Developmental Toxicity of Microplastic Leachates on Marine Larvae

Abstract

Marine plastic pollution is now considered a diverse contaminant suite, differing in product origin, polymer composition, size, morphology, colour, additives and environmental co-contaminants. The environmental hazards associated with marine plastic pollution have been widely documented, however much of the existing research has yet to document developmental abnormalities observed when biota develop in plastic contaminated systems. The effect of microplastic leachate exposure on two marine echinoderms early developmental stages were investigated. Psammechinus milaris and Paracentrotus lividus embryonic and larval cultures were exposed to leachates derived from industrial or environmental exposed plastic pellets to investigate the effect of polymer additives and environmental contaminants. Toxicity was evaluated morphologically using images of live embryos and larvae, along with immunostaining of key developmental tissue groups to determine the extent of impact on a physiological level. This body of work suggests that leachates from pellets exposed to environmental contaminates (biobead and pre-production nurdle pellets) and highly plasticised industrial pellets (polyvinyl chloride) elicit severe, consistent and treatment-specific phenotypes in P. lividus embryonic and larval developmental stages, with impacts on morphogenic processes. Key differences in larvae morphology were documented between plastic types and environmental exposure. Industrial polyvinyl chloride pellets elicited the most pronounced abnormalities from the wild type at 24 hours post-fertilisation. However, leachates from un-plasticised industrial polyethylene pellets showed little differences from the wildtype with regards to developmental timing and abnormalities. Leachates from environmental sourced pellets elicited the most severe developmental delays and abnormalities at 48 hours post-fertilisation. Preliminary chemical analysis was also performed on industrial and beached pellet leachates, to investigate compound composition and to determine possible contributors to the developmental defects. To summarise, the findings suggest industrial and environmental microplastic leachate exposure elicits morphological malformations and specific abnormalities in neural, cilia and muscle tissues groups in both embryonic and larval stages of marine larvae of P. lividus. However, more research and investigation are needed to draw conclusive data.