Nationwide monitoring of microplastics in bivalves from the coastal environment of Korea

Characterization and ecological risk assessment of microplastics accumulated in sea water, sand, sediment, shell water and selected tissues of hermit crab of Sundarban Biosphere Reserve

Sundarban, a Ramsar site of India, has been encountering an ecological threat due to the presence of microplastic (MP) wastes generated from different anthropogenic sources. Clibanarius longitarsus, an intertidal hermit crab of Sundarban Biosphere Reserve, resides within the abandoned shell of a gastropod mollusc, Telescopium telescopium. We characterized and estimated the MP in the gills and gut of hermit crab, as well as in the water present in its occupied gastropod shell. The average microplastic abundance in sea water, sand and sediment were 0.175 ± 0.145 MP L-1, 42 ± 15.03 MP kg-1 and 67.63 ± 24.13 MP kg-1 respectively. The average microplastic load in hermit crab was 1.94 ± 0.59 MP crab-1, with 33.89 % and 66.11 % in gills and gut respectively. Gastropod shell water exhibited accumulation of 1.69 ± 1.43 MP L-1. Transparent and fibrous microplastics were documented as the dominant polymers of water, sand and sediment. Shell water exhibited the prevalence of green microplastics followed by transparent ones. Microscopic examination revealed microplastics with 100-300 μm size categories were dominant across all abiotic compartments. ATR-FTIR and Raman spectroscopy confirmed polyethylene and polypropylene as the prevalent polymers among the five identified polymers of biotic and abiotic components. The target group index indicated green and black as the preferable microplastics of crab. The ecological risk analysis indicated a considerable level of environmental pollution risk in Sundarban and its inhabiting organisms. This important information base may facilitate in developing a strategy of mitigation to limit the MP induced ecological risk at Sundarban Biosphere Reserve.

Gut microbiota composition of the isopod Ligia in South Korea exposed to expanded polystyrene pollution

Plastics pose a considerable challenge to aquatic ecosystems because of their increasing global usage and non-biodegradable properties. Coastal plastic debris can persist in ecosystems; however, its effects on resident organisms remain unclear. A metagenomic analysis of the isopoda Ligia, collected from clean (Nae-do, ND) and plastic-contaminated sites (Maemul-do, MD) in South Korea, was conducted to clarify the effects of microplastic contamination on the gut microbiota. Ligia gut microbiota's total operational taxonomic units were higher in ND than in MD. Alpha diversity did not differ significantly between the two Ligia gut microbial communities collected from ND and MD, although richness (Observed species) was lower in MD than in ND. Proteobacteria (67.47%, ND; 57.30%, MD) and Bacteroidetes (13.63%, ND; 20.76%, MD) were the most abundant phyla found at both sites. Significant different genera in Ligia from EPS-polluted sites were observed. Functional gene analysis revealed that 19 plastic degradation-related genes, including those encoding hydrogenase, esterase, and carboxylesterase, were present in the gut microbes of Ligia from MD, indicating the potential role of the Ligia gut microbiota in plastic degradation. This study provides the first comparative field evidence of the gut microbiota dynamics of plastic detritus consumers in marine ecosystems.

Size-dependent effects of microplastics on intestinal microbiome for Perna viridis

Microplastics pollution threatens to marine organisms, particularly bivalves that actively ingest and accumulate microplastics of certain sizes, potentially disrupting intestinal homeostasis. This study investigated the microplastic abundance in wild and farmed mussels around Singapore, and examined the size-dependent effects of nano- to micro-scale polystyrene (0.5 µm/5 µm/50 µm) on the mussel intestinal microbiome in the laboratory. The field investigation revealed higher microplastic abundance in farmed mussels compared to wild ones. Experimentally, mussels exposed to 0.6 mg/L of microplastics for 7 days, followed by a 7-day depuration period, showed substantial impacts on Spirochaetes and Proteobacteria, facilitating the proliferation of pathogenic species and differentially affecting their pathogenic contributions. Metagenomics analysis revealed that microplastic exposure reduced Spirochaeta's contribution to virulence and pathogenicity loss, did not affect Vibrio and Oceanispirochaeta's pathogenicity, and increased Treponema and Oceanispirochaeta's contributions to pathogenicity loss. Moreover, microplastics increased transmembrane transporters and impacted oxidative phosphorylation enzymes, impairing energy metabolism. These effects persisted after depuration, indicating lack of resilience in the microbiome. Nano- and micro-scale plastics perturbed the mussel microbiome composition and functions in a size-dependent manner, with nano-plastics being the most disruptive. The increasing use and sale of aquaculture equipment of plastic may exacerbate the intestinal dysbiosis in bivalves, which threatens consumers' health.

Microplastics contamination and risk assessment in bivalves of economic importance from Beypore estuary, Southern India

Microplastics (MPs) are ubiquitous pollutant causing severe threat to the biotic and abiotic components of the coastal ecosystem. Accumulation of MPs in the commercially important bivalves Viz. Perna viridis (green mussel) and Meretrix casta (clam) collected from four different locations of Beypore estuary, Southern India was studied. The study focused on the accumulation, characteristics, diversity indices, and human health risk assessment of MPs in the bivalves of Beypore estuary. A total of 120 bivalve samples were examined for the MPs contamination. Whole tissue digestion method using 10% KOH was employed to retrieve the MP content. The results indicate that the average abundance of MPs in Perna viridis is 2.38 ± 1.56 MPs/individual and 0.15 ± 0.09 MP/g/wet weight whereas, for Meretrix casta it is 1.35 ± 1.02 MPs/individual and 0.3 ± 0.27 MP/g/wet weight. Spearman's correlation reveals that there is no significant correlation observed between the abundance of MPs in the bivalves with their morphomertric parameters. The characteristics of MPs in the bivalves are dominated by translucent colored particles (88.95%) in the form of films (45.13%) and fibers (33.6%) having a size ranged between 300 and 1000 μm (51.13%) and composed of polyethylene (54.5%) and polypropylene (20%) polymers. The microplastic index in Meretrix casta ranged between 0.02 and 0.07 whereas for Perna viridis it ranged between 0.08 and 0.10 indicating minimal to moderate MPs contamination. The microplastics diversity integrated index ranged between 0.67 and 0.69 for Meretrix casta whereas, for Perna viridis the value ranged between 0.34 and 0.60 suggests moderate diversity of MPs derived from multiple sources. Based on polymer hazard index, the potential health risk was assessed with a hazard level ranged between II and IV suggesting significant health risk. Systematic monitoring of MPs at river basin scale along with stringent plastic waste management is required to minimize plastic pollution load into the river system.

Mangrove mud clam as an effective sentinel species for monitoring changes in coastal microplastic pollution

The worldwide mangrove shorelines are experiencing considerable contamination from microplastics (MPs). Finding an effective sentinel species in the mangrove ecosystem is crucial for early warning of ecological and human health risks posed by coastal microplastic pollution. This study collected 186 specimens of the widely distributed mangrove clam (Geloina expansa, Solander, 1786) from 18 stations along the Leizhou Peninsula, the largest mangrove coast in Southern China. This study discovered that mangrove mud clams accumulated a relatively high abundance of MPs (2.96 [1.61 - 6.03] items·g-1) in their soft tissue, wet weight, as compared to previously reported levels in bivalves. MPs abundance is significantly (p < 0.05 or 0.0001) influenced by coastal urban development, aquaculture, and shell size. Furthermore, the aggregated MPs exhibit a significantly high polymer risk index (Level III, H = 353.83). The estimated annual intake risk (EAI) from resident consumption, as calculated via a specific questionnaire survey, was at a moderate level (990 - 2475, items·g -1·Capita -1). However, the EAI based on suggested nutritional standards is very high, reaching 113,990 (79,298 - 148,681), items·g -1·Capita -1. We recommend utilizing the mangrove mud clam as sentinel species for the monitoring of MPs pollution changing across global coastlines.

