Potential Toxic Effects of Environmental Plastic Litter on resident wharf roach (Ligia exotica)

Abstract

Although many field observations of microplastic contamination have been reported in marine environments, fewer studies have clarified the adverse effects derived from microplastic contamination in marine resident species. This is the first report to evaluate the toxic effects of environmental in situ plastic litter exposure on wharf roaches (Ligia exotica). L. exotica occupies an important ecological position as a detritus consumer. An experimental survey was conducted from May–June 2019 in two South Korean nearshore sites: Maemul-do [microplastic-contaminated] and Nae-do [microplastic-uncontaminated]. The average microplastic abundance (>20 μm) in L. exotica was higher at Maemul-do (50.56 particles/individual) than at Nae-do (1.00 particles/individual). The composition of microplastics was dominated by expanded polystyrene in L. exotica from Maemul-do (93%). Comparative transcriptomic analysis revealed significantly altered expression of genes associated with metabolic processes, mitotic cell cycle regulation and the immune system (cutoff: q<0.05) in L. exotica from Maemul-do. Our findings highlight the importance of understanding the toxic effects of translocated microplastics in resident species to better manage microplastic pollution using bioindicators.