Ecotoxicity of microplastics in embryos and newly hatched snails of Biomphalaria glabrata

Microplastics (MPs) are emerging pollutants widely found in aquatic ecosystems. Despite the increasing number of studies concerning the effects of MPs on aquatic organisms, few have focused on toxicity in the early developmental stages of gastropods living in freshwater ecosystems. Thus, the current study aimed to evaluate the effects of polyethylene MPs (PE-MPs) in the neotropical gastropod Biomphalaria glabrata embryos and newly hatched snails (NH). The ecotoxicity of PE-MPs (from 0.3 mg L− 1 – environmental relevant concentration – to 160 mg L− 1) was analyzed by Biomphalaria embryotoxicity test (BET) (192 h) and acute toxicity tests with NH (96 h). Mortality and behavior (locomotor and touch sensitivity) were assessed in both embryos and NH, while heart rate, hatching rate, embryo development, reactive oxygen species – ROS levels, and cell death were analyzed during BET. Results showed that PE-MPs did not induce mortality or changes in the hatching rate, developmental stages, and behavior of B. glabrata. However, sub-lethal effects were observed regarding heart rate, ROS, and cell death of embryos. These results indicate that embryos are more sensitive than NH. In addition, the lack of effects on hatched snails from BET suggests that the effects observed during their development were not strong enough to affect the completely formed snail, which could be related to additional protection provided by the gelatinous substance that composes the egg clutches.