doi: 10.1016/j.scitotenv.2019.135304 Fang C, Zheng R, Hong F, et al (2023) First evidence of meso- and microplastics on the mangrove leaves ingested by herbivorous snails and induced transcriptional responses. Sci Total Environ 865:161240. doi: 10.1016/j.scitotenv.2022.161240 Fang C, Zheng R, Zhang Y, et al (2018) Microplastic contamination in benthic organisms from the Arctic and sub-Arctic regions. Chemosphere 209:298–306. doi: 10.1016/j.chemosphere.2018.06.101 Fratini S, Cannicci S, Abincha LM, Vannini M (2000) Feeding, Temporal, and Spatial Preferences of Metopograpsus Thukuhar (Decapoda; Grapsidae): An Opportunistic Mangrove Dweller. J Crust Biol 2:326–333. https://doi.org/10.1163/20021975-99990044 Hu T, Shen M, Tang W (2022) Wet wipes and disposable surgical masks are becoming new sources of fiber microplastic pollution during global COVID-19. Environ Sci Pollut Res 29:284–292. https://doi.org/10.1007/s11356-021-17408-3. Jabeen K, Su L, Li J, et al (2017) Microplastics and mesoplastics in fish from coastal and fresh waters of China. Environ Pollut 221:141–149. doi: 10.1016/j.envpol.2016.11.055 Jiao M, Wang Y, Li T, et al (2022) Riverine microplastics derived from mulch film in Hainan Island: Occurrence, source and fate. Environ Pollut 312:120093. doi: 10.1016/j.envpol.2022.120093 Kannankai MP, Alex RK, Muralidharan VV, et al (2022) Urban mangrove ecosystems are under severe threat from microplastic pollution: a case study from Mangalavanam, Kerala, India. Environ Sci Pollut Res 29:80568–80580. doi: 10.1007/s11356-022-21530-1 Krumbein WC, Pettijohn FJ (1938) Manual of Sedimentary Petrography. D. Appleton-Century Company, Inc., New York, 549 pp Latreille PA (1803) Histoire Naturelle, Générale et Particulière, des Crustacés et des Insectes. Ouvrage Faisant Suite aux Oeuvres de Leclerc de Buffon, et Partie du cours Complet d'Histoire Naturelle Rédigé par C. S. Sonnini, Membre de Plusieurs Sociétés Savantes. Paris F Dufart 6:1-391, pls. 44-57 Li R, Wei C, Jiao M, et al (2022) Mangrove leaves: An undeniably important sink of MPs from tidal water and air. J Hazard Mater 426:128138. doi: 10.1016/j.jhazmat.2021.128138 Li R, Yu L, Chai M, et al (2020) The distribution, characteristics and ecological risks of microplastics in the mangroves of Southern China. Sci Total Environ 708:135025. doi: 10.1016/j.scitotenv.2019.135025 Martin C, Almahasheer H, Duarte CM (2019) Mangrove forests as traps for marine litter. Environl Pollut 247:499–508. doi: 10.1016/j.envpol.2019.01.067 Martin C, Baalkhuyur F, Valluzzi L, et al (2020) Exponential increase of plastic burial in mangrove sediments as a major plastic sink. Science Advances 6:eaaz5593. doi: 10.1126/sciadv.aaz5593 Miller ME, Hamann M, Kroon FJ (2020) Bioaccumulation and biomagnification of microplastics in marine organisms: A review and meta-analysis of current data. PLOS ONE 15:e0240792. doi: 10.1371/journal.pone.0240792 Nor NH, Obbard JP (2014) Microplastics in Singapore’s coastal mangrove ecosystems. Mar Pollut Bull 79:278–283. https://doi.org/10.1016/j.marpolbul.2013.11.025 Not C, Lui CYI, Cannicci S (2020) Feeding behavior is the main driver for microparticle intake in mangrove crabs. Limnol Oceanogr Letters 5:84–91. doi: 10.1002/lol2.10143 Owen R (1839) In: Beechey FW, The Zoology of Captain Beechey's Voyage; Compiled from the Collections and Notes Made by Captain Beechey, the Officers and Naturalists of the Expedition, during a Voyage to the Pacific and Behring Straits Performed in His Majesty's Ship Blossom, under the Command of Captain F.W. Beechey, R.N., F.R.S & C, in the years 1825, 26, 27 and 28: 77-97, pls. 24-28. London. Paduani M, Ross M, Odom G (2024) Mangrove Forests of Biscayne Bay, FL, USA may Act as Sinks for Plastic Debris. Wetlands 44:32. doi: 10.1007/s13157-024-01785-9 Prarat P, Hongsawat P, Chouychai B (2024) Microplastic occurrence in surface sediments from coastal mangroves in Eastern Thailand: Abundance, characteristics, and ecological risk implications. Reg Stud Mar Sci 71:103389. doi: 10.1016/j.rsma.2024.103389 Rahayu DL, Ng PK (2010) Revision of the Parasesarma plicatum (Latreille, 1803) species-group (Crustacea: Decapoda: Brachyura: Sesarmidae). Zootaxa 2327(1):1-22. Rahmawati NHF, Patria MP (2019) Microplastics Dissemination from Fish Mugil dussumieri and Mangrove Water of Muara Teluknaga, Tangerang, Banten. Journal of Physics: Conference Series 1282:012104. doi: 10.1088/1742-6596/1282/1/012104 Rani V, Sreelakshmi C, Nandan SB, et al (2023) Feeding ecology of Parasesarma plicatum and its relation to carbon structuring in mangrove ecosystem. Hydrobiologia 850:911–927. doi: 10.1007/s10750-022-05133-y Reddy CS (2008) Field Identification Guide for Indian Mangroves; Bishen Singh Mahendra Pal Singh: Dehradun, India, Volume 001. Sarker S, Huda ANMS, Niloy MdNH, Chowdhury GW (2022) Trophic transfer of microplastics in the aquatic ecosystem of Sundarbans mangrove forest, Bangladesh. Sci Total Environ 838:155896. doi: 10.1016/j.scitotenv.2022.155896 Shanij K, Praveen VP, Suresh S, Oommen MM, Nayar TS (2016) Tree climbing and temporal niche shifting: an anti-predatory strategy in the mangrove crab Parasesarma plicatum (Latreille, 1803). Curr Sci 111:1201-1207. Song YK, Hong SH, Eo S, Shim WJ (2022) The fragmentation of nano- and microplastic particles from thermoplastics accelerated by simulated-sunlight-mediated photooxidation. Environ Pollut 311:119847. https://doi.org/10.1016/j.envpol.2022.119847. Thompson RC, Olsen Y, Mitchell RP, et al (2004) Lost at Sea: Where Is All the Plastic? Science 304:838–838. doi: 10.1126/science.1094559 Tweedie MWF (1949) The species of Metopograpsus (Crustacea, Brachyura). Bijdragen tot de Dierkunde 28:466–471 Vannini M, Oluoch A, Ruwa RK (1997) The tree-climbing crabs of Kenyan mangroves. In: Kjerfve B, De Lacerda BL, Diop ES, (Eds.), Mangrove ecosystems studies in Latin America and Africa. UNESCO technical papers in marine sciences. New York: UNESCO; pp. 325–338. Wang Y, Jiao M, Li T, et al (2023) Role of mangrove forest in interception of microplastics (MPs): Challenges, progress, and prospects. J Hazard Mater 445:130636. doi: 10.1016/j.jhazmat.2022.130636 Wei Y, Jiao M, Zhao Z, et al (2024) Secreted salt and hydrodynamic factors combine to affect dynamic fluctuations of microplastics on mangrove leaves. J Hazard Mater 467:133698. https://doi.org/10.1016/j.jhazmat.2024.133698 White A (1847) No. VIII. Descriptions of a new genus and five new species of Crustacea. Appendix. p. 335-338. In: JB Jukes (Ed), Narrative of the surveying voyage of H.M.S. Fly , commanded by Captain F.P. Blackwood, R.N. in Torres Strait, New Guinea, and other Islands of the Eastern Archipelago, during the years 1842-1846: together with an excursion into the interior of the eastern part of Java, Vol. II. London, T. & W. Boone. Yin L, Wen X, Huang D, et al (2021) Interactions between microplastics/nanoplastics and vascular plants. Environ Pollut 290:117999. doi: 10.1016/j.envpol.2021.117999 Cite Share Download PDF Status: Published Journal Publication published 16 Jul, 2025 Read the published version in Wetlands → Version 1 posted Reviewers agreed at journal 01 Sep, 2024 Reviewers invited by journal 28 Apr, 2024 Editor invited by journal 25 Apr, 2024 Editor assigned by journal 18 Apr, 2024 First submitted to journal 17 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. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-4285631","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":296489215,"identity":"fbf8e4f4-55c7-41a6-a89d-9f77cffd7781","order_by":0,"name":"Gopika Sivan","email":"","orcid":"","institution":"Cochin University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Gopika","middleName":"","lastName":"Sivan","suffix":""},{"id":296489216,"identity":"b945efe3-847f-4331-b913-ee9cfb9dca28","order_by":1,"name":"Jestin M.S","email":"","orcid":"","institution":"Cochin University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Jestin","middleName":"","lastName":"M.S","suffix":""},{"id":296489217,"identity":"be9c57c9-ab45-4213-9de8-96681a054036","order_by":2,"name":"Apreshgi K.P","email":"","orcid":"","institution":"Department of Fisheries, DD Office, Kochi-18","correspondingAuthor":false,"prefix":"","firstName":"Apreshgi","middleName":"","lastName":"K.P","suffix":""},{"id":296489218,"identity":"f5e20e8c-9a97-406a-ac69-8ae044ac9e89","order_by":3,"name":"Priyaja P","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5ElEQVRIiWNgGAWjYFACxgYGBh6Gen52IM1gYEG8lgTJngMgLRLE25VgcCMBRBOhxVz6cJvEDxm7PIObz69u+FEgwcDf3p2AV4tlX2KbZA9PcrHk7Zyymz1Ah0mcObsBrxaDM4xtEjw8zIx9t3PSbvAAtRhI5BLWIvmHp56x4eaZtJt/iNUizcNzOHHCDfZjt4myxbKHsdlahue4sWRPDtttGQMJHoJ+Medhf3jzbU+1HD/78Wc33/yxkeNv7yXgMAYGFgnGHhCTxwBM4lUO1cL8geEHiMn+gKDqUTAKRsEoGJkAANyCRzFyTpF4AAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0001-8157-4177","institution":"Cochin University of Science and Technology","correspondingAuthor":true,"prefix":"","firstName":"Priyaja","middleName":"","lastName":"P","suffix":""}],"badges":[],"createdAt":"2024-04-18 06:52:57","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4285631/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4285631/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s13157-025-01960-6","type":"published","date":"2025-07-16T15:57:11+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":55809327,"identity":"2dd04ff4-4cfd-4e27-908c-fa33536ca55d","added_by":"auto","created_at":"2024-05-03 15:40:19","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":331739,"visible":true,"origin":"","legend":"\u003cp\u003eMap representing the study area of Chettuva mangrove island.