The patterns of trophic transfer of microplastic ingestion by fish in the artificial reef area and adjacent waters of Haizhou Bay

Microplastics footprint in nature reserves-a case study on the microplastics in the guano from Yancheng Wetland Rare Birds National Nature Reserve, China

Bio-ingestion of microplastics poses a global threat to ecosystems, yet studies within nature reserves, crucial habitats for birds, remain scarce despite the well-documented ingestion of microplastics by avian species. Located in Jiangsu Province, China, the Yancheng Wetland Rare Birds Nature Reserve is home to diverse bird species, including many rare ones. This study aimed to assess the abundance and characteristics of microplastics in common bird species within the reserve, investigate microplastic enrichment across different species, and establish links between birds' habitat types and microplastic ingestion. Microplastics were extracted from the feces of 110 birds, with 84 particles identified from 37.27% of samples. Among 8 species studied, the average microplastic abundance ranged from 0.97 ± 0.47 to 43.43 ± 61.98 items per gram of feces, or 1.5 ± 0.87 to 3.4 ± 1.50 items per individual. The Swan goose (Anser cygnoides) exhibited the highest microplastic abundance per gram of feces, while the black-billed gull (Larus saundersi) had the highest abundance per individual. The predominant form of ingested microplastics among birds in the reserve was fibers, with polyethylene being the most common polymer type. Significant variations in plastic exposure were observed among species and between aquatic and terrestrial birds. This study represents the first quantitative assessment of microplastic concentrations in birds within the reserve, filling a crucial gap in research and providing insights for assessing microplastic pollution and guiding bird conservation efforts in aquatic and terrestrial environments.

Trophic transfer and biomagnification of microplastics through food webs in coastal waters: A new perspective from a mass balance model

Since the 1950s, plastic pollution and its risk have been recognized as irreversible and nonnegligible problems as global plastic production has increased. In recent years, the transport and trophic transfer of microplastics (MPs) in biotic and abiotic environment have attracted extensive attention from researchers. In this study, based on the Ecotracer module from Ecopath with Ecosim (EwE) model, the marine ranching area of Haizhou Bay, Jiangsu Province, China, was taken as a case study by linking the environmental plastic inflow with MPs in organisms to simulate the variation of MPs in the marine food web for 20 years, as well as its potential trophic transfer and biomagnification. We found that the concentration of MPs in top consumers first increased when the concentration of MPs in the environment increased, while that in primary consumers first decreased when the concentration of MPs in the environment decreased. Moreover, high TL consumers had a stronger ability to accumulate MPs, and pelagic prey fishes was the opposite. From the perspective of the food web, all functional groups showed significant trophic magnification along with the trophic level and no biodilution. Generally, there is a direct relationship between the MPs in marine organisms and environmental inflow. If the pollutants flowing into the environment can be reduced, the MP pollution problem in coastal waters will be effectively alleviated. Our research can further provide a scientific basis for ecological risk assessment and management of MPs and biodiversity protection in marine ecosystems.

Fish microplastic ingestion may induce tipping points of aquatic ecosystems

Microplastics can be ingested by a wide range of aquatic animals. Extensive studies have demonstrated that microplastic ingestion-albeit often not lethal-can affect a range of species life-history traits. However, it remains unclear how the sublethal effects of microplastics on individual levels scale up to influence ecosystem-level dynamics through cascading trophic interactions. Here we employ a well-studied, empirically fed three-species trophic chain model, which was parameterized to mimic a common type of aquatic ecosystems to examine how microplastic ingestion by fish on an intermediate trophic level can produce cascading effects on the species at both upper and lower trophic levels. We show that gradually increasing microplastics in the ingested substances of planktivorous fish may cause population structure effects such as skewed size distributions (i.e. reduced average body length vs. increased maximal body size), and induce abrupt declines in fish biomass and reproduction. Our model analysis demonstrates that these abrupt changes correspond to an ecosystem-level tipping point, crossing which difficult-to-reverse ecosystem degradation can happen. Importantly, microplastic pollution may interact with other anthropogenic stressors to reduce safe operating space of aquatic ecosystems. Our work contributes to better understanding complex effects of microplastic pollution and anticipating tipping points of aquatic ecosystems in a changing world. It also calls attention to an emerging threat that novel microplastic contaminants may lead to unexpected and abrupt degradation of aquatic ecosystems, and invites systematic studies on the ecosystem-level consequences of microplastic exposure.

