Effects of feed satiation on energy metabolism in the mussel Mytilus coruscus under ocean acidification and warming and possible hormonal regulation

Abstract

Over the past several decades, it is thought that human activities have been a significant factor in bringing about increased atmospheric carbon dioxide concentrations, thereby contributing to elevated ocean acidification and warming. Due to their sessile nature, marine bivalves are considered to be particularly vulnerable to such alterations of the marine environment. Much remains unknown concerning the underlying strategies by which marine bivalves modify energy demand under such conditions. In addition, whether feed availability has an effect and plays a role in this respect is unclear. In the present study, we attempted to address these questions by investigating metabolism and energy pathways in the mussel Mytilus coruscus. Warming, acidification, and food shortage have significantly impacted metabolism, energy pathways, circadian rhythms, hormone activity, and gene expression related to metabolism and circadian rhythms in mussels, leading to energy limitations. Thermal tolerance data indicate that M. coruscus has substantial adaptive capacity to environmental stressors. Bivalves can regulate energy production pathways by modulating serotonin and triiodothyronine hormones, and adequate food availability enhances this regulation. Our findings suggest that ocean warming and acidification synergistically alter energy metabolism in mussels, causing energy limitations, and that food availability is crucial for maintaining mussel condition.