Depth profiles of microplastic in sediment cores in seagrass and adjacent areas

Seagrass beds reveal high abundance of microplastic in sediments: A case study in the Baltic Sea

The rapid rise of plastic production has resulted in significant concerns regarding microplastic (MP) contamination, particularly in blue carbon habitats. Microplastics (MPs) research in Southeast Asia is limited despite the region being a major contributor to global marine plastic pollution. This review focuses on Southeast Asia's blue carbon habitats, involving mangroves and seagrass meadows, which are highly susceptible to MPs contamination due to their proximity to pollution sources and sediment-trapping abilities. This study aims to identify trends and patterns in MPs contamination study and to evaluate the abundance and characteristics of MPs present in blue carbon habitats in Southeast Asian countries. The PRISMA guidelines were used to conduct the systematic review, and the bibliometric analysis of studies from 2019 to 2024 was done with R software. There were 32 datasets selected from six Southeast Asian countries, with mangrove ecosystems dominating the studies (79%), followed by the seagrass ecosystems (21%). The data recorded information on 154 authors featured in these documents, with Indonesia and Thailand reporting the most studies on this topic. This review summarises the abundance and characterisation of MPs in different ecosystems using various sample types (sediment, water, and biota). Microscopy and FTIR techniques were commonly used for MP analysis, with fibre and fragment predominantly found in all samples. MP abundance is summarised in a table to support comparison across studies and facilitate comparative analysis. As a result, this review highlights the necessity for targeted research and policymakers in guiding long-term management and mitigation solutions for future MP concerns.

Microplastics (MPs) contamination has increased significantly due to inadequate plastic waste, leading to MPs infiltration in marine organisms. Crustaceans, especially the anomuran crabs, represented significant benthic communities in the intertidal zone. The current investigation aims to check the variation in MP contamination in Hermit crab Clibanarius rhabdodactylus inhabiting the intertidal and subtidal zone of Gujarat state, India. A total of 50 crabs (25 males and 25 females) of C. rhabdodactylus were collected from both zones along the coast of Gujarat in January and February 2024. In the laboratory, hermit crabs were weighed, dissected, and processed for tissue digestion. Sediment and water samples also underwent digestion. All samples were then processed through flotation, filtration, microscopic observation, and chemical characterization. The higher contamination was recorded in intertidal specimens than in subtidal specimens. The MP contamination in C. rhabdodactylus varied significantly between intertidal and subtidal specimens. MP contamination in both habitats was greater in females than in males. MP contamination in sediment and water was higher in the intertidal region than in the subtidal region, with no significant difference. Morphometric examination of MPs indicated the maximum abundance of fibers in terms of MP shape, followed by fragments and films. Black coloured MPs with 0.5–1 mm size were recorded dominantly in both habitats. The isolated MPs were primarily composed of polyethylene and polypropylene polymers. This study proposed immediate measures to address the issue of effective management of plastic litter in the marine ecosystem of the state. The present study revealed that MPs are widely distributed in the intertidal region and possess a greater risk of MP accumulation than those in the subtidal region.

Seaweed as a Sink for Microplastic Contamination: Uptake, Identifications and Food Safety Implications.

Mangroves are areas that connect the land and sea, and are important to the ecosystem. They are important places for food sources and the habitat of aquatic fauna in the tidal areas. However, the existence of plastic debris poses a risk to the aquatic environment. This study aimed to investigate the accumulation of microplastics (MPs) in sediment cores from two mangrove areas. The first mangrove area is in the outer section of the Songkhla lagoon (SK), while the second is in the coastal area of Pattani province (PN). Sediment core sampling was performed from SK = 8 stations and PN = 5 stations. Surface enrichment of MP was observed, especially in sediments of 0–4 cm. MPs were found throughout the depth in both areas, while fewer MPs were found in deeper sediment core layers (p < 0.05) at some stations inside the mangrove zone. Simple linear regression of the observed MPs and distance in the horizontal were found to be significant at SK within the mangrove zone with r2 = 0.79 (p < 0.05). MP fibers were the most commonly found MP type in both areas and were less than 1 mm. Blue and black MPs were the most abundant colors found in both areas. The six polymer types reported in this study comprised polyethylene, rayon, rubber, styrene, Poly (vinyl acetate), and paint. The findings of the present study suggest that long-term monitoring of marine debris along coastlines is necessary to help improve national policies and measures related to marine plastic debris.