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-4285631/v1/7caff9ad4b57f146c88e3730.png"},{"id":55810086,"identity":"3d341f61-d052-4b5d-8938-df11af052ef0","added_by":"auto","created_at":"2024-05-03 15:48:19","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1039845,"visible":true,"origin":"","legend":"\u003cp\u003eCrab \u003cem\u003eParasesarma plicatum \u003c/em\u003efound on the stilt roots of \u003cem\u003eRhizophora mucronata\u003c/em\u003e collected from Chettuva mangrove island.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-4285631/v1/171350f4ee734c96f5760f26.png"},{"id":55809332,"identity":"8827f26c-a8e8-4ad8-88a1-5323a878da5b","added_by":"auto","created_at":"2024-05-03 15:40:19","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":790206,"visible":true,"origin":"","legend":"\u003cp\u003eBrachyuran crabs collected from Chettuva mangrove island. (\u003cstrong\u003eA\u003c/strong\u003e) \u003cem\u003eMetopograpsus latifrons\u003c/em\u003e, (\u003cstrong\u003eB\u003c/strong\u003e) \u003cem\u003eMetopograpsus thukuhar \u003c/em\u003eand (\u003cstrong\u003eC\u003c/strong\u003e) \u003cem\u003eParasesarma plicatum\u003c/em\u003e.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-4285631/v1/0807f890977c480ac53ddcc3.png"},{"id":55809321,"identity":"57608777-11a7-4e99-935f-8a9204f13651","added_by":"auto","created_at":"2024-05-03 15:40:19","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":860438,"visible":true,"origin":"","legend":"\u003cp\u003eMPs collected from water and sediment of Chettuva mangrove island; (\u003cstrong\u003eA\u003c/strong\u003e) Film, (\u003cstrong\u003eB\u003c/strong\u003e) Fragment and (\u003cstrong\u003eC\u003c/strong\u003e) Foam\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-4285631/v1/9ccbfc0ef57d58f9231caf8d.png"},{"id":55809320,"identity":"f0bb0587-13d2-47b1-b9bb-f564fc362701","added_by":"auto","created_at":"2024-05-03 15:40:19","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":206170,"visible":true,"origin":"","legend":"\u003cp\u003eSize combination (\u003cstrong\u003eA\u003c/strong\u003e) and colour combination of MPs (\u003cstrong\u003eB\u003c/strong\u003e) in water and sediment.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-4285631/v1/e54de5a595c6b27fb34e52fd.png"},{"id":55809324,"identity":"b01e5cf9-4556-4808-a537-9d6bf3e34657","added_by":"auto","created_at":"2024-05-03 15:40:19","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1230230,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of sections of stilt root (\u003cstrong\u003eA-C\u003c/strong\u003e) and leaf (\u003cstrong\u003eD\u003c/strong\u003e) of \u003cem\u003eRhizophora mucronata\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-4285631/v1/6953538f2331bd3be9a59ba2.png"},{"id":55810087,"identity":"728a08ee-6799-4809-bcca-eebb92e56f9c","added_by":"auto","created_at":"2024-05-03 15:48:19","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":809150,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of sections of stilt root (\u003cstrong\u003eA\u003c/strong\u003e), mangrove leaf (\u003cstrong\u003eB\u003c/strong\u003e) and the EDAX spectra of non-plastics observed in the stilt root (\u003cstrong\u003eC\u003c/strong\u003e) and the leaf (\u003cstrong\u003eD\u003c/strong\u003e) of \u003cem\u003eRhizophora mucronata\u003c/em\u003e.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-4285631/v1/29095d788b6bbf623a742a8c.png"},{"id":55809330,"identity":"e7bb0b4c-5ee6-41e9-bd47-f3e125f9b71f","added_by":"auto","created_at":"2024-05-03 15:40:19","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":3059503,"visible":true,"origin":"","legend":"\u003cp\u003eMPs (fibres) isolated from the three crab species; \u003cem\u003eMetopograpsus latifrons\u003c/em\u003e-\u003cem\u003e \u003c/em\u003e(\u003cstrong\u003eA\u003c/strong\u003e), \u003cem\u003eMetopograpsus thukuhar \u003c/em\u003e(\u003cstrong\u003eB\u003c/strong\u003e), \u003cem\u003eParasesarma plicatum \u003c/em\u003e(\u003cstrong\u003eC\u003c/strong\u003e). Gut contents of \u003cem\u003eM. latifrons\u003c/em\u003e-plant particles (\u003cstrong\u003eD\u003c/strong\u003e), \u003cem\u003eM. thukuhar\u003c/em\u003e- sand and plant particles (\u003cstrong\u003eE\u003c/strong\u003e), \u003cem\u003eP. plicatum\u003c/em\u003e- plant matter and detritus (\u003cstrong\u003eF\u003c/strong\u003e).\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-4285631/v1/45b77240f81cea1ccfc35441.png"},{"id":55809328,"identity":"c0670d66-a36d-4361-81f5-e3477f59a9fe","added_by":"auto","created_at":"2024-05-03 15:40:19","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":440717,"visible":true,"origin":"","legend":"\u003cp\u003eMorphotype combination of MPs in the crabs, fallen leaves, sediment and water.\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-4285631/v1/903183530da89430123646bb.png"},{"id":55809326,"identity":"16cd4c36-d0b5-49c0-963b-87a1ffce8827","added_by":"auto","created_at":"2024-05-03 15:40:19","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":63641,"visible":true,"origin":"","legend":"\u003cp\u003eColour combination of MPs in the claw muscle of \u003cem\u003eParasesarma plicatum, Metopograpsus thukuhar and Metopograpsus latifrons\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-4285631/v1/fc56e54b4ffa9f8b21fc0f10.png"},{"id":55809331,"identity":"6dcf29bb-0b20-4089-bd6e-322c37883dde","added_by":"auto","created_at":"2024-05-03 15:40:19","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":365239,"visible":true,"origin":"","legend":"\u003cp\u003eColour combination of MPs in the gastrointestinal tract of \u003cem\u003eParasesarma plicatum, Metopograpsus thukuhar and Metopograpsus latifrons\u003c/em\u003e.\u003c/p\u003e","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-4285631/v1/f5ea3ac970bf4b547292e302.png"},{"id":55810088,"identity":"12619da1-7bd6-49d2-b173-24b36ec454a7","added_by":"auto","created_at":"2024-05-03 15:48:19","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":308791,"visible":true,"origin":"","legend":"\u003cp\u003eFT-IR peaks of (\u003cstrong\u003eA\u003c/strong\u003e) Polyethylene, (\u003cstrong\u003eB\u003c/strong\u003e) Polypropylene, (\u003cstrong\u003eC\u003c/strong\u003e) High-Density Polyethylene, and (\u003cstrong\u003eD\u003c/strong\u003e) Polystyrene\u003c/p\u003e","description":"","filename":"floatimage12.png","url":"https://assets-eu.researchsquare.com/files/rs-4285631/v1/d4989cfcb7ecab0abf5ca07f.png"},{"id":87219333,"identity":"54a06815-2e49-48ab-a6ed-58c5fd384bbb","added_by":"auto","created_at":"2025-07-21 16:03:43","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":15306824,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4285631/v1/3d4aea38-c98b-41ae-bbaa-bff04506bc9f.pdf"}],"financialInterests":"","formattedTitle":"Characterisation of microplastics in an isolated mangrove island using multiple ecosystem components including brachyuran crabs","fulltext":[{"header":"Introduction","content":"\u003cp\u003eMangroves are vital intertidal ecosystems renowned for their high biological productivity, serving as primary feeding and breeding grounds for a diverse array of organisms (Arceo-Carranza et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Das et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Bacar et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). These ecosystems are highly susceptible to microplastic (MP) accumulation due to their distinct geography, high primary productivity, complex hydrodynamic and topographical factors. Mangroves are recognized as prospective sinks for plastics due to the structural complexity of roots with high trapping potential (Martin et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Deng et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Paduani