Hot and toxic: Accumulation dynamics and ecotoxicological responses of mussel Mytilus galloprovincialis exposed to marine biotoxins during a marine heatwave

Abstract

Climate change is increasing marine heatwaves (MHWs) frequency and severity worldwide. These extreme events often cause bivalves' mass mortality and facilitate the growth, proliferation and dispersion of toxin-producing microalgae blooms associated with threats to seafood safety. Yet, the interactive effects between MHW and uptake of marine biotoxins by biota are a novel topic still lacking thorough research, from both the ecotoxicological and seafood safety standpoints. This study assessed the effects of a MHW event on the accumulation/elimination dynamics of diarrhetic shellfish toxins in Mytilus galloprovincialis exposed to Prorocentrum lima and the ecotoxicological responses of mussels co-exposed to these two stressors. Results showed that acute exposure to +4 °C reduced toxins accumulation (−49 %) and elimination (−77 %) compared to control temperature. Moreover, exposure to MHW and toxins affected mussels' antioxidant activity, lipid and protein damage, and metabolism in a tissue-specific manner. These findings highlight that M. galloprovincialis can face higher vulnerability to toxins when MHW events strike.