Current environmental microplastic levels do not alter emergence behaviour in the intertidal gastropod Littorina littorea

Microplastic ingestion by intertidal fauna is a well-documented phenomenon, with emphasis on the physiological consequences of microplastic exposure. However, the behavioural effects of microplastic ingestion have not been explored to the same degree, even in species with documented microplastic ingestion. In this study, the predator-avoidance emergence response of Littorina littorea was assessed and related to microplastic levels within the samples. This is a novel approach to microplastic behavioural experiments, whereby current environmental L. littorea microplastic levels are assessed, rather than levels vastly in excess of those recorded under field conditions. The results showed no difference in emergence likelihood or emergence latency related to microplastic abundance, sex, or treatment. However, L. littorea size did have a significant effect on emergence likelihood and emergence latency, with smaller individuals emerging faster and more frequently. This study shows that microplastics, at their current environmental levels, do not seem to affect L. littorea emergence behaviour.