The effects of seagrass (Zostera japonica) canopy structure on associated fauna: a study using artificial seagrass units and sampling of natural beds.

Seagrass meadows provide an important nursery and feeding habitat for fish, globally. However, limited data exist on how these vegetated coastal ecosystems affect local fish stocks over longer time periods. By means of beach seine hauling with a bio‐monitoring seine net, we collected fish data in Kronborg Bay (Denmark) over 4 years. The bay contains both vegetated and bare sediment areas in close proximity to Kronborg Castle in Elsinore and is part of the Øresund strait; a dynamic marine environment linking the Baltic Sea with the inner Danish waters (Kattegat). We investigated the biodiversity and fish abundance in a healthy seagrass meadow and compared it with a bare adjacent sediment area. We show that seagrass is important for fish species like the Atlantic cod, the two‐spotted goby, and the broadnosed pipefish. The seagrass meadow harboured more fish species and higher biodiversity, while the number of individuals was higher in the adjacent bare sediment area as a result of high abundances of lesser sand eel. Pilou's evenness and the Shannon‐Wiener index showed 2–4‐fold higher biodiversity in the seagrass meadow. The seagrass meadow harboured about 35% more fish species than the bare adjacent sediment. The Atlantic cod was almost entirely found in the seagrass meadow, while lesser sand eel that showed an overall increase in abundance in both habitats, represented the largest proportion of the total number of fish individuals (up to about 60%) and was mostly found on the bare adjacent sediment. Species abundance was analysed for changes over time, where, for example the European plaice showed an increase in abundance over the 4‐year period of investigation. Seagrass meadows can thus be very important for the Atlantic cod population in the Øresund strait and generally for local fish productivity, abundance and diversity.

Fish assemblage structures in an intertidal sand/mud area invaded by short seagrass Halophila ovalis and a nearby non-invaded sand/mud area in Trang Province, Thailand, were examined in detail by visual census to elucidate the effects of such habitat change on assemblage structure. The assemblage structure in the newly established seagrass bed showed a significant shift from that in the sand/mud area, despite the total fish species numbers remaining similar to each other (i.e., 30 and 29 species, respectively). Total fish density was significantly lower in the seagrass bed. In addition, differences in density patterns of component species between seagrass and sand/mud fish assemblages were evident, some fish species being restricted to or more abundant in the alternative habitat. Such differences may have arisen, at least in part, from differences in practical food availability/accessibility between the two habitat types, and/or specific microhabitat preferences of the resident fishes. Although seagrass habitats are often regarded as supporting a richer fish assemblage compared with bare sand/mud areas, the present study clearly indicated that the latter also supported a unique fish assemblage, including juveniles of fishery target species. Accordingly, both seagrass and bare sand/mud habitats should be taken into consideration for both the conservation of greater overall biodiversity in the coastal environment and the continued existence of local fisheries.

Fish assemblage structures in fragmented and continuous seagrass habitats in Trang Province, Thailand, were examined in detail to elucidate the effects of habitat fragmentation. The assemblage structures clearly differed: fish species diversity was apparently higher in the fragmented seagrass beds, although total fish numbers did not differ between them. A total of 37 fish species were collected, including 24 and 34 species from the continuous and fragmented beds, respectively. Thirteen species were restricted to the fragmented beds, compared with three restricted to the continuous beds. In addition, eight species were more abundant in the fragmented beds and only two in the continuous beds. Such differences may have arisen, at least in part, from differences in microhabitat diversity and the relative amounts of microhabitats between the two habitat types, as well as specific microhabitat preferences of the resident fishes. Although fragmented beds supported greater fish species diversity at the present study sites, it is axiomatic that habitat fragmentation caused by anthropogenic disturbance is unacceptable, with seagrass-habitat conservation being essential for both the preservation of high overall biodiversity and the successful management of local fisheries.