Assessment of microplastic presence in coastal environments and organisms of Da Nang, Vietnam

This study investigates the presence of microplastics (MPs) in seawater, sediments, and organisms along the coastal areas of Da Nang, Vietnam. The results obtained revealed MP concentrations ranging from 111 to 304 MPs/L in seawater and 2267 to 4600 MPs/kg in sediment. In organisms such as oysters, mussels, crabs, snails, and fish, MP levels ranged from 1.8 to 17.3 MPs/g (wet weight). Fiber MPs were found to be predominant across seawater, sediment, and organisms. The study identified eight, ten, and eleven types of MPs in seawater, sediment, and organisms, respectively, with Nylon, Polytetrafluoroethylene (PTFE), and Ethylene vinyl alcohol (EVOH) being the most prevalent. Notably, MP concentrations were significantly higher in benthic organisms such as oysters, mussels, and crabs compared to fish (t-test, p < 0.05), suggesting habitat dependency. Similar concentrations, shapes, and types of MPs in seawater, sediments, and organisms demonstrate a tendency for MP accumulation in aquatic organisms within the marine environment.

Abundance of microplastics at and near a shellfish aquaculture farm: An eastern oyster (Crassostrea virginica) transplant study

Microplastics (MP) have repeatedly been found in commercially cultured species of bivalves. There are concerns regarding the amount of MP released into the environment by aquaculture activities, and questions regarding possible higher MP loads in farm-grown shellfish compared to levels in shellfish collected from recreational beds. To explore this concept, seawater, aquaculture gear, and eastern oysters (Crassostrea virginica) were sampled from an aquaculture site in Niantic Bay, CT, USA, and a 2-week transplantation experiment was performed in which oysters were transplanted between the aquaculture site and a plastic-free cage off the dock at the University of Connecticut-Avery Point campus. The digestive gland-stomach complex (gut) was dissected from the oysters and MP were extracted from the adjacent seawater and oyster gut samples using previously validated extraction methods. Extensive quality assurance and control measures were taken to reduce MP contamination. Particles in all samples were isolated, imaged under a stereomicroscope, and characterized (size, shape, polymer) using ImageJ software and micro-Fourier transform infrared spectroscopy. Water samples contained 0-0.3 MP/L and oyster gut samples contained 0-1.3 MP/g wet weight indicating very low concentrations of MP at the farm (0-2 MP/individual) or away from the farm (0-3 MP/individual). Aquaculture gear in this area is not contributing to MP ingestion in farmed oysters or elevated MP levels in the surrounding water.

Microplastics and environmental effects: investigating the effects of microplastics on aquatic habitats and their impact on human health

Microplastics (MPs) are particles with a diameter of <5 mm. The disposal of plastic waste into the environment poses a significant and pressing issue concern globally. Growing worry has been expressed in recent years over the impact of MPs on both human health and the entire natural ecosystem. MPs impact the feeding and digestive capabilities of marine organisms, as well as hinder the development of plant roots and leaves. Numerous studies have shown that the majority of individuals consume substantial quantities of MPs either through their dietary intake or by inhaling them. MPs have been identified in various human biological samples, such as lungs, stool, placenta, sputum, breast milk, liver, and blood. MPs can cause various illnesses in humans, depending on how they enter the body. Healthy and sustainable ecosystems depend on the proper functioning of microbiota, however, MPs disrupt the balance of microbiota. Also, due to their high surface area compared to their volume and chemical characteristics, MPs act as pollutant absorbers in different environments. Multiple policies and initiatives exist at both the domestic and global levels to mitigate pollution caused by MPs. Various techniques are currently employed to remove MPs, such as biodegradation, filtration systems, incineration, landfill disposal, and recycling, among others. In this review, we will discuss the sources and types of MPs, the presence of MPs in different environments and food, the impact of MPs on human health and microbiota, mechanisms of pollutant adsorption on MPs, and the methods of removing MPs with algae and microbes.

Contamination by microplastics in oysters shows a widespread but patchy occurrence in a subtropical estuarine system

Microplastics (MPs) have been widely documented in marine biota, with a notable presence in bivalve species. This study examines microplastic (MP) contamination in oysters across a subtropical estuarine system, revealing widespread and highly variable levels of contamination. Our results indicate a general trend of higher contamination in areas with greater anthropogenic impact, and unexpectedly high values in remote Marine Protected Areas, suggesting alternative sources of MPs. We observed a 94.31 % frequency of occurrence and an average contamination level of 8.16 ± 6.39 MP.ind-1, 1.06 ± 1.28 MP.g-1ww, and 7.54 ± 6.55 MP.g-1dw. Transparent fibers, predominantly composed of polyester and polyethylene from likely textile origins, were the most common. The findings underscore the significance of MP pollution in marine environments, even in protected zones. For enhanced spatial assessment and consistent data comparison, we recommend that future studies include MP quantities in terms of dry weight (MP.g-1dw) and biometric data such as size and weight.

Landscape and risk assessment of microplastic contamination in farmed oysters and seawater along the coastline of China

Microplastic (MP) pollution poses a significant threat to marine ecosystem and seafood safety. However, comprehensive and comparable assessments of MP profiles and their ecological and health in Chinese farming oysters are lacking. This study utilized laser infrared imaging spectrometer (LDIR) to quantify MPs in oysters and its farming seawater at 18 sites along Chinese coastlines. Results revealed a total of 3492 MPs in farmed oysters and seawater, representing 34 MP types, with 20-100 µm MP fragments being the dominant. Polyurethane (PU) emerged as the predominant MP type in oysters, while polysulfones were more commonly detected in seawater. Notably, oysters from the Bohai Sea exhibited a higher abundance of MPs (13.62 ± 2.02 items/g) and estimated daily microplastic intake (EDI, 2.14 ± 0.26 items/g/kg·bw/day), indicating a greater potential health risk in the area. Meanwhile, seawater from the Yellow Sea displayed a higher level (193.0 ± 110.7 items/L), indicating a greater ecological risk in this region. Given the pervasiveness and abundance of PU and its high correlation with other MP types, we proposed PU as a promising indicator for monitoring and assessing the risk MP pollution in mariculture in China. These findings provide valuable insights into the extent and characteristics of MP pollution in farmed oysters and seawater in China.

Assessing biofilm formation and resistance of vibrio parahaemolyticus on UV-aged microplastics in aquatic environments

UV degradation of marine microplastics (MPs) could increase their vector potential for pathogenic bacteria and threaten human health. However, little is known about how the degree of UV aging affects interactions between MPs and pathogens and how various types of MPs differ in their impact on seafood safety. This study investigated five types of UV-aged MPs and their impact on Vibrio parahaemolyticus, a seafood pathogen. MPs exposed to UV for 60 days showed similar physicochemical changes such as surface cracking and hydrophobicity reduction. Regardless of the type, longer UV exposure of MPs resulted in more biofilm formation on the surface under the same conditions. V. parahaemolyticus types that formed biofilms on the MP surface showed 1.4- to 5.0-fold upregulation of virulence-related genes compared to those that did not form biofilms, independently of UV exposure. However, longer UV exposure increased resistance of V. parahaemolyticus on MPs to chlorine, heat, and human gastrointestinal environment. This study implies that the more UV degradation occurs on MPs, the more microbial biofilm formation is induced, which can significantly increase virulence and environmental resistance of bacteria regardless of the type of MP.

Microplastic contamination in filter-feeding oyster Saccostrea cuccullata: Novel insights in a marine ecosystem

Microplastic (MP) pollution has become a pressing global concern. Oysters are well-known filter feeders who ingest food by filtering microscopic particles suspended in the surrounding water. Along with organic matter, filter-feeding also causes accidental ingestion of MP by oysters. Hence, the aim of the current investigation is to understand the MP contamination in filter-feeding oysters. A total of 500 specimens of oyster Saccostrea cuccullata collected from the intertidal zone of five sampling locations on the Gujarat coast, India. Specimens underwent analysis following established protocols. Each specimen was found to exhibit MP contamination, showing an abundance of 2.72 ± 1.98 MPs/g. A negative relationship was found between shell length and MP abundance. Predominantly, fibers were documented across all study sites. Black, blue, and red-colored MPs with 1-2 mm sizes were most dominant. MP polymer composition was identified as polyethylene terephthalate and polypropylene. Findings provide baseline information on levels of MPs contamination, which can be used to monitor future effects of MP pollution.