Plastic, It's What's for Dinner: A Preliminary Comparison of Ingested Particles in Bottlenose Dolphins and Their Prey

Microplastic ingestion was reported for common bottlenose dolphins (Tursiops truncatus) inhabiting Sarasota Bay, FL, USA, a community that also has prevalent exposure to plasticizers (i.e., phthalates) at concentrations higher than human reference populations. Exposure sources are currently unknown, but plastic-contaminated prey could be a vector. To explore the potential for trophic exposure, prey fish muscle and gastrointestinal tract (GIT) tissues and contents were screened for suspected microplastics, and particle properties (e.g., color, shape, surface texture) were compared with those observed in gastric samples from free-ranging dolphins. Twenty-nine fish across four species (hardhead catfish, Ariopsis felis; pigfish, Orthopristis chrysoptera; pinfish, Lagodon rhomboides; and Gulf toadfish, Opsanus beta) were collected from Sarasota Bay during September 2022. Overall, 97% of fish (n = 28) had suspected microplastics, and GIT abundance was higher than muscle. Fish and dolphin samples contained fibers and films; however, foams were common in dolphin samples and not observed in fish. Suspected tire wear particles (TWPs) were not in dolphin samples, but 23.1% and 32.0% of fish muscle and GIT samples, respectively, contained at least one suspected TWP. While some similarities in particles were shared between dolphins and fish, small sample sizes and incongruent findings for foams and TWPs suggest further investigation is warranted to understand trophic transfer potential.

Transfer pattern of microplastics at an individual level: A case study of two typical Sciaenidae fish in coastal waters

Microplastics (MPs) are recognized as global pollutants. The occurrence and distribution of MP transfer at the species level have been reported, but few studies have focused on the individual level. In this study, two typical migratory demersal species (Collichthys lucidus and Larimichthys polyactis, family Sciaenidae) from the coastal waters of the Lvsi fishing ground were selected to analyze the distribution characteristics of MPs in their gastrointestinal tracts and to explore the potential biomagnification of MPs in different body lengths. The results showed that the main MP color found in both species was blue (>80 %), while the main MP shape was fiber (>90 %), and the main MP polymer type was polyethylene terephthalate (PET) (>70 %). Overall, the abundance of MPs in C. lucidus (3.24 ± 1.57 pieces/fish) was higher than that in L. polyactis (2.24 ± 0.56 pieces/fish). The abundance of MPs in C. lucidus with a body length >90 mm was significantly higher than that with a body length <90 mm, and no significant difference was found in L. polyactis. We believe that the shift in feeding habits during the life history of the two species is an important factor that affects the variation in MPs between body lengths. Additionally, there was a significant positive correlation between MPs and the length (weight) of C. lucidus but no correlation in L. polyactis. There was no significant correlation between trophic level and MPs in either species. This indicated that MP bioaccumulation only occurred in C. lucidus, and MP biomagnification did not occur in either species. We suggest that further research be conducted on MPs ingested by more species at an individual level regarding the biomagnification/bioaccumulation phenomenon. This will help further elucidate the characteristics of MP transfer in the food webs of ecosystems and provide theoretical support for understanding MP pollution in coastal waters.

Occurrence and accumulation of microplastics in commercial fish in the coastal waters of the Lvsi fishing ground in China

In recent years, there has been an exponential increase in the research popularity of microplastics (MPs) in offshore marine environments. However, there is still a gap in the research on the accumulation of MPs in different tissues of aquatic organisms and the trophic transfer of MPs between aquatic organisms. The common occurrence of MPs in the gills and guts of 11 species of commercial fishes was examined in the coastal waters of the Lvsi fishing ground (LSFG). The obtained results showed that >85 % of MPs existed in the gills and guts of these fish, and the abundance was 2.39 ± 1.38 pieces/fish and 2.56 ± 1.42 pieces/fish, respectively. Fibrous and blue are the most common colors and shapes of MPs, and PET is the main polymer type. At the species level, the abundance of MPs in the gills and guts of a few fishes (e.g., Larimichthys polyactis, Setipinna tenuifilis, Collichthys lucidus) decreased with increasing body length and body weight (P < 0.05). At the community level, this situation was not significant (P > 0.05). With increasing trophic level (TL), MPs tended to decrease in the gills (trophic magnification factor, TMF = 0.86) but did not significantly vary in the gut. We believe that MPs are multidimensional pollutants, and their accumulation in tissues/organs of organisms has not been accurately and qualitatively determined. To establish the relationship of MP transport and trophic transfer among water, sediments and organisms, we suggest that more efforts should be made to investigate MPs in aquatic organisms in the coastal waters of LSFG and to increase the examination of MPs in the water column and sediments. This study will help us improve our understanding of MPs pollution, and provide a good reference and basis for the management, monitoring and implementation of pollutants in marine organism of coastal water.

Trophic niche influences ingestion of micro- and mesoplastics in pelagic and demersal fish from the Western Mediterranean Sea

Plastic pollution has been extensively documented in the marine food web, but targeted studies focusing on the relationship between microplastic ingestion and fish trophic niches are still limited. In this study we investigated the frequency of occurrence and the abundance of micro- and mesoplastics (MMPs) in eight fish species with different feeding habits from the western Mediterranean Sea. Stable isotope analysis (δ13C and δ15N) was used to describe the trophic niche and its metrics for each species. A total of 139 plastic items were found in 98 out of the 396 fish analysed (25%). The bogue revealed the highest occurrence with 37% of individuals with MMPs in their gastrointestinal tract, followed by the European sardine (35%). We highlighted how some of the assessed trophic niche metrics seem to influence MMPs occurrence. Fish species with a wider isotopic niche and higher trophic diversity were more probable to ingest plastic particles in pelagic, benthopelagic and demersal habitats. Additionally, fish trophic habits, habitat and body condition influenced the abundance of ingested MMPs. A higher number of MMPs per individual was found in zooplanktivorous than in benthivore and piscivorous species. Similarly, our results show a higher plastic particles ingestion per individual in benthopelagic and pelagic species than in demersal species, which also resulted in lower body condition. Altogether, these results suggest that feeding habits and trophic niche descriptors can play a significant role in the ingestion of plastic particles in fish species.