et al. \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). They tend to accumulate more MPs compared to neighbouring ecosystems, regardless of whether the MPs are suspended in water, buried in sediment, ingested by organisms or attached to leaves or plants (Wang et al. \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Mangroves intercept MPs from various sources, including riverine sources, atmospheric deposition and marine origin (Li et al. \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). This interception trend raises concern, as the build-up of MPs could endanger mangrove ecosystems over time, as these particles have the potential to persist for decades and the accumulation of MPs in these habitats is increasing at an exponential rate (Jiao et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Wang et al. \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eCrabs, particularly brachyuran crabs, dominate the benthic fauna of the mangrove ecosystems, primarily consuming leaves and organic debris on the forest floor (Shanij et al. \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Among them, sesarmid crabs (\u003cem\u003eParasesarma plicatum\u003c/em\u003e) are significant initial processors of mangrove leaf litter (Rani et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Grapsid crabs like \u003cem\u003eMetopograpsus latifrons\u003c/em\u003e exhibit opportunistic feeding habits, consuming leaves, molluscs and crustaceans (Vannini et al. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e1997\u003c/span\u003e) and while \u003cem\u003eMetopograpsus thukuhar\u003c/em\u003e feeds on macroalgae and mangrove leaves (Fratini et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Despite being non-edible, these three crab species play a vital role in linking lower-level consumers with those higher in the food chain. MPs have a strong affinity for mangrove leaves due to their lipophilic surface and so they act as temporary sinks of MPs from both air and water (Bi et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Yin et al. \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Wei et al. \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Crabs are the initial processors of mangrove leaf litter and their bioturbation activity causes MPs to enter their bodies directly (Capparelli et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). These crabs become prey for large carnivorous crabs, fishes and herons (Brennecke et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Shanij et al. \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), thereby facilitating the transfer of MPs across higher trophic levels.\u003c/p\u003e \u003cp\u003eAs mangroves are transition zones between land and sea, most of the plastics are intercepted among the roots and so there is a high chance of trophic transfer of these particles through the food chain. In an isolated mangrove island, direct input from the land is absent. So, in this study, we characterised the status of MPs in an isolated mangrove ecosystem along the south west coast of India. Assessment of MPs was done in multiple ecosystem components of the mangrove island including water, sediment, leaves, stilt root and fallen leaf of dominating mangrove species (\u003cem\u003eRhizophora mucronata\u003c/em\u003e) along with three species of mangrove crabs (\u003cem\u003eMetopograpsus latifrons, Metopograpsus thukuhar\u003c/em\u003e and \u003cem\u003eParasesarma plicatum\u003c/em\u003e). There is a lack of information about the bioavailability of MPs that adhere to mangrove leaves and their trophic transfer (Fang et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Also, holistic studies on MPs from the mangrove ecosystems are relatively scarce (Batel et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Miller et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Sarker et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003e \u003cb\u003eSampling\u003c/b\u003e \u003c/p\u003e \u003cp\u003eSamples were collected from a remote mangrove island of Chettuva, along the southwest coast of India (10\u0026deg; 53ꞌ 74 N, 76\u0026deg; 04ꞌ 98 E) during March 2022 (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Chettuva is known for one of the biggest mangrove forests in Kerala, situated at the confluence of the Chettuva river and the Arabian Sea and a site of migratory birds including herons, egrets and kingfishers. This remote mangrove island is devoid of human habitation, but serves as a popular destination for ecotourism activities. This mangrove forest is dominated by the species, \u003cem\u003eRhizophora mucronata\u003c/em\u003e. Surface water temperature was measured using a mercury-in-glass thermometer, pH and salinity was measured using portable water analyser. Dissolved oxygen was determined by Winkler method (APHA \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Water and sediment samples were collected and transferred to sample containers. Crabs were collected using scoop nets and hand-picking. The leaves (n\u0026thinsp;=\u0026thinsp;12) and stilt roots of mangroves were also collected and all the samples were brought to the laboratory in ice-freezed conditions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eSediment texture analysis\u003c/h3\u003e\n\u003cp\u003eSediment texture analysis was carried out using wet sieving (Krumbein and Pettijohn \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e1938\u003c/span\u003e). 100g of wet sediment samples were treated with 30% H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e and rinsed with distilled water to remove organic components. 1N HCl was added to remove the CaCO\u003csub\u003e3\u003c/sub\u003e and washed with distilled water to remove residual HCl. The sediment was dried in a hot air oven at 60\u0026deg;C for 3 hours. About 10g of the dried sediment sample was weighed out. A suspension of 20 ml of 20% sodium hexametaphosphate was added, diluted with distilled water and it was sieved through a 63 \u0026micro;m mesh. The sand retained was transferred to a pre-weighed Petri dish, dried at 60\u0026deg;C, and weighed. The filtered sample was made up to 1000 ml, well agitated, and allowed to settle. From this, about 10 ml was pipetted out from a height of 10-20cm after 51 minutes and 39 seconds. It was also transferred to a small pre-weighed beaker, dried, and weighed to quantify silt and clay fractions.\u003c/p\u003e\n\u003ch3\u003eIdentification of mangrove \u003c/h3\u003e\n\u003cp\u003eField identification of mangrove was done following Reddy (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). Length, width and surface area of leaves were measured using ImageJ software.\u003c/p\u003e\n\u003ch3\u003eIdentification of mangrove crabs\u003c/h3\u003e\n\u003cp\u003eCrabs of approximately equal length were selected for the study and morphometric measurements (carapace length, carapace width and weight) were taken. Crabs were morphologically identified using taxonomic keys (Tweedie \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e1949\u003c/span\u003e; Al-Ghais and Cooper \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e1996\u003c/span\u003e; Rahayu and Ng \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eAnalysis of MPs in water\u003c/h3\u003e\n\u003cp\u003e50L of water was collected and sieved through stacked sieves (500\u0026micro;, 350\u0026micro; and 180\u0026micro;) and the filtrate was washed using pre-filtered distilled water and transferred to respective sample containers. The filtrate obtained after passing 50L of water through stacked sieves of different mesh sizes were pre-treated by density separation (using concentrated NaCl solution), hydrogen peroxide treatment (30% H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e), and vacuum filtration (1.2\u0026micro;m GF/C glass microfiber filter, Whatman\u0026trade;) followed by visual sorting under a stereomicroscope.\u003c/p\u003e\n\u003ch3\u003eAnalysis of MPs in sediment\u003c/h3\u003e\n\u003cp\u003eMPs in sediment samples were extracted following modified floatation method (Thompson et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Nor and Obbard \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Falahudin et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). About 1 Kg of sediment was weighed and transferred to a glass beaker and allowed to suspend in concentrated NaCl solution (3 L). The same is stirred vigorously for 5\u0026ndash;10 minutes and allowed to settle for 2 hrs. 30% H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e was added to the sediment to digest organic material and the mixture was allowed to stand for 24 hrs (Cordova et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The supernatant was concentrated by passing through a stacked arranged sieve of 500\u0026micro;, 350\u0026micro;, and 180\u0026micro; respectively. The sieves were carefully washed so as to transfer the particles including MPs into the labelled container for vacuum filtration. Pre-treated sediment samples were filtered through a 1.2\u0026micro;m glass microfiber filter (GF/C, 47 mm diameter, Whatman\u0026trade;) to isolate the MPs followed by visual sorting under a stereomicroscope.