Assessing the effect of microplastics on marine invertebrates: the consequence of exposure of sea urchin larvae to polystyrene microplastics

Polystyrene (PS) microplastics (PSMPs) represent a pervasiveenvironmental pollutant in marine ecosystems, originating from thefragmentation of widely used, non-biodegradable plastic materials suchas disposable plates. Despite growing concern over their ecologicalimpacts, the mechanistic understanding of PSMP toxicity during criticalearly developmental stages remains limited. Here, we employed the seaurchin Paracentrotus lividus, a well-established model organism inmarine ecotoxicology due to its sensitivity to environmental stressors,to investigate the effects of PSMPs derived from commercial disposableplates on fertilization, early embryogenesis, and larval development. Weassessed morphological malformations, alterations in gene expressionprofiles related to detoxification, skeletogenesis, development, andstress responses, as well as embryo resilience to physical stress. Ourresults demonstrated that PSMP exposure induced significantdevelopmental malformations and downregulation of multiple gene networkscritical for normal development. Notably, the toxicity was doseandtime-dependent, with smaller particles and higher concentrationsexerting more pronounced effects. Importantly, we observed that embryosretained the capacity for physiological recovery following PSMP removal,indicating a reversible toxic effect under certain conditions. Thesefindings provided novel insights into the molecular and developmentalpathways affected by PSMPs, revealing complex interactions betweenparticle properties and biological responses. The study underlined thesubstantial risks posed by PSMP contamination to marine invertebrateearly life stages, with potential cascading consequences for populationdynamics and ecosystem health. Our work highlighted the urgent need forimproved management of plastic waste and further mechanistic research toinform conservation strategies aimed at mitigating microplasticpollution in marine environments.