Expanded polystyrene microplastic is more cytotoxic to seastar coelomocytes than its nonexpanded counterpart: A comparative analysis

Microplastics (MPs) are established contaminants of coastal ecosystem. Present investigation is aimed to assess comparative toxicity of polystyrene microplastic (PS-MP) and expanded polystyrene microplastic (EPS-MP) in the coelomocytes of Astropecten indicus, a common seastar of Digha coast of Bay of Bengal, India. Coastal water of Digha, a tourist spot of attraction, bears the ecotoxicological risk of contamination by various agents including expanded and nonexpanded microplastics of industrial origin. Coelomocytes of seastar perform multiple physiological functions including pathogen engulfment, cytotoxicity and respiratory gas exchange and considered as immunoeffector cells in echinoderms. We report an adverse shift in total count, phagocytic response, cytotoxicity and oxidative potential of the coelomocytes of A. indicus under the exposures of 0.5 and 1 mg L−1 PS-MP and EPS-MP for 7 and 14 d. Experimental data suggested a higher level of cytotoxicity of EPS-MP in coelomocytes in comparison to that of PS-MP. Seastar is considered as a keystone species, which plays an important role in maintaining the functional homeostasis of coastal ecosystem. Unrestricted contamination of coastal water by MPs may lead to a persistent immunophysiological stress in seastar. Experimental endpoints may be considered as effective monitoring tool to assess ecotoxicity of MPs in seastar and alike organisms sharing the same habitat.