Plastic occurrence in fish caught in the highly industrialized Gulf of Izmit (Eastern Sea of Marmara, Türkiye).

Occurrence of micro- (<5 mm) and mesoplastics (5-25 mm) in twelve fish species caught off Gulf of Izmit in the Sea of Marmara was investigated. Plastics were found in the gastrointestinal tracks of all the analysed species: Trachurus mediterraneus, Chelon auratus, Merlangius merlangus, Mullus barbatus, Symphodus cinereus, Gobius niger, Chelidonichthys lastoviza, Chelidonichthys lucerna, Trachinus draco, Scorpaena porcus, Scorpaena porcus, Pegusa lascaris, Platichthys flesus. From a total of 374 individuals examined plastics were found in 147 individuals (39%). The average plastic ingestion was 1.14 ± 1.03 MP. fish-1 (considering all the analysed fish) and 1.77 ± 0.95 MP. fish-1 (considering only the fish with plastic). Fibres were the primary plastic types found in GITs (74%), followed by films (18%) and fragments (7%), no foams and microbeads were found. A total of ten different colours of plastics were found with blue (62%) being the most common colour. Length of plastics ranged from 0.13 to 11.76 mm with an average of 1.82 ± 1.59 mm. A total of 95.5% of plastics were microplastics, and 4.5% as mesoplastics. The mean frequency of plastic occurrence was higher in pelagic fish species (42%), followed by demersal (38%) and bentho-pelagic species (10%). Fourier-transform infrared spectroscopy confirmed that 75% of polymers were synthetic with polyethylene terephthalate being the most common polymer. Our results indicated that carnivore species with a preference for fish and decapods were the highest impacted trophic group in the area. Fish species in the Gulf of Izmit are contaminated with plastics, representing a potential risk to ecosystem and human health. Further research is needed to understand the effects of plastic ingestion on biota and possible pathways. Results of this study also provide baseline data for the implementation of the Marine Strategy Framework Directive Descriptor 10 in the Sea of Marmara.

Effect of biological and environmental factors on microplastic ingestion of commercial fish species.

Marine litter is an emerging pollution all over the world. In addition to the macro sized plastics, ongoing scientific efforts revealed risks of micro and nano sized plastic particles in marine environment. In the past decades, an increasing number of studies have been carried out to understand the dynamics of this pollution. The aim of the present study was to investigate the microplastic (MPs) ingestion in commercially important fish species and to evaluate biological and environmental factors influencing the ingestion status. Gastrointestinal tract content of a total of 2222 individuals belonging to 17 species were examined for MPs existence. Out of 17 species evaluated, 13 of them was detected to ingest MPs. Our results showed that 18.1% of investigated fishes ingested MPs and the average length of the detected particles was 1.26 ± 1.38 (±SD) mm. The most dominant MP type was fiber (90.1%), while the most common particle colours were black (46.9%) and blue (29.4%). Polypropylene (85%) was the most common polymer type detected. Our evaluations indicated that the exposure of fish distributed in coastal areas to microplastic pollution is corelated to physical (precipitation and distance to nearest shore) and biological (functional trophic group, habitat of the species) factors. In order to design a more effective control mechanism, these impacts should be included in the assessments in future practices to reveal the effects of microplastic pollution on biota.

The fate of microplastics during uptake and depuration phases in a blue mussel exposure system.

We present a blue mussel exposure system where the fate of microplastics (polystyrene beads) is tracked during exposure and depuration phases. This enabled the establishment of a complete mass balance. Quantification of beads in mussels was done with a novel enzymatic digestion protocol. We found a similar relative distribution of beads for 2 environmentally realistic concentrations (5 and 100 beads L-1 ) and no substantial egestion of particles within 2 h of depuration. Environ Toxicol Chem 2019;38:99-105. © 2018 SETAC.

Virgin microplastics are not causing imminent harm to fish after dietary exposure.