\u003c/p\u003e\n\u003ch3\u003eAnalysis of MPs in the leaf and stilt root of mangrove\u003c/h3\u003e\n\u003cp\u003eFor isolating MPs, the leaves and roots of mangrove tree were washed with Milli-Q\u0026reg; water and cut in to small pieces followed by treatment with 10% KOH at 40˚C for 48 hrs (Fang et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). When the solution became clear and yellow, digestion was considered as complete and the solution was diluted with warm Milli-Q\u0026reg; water in 1:10 ratio. The supernatant was filtered through 1.2 \u0026micro;m glass microfiber filter (Whatman GF/C). MPs on the fallen leaves (N\u0026thinsp;=\u0026thinsp;12) was extracted following Fang et al. (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Each glass bottle with four fallen mangrove leaves was filled with Milli-Q water and was placed in ultrasonic bath for 5 minutes to promote the MPs from falling off the leaves. Water was then transferred to a pre-cleaned glass beaker and the process was repeated three times. All the water collected in glass beaker was then filtered through a GF/C membrane filter (1.2 \u0026micro;m pore size, 47 mm diameter, Whatman\u0026trade;) followed by visual sorting.\u003c/p\u003e\n\u003ch3\u003eAnalysis of MPs in mangrove crabs\u003c/h3\u003e\n\u003cp\u003eBody parts of the crab such as the carapace, gastro-intestinal tract (GIT) and claw muscle (CM) were dissected out using forceps and scalpel and were weighed. 25 crabs of each species were pooled together for MPs analysis. NaCl and H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e were pre-filtered through 1.2\u0026micro;m filter prior to use. For isolating MPs, the carapace was washed thoroughly with Milli-Q\u0026reg; water and cut into small pieces followed by treatment with 10% KOH at 40˚C for 48 hrs (Fang et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). When the solution became clear and yellow, digestion was considered as complete and the solution was diluted with warm Milli-Q\u0026reg; water in 1:10 ratio. The supernatant was filtered through 1.2 \u0026micro;m filter (Whatman GF/C).\u003c/p\u003e \u003cp\u003eFor isolating MPs, the GIT and CM were put in to 1L glass beaker and digested separately. About 200\u0026ndash;400 ml of 30% H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e was added to the beakers to digest the organic matter. Beakers were covered with lid immediately and were placed in oscillation incubator at 65˚C with 80 rpm for 24\u0026ndash;72 hrs depending upon the digestion level (Jabeen et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). About 800 ml of saturated NaCl was added to the beakers to separate MPs from dissolved solution of samples via floatation. The solution was mixed by stirring and kept overnight to observe the clearance level. Then the overlying water was directly filtered through 1.2 \u0026micro;m microfiber filters (Whatman GF/C), using a vacuum pump. After the filtration, filters were placed in cleaned Petri dishes with lids for microscopic observation of plastic items. The abundance, morphotype and the colour of the MPs were recorded.\u003c/p\u003e\n\u003ch3\u003eFourier-transform infrared spectroscopy (FTIR) analysis \u003c/h3\u003e\n\u003cp\u003eTo identify the polymer, representative samples of MPs (N\u0026thinsp;=\u0026thinsp;20) were selected randomly and analysed by FT-IR spectrometer (PerkinElmer Spectrum 100 FT-IR).\u003c/p\u003e\n\u003ch3\u003eScanning electron microscope (SEM) and Energy dispersive X-ray (EDAX) analysis\u003c/h3\u003e\n\u003cp\u003eTo determine the surface morphology and elemental composition of suspected microplastics, we carried out SEM/EDAX (Zeiss Microsystems EVO 18) analysis on the stilt root and leaf of the mangrove.\u003c/p\u003e\n\u003ch3\u003eQuality control\u003c/h3\u003e\n\u003cp\u003eAll the sampling equipment\u0026rsquo;s was washed with Milli-Q water to prevent contamination. All the samples were collected in glass containers. Reagents were also filtered through 1.2\u0026micro;m filter prior to use. Lab coats and gloves were worn during sample preparation and processing. After filtration, the filter papers were kept in pre-cleaned glass Petri dishes until identification and characterization.\u003c/p\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eOne-way ANOVA was used to determine the variation of MP abundance in three crab species and fallen leaves. Results were considered with a significance level of 0.05 and the data were analysed using IBM-SPSS Statistics for Windows (Version 26.0).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e \u003cb\u003ePhysico-chemical parameters\u003c/b\u003e \u003c/p\u003e \u003cp\u003eTemperature of the water was 33.7\u0026ordm; C. Salinity and pH were 25 psu and 8.3 respectively and dissolved oxygen was 7.25 mg/L.\u003c/p\u003e\n\u003ch3\u003eSediment texture analysis\u003c/h3\u003e\n\u003cp\u003eAccording to the sediment texture analysis, sediment constituted 92.6% of sand followed by silt (6.8%) and clay (0.6%).\u003c/p\u003e\n\u003ch3\u003eIdentification of mangrove\u003c/h3\u003e\n\u003cp\u003eMangrove was identified as \u003cem\u003eRhizophora mucronata\u003c/em\u003e. Tall-sized tree, stilt roots emerging from the lower trunk, woody, slender and cylindrical. Leaves were simple and opposite, dark glossy green, mucronate. Morphometrics of leaves (mean value\u0026thinsp;\u0026plusmn;\u0026thinsp;SE) are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMorphometrics of leaves (mean value\u0026thinsp;\u0026plusmn;\u0026thinsp;SE)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLength (cm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWidth (cm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWeight (g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eArea (sq.cm)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12.47\u0026thinsp;\u0026plusmn;\u0026thinsp;2.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.54\u0026thinsp;\u0026plusmn;\u0026thinsp;1.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.91\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e54.58\u0026thinsp;\u0026plusmn;\u0026thinsp;16.31\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eIdentification of mangrove crabs\u003c/h3\u003e\n\u003cp\u003eA total of 25 crabs of each species were collected from the study area and identified. They belonged to 3 species namely \u003cem\u003eMetopograpsus latifrons\u003c/em\u003e (White \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e1847\u003c/span\u003e), \u003cem\u003eMetopograpsus thukuhar\u003c/em\u003e (Owen \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e1839\u003c/span\u003e) and \u003cem\u003eParasesarma plicatum\u003c/em\u003e (Latreille \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e1803\u003c/span\u003e) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e2\u003c/span\u003e, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Mean values for carapace length, carapace width and weight of crabs are given in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMorphometrics of the mangrove crabs with their standard deviation\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameters\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eMetopograpsus latifrons\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eMetopograpsus thukuhar\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eParasesarma plicatum\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCarapace width (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e2.9\u0026ndash;3.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e2.7\u0026ndash;3.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.5\u0026ndash;3.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.19\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCarapace length (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e2.5\u0026ndash;2.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e2.2\u0026ndash;2.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.2\u0026ndash;2.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight (g)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e2.9\u0026ndash;3.