A systematic review on microplastic contamination in marine Crustacea and Mollusca of Asia: Current scenario, concentration, characterization, polymeric risk assessment, and future Prospectives

Microplastics (MPs) pollution has wreaked havoc on biodiversity and food safety globally. The false ingestion of MPs causes harmful effects on organisms, resulting in a decline in biodiversity. The present review comprehended the current knowledge of MP contamination in Crustacea and Mollusca from 75 peer-reviewed articles published in Asia between 2015 and 2023. A total of 79 species (27 Crustacea and 52 Mollusca) have been recorded to be contaminated with MPs. Out of the total 27 species of Crustacea, Metopograpsus quadridentatus (327.56 MPs/individual) and Balanus albicostatus (0.42 MPs/individual) showed the highest and lowest contamination, respectively. Out of the total 52 species of Mollusca, Dolabella auricularia (2325 MPs/individual) and Crassostrea gigas and Mytilus edulis (0.2 MPs/individual) showed the highest and lowest contamination, respectively. In terms of country-wise MP contamination, China has the highest number of contaminated species in both phylums among Asia. Findings of pollution indices revealed a very high risk of MP contamination in all the countries. Fiber was reported predominantly in both groups. Blue and black-colored MPs having <500 μm and <500 μm-1 mm size were found dominantly in Crustacea and Mollusca, respectively. Polypropylene was recorded as the dominant plastic polymer in both Crustacea and Mollusca. In essence, this review has provided a comprehensive insight into MP concentration in Crustacea and Mollusca of Asia, highlighting variations among species and geographic locations. This understanding is crucial for tackling urgent environmental challenges, safeguarding human health, and promoting global sustainability initiatives amid the escalating issue of plastic pollution. PRACTITIONER POINTS: Microplastic pollution has created havoc on biodiversity and food safety. A total of 27 and 52 species of crustaceans and Mollusca have been recorded to be contaminated with MPs. Metopograpsus quadridentate and Dolabella auricularia have shown higher MPs contamination. Polypropylene was recorded as the dominant plastic polymer in both crustacean and Mollusca. Findings of pollution indices revealed a very high risk of MP contamination in all the countries.

Microplastic contamination in different shell length in Tivela mactroides (Born, 1778)

Microplastic identification and distribution throughout oceans has become a great concern due to its substantial uprising and its consequent interactions with marine biota. Microplastics can be absorbed and adsorbed by several marine species owing to their very small size. Among these organisms are bivalves, including ones used as food for humans. In this context, this research aims to understand the absorption scale of microplastics by Tivela mactroides according to their size and consequently life stage. Thus, T. mactroides mussels were collected at Camburi Beach (Brazil) and grouped into 30 different size classes from 06 to 35 mm. Later, 20 specimens from each size class (N = 600) had the soft tissues removed and a pool was performed through digestion with 10 % KOH solution. Results showed the presence of microplastics in all size classes of T. mactroides, evidencing that organisms from 06 mm can already be contaminated by microplastics and a tendency of the number of microplastics particles to increase as shell size increases. Furthermore, the amount of blue filament-type MPs was significantly higher than the other types and colors. Additionally, analyzes performed by Raman spectroscopy showed that the blue filaments have a PET composition. Finally, larger individuals presented larger quantities of MPs, as well as larger filaments. This might suggest that there are differences between the assimilation of the size of MPs in the different size classes, i.e. that size makes a difference.

Microplastics in retail shellfish from a seafood market in eastern Thailand: Occurrence and risks to human food safety

This study aimed to investigate the presence of microplastics in three economically essential shellfish species: green mussels, cockles and spotted babylon. The average abundance of microplastics ranged from 2.41 to 2.84 particles/g wet weight. The predominant shape was fiber, with colors ranging from black-grey to transparent. The size of the microplastics discovered was <1.0 mm. Polystyrene and polyethylene were the most detected types in mussels and cockles, while linen was the predominant type in spotted babylon. The Thai population's estimated annual intake (EAI) of microplastics through shellfish consumption ranged from 20.23 to 1178.42 particles/person/year. The potential human health risks were evaluated using the polymer hazard index (PHI), which led to risk categories III-IV. These findings, along with others from the literature, indicate that shellfish consumption may pose risks to human health, depending on the species consumed and the origin of the specimens.

Microplastics in rocky shore mollusks of different feeding habits: An assessment of sentinel performance

Microplastics (MPs) accumulation in rocky shore organisms has limited knowledge. This study investigated MPs accumulation in filter-feeding oysters, herbivorous limpets and carnivorous snails to assess their performance as sentinel species in the MPs trophic transfer. The samples were obtained along a contamination gradient in the Santos Estuarine System, Brazil. All three studied species showed MPs concentrations related to the contamination gradient, being the oysters the species that showed the highest levels, followed by limpets and snails (average of less and most contaminated sites of 1.06-8.90, 2.28-5.69 and 0.44-2.10 MP g-1, respectively), suggesting that MPs ingestion rates are linked to feeding habits. MPs were mainly polystyrene and polyacetal. The polymer types did not vary among sites nor species. Despite minor differences in percentages and diversity of size, shape, and color classes, the analyzed species were equally able to demonstrate dominance of small, fiber, transparent, black and blue MPs. Thus, oysters, limpets, and snails are proposed as sentinels of MPs in monitoring assessments.

Detection of plastic, cellulosic micro-fragments and microfibers in Laternula elliptica from King George Island (Maritime Antarctica)

It is generally acknowledged that microplastic pollutants are prevalent in ocean waters and sediments across a range of tropical, temperate, subpolar, and polar regions. The waters surrounding King George Island are significantly impacted by human activities, particularly those related to scientific stations, fishing, and tourism. Organisms, such as Laternula elliptica, can be used as environmental monitors due to the likelihood that they will bioaccumulate pollutants. The goal of this study was to quantify and identify plastic and cellulosic micro-fragments and microfibers present in the soft body of clams (n = 21), collected from Fildes Bay near sewage and wastewater discharges. Plastic and cellulose microfragments and microfibers were counted, and their compositions were determined using FT-IR. All 21 individuals sampled contained fragments and fibers, with a total of 900 items detected (42.86 ± 25.36 mean ± SD items per individual), or 1.82 items g.wet mass-1. 58 % of items were cellulose and 22 % plastic. Considering the plastic polymer compositions, 28.57 % were polyethylene terephthalate (PET), 21.43 % acrylic, 14.29 % high-density polyethylene (HDPE), 14.29 % Polypropylene (PP), 7.14 % ultra-high drawn polyethylene filament (UHMWPE), 7.14 % polyester and 7.14 % Polyethylene. The quantities and prevalence of MP in L. elliptica were higher than those found in other Antarctic marine species, and even in bivalves from populated regions of the world. Our work assessed the pollution status of L. elliptica near an effluent of wastewater plants and found that 95 % of individuals displayed MP and 100 % microfibers that could impact their population.

Microplastic in clams: An extensive spatial assessment in south Brazil

Microplastic pollution is becoming a continuously growing environmental concern, while bivalve mollusks are particularly vulnerable due to their sessile habits and feeding through water filtration processes. Microplastic incidence in soft tissues of the clam Amarilladesma mactroides was assessed along unconsolidated substrates distributed in extensive coastal regions of southern Brazil. Influence of urbanization levels, distance to rivers and local hydrodynamics on microplastic accumulation by the clam was tested. The average concentration of microplastics was high (3.09 ± 2.11 particles.g-1), considering 16 sampled sites. Particles were mainly composed by polyamide, polyethylene and polyethylene terephthalate, while were mainly smaller, fibrous and colorless. High urbanization and closer proximity to rivers insured higher contamination, which is a trend observed globally. No influence of coastal hydrodynamics was seen. Considering obtained findings, A. mactroides presents good potential to be used as a valuable tool to assess microplastic contamination in unconsolidated substrates of beach areas.

Assessment of microplastic contamination in shrimps from the Bay of Bengal and associated human health risk

Microplastics (MPs) were analyzed in seven shrimp species Tiger shrimp (Penaeus monodon), Red tiger shrimp (Caridina cantonensis), Indian shrimp (Penaeus indicus), Red shrimp (Metapenaeus dobsoni), White shrimp (Penaeus merguiensis), Brown shrimp (Metapenaeus monoceros), and Roshna shrimp (Palaemon styliferus) collected from the Bay of Bengal. The abundance and characteristics of MPs were assessed in the gastrointestinal tract (GIT), which certainly translocated to the muscle of shrimp species. The highest MP abundance was found in C. cantonensis with 7.2 items/individual (25.3 items/g in the GIT and 6.3 items/g in muscle). The prominent types of MPs in shrimp samples were fibers (30 %) and fragments (29 %). The ingestion rate of MPs of black and transparent color was comparatively higher, with 64 % of the ingested MPs were < 100 μm. The primary polymer types detected based on Fourier Transform Infrared (FTIR) analysis were Low-Density Polyethylene (LDPE), High-Density Polyethylene (HDPE), Polymethyl Methacrylate (PMMA), Polyvinyl Chloride (PVC), Polypropylene (PP), and Ethylene Vinyl Acetate (EVA). Results from Scanning Electron Microscopy (SEM) showed rough surface textures and adhered particles on the MPs isolated from shrimps. The margin of exposure for females was 71.42, and for males, it was 80.64, indicating that women in Bangladesh are more likely to be exposed to MPs and face a higher risk than men. Sensitivity analysis revealed that MPs particle size was the most sensitive parameter. These findings provide a comprehensive understanding of MP ingestion, human exposure, and contamination in shrimps of Bangladesh, which can help future monitoring efforts.

