Multiple species ingest microplastic but few reflect sediment and water pollution on sandy beaches: A baseline for biomonitoring.

Databases recording the ingestion of microplastics by marine animals are growing. This is also recurrent on sandy beaches, where different biomonitors have been proposed to monitor the impacts of plastic pollution. We aimed to record the occurrence of suspected microplastic (SMP) in the digestive tract of multiple taxa (n = 45 identified species) and test whether some macroinvertebrates and fishes ingested SMPs proportionally with the pollution level of sediment and water; thus, we aimed to depict which sandy beach species could be used as biomonitors. Among all taxa, 10 macroinvertebrates and 12 fish species were reported to ingest SMP for the first time. SMP morphotypes proportion differed between abiotic and biotic compartments. Moreover, 10 of 12 taxa did not have SMP concentration linearly related with SMP in sediment and water. Our findings suggest that few species from sandy beaches can be used as efficient biomonitors, although almost all ingest plastic polymers.

Quantifying microplastics in fishes: The first case study contrasting the perspective of untrained and experienced researchers.

Microplastic studies hold a low explored potential for citizen science and environmental education, but methodological issues challenge data produced by non-specialists. We compared microplastic abundance and diversity in the red tilapia Oreochromis niloticus recovered by untrained students with those recovered by researchers that have experience of three years studying the incorporation of this pollutant by aquatic organisms. Seven students dissected 80 specimens and performed digestion of digestive tract in hydrogen peroxide. The solution was filtered and inspected under a stereomicroscope by the students and by two expert researchers. A control treatment consisted of 80 samples handled only by experts. The students overestimated the abundance of fibers and fragments. Striking differences in abundance and richness of microplastics were verified between the fish dissected by students and by expert researchers. Therefore, citizen science projects involving the uptake of microplastics by fish should provide training until a satisfactory level of expertise is reached.

Microplastics in fishes in amazon riverine beaches: Influence of feeding mode and distance to urban settlements.

Microplastic (MP) pollution is a global problem and has affected several biological levels even in protected areas. In the present study, MP contamination was investigated in fish associated with sandy beaches in a permanent environmental protection area in the Amazon. In order to achieve this goal, the shape, color, abundance, richness, and chemical composition of MPs in the digestive tract of 29 fish species in 24 beaches of the Machado River, western Brazilian Amazon, were evaluated. Linear mixed models (LMMs) were adjusted to test the effects of local human modification (HMc), distance from urban settlements, distance from the closest affluent, and trophic categories of fish species on microplastic abundance and richness in their digestive tracts. From the 1082 fish analyzed, 332 (30 %) presented MPs in their digestive tracts. A total of 617 MPs was found (1.8 ± 1.6 MPs; 4.5 ± 1.9 MPs/g fish). Omnivorous and insectivorous fish presented more MPs in sandy beaches located closer to urban settlements. However, carnivorous fish presented a higher abundance of MPs in their digestive tracts compared with the other trophic guilds. This is the first study to analyze plastic contamination in fish associated with sandy beaches in the Amazon (Brazil), and it revealed contamination of the ichthyofauna mainly related to the distance from urban settlements. Our results reinforce the need for better management of landscape surrounding protected areas to mitigate MP pollution.