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e4.0-7.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e2.8-4.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.87\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eAnalysis of MPs in water\u003c/h3\u003e\n\u003cp\u003eIn water, abundance of MPs was found to be 5.42\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2 particles/L, and the morphotype of MPs was dominated by fibres (89.5%) followed by fragment (10.5%) (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Foams were absent in water samples. Based on mesh sizes used for sieving, MPs were classified in to \u0026gt;\u0026thinsp;500\u0026micro;, \u0026gt;\u0026thinsp;350\u0026micro;, and \u0026gt;\u0026thinsp;180\u0026micro; respectively. In water samples, 500\u0026micro; mesh retained 2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 particles/L followed by 350\u0026micro; (1.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 particles/L) and 180\u0026micro; (0.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 particles/L) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA). MPs obtained from the water samples were grouped into four major colours (transparent, red, blue and black) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eB). In water, transparent MPs constituted 63% followed by blue (21%) and red colour (15.7%). Black-coloured MPs were absent in water samples.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eAnalysis of MPs in sediment\u003c/h3\u003e\n\u003cp\u003eAbundance of MPs was relatively high in sediment (400\u0026thinsp;\u0026plusmn;\u0026thinsp;86 particles/Kg), dominated by fibres (61.6%), films (21.2%), fragments (16.2%) and foams (1%). In sediment, 500\u0026micro; mesh retained a greater number of 165\u0026thinsp;\u0026plusmn;\u0026thinsp;37 particles/Kg. 350\u0026micro; and 180\u0026micro; mesh retained 155\u0026thinsp;\u0026plusmn;\u0026thinsp;18 particles/Kg and 80\u0026thinsp;\u0026plusmn;\u0026thinsp;9 particles/Kg respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA). MPs with transparent colour (47%) was dominated followed by red (26%), blue (18.7) and black (7.5%) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eAnalysis of MPs in the leaf and stilt root\u003c/h3\u003e\n\u003cp\u003eMPs were not observed in the digested leaf and root samples, but was detected in the fallen leaves. MP abundance on the fallen leaves were (0.062\u0026thinsp;\u0026plusmn;\u0026thinsp;0.054 particles/cm\u003csup\u003e2\u003c/sup\u003e). Fibre was the only morphotype found on the fallen leaves and were dominated by black colour (41.6%) followed by blue (33.3%) and red (25%).\u003c/p\u003e\n\u003ch3\u003eSEM/EDAX analysis\u003c/h3\u003e\n\u003cp\u003eSEM/EDAX analysis provided high-resolution images and the elemental composition of stilt root and leaf to screen whether the suspected particles are microplastics or not. SEM/EDAX analysis of particles that were identified as non-plastics are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e6\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e. Carbon EDAX peak which is characteristic of commonly found plastics like polyethylene and polypropylene was not detected.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eAnalysis of MPs in mangrove crabs\u003c/h3\u003e\n\u003cp\u003eFibres were detected in the CM and GIT of three crab species (Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e8\u003c/span\u003e, \u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e9\u003c/span\u003e). In CM, relatively higher abundance of MPs (1.75 particles/g) was found in both \u003cem\u003eP. plicatum\u003c/em\u003e and \u003cem\u003eM. latifrons\u003c/em\u003e followed by \u003cem\u003eM. thukuhar\u003c/em\u003e (1 particle/g) (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The CM of \u003cem\u003eM. latifrons\u003c/em\u003e was dominated by transparent colour (60%), \u003cem\u003eM. thukuhar\u003c/em\u003e by red colour (50%) and \u003cem\u003eP. plicatum\u003c/em\u003e by blue colour (60%) (Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e10\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn the GIT, highest ingestion of MPs was found in \u003cem\u003eP. plicatum\u003c/em\u003e with 6 particles/g. \u003cem\u003eM. thukuhar\u003c/em\u003e and \u003cem\u003eM. latifrons\u003c/em\u003e ingested 5 particles/g and 2.5 particles/g respectively (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). MPs with blue colour dominated in the GIT of \u003cem\u003eP. plicatum\u003c/em\u003e (58.4%) and \u003cem\u003eM. thukuhar\u003c/em\u003e (40%) (Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e11\u003c/span\u003e). Gut contents of three crab species are represented in Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e8\u003c/span\u003eD-F. No significant difference was observed in the abundance and the colour of the MPs between the tissues of three crab species (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). MPs were absent in the carapace of the three crab species.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e11\u003c/span\u003e Colour combination of MPs in the gastrointestinal tract of \u003cem\u003eParasesarma plicatum, Metopograpsus thukuhar and Metopograpsus latifrons\u003c/em\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAbundance of MPs in the claw muscle (CM) and gastro-intestinal tract (GIT) of three crab species (\u003cem\u003eMetopograpsus latifrons\u003c/em\u003e, \u003cem\u003eMetopograpsus thukuhar\u003c/em\u003e, \u003cem\u003eParasesarma plicatum\u003c/em\u003e).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBody parts\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eM. latifrons\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eM. thukuhar\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP. plicatum\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.75 particles/g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 particle/g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.75 particles/g\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGIT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5 particles/g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.5 particles/g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6 particles/g\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eFourier-transform infrared spectroscopy (FTIR) analysis\u003c/h3\u003e\n\u003cp\u003eAmong the different MPs (N\u0026thinsp;=\u0026thinsp;25) analysed, different spectral peaks were obtained (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e12\u003c/span\u003e). The comparison of the spectral peaks with the spectral libraries revealed the identity of the polymer. The most abundant polymers in the analysed samples were high-density polyethylene-HDPE (55%), followed by low-density polyethylene-LDPE (30%), polypropylene-PP (5%), and polystyrene-PS (5%).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eMangrove ecosystems have become a focal point for the accumulation of MPs, which can be attributed to the elevated productivity and biomass of mangroves, coupled with hydrodynamic conditions (Wang et al. \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Prarat et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). The fate of MPs intercepted within mangroves encompasses various pathways including sediment deposition, suspension in water, biological deposition (ingestion by organisms) and attachment to leaves and other structures within the mangrove environment (Wang et al. \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). In this study, we made an assessment of MPs within multiple ecosystem components including water, sediment, leaves, stilt root and fallen leaves of \u003cem\u003eR. mucronata\u003c/em\u003e, and mangrove crabs (\u003cem\u003eM. latifrons, M. thukuhar\u003c/em\u003e and \u003cem\u003eP. plicatum\u003c/em\u003e), within an isolated mangrove island.\u003c/p\u003e \u003cp\u003eThe study location is a remote mangrove island along the southwest coast of India, devoid of human habitation, but serving as a popular destination for ecotourism activities with efficient management of discarded plastics. Despite these efforts, MPs were detected in all components of the island\u0026rsquo;s ecosystem, except fresh leaves and stilt roots. The island receives wastewater discharges from residential areas, with the Kecheeri River serving as a major input into the Arabian Sea at Chettuva Lake, potentially acting as a carrier of MPs.