Environmental risk assessment of heavy metals and microplastics in marine biota along Gujarat coastline, India

Heavy metal and microplastic pollution are a threat to marine ecosystems. Thus, the present study aims to assess the risk of these contaminants on edible organisms. Water and tissues of macroalgae, prawns, and crabs collected from 27 sites (3 zones) across the Gujarat coast were evaluated for heavy metal and microplastic presence. Chromium and nickel concentrations were highest in water samples of Alang and Nishkalank and in muscles of Penaeus japonicus, and Portunus sanguinolentus, while copper was highest in Ulva lactuca. Additionally, the bioconcentration factor highlighted mercury accumulation in macroalgae and nickel in prawns and crabs. Water and tissue samples revealed an abundance of microplastics (0.5- 4 mm) consisting of threads (49 %), fragments (33 %), and films (18 %) representing polymers like polyvinyl chloride, nylon, polypropylene, and polystyrene. Our findings indicate that contamination exceeds permissible limits in all three trophic levels studied, attributed to elevated anthropogenic activities, requiring immediate intervention for policy-driven decisions. •Chromium, nickel, and lead were highest in water, macroalgae, prawns, and crabs.•Polyvinyl chloride, nylon, polypropylene, and polystyrene were detected in samples.•Alang and Nishkalank from zone 2 were highly contaminated.•Anthropogenic activities pose a serious threat to marine biota and its habitat.