Microplastic (MP) contamination in the marine environment has received growing attention. In 2022, the surface water of the U-Taphao River was sampled four times, in February, April, June, and August. The surface water samples were taken at seven different locations, ranging from upstream to downstream parts of the river. The results reveal that the number of MPs detected at the U-Taphao River in February, April, June, and August were 0.41 ± 0.08, 0.25 ±0.06, 0.24 ± 0.11, and 0.26 ± 0.06 particles/L, respectively. The MPs in the U-Taphao River each month were not statistically different (p = 0.190). The trend of the number of MPs found declined from upstream to downstream. Fibers were the most commonly found MPs in the U-Taphao River in this study and were found at more than 80% of all stations during all sample collection periods. Our results indicate that MP contamination is present in the river water, but it is noted that slightly different polymer types were found during each collection month. MPs can be transferred through the food chain and potentially to humans. Regular monitoring of MPs in the riverine system is, therefore, important, for which the findings of the present study can be used as a baseline for the number of MPs in the river water in the region.

Lake Gölcük represents a significant natural freshwater resource within the Gediz River basin, located in the Ödemiş district of İzmir, Türkiye. The ecosystem has experienced considerable anthropogenic pressure from expanding settlements and tourism activities. This study aimed to assess the spatial distribution and severity of microplastic (MP) contamination in the lake. Microplastics (MPs) were quantified and characterized in water, sediment, fish muscle, gastrointestinal tract, and macroinvertebrate tissues collected from three spatially distinct stations using integrated morphological and spectroscopic methods. Macroinvertebrate samples were processed for MP contamination following standardized field sampling and laboratory protocols. The results show that Station 2, corresponding to the primary recreational zone, exhibited the highest MPs concentrations in water (81.33 ± 4.16 particles L⁻ 1 ) and sediment (30.00 ± 4.16 particles kg⁻ 1 ). In macroinvertebrates, MP loads ranged from 0.01 to 0.09 particles mg⁻ 1 , with peak values observed in Haliplidae and Veliidae taxa. European perch (Perca fluviatilis) contained 7.00 ± 2.00 particles g⁻ 1 in muscle tissue and 1.67 ± 0.58 particles g⁻ 1 in the gastrointestinal tract, whereas gibel carp ( Carassius gibelio ) from Station 1 showed no detectable MPs. Fibers dominated the morphotype distribution, with blue, black, and transparent particles most prevalent. Polyethylene, polypropylene, polyethylene terephthalate, and nylon constituted the predominant polymer compositions. Collectively, these findings confirm substantial MP contamination across both abiotic (water, sediment) and biotic (fish, macroinvertebrates) compartments of Lake Gölcük, posing potential ecological risks to resident biota and overall ecosystem integrity. The results contribute critical baseline data on MP distribution in Turkish inland waters and underscore the urgent need for protective measures amid escalating tourism pressure.

Research on the occurrence and the characteristics of microplastics (MPs) sedimentary in seagrass meadows at the area of Mare Island conservation is the very first study in this region. The objectives of this work is to determine the abundance and the characteristics of MPS and its diversity in the two villages namely Maregam and Marekofo at the Island. Samples are collected using sediment core, then dried and extracted using NaCl to separate the density. MPs were identified under a microscope after going through the filtering process. The abundance of MPs particles ranges from 17,000 - 37,000 particles. kg-1dry weight (dw) sediment at Station 1 (Maregam) and 13.839 - 30,666 particles.kg-1 dw sediment at Station 2 (Marekofo). In general, the average value of MPs abundance at station 1 higher than station 2 were 27.090 ± 13.908 particles.kg-1 dw of sediment and 18,368 ± 10,625 particles.kg-1 dw of sediment, respectively. Statistically there no significance difference of the MPs abundance between the two station Furthermore, the predominance of MPs types were fiber and fragments, while the majority of colors of particles were blue. While the results of the microplastic diversity test indicated that MPS particles at Mare Island were not too complex and were in unstable conditions. Even though the less density of the population at the island, MPs were quite high compared to other areas in the world. This finding is allegedly that those MPs were supplied from the distance which transmitted by hydro-oceanographic and meteorology factors, beyond of local contribution.Keywords: Microplastic, seagrass bed, sediment, conservation area, Mare Island

Seagrass fish assemblages in the Namhae Island, Korea: The influences of seagrass vegetation and biomass

Ingestion of microplastics by commercial fish species from the southern Black Sea coast

Investigation of physiological energetic response of the thick shell mussel, Mytilus coruscus, to microplastics and low salinity: Potential countermeasures to multi-environmental changes