\u003c/p\u003e \u003cp\u003eThe abundance of MPs in sediment (400\u0026thinsp;\u0026plusmn;\u0026thinsp;86 particles/Kg) far exceeded that of water (5.42\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2 particles/L). Owing to high organic matter, mangrove sediment can absorb MPs through a range of physical, chemical, and biological processes (Martin et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Despite the thick mangrove cover along the southwest coast of India, studies on MPs from mangroves remain scarce. Kannankai et al. (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) reported higher concentrations of MPs (1275\u0026thinsp;\u0026plusmn;\u0026thinsp;532 particles/Kg in the sediment and 101.6 particles/L in the surface waters) in an urban mangrove ecosystem along the southwest coast compared to the island ecosystem.\u003c/p\u003e \u003cp\u003eFibres were the most abundant morphotype in both water and sediment, consistent with previous findings in various mangrove ecosystems (Rahmawati and Patria, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Duan et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Kannankai et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Fibres are derived presumably from synthetic clothing, fragmentation of MPs, fibrous fishing gears and atmospheric fallout (Dris et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Hu et al. 2020). Fragments, primarily formed through photooxidation of larger plastic debris or mechanical abrasion of packaging and clothing wastes were also prevalent (Song et al. 2015). Mangrove ecosystems play a crucial role in intercepting a substantial portion of riverine MPs, with the interception rates influenced by MPs characteristics, sediment properties and hydrodynamic factors (Jiao et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe dominant crab taxa in mangrove ecosystems include sesarmids and grapsid crabs (Apreshgi and Abraham \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Fibres were detected in both the CM and the GIT of the three crab species, indicating their transfer from water and sediment. The abundance of MPs in mangrove crabs can be attributed to the availability of plastics within the mangrove environment and their feeding behaviour (Not et al. \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Abd Rahim et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). This study is the first to report MPs in the CM and GIT of \u003cem\u003eP. plicatum\u003c/em\u003e, \u003cem\u003eM. thukuhar\u003c/em\u003e and \u003cem\u003eM. latifrons\u003c/em\u003e from southwest coast of India. Among the three crab species, sesarmid crab \u003cem\u003eP. plicatum\u003c/em\u003e exhibited the highest abundance of MPs in the GIT, likely due to its preference for mangrove leaf litter as a primary food source. The presence of MPs in brachyuran crabs makes them ideal indicators of MPs contamination (Abd Rahim et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Hence, the crab \u003cem\u003eP. plicatum\u003c/em\u003e can be used as an indicator of MP pollution in tropical mangrove ecosystems. The presence of MPs in CM of crabs is not reported in earlier studies. Translocation of MPs into different organs including gills, stomach and hepatopancreas of the fiddler-crab \u003cem\u003eUca rapax\u003c/em\u003e has been documented (Brennecke et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFibres were the only morphotype found on fallen mangrove leaves, potentially serving as a pathway for MPs to enter the crab\u0026rsquo;s body, as they feed on leaf litter. Fallen mangrove leaf as a potential pathway for MPs to enter the snails with opportunistic feeding behaviour has been reported by Fang et al. (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). A previous study has reported an abundance of 1.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9 particles/g in the mangrove crab \u003cem\u003eUcides occidentalis\u003c/em\u003e of Tumbes mangroves (Aguirre-Sanchez et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eWater and sediment were dominated by transparent MPs. Studies in mangrove ecosystems have reported transparent and white as the main colours in water and sediment of mangroves (Aliabad et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Li et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, Duan et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Fallen mangrove leaves were dominated by black, blue and red coloured MPs. Fang et al. (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) reported black, blue, transparent and white coloured mesoplastics and MPs in mangrove leaves and herbivorous snails. Colour of MPs is considered crucial as it influences species ingesting behaviour (Cverenk\u0026aacute;rov\u0026aacute; et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Blue-coloured MPs dominated in the GIT of \u003cem\u003eM. thukuhar\u003c/em\u003e and \u003cem\u003eP. plicatum\u003c/em\u003e, and transparent MPs in \u003cem\u003eM. latifrons\u003c/em\u003e. A striking variation in the MPs colouration was observed in the CM of three crab species, with \u003cem\u003eM. latifrons\u003c/em\u003e dominated by transparent colour, \u003cem\u003eM. thukuhar\u003c/em\u003e by red colour and \u003cem\u003eP. plicatum\u003c/em\u003e by blue colour.\u003c/p\u003e \u003cp\u003eThe polymers identified in the samples predominantly included HDPE, LDPE, PP and PS. LDPE and PP were reported as dominant polymers in urban mangrove ecosystems along the southwest coast (Kannankai et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). An increase in the MP abundance and trophic level transfer could pose significant hazards to both inhabitants and ecosystem functioning (Daniel et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study provides insights into the distribution of MPs within various components of an isolated mangrove island ecosystem. The mangrove island serves as a focal point for the interception of MPs due to its geographical location near the river mouth, facilitating the accumulation of plastic debris carried by freshwater runoff from inland areas. The prevalence of the fibre morphotype across different environmental compartments such as water, sediment, fallen mangrove leaves, claw muscle (CM) and gastrointestinal tract (GIT) of crabs underlines the pervasive nature of MPs in the mangrove ecosystem. The detection of MPs in the fallen leaves suggests a potential pathway for trophic transfer directly through the food chain. The relatively high abundance of MPs in the GIT of sesarmid crab \u003cem\u003eP. plicatum\u003c/em\u003e highlights the susceptibility of certain species to MPs uptake and accumulation. Understanding the presence of MPs at different trophic levels is crucial for comprehending their transport and transformation mechanisms within the mangrove ecosystem. An upsurge in the MPs abundance poses a threat to benthic biota and higher trophic levels, potentially impacting the health and resilience of the mangrove ecosystem.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe first author is grateful to the Cochin University of Science and Technology, Kerala for the award of University Senior Research Fellowship. We express our gratitude to the Head of the Department of Chemical Oceanography, Cochin University of Science and Technology for their invaluable assistance with FT-IR analysis. We thank Mr. Usman and Ms. Chandramathy A.K for their assistance during field work.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cem\u003e\u003cstrong\u003eAuthor contributions\u0026nbsp;\u003c/strong\u003e\u003c/em\u003e\u003cem\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Gopika Sivan, Jestin M.S, Apreshgi K.P and Priyaja P. The first draft of the manuscript was written by Gopika Sivan and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003cem\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eCode availability\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eData availability\u0026nbsp;\u003c/strong\u003eAll data generated or analysed during this study are included in this manuscript.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eEthics approval\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eConflicts of interest\u003c/strong\u003e \u003cem\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/em\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbd Rahim NH, Cannicci S, Ibrahim YS, et al (2023) Commercially important mangrove crabs are more susceptible to microplastic contamination than other brachyuran species. Sci Total Environ 903:166271. doi: 10.1016/j.scitotenv.2023.166271\u003c/li\u003e\n\u003cli\u003eAguirre-Sanchez A, Purca S, Cole M, et al (2024) Prevalence of microplastics in Peruvian mangrove sediments and edible mangrove species. Mar Pollut Bull 200:116075. doi: 10.1016/j.marpolbul.2024.116075\u003c/li\u003e\n\u003cli\u003eAl-Ghais SM, Cooper RT (1996) Brachyura (Grapsidae, Ocypodidae, Portunidae, Xanthidae and Leucosiidae) of Umm Al Quwain mangal, United Arab Emirates. Trop Zool 9:409\u0026ndash;430.