Size-dependent effects of plastic particles on antioxidant and immune responses of the thick-shelled mussel Mytilus coruscus

Micro-/nano-plastic particles (MNPs) are present in the ocean with potential detrimental impacts on marine ecosystems. Bivalves are often used as marine bioindicators and are ideal to evaluate the threat posed by various-sized MNPs. We exposed the mussel Mytilus coruscus to MNPs with different particle sizes (70 and 500 nm, 5, 10 and 100 μm) for 3, 72 h and 30 days. The antioxidant responses in digestive gland and the hemolymph were then evaluated. The time of exposure played a strong modulating role in the biological response. A 3-hour exposure had no significant impact on the digestive gland. After 72 h, an increase in oxidative stress was observed in the digestive gland, including increased hydrogen peroxide (H2O2) level, catalase (CAT), glutathione peroxidase (GPx) activities and malondialdehyde (MDA) production. After a 30-day exposure, the oxidative stress decreased while lipid peroxidation increased. A 30-day exposure increased hemocyte mortality (HM) and reactive oxygen species (ROS) levels in the hemolymph, while phagocytosis (PA), lysosome content (LC), mitochondrial number (MN) and mitochondrial membrane potential (MMP) significantly decreased. Longer-term exposure to MNPs caused oxidative stress in the digestive gland as well as impaired viability and immunity of hemocytes. Particle size also influenced the response with smaller particles having more severe effects. A depuration for 7 days was enough to reverse the negative effects observed on the digestive gland and hemolymph. This study provides new insights on the effects of small-sized MNPs, especially nanoplastic particles (NPs), on aquatic organisms, and provides a solid theoretical knowledge background for future studies on toxic effects of MNPs.

Evaluation of the microplastics in bivalves and water column at Pantai Teluk Likas, North Borneo, Malaysia

Microplastics (MPs) are a pervasive pollutant in the marine environment. Pantai Teluk Likas in Sabah, Malaysia is one of the most visited beaches where tourism, recreational, and fisheries activities are high in this area. Hence, the area suffers from severe pollution, particularly from plastics. This study aims to quantify the microplastic composition in terms of color, shapes, and polymer types in marine bivalves (Anadara granosa, Glauconome virens, and Meretrix lyrata) and water column samples from Pantai Teluk Likas. All samples were digested using sodium hydroxide (NaOH) and incubated in the oven for at least 48 h. Serial filtration was done for each sample before they were observed under the dissecting microscope. The microplastics were identified and counted based on their physical attributes which were colors and shapes. The functional group of the polymers was determined using FTIR spectroscopy. Microplastics were found present in all samples collected. G. virens had the highest abundance of microplastics at 113.6 ± 6.5 particles/g followed by M. lyrata at 78.4 ± 3.7 particles/g. On the contrary, A. granosa had the least microplastics with an abundance of 24.4 ± 0.6 particles/g. Meanwhile, 110.0 ± 36.2 particles/L of microplastics were found in water column samples from Pantai Teluk Likas. Based on the analysis, fibers were the most common shape in bivalves, while fibers and films were common in the water column. In terms of colors, black, blue, and red were a few of the most abundant colors observed in both samples. The most common polymer detected in all bivalve species and water column samples is polycarbonate (PC), followed by polymethyl methacrylate (PMMA). Future study that focuses on the correlation between microplastic abundance in the marine biota and the water column is recommended to better understand microplastic availability and exposure.

The pollution characteristics and risk assessment of microplastics in mollusks collected from the Bohai Sea

Microplastics (MPs) pollution in the marine environment has become a global problem. In this study, a number of 21 mollusk species (n = 2006) with different feeding habits were collected from 11 sites along the Bohai Sea for MPs uptake analysis. The MPs in mollusk samples were isolated and identified by micro-Fourier Transform Infrared Spectroscopy (μ-FTIR), and an assessment of the health risks of MPs ingested by mollusk consumption is also conducted. Approximately 91.9 % of the individuals among all the collected species inhaled MPs, and there was an average abundance of 3.30 ± 2.04 items·individual-1 or 1.04 ± 0.74 items·g-1 of wet weight. The shape of MPs was mainly fiber, and a total number of 8 polymers were detected, of which rayon had the highest detection rate (58.3 %). The highest abundance, uptake rate and polymer composition of MPs was observed in creeping types, suggesting that they might ingest these MPs from their food. The gastropod Siphonalia subdilatata contains the highest levels of MPs, which may increase the risk of human exposure if consumed whole without removing the digestive gland. The polymer risk level of MPs in these mollusks was Level III (H = 299), presenting harmful MPs such as polyvinyl chloride. In terms of human exposure risk, the average risk of human exposure to MPs through consumption of Bohai mollusks is estimated to be 3399 items·(capita·year)-1 (424-9349 items·(capita·year)-1). Overall, this study provides a basis for the ecological and health Risk assessment of MPs in mollusks collected from the coastline of China.

The Occurrence of Microplastics in Donax trunculus (Mollusca: Bivalvia) Collected along the Tuscany Coast (Mediterranean Sea)

Microplastics (MPs) (0.1 µm-5 mm particles) have been documented in oceans and seas. Bivalve molluscs (BMs) can accumulate MPs and transfer to humans through the food chain. BMs (especially mussels) are used to assess MPs' contamination, but the genus Donax has not been thoroughly investigated. The aim of this study was to detect and characterize MPs in D. trunculus specimens collected along the Tuscan coast (Italy), and to assess the potential risk for consumers. The samples (~10 g of tissue and intervalval liquid from 35 specimens) were digested using a solution of 10% KOH, subjected to NaCl density separation, and filtered through 5 μm pore-size filters. All items were morphologically classified and measured, and their mean abundance (MA) was calculated. Furthermore, 20% of them were analyzed by Raman spectroscopy and, based on the obtained results, the MA was recalculated (corrected MA) and the annual human exposure was estimated. In the 39 samples analyzed, 85 items fibers (n = 45; 52.94%) and fragments (n = 40; 47.06%) were found. The MA was 0.23 ± 0.17 items/grww. Additionally, 83.33% of the items were confirmed as MPs (polyethylene and polyethylene terephthalate). Based on the correct MA (0.18 MPs/grww), D. trunculus consumers could be exposed to 19.2 MPs/per capita/year. The health risk level of MPs was classified as level III (moderate).

Occurrence and characteristics of microplastics in greywater from a research vessel

The discharge of greywater from ships, an uncounted sea-based source of microplastics (MPs), is a growing concern. Yet, empirical data on MPs from this source are currently limited. Here, the abundances and characteristics of MPs in greywater from a research vessel were investigated according to water usage type (e.g., galley, cabin, and laundry). The mean abundance of MPs was highest in greywater from the laundry (177,667 n/m3), followed by the cabins (133,833 n/m3) and galley (75,000 n/m3). However, no significant differences were found in the MP abundances among greywater types due to high variability of triplicate samples collected every five days. Fiber-type MPs accounted for 66% of the total MP abundance and fragment-type MPs for 34%. Microplastics in the size range of 100-200 μm exhibited the highest levels among size classes. The dominant polymer identified in all greywater samples was polyester (53%), followed by polypropylene (23%). Marine coating origin MPs (6%) were also observed in all types of greywater. The greywater generation rate during the cruise was 0.15 m3/person∙day. Annual MP emissions per person by the greywater discharge of the research vessel was estimated to be 4.1 × 106 n/person∙year (equivalent to 3.0 g/person∙year).

