Diet characteristics of tidal creek-associated fishes of the northeastern Arabian Sea with special reference to microplastic ingestion

Abstract

The present study assessed the diet characteristics, trophic guild structure, and microplastics (MPs) ingestion by a group of fish sourced from the tidal creeks of the Mumbai coast along the Eastern Arabian Sea. The diet patterns were characterized using gastro-somatic index (GaSI), relative length of gut (RGL), diet overlap (α), diet breadth (Bi), and relative abundance of food items (%IOP), with a special emphasis on MPs contamination. The findings revealed that teleost and shrimps are the most preferred food items for these species. Whereas MPs contribute 5.50% of the total diet composition of the selected fishes. Additionally, we tried to find out the influence of fish size and dietary attributes on MP ingestion, identifying trophic level as a significant factor influencing contamination levels. Using the Polymer Hazard Index (PHI), the potential risks posed by MPs in fish samples were assessed, revealing notable discrepancies among polymers. For instance, polyvinyl chloride showed the highest PHI score of 198.75 and a hazard score reaching the highest risk category (IV), indicating substantial environmental risk. In summary, our findings highlight the impact of fish diet characteristics on MPs contamination and the varying levels of MP risks along the Mumbai coast, categorized according to polymer type from low to high risk.