Can leachates of environmentally relevant concentrations of microplastics in marine sediments affect the reproduction of an epibenthic copepod?

Most studies on the effects of microplastics on marine biota are carried out using unrealistically high concentrations. Moreover, although microplastics are capable of carrying toxic substances and thus can cause adverse effects even without coming into direct contact with organisms, little is known about the effects of not accessible for ingestion microplastics on benthic biota. Considering that the presence of microplastic particles can itself cause effects to the biota due to toxic substances leached, the present study evaluated the ecotoxicological effects of microplastic leachates of virgin and beach stranded in marine sediments (whole sediments and elutriates) on the epibenthic copepod Nitokra sp. (size 3 ± 1 mm). Effects on reproduction were evaluated using clean sediment enriched with environmentally relevant concentrations [1 pellet: 46.67g sediment (Low) and 1 pellet: 1.67g sediment (High)] of two types of plastic pellets (size 4 ± 1 mm) (i) virgin (obtained from the manufacturer) or (ii) stranded (collected from Santos beach, São Paulo, Brazil, a highly urbanized beach). The results of the present study showed that microplastics leachate (virgin or from the environment) did not cause an inhibiting effect on reproduction in Nitokra sp. in any of the scenarios tested. These results contribute to further risk assessments of plastic particles for marine biota.