Bioaccumulation, microbiome composition and immunity, and epigenetic signatures associated with exposure to spherical, fibrous, and fragmented microplastics in the mussel Mytilus galloprovincialis

Microplastic (MP) pollution has become a major global concern due to the widespread use and discharge of plastics into the environment. However, very few studies have assessed the potential variations in the toxicity of MPs according to their shape and size. Therefore, our study sought to identify the biotoxic effects of spherical, fiber-shaped, and fragment-shaped polyethylene terephthalate MPs of different sizes at different concentrations on the Mediterranean mussel Mytilus galloprovincialis. The survival rate after exposure to small-sized MPs was lower than that observed for the larger type MPs. Bioaccumulation of MPs was different depending on the exposure periods and MP shapes. Interestingly, the fiber-shaped MPs underwent morphological modifications in the mussel body upon uptake. MP exposure also increased the global DNA methylation levels (i.e., an epigenetic signature), expression of the microbiota immunity-related toll-like receptor gene, and alteration of the gut microbial composition in the mussel. These findings indicated that MPs of different shapes and sizes at different concentrations can alter the bioaccumulation sensitivity of mussels according to the exposure periods, and the balance of gut immunity and epigenetic process. Furthermore, our results demonstrated that MPs of different shapes, particularly fiber types, can undergo morphological modification in mussel tissues, thus posing a hazardous threat.

Transgenerational adaptation to ocean acidification determines the susceptibility of filter-feeding rotifers to nanoplastics

The adaptation of marine organisms to the impending challenges presented by ocean acidification (OA) is essential for their future survival, and mechanisms underlying OA adaptation have been reported in several marine organisms. In the natural environment, however, marine organisms are often exposed to a combination of environmental stressors, and the interactions between adaptive responses have yet to be elucidated. Here, we investigated the susceptibility of filter-feeding rotifers to short-term (ST) and long-term (LT) (≥180 generations) high CO2 conditions coupled with nanoplastic (NPs) exposure (ST+ and LT+). Adaptation of rotifers to elevated CO2 caused differences in ingestion and accumulation of NPs, resulting in a significantly different mode of action on in vivo endpoints between the ST+ and LT+ groups. Moreover, microRNA-mediated epigenetic regulation was strongly correlated with the varied adaptive responses between the ST+ and LT+ groups, revealing novel regulatory targets and pathways. Our results indicate that pre-exposure history to increased CO2 levels is an important factor in the susceptibility of rotifers to NPs.

A case study on microplastics pollution characteristics in fouling organisms in typical aquaculture bay, China

Microplastics (MPs) and fouling organisms are prevalent in oceans worldwide. The study aims to investigate the pollution characteristics of MPs in fouling organisms. The study found significant inter-specific differences in the MPs abundance, while the length of MPs is consistent. The average number of MPs in N. exigua is 0.00 ± 0.00. There is a correlation between MPs abundance and weight in sessile group, while gastropods don't. Direct observation has demonstrated that the radulae of N. radula can envelop MPs. Fiber and blue are the predominant forms and colors of MPs found in fouling organisms. It is noteworthy that all film and fragment MPs observed were of a blue hue and had a size limitation of 500 μm. The characteristics of MPs between sessile organisms are more similar than those between gastropods. This study has improved our understanding of the pollution characteristics of MPs in fouling organisms, specifically gastropods.

The path of microplastics through the rare biodiversity estuary region of the northern Bay of Bengal

Due to its harmful effects on ecosystems and human health, microplastic (MP) pollution has become a significant environmental problem on a global scale. Although MPs' pollution path and toxic effects on marine habitats have been examined worldwide, the studies are limited to the rare biodiversity estuary region of Hatiya Island from the northern Bay of Bengal. This study aimed to investigate the MP pollution path and its influencing factors in estuarine sediments and water in rare biodiversity Hatiya Island in the northern Bay of Bengal. Sixty water and sediment samples were collected from 10 sampling sites on the Island and analyzed for MPs. The abundance of MPs in sediment ranged from 67 to 143 pieces/kg, while the abundance in water ranged from 24.34 to 59 pieces/m3. The average concentrations of MPs in sediment and water were 110.90 ± 20.62 pieces/kg and 38.77 ± 10.09 pieces/m3, respectively. Most identified MPs from sediment samples were transparent (51%), while about 54.1% of the identified MPs from water samples were colored. The fragment was the most common form of MP in both compartments, with a value of 64.6% in sediment samples and 60.6% in water samples. In sediment and water samples, almost 74% and 80% of MP were <0.5 mm, respectively. Polypropylene (PP) was the most abundant polymer type, accounting for 51% of all identified polymers. The contamination factor, pollution load index, polymer risk score, and pollution risk score values indicated that the study area was moderately polluted with MPs. The spatial distribution patterns and hotspots of MPs echoed profound human pathways. Based on the results, sustainable management strategies and intervention measures were proposed to reduce the pollution level in the ecologically diverse area. This study provides important insights into evaluating estuary ecosystem susceptibility and mitigation policies against persistent MP issues.

Characteristics and potential human health risks of microplastics identified in typical clams from South Yellow Sea Mudflat

The ingestion of clams (Meretrix) with microplastics (MP) contamination could pose potential risk to human health. The characteristics and potential risks of MP identified in wild-clam and farm-clam from South Yellow Sea Mudflat were studied comprehensively in this paper. The results indicated that MP were identified in both wild-clam (3.4-21.3 items/individual, 2.11-10.65 items/g) and farm-clam (1.3-20.8 items/individual, 0.62-8.67 items/g) among 21 sampling sites along South Yellow Sea Mudflat. The MP abundance of clams from marine estuarine or coast ports were significantly higher than those from purely marine coast mudflat, implying that environmental habitats played an important role on MP characteristics. MP abundance were significantly and positively related to shell length, shell height, shell width and soft tissue wet weight by Pearson test, suggesting the bigger the shell, there existed more MP abundance. Among MP in wild-clams and farm-clams, fragment, fiber were most abundant MP shapes, most MP's sizes were lower than 0.25 mm, the predominant colors were black, red, blue and transparent, chlorinated polyethylene (CPE) was the major polymer. Additionally, estimated dietary intake (EDI) of MP for adults via consumption of wild-clam and farm-clam were 1123.33 ± 399.97 and 795.07 ± 326.72 items/kg/year, respectively, suggesting EDI values of wild-clams were higher than those of farm-clams, and MP intake via wild-clam consumption were more than that via farm-clam consumption. The polymer risk indexes (PRI) of MP in total tissue and digestive system for wild-clam were 1297.8 ± 92.15 (hazard level: IV ~ V), 1038 ± 69.55 (IV ~ V), respectively, while PRI of MP in total tissue and digestive system for farm-clam were 979.92 ± 75.45 (III ~ IV), 735 ± 47.78 (III ~ IV), respectively, implying that PRI and hazard level of MP from wild-clam were higher than those from farm-clam, and the potential risks would decrease greatly when digestive systems of clams are removed during ingestion.

Microplastics in marine mussels, biological effects and human risk of intake: A case study in a multi-stressor environment

This study documented seasonal levels of microplastics (MPs) and biomarkers (condition index, neurotoxicity, energy, oxidative stress) in mussels (Mytilus galloprovincialis), and water physico-chemical parameters in the Douro estuary (NE Atlantic coast), and estimated the human risk of MP intake (HRI) through mussels. Mussel stress was determined through the Integrated Biomarker Response (IBR). HRI was estimated from mussel MP concentrations and consumer habits. MPs were mainly micro-fibres (72 %) with varied chemical composition. Seasonal MP means (±SEM) in mussels ranged from 0.111 ± 0.044 (spring) to 0.312 ± 0.092 MPs/g (summer). Seasonal variations of mussel stress (IBR: 1.4 spring to 9.7 summer) and MP concentrations were not related. MeO-BDEs, PBDEs, temperature, salinity and other factors likely contributed to mussel stress variation. HRI ranged from 2438 to 2650 MPs/year. Compared to the literature, MP contamination in mussels is low, as well as the human risk of MP intake through their consumption.

