A study of microplastics in marine organisms across trophic levels on the west coast of India

Abstract

Plastic pollution is rapidly increasing globally, posing a threat to marine organisms. Microplastics negatively impact the biological processes of marine organisms when ingested. It is still unclear how microplastics accumulate in the food web and how microplastic biomagnification varies at different trophic levels. There is a general lack of research on this subject, particularly along the Indian coast. This study aimed to compare the abundance and diversity of microplastics (MPs) across benthic and pelagic species, between two locations with varying anthropogenic pressure (Kochi, Kerala, and Malvan, Maharashtra), and between different tissues. I also investigated whether biomagnification of MPs occurs across trophic levels at both locations. A total of 125 individuals from both locations were sampled and analyzed for microplastics. Additionally, six seawater samples were collected from Malvan for microplastic analysis. Three types of microplastics (fibers, fragments, and films) were observed in the sampled species and water samples. Transparent fibers, mainly derived from degraded fishing lines and nets, were the most abundant type of microplastics observed. Pelagic feeders showed a significantly higher microplastic concentration than benthic feeding species. There was no difference in microplastic concentration between samples from Malvan and Kochi. Microplastics were observed in both the gut and liver of the sampled individuals and was significantly higher in the liver than in the gut of primary consumers (TL1). On the contrary, microplastic concentration was significantly higher in the gut than in the liver of secondary consumers (TL2). No evidence for biomagnification was observed in samples from both locations.