\u003c/li\u003e\n\u003cli\u003eAliabad MK, Nassiri M, Kor K (2019) Microplastics in the surface seawaters of Chabahar Bay, Gulf of Oman (Makran Coasts). Mar Pollut Bull 143:125\u0026ndash;133. doi: 10.1016/j.marpolbul.2019.04.037\u003c/li\u003e\n\u003cli\u003eAPHA (2000) Standard methods for the examination of water and wastewater, 18th ed. American Public Health Association (APHA), American Water Works Association (AWWA) and Water Pollution Control Federation (WPCF), Washington, DC.\u003c/li\u003e\n\u003cli\u003eApreshgi KP, Abraham KM (2019) Brachyuran crab diversity in an isolated mangrove patch of the Cochin backwater, central Kerala, India. J Aquat Biol Fish 7(1\u0026amp;2):8-14. \u003c/li\u003e\n\u003cli\u003eArceo-Carranza D, Chiappa-Carrara X, Ch\u0026aacute;vez L\u0026oacute;pez R, Y\u0026aacute;\u0026ntilde;ez Arenas C (2021) Mangroves as Feeding and Breeding Grounds. In: Rastogi RP, Phulwaria M, Gupta DK (eds) Mangroves: Ecology, Biodiversity and Management. Springer Singapore, Singapore, pp 63\u0026ndash;95\u003c/li\u003e\n\u003cli\u003eBacar FF, Lisboa SN, Sitoe A (2023) The Mangrove Forest of Quirimbas National Park Reveals High Carbon Stock Than Previously Estimated in Southern Africa. Wetlands 43:60. doi: 10.1007/s13157-023-01707-1\u003c/li\u003e\n\u003cli\u003eBatel A, Linti F, Scherer M, et al (2016) Transfer of benzo [ \u003cem\u003ea\u003c/em\u003e ] pyrene from microplastics to \u003cem\u003eArtemia\u003c/em\u003e nauplii and further to zebrafish via a trophic food web experiment: CYP1A induction and visual tracking of persistent organic pollutants. Environ Toxicol Chem 35:1656\u0026ndash;1666. doi: 10.1002/etc.3361\u003c/li\u003e\n\u003cli\u003eBi M, He Q, Chen Y (2020) What Roles Are Terrestrial Plants Playing in Global Microplastic Cycling?. Environ Sci Technol 54:5325\u0026ndash;5327. doi: 10.1021/acs.est.0c01009\u003c/li\u003e\n\u003cli\u003eBrennecke D, Ferreira EC, Costa TMM, et al (2015) Ingested microplastics (\u0026gt;100\u0026mu;m) are translocated to organs of the tropical fiddler crab \u003cem\u003eUca rapax\u003c/em\u003e. Mar Pollut Bull 96:491\u0026ndash;495. doi: 10.1016/j.marpolbul.2015.05.001\u003c/li\u003e\n\u003cli\u003eCapparelli MV, Mart\u0026iacute;nez-Col\u0026oacute;n M, Lucas-Solis O, et al (2022) Can the bioturbation activity of the fiddler crab Minuca rapax modify the distribution of microplastics in sediments? Mar Pollut Bull 180:113798. doi: 10.1016/j.marpolbul.2022.113798\u003c/li\u003e\n\u003cli\u003eCordova MR, Ulumuddin YI, Purbonegoro T, Shiomoto A (2021) Characterization of microplastics in mangrove sediment of Muara Angke Wildlife Reserve, Indonesia. Mar Pollut Bull 163:112012. doi: 10.1016/j.marpolbul.2021.112012\u003c/li\u003e\n\u003cli\u003eCverenk\u0026aacute;rov\u0026aacute; K, Valachovičov\u0026aacute; M, Mackuľak T, et al (2021) Microplastics in the Food Chain. Life 11:1349. doi: 10.3390/life11121349\u003c/li\u003e\n\u003cli\u003eDaniel DB, Ashraf PM, Thomas SN (2022) Impact of 2018 Kerala flood on the abundance and distribution of microplastics in marine environment off Cochin, Southeastern Arabian Sea, India. Reg Stud Mar Sci 53:102367. doi: 10.1016/j.rsma.2022.102367\u003c/li\u003e\n\u003cli\u003eDas SC, Das S, Tah J (2022) Mangrove Forests and People\u0026rsquo;s Livelihoods. In: Das SC, Pullaiah, Ashton EC (eds) Mangroves: Biodiversity, Livelihoods and Conservation. Springer Nature Singapore, Singapore, pp 153\u0026ndash;173\u003c/li\u003e\n\u003cli\u003eDeng H, He J, Feng D, et al (2021) Microplastics pollution in mangrove ecosystems: A critical review of current knowledge and future directions. Sci Total Environ 753:142041. doi: 10.1016/j.scitotenv.2020.142041\u003c/li\u003e\n\u003cli\u003eDris R, Gasperi J, Saad M, et al (2016) Synthetic fibers in atmospheric fallout: A source of microplastics in the environment? Mar Pollut Bull 104:290\u0026ndash;293. doi: 10.1016/j.marpolbul.2016.01.006\u003c/li\u003e\n\u003cli\u003eDuan J, Han J, Cheung SG, et al (2021) How mangrove plants affect microplastic distribution in sediments of coastal wetlands: Case study in Shenzhen Bay, South China. Sci Total Environ 767:144695. doi: 10.1016/j.scitotenv.2020.144695\u003c/li\u003e\n\u003cli\u003eFalahudin D, Cordova MR, Sun X, et al (2020) The first occurrence, spatial distribution and characteristics of microplastic particles in sediments from Banten Bay, Indonesia. Sci Total Environ 705:135304. doi: 10.1016/j.scitotenv.2019.135304\u003c/li\u003e\n\u003cli\u003eFang C, Zheng R, Hong F, et al (2023) First evidence of meso- and microplastics on the mangrove leaves ingested by herbivorous snails and induced transcriptional responses. Sci Total Environ 865:161240. doi: 10.1016/j.scitotenv.2022.161240\u003c/li\u003e\n\u003cli\u003eFang C, Zheng R, Zhang Y, et al (2018) Microplastic contamination in benthic organisms from the Arctic and sub-Arctic regions. Chemosphere 209:298\u0026ndash;306. doi: 10.1016/j.chemosphere.2018.06.101\u003c/li\u003e\n\u003cli\u003eFratini S, Cannicci S, Abincha LM, Vannini M (2000) Feeding, Temporal, and Spatial Preferences of \u003cem\u003eMetopograpsus Thukuhar\u003c/em\u003e (Decapoda; Grapsidae): An Opportunistic Mangrove Dweller. \u003cem\u003eJ Crust Biol\u003c/em\u003e 2:326\u0026ndash;333. https://doi.org/10.1163/20021975-99990044\u003c/li\u003e\n\u003cli\u003eHu T, Shen M, Tang W (2022) Wet wipes and disposable surgical masks are becoming new sources of fiber microplastic pollution during global COVID-19. Environ Sci Pollut Res 29:284\u0026ndash;292. https://doi.org/10.1007/s11356-021-17408-3.\u003c/li\u003e\n\u003cli\u003eJabeen K, Su L, Li J, et al (2017) Microplastics and mesoplastics in fish from coastal and fresh waters of China. Environ Pollut 221:141\u0026ndash;149. doi: 10.1016/j.envpol.2016.11.055\u003c/li\u003e\n\u003cli\u003eJiao M, Wang Y, Li T, et al (2022) Riverine microplastics derived from mulch film in Hainan Island: Occurrence, source and fate. Environ Pollut 312:120093. doi: 10.1016/j.envpol.2022.120093\u003c/li\u003e\n\u003cli\u003eKannankai MP, Alex RK, Muralidharan VV, et al (2022) Urban mangrove ecosystems are under severe threat from microplastic pollution: a case study from Mangalavanam, Kerala, India. Environ Sci Pollut Res 29:80568\u0026ndash;80580. doi: 10.1007/s11356-022-21530-1\u003c/li\u003e\n\u003cli\u003eKrumbein WC, Pettijohn FJ (1938) Manual of Sedimentary Petrography. D. Appleton-Century Company, Inc., New York, 549 pp\u003c/li\u003e\n\u003cli\u003eLatreille PA (1803) Histoire Naturelle, G\u0026eacute;n\u0026eacute;rale et Particuli\u0026egrave;re, des Crustac\u0026eacute;s et des Insectes. Ouvrage Faisant Suite aux Oeuvres de Leclerc de Buffon, et Partie du cours Complet d\u0026apos;Histoire Naturelle R\u0026eacute;dig\u0026eacute; par C. S. Sonnini, Membre de Plusieurs Soci\u0026eacute;t\u0026eacute;s Savantes. \u003cem\u003eParis F Dufart\u003c/em\u003e\u003cem\u003e \u003c/em\u003e6:1-391, pls. 44-57\u003c/li\u003e\n\u003cli\u003eLi R, Wei C, Jiao M, et al (2022) Mangrove leaves: An undeniably important sink of MPs from tidal water and air. J Hazard Mater 426:128138. doi: 10.1016/j.jhazmat.2021.128138\u003c/li\u003e\n\u003cli\u003eLi R, Yu L, Chai M, et al (2020) The distribution, characteristics and ecological risks of microplastics in the mangroves of Southern China. Sci Total Environ 708:135025. doi: 10.1016/j.scitotenv.2019.135025\u003c/li\u003e\n\u003cli\u003eMartin C, Almahasheer H, Duarte CM (2019) Mangrove forests as traps for marine litter. Environl Pollut 247:499\u0026ndash;508. doi: 10.1016/j.envpol.2019.01.067\u003c/li\u003e\n\u003cli\u003eMartin C, Baalkhuyur F, Valluzzi L, et al (2020) Exponential increase of plastic burial in mangrove sediments as a major plastic sink. Science Advances 6:eaaz5593. doi: 10.1126/sciadv.aaz5593\u003c/li\u003e\n\u003cli\u003eMiller ME, Hamann M, Kroon FJ (2020) Bioaccumulation and biomagnification of microplastics in marine organisms: A review and meta-analysis of current data. PLOS ONE 15:e0240792. doi: 10.1371/journal.pone.0240792\u003c/li\u003e\n\u003cli\u003eNor NH, Obbard JP (2014) Microplastics in Singapore\u0026rsquo;s coastal mangrove ecosystems. Mar Pollut Bull 79:278\u0026ndash;283. https://doi.org/10.1016/j.marpolbul.2013.11.025\u003c/li\u003e\n\u003cli\u003eNot C, Lui CYI, Cannicci S (2020) Feeding behavior is the main driver for microparticle intake in mangrove crabs. Limnol Oceanogr Letters 5:84\u0026ndash;91. doi: 10.1002/lol2.10143\u003c/li\u003e\n\u003cli\u003eOwen R (1839) In: Beechey FW, The Zoology of Captain Beechey\u0026apos;s Voyage; Compiled from the Collections and Notes Made by Captain Beechey, the Officers and Naturalists of the Expedition, during a Voyage to the Pacific and Behring Straits Performed in His Majesty\u0026apos;s Ship Blossom, under the Command of Captain F.W. Beechey, R.N., F.R.S \u0026amp; C, in the years 1825, 26, 27 and 28: 77-97, pls. 24-28. London. \u003c/li\u003e\n\u003cli\u003ePaduani M, Ross M, Odom G (2024) Mangrove Forests of Biscayne Bay, FL, USA may Act as Sinks for Plastic Debris. Wetlands 44:32. doi: 10.1007/s13157-024-01785-9\u003c/li\u003e\n\u003cli\u003ePrarat P, Hongsawat P, Chouychai B (2024) Microplastic occurrence in surface sediments from coastal mangroves in Eastern Thailand: Abundance, characteristics, and ecological risk implications. Reg Stud Mar Sci 71:103389. doi: 10.1016/j.rsma.2024.103389\u003c/li\u003e\n\u003cli\u003eRahayu DL, Ng PK (2010) Revision of the \u003cem\u003eParasesarma plicatum\u003c/em\u003e (Latreille, 1803) species-group (Crustacea: Decapoda: Brachyura: Sesarmidae). Zootaxa 2327(1):1-22.