Microplastics in marine invertebrates from the Red Sea Coast of Egypt: Abundance, composition, and risks

This study marked the first exploration of microplastics in marine invertebrates in the Red Sea Coast of Egypt. 110 individuals from 11 different species, including Bivalvia, Gastropoda, Echinoidea, and Holothuroidrea, were collected near a popular tourist destination. The average concentrations of microplastics varied among species, ranging from 8.2 to 136.5 items per individual or 0.2 to 18.1 items per gram of tissue wet weight, with 100 % occurrence. Bivalves had higher concentrations per gram of tissue compared to sediment dwellers and grazers, with Brachidontes pharaonis showing the highest levels. Actinopyga crassa, a sea cucumber, displayed the highest abundance per individual due to its large size and behavior. The identified plastic polymers suggested sources associated with tourism and maritime activities. The estimated human exposure to microplastics through bivalve consumption was minimal. Further research is needed to examine microplastics contamination in the Red Sea and its potential impacts on ecosystems and human well-being.

Microplastic accumulation in bivalves collected from different coastal areas of Vietnam and an assessment of potential risks

Microplastic (MP) pollution is an emerging problem in many areas around the world and in coastal areas of Vietnam, requiring more studies dedicated to the accumulation of this pollutant in the food chain as well as its potential risk to human health. This study investigated MP levels in tissues of five common bivalve species collected from aquaculture areas along the coast of Vietnam. MPs were found in all bivalve samples, with average values of 10.84 ± 2.61 items/individual or 2.40 ± 1.34 items/g wet weight. Impacts of feeding habits of bivalves showed influences on MP abundance in the samples. Fibers were the dominant shape of MPs recorded, most of which accumulated in the gills and digestive glands of all bivalve samples, with the majority falling within the size range of 300-2000 µm. MPs found in all studied species had relatively similar chemical compositions, mainly composed of polypropylene (PP) and polyethylene (PE). In this study, a diverse diet consisting of different bivalve species and detailed data on the consumption rate of these species were used to assess the human health risk of MPs dedicated to the coastal communities of Vietnam. The results suggested a significant part of MP uptake by human could be via bivalve consumption, in which removing viscera and proper depuration should be applied prior to eating, thereby reducing the risk.

Intra-annual variation in microplastics in mussels (Mytilus galloprovincialis) inhabiting an urbanized bay of South Korea

This study investigated the presence of microplastics (MPs) in mussels from an urbanized bay in Korea, focusing on intra-annual variation. The average MP concentration was 0.36 ± 0.14 n/g w.w. (1.24 ± 0.56 n/individual). MPs were detected throughout the year with minor monthly variation and no significant monthly changes. Although there was no correlation between MP concentration in mussel and seawater, a positive relationship was observed when normalizing MPs to mussel's condition index (except for July). Polypropylene, polyethylene and acrylate polymer were dominant MPs, with high-density polymers comprising 59 % of the total. Most MPs were fragments and particles <200 μm. This study indicates that strict time restrictions for mussel sampling may not be necessary to assess MP levels in this bay. Additionally, considering MPs in seawater, biological conditions of mussel may be essential for understanding variations in MP levels in mussels. Including small MPs (<200 μm) and high-density polymers in MP assessment is recommended.

One-year variation in quantity and properties of microplastics in mussels (Mytilus galloprovincialis) and cockles (Cerastoderma edule) from Aveiro lagoon

As filter feeders, marine bivalves inhabiting estuarine and coastal areas are directly exposed to microplastics (MPs) in water. To assess whether MPs number, and their shape, size, colour, and polymer type present in mussels (Mytilus galloprovincialis) and cockles (Cerastoderma edule) varied over one year, bivalves were collected over the year of 2019 in the lower part of the coastal Aveiro lagoon, Portugal. After extraction from the bivalve's whole-body soft tissues, a subset of the visually inspected particles was randomly separated for identification using the Fourier-transform mid-infrared (FT-MIR) spectroscopy. A fraction of the inspected particles, 26-32% of particles >100 μm, and 59-100% of smaller ones were confirmed as MPs. Concentrations varied within the intervals of 0.77-4.3 items g-1 in mussels and 0.83-5.1 items g-1 in cockles, with the lowest values observed in January. In winter, the accumulation of large-sized fibers was composed of a mixture of plastic types, which contrasted against the most abundant MPs in summer consisting mainly of polyethylene of diverse size classes and shapes. Temperature decrease registered in winter might have triggered a lower filtration rate, resulting in lower MPs concentrations in the whole-soft body tissues of organisms. Different properties of MPs found in bivalves between January-February and August-September appear to reflect changes in the characteristics of MPs available in the Aveiro lagoon.

The impact of microplastics on bivalve mollusks: A bibliometric and scientific review

Bivalves are important members of the ecosystem and their populations are declining globally, making them a concern for their role in ecosystem services and the fishing industry. Bivalves are excellent bioindicators of MPs pollution due to their widespread distribution, filtering capabilities, and close association with human health. Microplastics (MPs) have direct and indirect impacts on bivalves, affecting their physiology, habitat structure, food sources, and persistence of organic pollutants. This review provides an extensive overview of the impact of MPs on bivalves, covering various aspects such as their economic significance, ecological roles, and importance in biomonitoring environmental quality. The article presents the current state of knowledge on the sources and pathways of MPs in aquatic environments and their effects on bivalves. The mechanisms underlying the effects of MPs on bivalves, including ingestion, filtration activity, feeding inhibition, accumulation, bioaccumulation, and reproduction, are also discussed. Additionally, a bibliometric analysis of research on MPs in bivalves is presented, highlighting the number of papers, geographical distribution, and keyword clusters relating to MPs. Finally, the review emphasizes the importance of ongoing research and the development of mitigation strategies to reduce the negative effects of MPs pollution on bivalves and their habitats in oceans and coastal waters.

Environmental risk of microplastics in a Mexican coastal lagoon ecosystem: Anthropogenic inputs and its possible human food risk

Coastal lagoons are ecosystems that are considered providers of a variety species of commercial value to the humans. However, they are currently threatened by a variety of anthropogenic-derived impacts, including environmental pollution by microplastics (MPs). For these reasons, it is necessary to identify suitable biomonitors for monitoring MP activities in aquatic environments and for estimating human ingestion of MPs from the consumption of commercial shellfish species. Therefore, our aims were to identify the anthropogenic activities that supply MPs into a coastal lagoon in the southern Gulf of Mexico and their variety; to determine whether oysters (Crassostrea virginica) are suitable biomonitors to perform MPs monitoring activities and to conduct an estimation of how many MPs could a human consume by the ingestion of a commercial portion of oysters harvested in this coastal lagoon. Our results noted that MP concentrations from water and sediment collected in Laguna de Terminos were 210,000 and 11.3 times higher than values reported in other protected areas worldwide. MPs chemical composition revealed that fishing and urban activities supply mainly polyethylene (21.1 %), poly (butadiene) diol (12.6 %) and polyethylene terephthalate (9.5 %). It was also determined that oysters did not reflect the spatial distribution of MPs within the study area and that a human could consume up to 806.1 MPs per 237.1 g serving of an oyster cocktail. Finally, a coastal lagoon polluted with MPs increases the risk of affecting species used for human consumption.

The relationship between microplastics in eastern oysters (Crassostrea virginica) and surrounding environmental compartments in Long Island Sound

Microplastics (MP, <5 mm) are found in coastal waters across various environmental compartments (biota, water, marine snow, sediment). The eastern oyster (Crassostrea virginica) is a commercially important species that ingests MP; however, oysters are discriminant suspension feeders that do not consume all particles to which they are exposed. This study explored the relationship between MP in oysters on a recreational oyster bed and the surrounding environmental compartments in Long Island Sound (LIS; USA). The quantity and types of MP in oysters, water, marine snow, and sediment samples were determined. Precautions were taken to minimize and monitor MP contamination in the field and laboratory to improve the quality of data collected. Microplastics were isolated from samples via chemical digestion, and any suspected particles were identified using micro-Fourier transform infrared spectroscopy. A total of 86 MP were identified out of 885 suspected particles across environmental media. The highest MP count in an individual oyster was nine, indicating low concentrations of MP in oysters and the surrounding environment. Few polymers, except polyethylene terephthalate, were shared between oysters and the surrounding environmental compartments. Sediments contained the highest number of MP across all environmental compartments (42 total). These data aid in determining the types of MP (polymer composition, shape, size) to which oysters are exposed and identified those ingested. The low numbers of MP recorded, coupled with the lack of alignment of polymers between oysters and their surrounding environment, demonstrates further that oysters are a poor bioindicator species for MP pollution.

