Sex-specific digestive performance of mussels exposed to warming and starvation.

As global climate change has dramatically impacted the ocean, severe temperature elevation and a decline in primary productivity has frequently occurred, which has affected the structure of coastal biomes. In this study, the sex-specific responses to temperature change and food availability in mussels were determined in terms of digestive performance. The thick-shelled mussels Mytilus coruscus (male and female) were exposed to different temperature and nutritional conditions for 30 days. The results showed that the digestive enzymes of mussels were significantly affected by temperature, food, sex, and their interactions. High temperature (30°C) and starvation significantly decreased amylase, lysozyme, and pepsase activities of female mussels, while trypsin and trehalase did not change significantly at the experimental end. The activity of amylase, trypsin, and trehalase was significantly reduced in males at high temperature (30°C) under starvation treatment, but high temperature (30°C) elevated pepsase. Unsurprisingly, starvation caused the reduction of lysozyme and pepsase under 25°C in males. Amylase, lipase, and trehalase were higher in female mussels compared with males, while the enzymatic activities of lysozyme, pepsase, and trypsin were higher in male mussels than females. Principal component analysis showed that different enzyme activity indexes were separated in male and female mussels, indicating that male and female mussels exhibited significantly different digestive abilities under temperature and food condition change. The study clarified sex-specific response difference in mussel digestive enzymes under warming and starvation and provided guidance for the development of mussel aquaculture (high temperature management and feeding strategy) under changing marine environments.

Ingestion of nano/micro plastic particles by the mussel Mytilus coruscus is size dependent.

Plastic particles are thought to accumulate in aquatic organisms and cause potential physiological effects. The uneven sizes of plastic particles may affect the ingestion by marine filter feeding bivalves and may lead to differential further physiological effects. To tackle this scientific question, we investigated the size dependent ingestion and dynamic accumulation of nano/micro plastic particles with different diameters (0.07, 0.5, 5, 10 and 100 µm) in the thick shell mussel Mytilus coruscus. The accumulation of particles in gill, digestive tract and mantle of mussels was measured after 3, 15, 87 h exposure and following 87 h depuration. The results showed that particle ingestion was negatively size dependant and positively related to time in digestive tract. In mantle, particles accumulated over the depuration time with a delay, indicating the translocation of particles. Moreover, our results showed that gill was not a target tissue for steady particle accumulation but the digestive tract was. This study showed size dependent and dynamic ingestion of nano/micro particles in mussels which are one of the main marine organisms for accumulating microplastics.