\u003c/li\u003e\n\u003cli\u003eRahmawati NHF, Patria MP (2019) Microplastics Dissemination from Fish Mugil dussumieri and Mangrove Water of Muara Teluknaga, Tangerang, Banten. Journal of Physics: Conference Series 1282:012104. doi: 10.1088/1742-6596/1282/1/012104\u003c/li\u003e\n\u003cli\u003eRani V, Sreelakshmi C, Nandan SB, et al (2023) Feeding ecology of Parasesarma plicatum and its relation to carbon structuring in mangrove ecosystem. Hydrobiologia 850:911\u0026ndash;927. doi: 10.1007/s10750-022-05133-y\u003c/li\u003e\n\u003cli\u003eReddy CS (2008) Field Identification Guide for Indian Mangroves; Bishen Singh Mahendra Pal Singh: Dehradun, India, Volume 001.\u003c/li\u003e\n\u003cli\u003eSarker S, Huda ANMS, Niloy MdNH, Chowdhury GW (2022) Trophic transfer of microplastics in the aquatic ecosystem of Sundarbans mangrove forest, Bangladesh. Sci Total Environ 838:155896. doi: 10.1016/j.scitotenv.2022.155896\u003c/li\u003e\n\u003cli\u003eShanij K, Praveen VP, Suresh S, Oommen MM, Nayar TS (2016) Tree climbing and temporal niche shifting: an anti-predatory strategy in the mangrove crab \u003cem\u003eParasesarma plicatum\u003c/em\u003e (Latreille, 1803). Curr Sci 111:1201-1207. \u003c/li\u003e\n\u003cli\u003eSong YK, Hong SH, Eo S, Shim WJ (2022) The fragmentation of nano- and microplastic particles from thermoplastics accelerated by simulated-sunlight-mediated photooxidation. Environ Pollut 311:119847. https://doi.org/10.1016/j.envpol.2022.119847.\u003c/li\u003e\n\u003cli\u003eThompson RC, Olsen Y, Mitchell RP, et al (2004) Lost at Sea: Where Is All the Plastic? Science 304:838\u0026ndash;838. doi: 10.1126/science.1094559\u003c/li\u003e\n\u003cli\u003eTweedie MWF (1949) The species of Metopograpsus (Crustacea, Brachyura). Bijdragen tot de Dierkunde 28:466\u0026ndash;471\u003c/li\u003e\n\u003cli\u003eVannini M, Oluoch A, Ruwa RK (1997) The tree-climbing crabs of Kenyan mangroves. In: Kjerfve B, De Lacerda BL, Diop ES, (Eds.), Mangrove ecosystems studies in Latin America and Africa. UNESCO technical papers in marine sciences. New York: UNESCO; pp. 325\u0026ndash;338.\u003c/li\u003e\n\u003cli\u003eWang Y, Jiao M, Li T, et al (2023) Role of mangrove forest in interception of microplastics (MPs): Challenges, progress, and prospects. J Hazard Mater 445:130636. doi: 10.1016/j.jhazmat.2022.130636\u003c/li\u003e\n\u003cli\u003eWei Y, Jiao M, Zhao Z, et al (2024) Secreted salt and hydrodynamic factors combine to affect dynamic fluctuations of microplastics on mangrove leaves. J Hazard Mater 467:133698. https://doi.org/10.1016/j.jhazmat.2024.133698\u003c/li\u003e\n\u003cli\u003eWhite A (1847) No. VIII. Descriptions of a new genus and five new species of Crustacea. Appendix. p. 335-338. In: JB Jukes (Ed), Narrative of the surveying voyage of H.M.S. \u003cem\u003eFly\u003c/em\u003e, commanded by Captain F.P. Blackwood, R.N. in Torres Strait, New Guinea, and other Islands of the Eastern Archipelago, during the years 1842-1846: together with an excursion into the interior of the eastern part of Java, Vol. II. London, T. \u0026amp; W. Boone.\u003c/li\u003e\n\u003cli\u003eYin L, Wen X, Huang D, et al (2021) Interactions between microplastics/nanoplastics and vascular plants. Environ Pollut 290:117999. doi: 10.1016/j.envpol.2021.117999\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"wetlands","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wela","sideBox":"Learn more about [Wetlands](https://www.springer.com/journal/13157)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/wela/default.aspx","title":"Wetlands","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Plastics, leaf litter, pollution, bioindicator","lastPublishedDoi":"10.21203/rs.3.rs-4285631/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4285631/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMangroves serving as interfaces between land and sea, function as significant filtration and interception systems for environmental microplastics (MPs). The structural complexity of mangrove roots enhances their trapping potential, making them prospective sinks for plastics. MPs have a strong affinity for mangrove leaves due to their lipophilic surface, temporarily accumulating MPs from both air and water. Brachyuran crabs, the core processors of mangrove litter can ingest MPs bound to leaves, potentially transferring them through the food chain to apex predators. Currently, studies from isolated mangrove islands are lacking. So, we conducted a holistic study examining MPs within multiple ecosystem components of an isolated mangrove island including water, sediment, leaves, stilt root and fallen leaves of mangrove as well as body parts of three species of mangrove crabs along southwest coast of India. Scanning electron microscopy with energy-dispersive X-ray spectroscopy was carried out to confirm the suspected MPs in root and leaf. MPs were detected in water, sediment, fallen leaves and crabs. Abundance of MPs in water and sediment was 5.42\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2 particles/L and 400\u0026thinsp;\u0026plusmn;\u0026thinsp;86 particles/Kg respectively, with the size range\u0026thinsp;\u0026gt;\u0026thinsp;350 \u0026micro;. Fallen leaves showed an abundance of 0.062\u0026thinsp;\u0026plusmn;\u0026thinsp;0.054 particles/cm\u003csup\u003e2\u003c/sup\u003e. A higher abundance of MPs was observed in the gastro-intestinal tract of mangrove crabs. Fibre was the dominant morphotype in all components, revealing trophic transfer from water and sediment to crabs via fallen leaves and direct ingestion. The findings indicate that even isolated mangrove islands serve as repositories for MPs, affecting the mangrove food chain.\u003c/p\u003e","manuscriptTitle":"Characterisation of microplastics in an isolated mangrove island using multiple ecosystem components including brachyuran crabs","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-05-03 15:40:14","doi":"10.21203/rs.3.rs-4285631/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2024-09-01T23:02:48+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-04-29T02:34:09+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Wetlands","date":"2024-04-25T14:51:41+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-04-19T03:15:46+00:00","index":"","fulltext":""},{"type":"submitted","content":"Wetlands","date":"2024-04-18T02:52:44+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"wetlands","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"wela","sideBox":"Learn more about [Wetlands](https://www.springer.com/journal/13157)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/wela/default.aspx","title":"Wetlands","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"324fe2fc-b0e8-43f2-b207-f2644a44a7bd","owner":[],"postedDate":"May 3rd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-07-21T15:59:34+00:00","versionOfRecord":{"articleIdentity":"rs-4285631","link":"https://doi.org/10.1007/s13157-025-01960-6","journal":{"identity":"wetlands","isVorOnly":false,"title":"Wetlands"},"publishedOn":"2025-07-16 15:57:11","publishedOnDateReadable":"July 16th, 2025"},"versionCreatedAt":"2024-05-03 15:40:14","video":"","vorDoi":"10.1007/s13157-025-01960-6","vorDoiUrl":"https://doi.org/10.1007/s13157-025-01960-6","workflowStages":[]},"version":"v1","identity":"rs-4285631","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4285631","identity":"rs-4285631","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}