The effects of environmental Microplastic on wharf roach (Ligia exotica): A Multi-Omics approach

This is the first report to evaluate the potential effects of microplastics (MPs) on wild wharf roaches (Ligia exotica) in a shoreline habitant. L. exotica is an important plastic detritus consumer in coastal area. A survey was conducted from May to June in the years 2019 and 2020 in two South Korean nearshore sites: Nae-do (as MPs-uncontaminated) and Maemul-do (as MPs-contaminated). MPs (>20 μm in size) were detected highly in gastrointestinal tracts of the L. exotica from Maemul-do, at an average level of 50.56 particles/individual. They were detected in much lower levels in the L. exotica from Nae-do. at an average rate of 1.00 particles/individual. The polymer type and shape were dominated by expanded polystyrene (EPS, 93%) and fragment (99.9%) in L. exotica from Maemul-do. Especially, Hexabromocyclododecanes, brominated flame retardants added to EPS, have been detected highly in L. exotica from Maemul-do (630.86 ± 587.21 ng/g l. w.) than those of Nae-do (detection limit: 10.5 ng/g l. w). Genome-wide transcriptome profiling revealed altered expression of genes associated with fatty acid metabolic processes, the innate-immune response-activating system and vesicle cytoskeletal trafficking in L. exotica from Maemul-do. The activation of the p53 signaling pathway (which is related to proteasome, ER regulation and cell morphogenesis) is likely to be involved in the EPS-uptake of wild L. exotica. Four neurosteroids were also detected in head tissue, and cortisol and progesterone concentrations differed significantly in L. exotica from Maemul-do. Our findings also suggest that resident plastic detritus consumer might be a useful indicator organism for evaluating pollution and potential effects of environmental microplastics.

Microplastic contamination in edible clams from popular recreational clam-digging sites in Hong Kong and implications for human health

The ubiquitous presence of microplastics in edible bivalves and the human health risks associated with bivalve consumption have raised public concerns. Farmed and market-sold bivalves have received the most attention, while wild bivalves have received much less scrutiny. In the present study, 249 individuals were examined across six wild clam species from two popular recreational clam-digging sites in Hong Kong. Of the clams, 56.6 % contained microplastics, with an average abundance of 1.04 items/g (wet weight) and 0.98 items/individual. This resulted in an estimated annual dietary exposure of 14,307 items per Hong Kong resident. Moreover, the potential microplastic risks for humans associated with wild clam consumption were assessed using the polymer hazard index, and the results indicated a medium degree of risk, indicating that exposure to microplastics through wild clam consumption is inevitable and poses a potential health threat to humans. Further research is needed to facilitate a better understanding of the widespread occurrence of microplastics in wild bivalves, and further refinements of the risk assessment framework can hopefully allow a more accurate and holistic health risk assessment for microplastics.

How to establish detection limits for environmental microplastics analysis

Establishing analytical detection limits is crucial. Common methods to do so are suitable only for variables with continuous distributions. Because count data for microplastic particles is a discrete variable following the Poisson distribution, currently-used approaches for estimating the detection limit in microplastics analysis are inadequate. Here we evaluate detection limits with techniques for low-level discrete observations to develop proper approaches for estimating the minimum detectable amount (MDA) in microplastic particle analysis, using blank sample data from an interlaboratory calibration exercise for clean water (representing drinking water), dirty water (ambient water), sediment (porous media) and fish tissue (biotic tissues). Two MDAs are applicable: MDA_A to evaluate analytical methods, estimated with replicate blank data; and MDA_B for individual sample batches, calculated with a single blank count. For illustrative purposes, this dataset's overall MDA_A values were 164 counts (clean water), 88 (dirty water), 192 (sediment), and 379 (tissue). MDA values should be reported on a laboratory-specific basis and for individual size fractions, as this provides more useful information about capabilities of individual laboratories. This is due to wide variation in blank levels, as noted by MDA_B values (i.e., among different laboratories) from 14 to 158 (clean water), 9 to 86 (dirty water, 9 to 186 (sediment), and 9 to 247 (tissue). MDA values for fibers were considerably greater than for non-fibers, suggesting that separate MDA values should be reported. This study provides a guideline for estimation and application of microplastics MDA for more robust data to support research activities and environmental management decisions.

Combined exposure to microplastics and amitriptyline caused intestinal damage, oxidative stress and gut microbiota dysbiosis in zebrafish (Danio rerio)

The potential toxicity of microplastics (MPs) and hydrophilic pharmaceuticals to aquatic organisms has recently raised great public concern, yet their combined effects on aquatic organisms remain largely unknown. Herein, the combined effects of MPs and the commonly prescribed amitriptyline hydrochloride (AMI) on the intestinal tissue and gut microbiota of zebrafish (Danio rerio) were investigated. Adult zebrafish were exposed to microplastics (polystyrene, PS, 440 µg/L), AMI (2.5 µg/L), PS+AMI (440 µg/L PS + 2.5 µg/L AMI), and dechlorinated tap water (control) for 21 days, respectively. Our results showed that zebrafish rapidly ingested PS beads and accumulated them in the gut. Exposure to PS+AMI significantly enhanced the SOD and CAT activities compared to the control group, suggesting that combined exposure might increase ROS production in the zebrafish gut. Exposure to PS+AMI led to severe gut injuries, including cilia defects, partial absence and cracking of intestinal villi. Exposure to PS+AMI caused shifts in the gut bacterial communities, increasing the abundance of Proteobacteria and Actinobacteriota, and decreasing the abundance of Firmicutes, Bacteroidota and beneficial bacteria Cetobacterium, which caused dysbiosis in the gut microbiota, and subsequently may induce intestinal inflammation. Furthermore, exposure to PS+AMI disordered the predicted metabolic functions of gut microbiota, but functional changes in the PS+AMI group at KEGG level 1 and level 2 were not significantly different from those in the PS group. The results of this study extend our knowledge of the combined effects of MPs and AMI on the health of aquatic organisms, and will be helpful in assessing the combined effects of MPs and tricyclic antidepressants on aquatic organisms.

Oysters and mussels as equivalent sentinels of microplastics and natural particles in coastal environments

Filter-feeder organisms such as oyster and mussels are exposed to particles like microplastics (MPs). Although widely used to monitor MPs contamination, little is known about their performance as sentinels, which are biological monitors accumulating contaminants without significant adverse effects. This study comparatively evaluated the quantitative and qualitative accumulation of MPs by oysters (Crassostrea brasiliana) and mussels (Perna perna) along a gradient of contamination in a highly urbanized estuarine system of Brazil. In the most contaminated site, both species presented the worst status of nutrition and health, and also one of the highest MPs levels reported for molluscs to date (up to 44.1 particles·g^-1). Despite some inter-specific differences, oysters and mussels were suitable and showed an equivalent performance as sentinels, reflecting the gradient condition demonstrated for other contaminants in the region. The similarity in MPs accumulation was also observed for qualitative aspects (polymer composition, sizes, shapes and colors). Particles were mostly <1000 μm, fibrous, colorless and composed by cellulose and polymethyl methacrylate (PMMA). Thus, despite small variations, the usage of C. brasiliana and P. perna is recommended and provides reliable information for environmental levels of microplastics.

Effects of nanoplastics on clam Ruditapes philippinarum at environmentally realistic concentrations: Toxicokinetics, toxicity, and gut microbiota

Nanoplastics are ubiquitous in marine environments, understanding to what extent nanoplastics accumulate in bivalves and the adverse effects derived from their retention is imperative for evaluating the detrimental effects in the benthic ecosystem. Here, using palladium-doped polystyrene nanoplastics (139.5 nm, 43.8 mV), we quantitatively determined nanoplastic accumulation in Ruditapes philippinarum and investigated its toxic effects by combining physiological damage assessments with a toxicokinetic model and 16 S rRNA sequencing. After a 14 days exposure, significant nanoplastic accumulation was observed, up to 17.2 and 137.9 mg·kg^-1 for the environmentally realistic (0.02 mg·L^-1) and ecologically (2 mg·L^-1) relevant groups, respectively. Ecologically relevant nanoplastic concentrations evidently attenuated the total antioxidant capacity and stimulated excessive reactive oxygen species, which elicited lipid peroxidation, apoptosis, and pathological damage. The modeled uptake (k₁) and elimination (k₂) rate constants (from physiologically based pharmacokinetic model) were significantly negatively correlated with short-term toxicity. Although no obvious toxic effects were found, environmentally realistic exposures notably altered the intestinal microbial community structure. This work increases our understanding of how the accumulation of nanoplastics influences their toxic effects in terms of the toxicokinetics and gut microbiota, providing further evidence of their potential environmental risks.