Among aquatic organisms, fish are particularly susceptible to ingesting microplastic particles due to their attractive coloration, buoyancy, and resemblance to food. However, in previous experimental setups, fish were usually exposed to unrealistically high concentrations of microplastics, or the microplastics were deliberately contaminated with persistent organic chemicals; also, in many experiments, the fish were exposed only during the larval stages. The present study investigated the effects of virgin microplastics in gilt-head seabream (Sparus aurata) after 45 days' exposure at 0.1 g kg-1 bodyweight day-1 to 6 common types of microplastics. The overall growth, biochemical analyses of the blood, histopathology, and the potential of the microplastics to accumulate in gastrointestinal organs or translocate to the liver and muscles were monitored and recorded. The results revealed that ingestion of virgin microplastics does not cause imminent harm to the adult gilt-head seabream during 45 days of exposure and an additional 30 days of depuration. The retention of virgin microplastics in the gastrointestinal tract was fairly low, indicating effective elimination of microplastics from the body of the fish and no significant accumulation after successive meals. Therefore, both the short- and the long-term retention potential of microplastics in the gastrointestinal tract of fish is close to zero. However, some large particles remained trapped in the liver, and 5.3% of all the livers analyzed contained at least one microplastic particle. In conclusion, the dietary exposure of S. aurata to 6 common types of virgin microplastics did not induce stress, alter the growth rate, cause pathology, or cause the microplastics to accumulate in the gastrointestinal tract of the fish.

Microplastic does not magnify the acute effect of PAH pyrene on predatory performance of a tropical fish (Lates calcarifer).

Microplastic (MP) leads to widespread pollution in the marine ecosystem. In addition to the physical hazard posed by ingestion of microplastic particles, concern is also on their potential as vector for transport of hydrophobic contaminants. We experimentally studied the single and interactive effects of microplastic and pyrene, a polycyclic aromatic hydrocarbon, on the swimming behaviour and predatory performance of juvenile barramundi (Lates calcarifer). Juveniles (18+ days post hatch) were exposed to MPs, or pyrene (100 nM), or combination of both, and feeding rate and foraging activity (swimming) were analysed. Exposure to MPs alone did not significantly influence feeding performance of the juveniles, while a dose-effect series of pyrene showed strong effect on fish behaviour when concentrations were above 100 nM. In the test of combined MP and pyrene exposure, we observed no effect on feeding while swimming speed decreased significantly. Thus, our results confirm that short-time exposure to pyrene impacts the performance of fish juveniles, while additional exposure to microplastic at the given conditions influenced their activity only and not their feeding rate. Further studies of the combined effects of microplastics and pollutants on tropical fish behaviour are encouraged.

Microplastic litter composition of the Turkish territorial waters of the Mediterranean Sea, and its occurrence in the gastrointestinal tract of fish.

Microplastic pollution of marine environment is receiving increased publicity over the last few years. The present survey is, according to our knowledge, the survey with the largest sample size analyzed, to date. In total, 1337 specimens of fish were examined for the presence of plastic microlitter representing 28 species and 14 families. In addition, samples of seawater and sediment were also analyzed for the quantification of microplastic in the same region. Samples of water/sediment were collected from 18 locations along the Mediterranean coast of Turkey. 94% of all collected plastic microlitter from the sea was in the size range between 0.1 and 2.5 mm, while the occurrence of other sizes was rare. The quantity of microplastic particles in surface water samples ranged from 16 339 to 520 213 per km2. Fish were collected from 10 locations from which 8 were either shared with or situated in the proximity of water/sediment sampling locations. A total of 1822 microplastic particles were extracted from stomach and intestines of fish. Majority of ingested particles were represented by fibers (70%) and hard plastic (20.8%), while the share of other groups: nylon (2.7%), rubber (0.8%) and miscellaneous plastic (5.5%) were low. The blue color of plastic was the most dominant color. 34% of all examined fish had microplastic in the stomach. On average, fish which had microplastic contained 1.80 particles per stomach. 41% of all fish had microplastic in the intestines with an average of 1.81 particles per fish. 771 specimens contained microplastic in either stomach and/or intestines representing 58% of the total sample with an average of 2.36 particles per fish. Microplastic was found in all species/families that had sample size of at least 2 individuals. The number of particles present in either stomach or intestines ranged between 1 and 35. Ingested microplastic had an average diameter ±SD of 656 ± 803 µm, however particles as small as 9 µm were detected. The trophic level of fish species had no influence whatsoever on the amount of ingested microplastic. Pelagic fish ingested more microplastic than demersal species. In general, fish that ingested higher number of microplastic particles originated from the sites that also had a higher particle count in the seawater and sediment.