A global snapshot of microplastic contamination in sediments and biota of marine protected areas

Microplastics (MPs) become ubiquitous contaminants in Marine Protected Areas (MPA) that have been planned as a conservation strategy. The present study provides a comprehensive overview of the occurrence, abundance, and distribution of MPs potentially affecting MPA worldwide. Data on MP occurrence and levels in sediment and biota samples were collected from recent peer-reviewed literature and screened using a GIS-based approach overlapping MP records with MPA boundaries. MPs were found in 186 MPAs, with levels ranging from 0 to 9187.5 items/kg in sediment and up to 17,461.9 items/kg in organisms. Peaked MPs concentrations occurred within multiple-use areas, and no-take MPAs were also affected. About half of MP levels found within MPA fell into the higher concentration quartiles, suggesting potential impacts on these areas. In general, benthic species were likely more affected than pelagic ones due to the higher concentrations of MP reported in the tissues of benthic species. Alarmingly, MPs were found in tissues of two threatened species on the IUCN Red List. The findings denote urgent concerns about the effectiveness of the global system of protected areas and their proposed conservation goals.

Transfer of Microplastics in Terrestrial and Aquatic Food Webs: The Impact of E-Waste Debris and Ecological Traits

Factors affecting the trophic transfer of microplastics (MPs) in aquatic and terrestrial ecosystems remain to be clarified. Here, we determined the abundances of MPs in multiple terrestrial and aquatic species, including insects, snails, crustaceans, fishes, snakes, birds, and voles, from an abandoned e-waste recycling site. Approximately 80% of MPs were within the size range 20-50 μm. In wildlife, the MP abundances per individual and per body weight were found to be positively and negatively correlated with body weight, respectively. Herein, terrestrial vertebrates, primarily birds, exhibited more complex compositions of polymer types than other organisms owing to the wide foraging areas and diverse food sources. However, according to the MPs modeled and the observed results in bird food chains, MPs do not appear to be preferentially retained in the bird gastrointestinal tract. The species-specific polymer types identified indicate the influences of habitat on MP pollution in organisms, which is further supported by significant correlations between the abundance of MPs and δ13C in the terrestrial food web (p < 0.05). In the analyzed bird species, the low MP abundance detected in birds compared with the amount of food ingested indicates that MPs constitute a negligible factor in the bioaccumulation of chemical pollutants.

Environmentally relevant concentrations of microplastics modulated the immune response and swimming activity, and impaired the development of marine medaka Oryzias melastigma larvae

Microplastics (MPs), due to their impacts on the ecosystem and their integration into the food web either through trophic transfer or ingestion directly from the ambient environment, are an emerging class of environmental contaminants posing a great threat to marine organisms. Most reports on the toxic effects of MPs exclusively focus on bioaccumulation, oxidative stress, pathological damage, and metabolic disturbance in fish. However, the collected information on fish immunity in response to MPs is poorly defined. In particular, little is known regarding mucosal immunity and the role of mucins. In this study, marine medaka (Oryzias melastigma) larvae were exposed to 6.0 µm beads of polystyrene microplastics (PS-MPs) at three environmentally relevant concentrations (10² particles/L, 10⁴ particles/L, and 10⁶ particles/L) for 14 days. The experiment was carried out to explore the developmental and behavioural indices, the transcriptional profiles of mucins, pro-inflammatory, immune, metabolism and antioxidant responses related genes, as well as the accumulation of PS-MPs in larvae. The results revealed that PS-MPs were observed in the gastrointestinal tract, with a concentration- and exposure time-dependent manner. No significant difference in the larval mortality was found between the treatment groups and the control, whereas the body length of larvae demonstrated a significant reduction at 10⁶ particles/L on 14 days post-hatching. The swimming behaviour of the larvae became hyperactive under exposure to 10⁴ and 10⁶ particles/L PS-MPs. In addition, PS-MP exposure significantly up-regulated the mucin gene transcriptional levels of muc7-like and muc13-like, however down-regulated the mucin gene expression levels of heg1, muc2, muc5AC-like and muc13. The immune- and inflammation and metabolism-relevant genes (jak, stat-3, il-6, il-1β, tnf-а, ccl-11, nf-κb, and sod) were significantly induced by PS-MPs at 10⁴ and 10⁶ particles/L compared to the control. Taken together, this study suggests that PS-MPs induced inflammation response and might obstruct the immune functions and retarded the growth of the marine medaka larvae even at environmentally relevant concentrations.