Microplastics in Perna viridis and Venerupis species: assessment and impacts of plastic pollution

This study is divided into two parts. The first part aims to verify the presence of microplastics in bivalves, namely Perna viridis and Venerupis spp. using microscopy and Fourier transform infrared spectroscopy. The second part explores the knowledge, attitude and perception (KAP) of bivalve gleaners on microplastics and plastics. Results of the study confirmed the presence of microplastics in both bivalves, with polyamide fibers being the most common polymer found in the bivalves. The mean size of microplastics found in Perna viridis and Venerupis spp. was 0.25 ± 0.05 mm and 0.33 ± 0.03 mm, respectively. Varying colors and shapes were also observed in both bivalves. Further, results of the KAP showed the lack of knowledge of the gleaners in terms of the basic information about microplastics. Nevertheless, they showed a positive attitude in terms of reducing plastic pollution and perceived coastal waters as important to them. The data on the two parts were used to compute for the estimate of the amount of microplastics that can be transferred to humans through consumption of bivalves, which was found to be 0.003 mg/day.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13762-023-04982-x.

Characteristics and hazard risk of microplastics in Sinonovacula constricta: from farming to market

In this paper, I selected Sinonovacula constricta, a typical representative of commercial bivalve shellfish from Zhangzhou City, and found that microplastics were detected in all the samples with small sizes. The abundance in farm samples (3.65 n/g) was higher than in market samples (0.89 n/g), despite their smaller weight, which was mainly contributed by body fluid. Microplastics transported from the body fluid to the viscera and then metabolized into muscle were substantially reduced (69.3%), with only 0 or 1 microplastic observed in the muscles on the micron scale. The microplastics detected in the market samples were mainly concentrated in the viscera, accounting for 81%, while distributed in all the organs of farm samples, with body fluids accounting for 52%. A total of four shapes were detected, with the highest percentage of fibrous shape, while foam-like microplastics were not detected in the market samples. The abundance was not correlated with sample weight, but market samples showed a positive correlation. A total of seven polymers were detected, with the highest rate of polypropylene (PP) (27%). The polymer risk level reached level III. The percentage of polyvinyl chloride (PVC) in the market samples exceeded that of farms, which resulted in a higher hazard risk index despite their lower abundance. The cleaning process and excretory behavior, from farms to markets, greatly reduced microplastic contamination.

Distribution of Micro-Nano PS, DEHP, and/or MEHP in Mice and Nerve Cell Models In Vitro after Exposure to Micro-Nano PS and DEHP

Polystyrene (PS) and di-(2-ethylhexyl) phthalate (DEHP) exist widely in the environment. However, their distribution in organisms remains unclear. We used three sizes (50 nm, 500 nm, and 5 μm) of PS and DEHP to study the distribution and accumulation of PS, DEHP, and mono(2-ethylhexyl) phthalate (MEHP) in mice and nerve cell models (HT22 and BV2 cells) and their potential toxicity. Results showed that PS entered the blood of mice, and the distribution of different particle sizes in different tissues was different. After the combined exposure to PS and DEHP, PS carried DEHP, which significantly increased the DEHP content and MEHP content and the highest content of MEHP was in the brain. With the decrease in PS particle size, the contents of PS, DEHP, and MEHP in the body increased. The levels of inflammatory factors were increased in the serum of the PS or/and DEHP group. In addition, 50 nm polystyrene can carry MEHP into nerve cells. These results suggest for the first time that PS and DEHP combined exposure can induce systemic inflammation, and the brain is an important target organ of PS and DEHP combined exposure. This study may serve as a reference for further evaluation of the neurotoxicity induced by combined exposure to PS and DEHP.

Nanoplastics induce epigenetic signatures of transgenerational impairments associated with reproduction in copepods under ocean acidification

Ocean acidification (OA) is one of many major global climate changes that pose a variety of risks to marine ecosystems in different ways. Meanwhile, there is growing concern about how nanoplastics (NPs) affect marine ecosystems. Combined exposure of marine organisms to OA and NPs is inevitable, but their interactive effects remain poorly understood. In this study, we investigated the multi- and transgenerational toxicity of NPs on copepods under OA conditions for ten generations. The findings revealed that OA and NPs have a synergistic negative effect on copepod reproduction across generations. In particular, the transgenerational groups showed reproductive impairments in the F1 and F2 generations (F1T and F2T), even though they were never exposed to NPs. Moreover, our epigenetic examinations demonstrated that the observed intergenerational reproductive impairments are associated with differential methylation patterns of specific genes, suggesting that the interaction of OA and NPs can pose a significant threat to the sustainability of copepod populations through epigenetic modifications. Overall, our findings provide valuable insight into the intergenerational toxicity and underlying molecular mechanisms of responses to NPs under OA conditions.

Mission Tara Microplastics: a holistic set of protocols and data resources for the field investigation of plastic pollution along the land-sea continuum in Europe

The Tara Microplastics mission was conducted for 7 months to investigate plastic pollution along nine major rivers in Europe-Thames, Elbe, Rhine, Seine, Loire, Garonne, Ebro, Rhone, and Tiber. An extensive suite of sampling protocols was applied at four to five sites on each river along a salinity gradient from the sea and the outer estuary to downstream and upstream of the first heavily populated city. Biophysicochemical parameters including salinity, temperature, irradiance, particulate matter, large and small microplastics (MPs) concentration and composition, prokaryote and microeukaryote richness, and diversity on MPs and in the surrounding waters were routinely measured onboard the French research vessel Tara or from a semi-rigid boat in shallow waters. In addition, macroplastic and microplastic concentrations and composition were determined on river banks and beaches. Finally, cages containing either pristine pieces of plastics in the form of films or granules, and others containing mussels were immersed at each sampling site, 1 month prior to sampling in order to study the metabolic activity of the plastisphere by meta-OMICS and to run toxicity tests and pollutants analyses. Here, we fully described the holistic set of protocols designed for the Mission Tara Microplastics and promoted standard procedures to achieve its ambitious goals: (1) compare traits of plastic pollution among European rivers, (2) provide a baseline of the state of plastic pollution in the Anthropocene, (3) predict their evolution in the frame of the current European initiatives, (4) shed light on the toxicological effects of plastic on aquatic life, (5) model the transport of microplastics from land towards the sea, and (6) investigate the potential impact of pathogen or invasive species rafting on drifting plastics from the land to the sea through riverine systems.

Binational survey using Mytilus galloprovincialis as a bioindicator of microplastic pollution: Insights into chemical analysis and potential risk on humans

Microplastic (MP) contamination in edible mussels has raised concerns due to their potential risk to human health. Aiming to provide valuable insights regarding the occurrence, physicochemical characteristics, and human health implications of MP contamination, in the present study, two nationwide surveys of MP contamination in mussels (Mytilus galloprovincialis) were conducted in Morocco and Tunisia. The results indicated that MP frequency ranged from 79 % to 100 % in all the analyzed samples. The highest MP density was detected in mussels from Morocco (gills "GI": 1.88 MPs/g ww^-1; digestive glands "DG": 0.92 MPs/g ww^-1) compared to mussels of Tunisia (GI: 1.47 MPs g^{- 1}; DG: 0.79 MPs g^{- 1}). No significant differences in MP density were found between the two organs (GI and DG) for both countries. MPs were predominantly blue and black fibers, and smaller than 1000 μm. Seven polymeric types were identified, of which PET, PP, and PE were the most abundant, accounting for >87 % of all samples. Scanning Electron Microscopy (SEM) coupled with Energy dispersive X-ray (EDX) showed that most MPs have noticeable signs of weathering and inorganic components on their surface. The highest MP daily intake was found in children, while the lowest was estimated in women and men. Moreover, the annual dietary exposure of MPs through mussel consumption was estimated to be 1262.17 MPs/year in Morocco and 78.18 MPs/year in Tunisia. The potential risk assessment of MPs in mussels based on the polymer hazard index (PHI) was estimated in the high-risk levels, implying that MPs may pose health risks to humans. Overall, this research suggests that the consumption of mussels represents a considerable MP exposure route for the Moroccan and Tunisian populations.