The energetic cost of byssus production in Mytilus trossulus

Abstract

Many stress factors affect energy budgets of species in the intertidal zone Specifically, mussels must distribute energy between processes such as attachment, shell growth, metabolism, and reproduction, all of which may be influenced not only by seasonality, but also by anthropogenic stressors. Understanding patterns of energy distribution between biologic processes is critical when deriving energy budgets of intertidal organisms. In the present study, we investigated the energetic cost of byssus production for the intertidal mussel Mytilus trossulus. Methods were established and administered for a four-week period, which involved exposing collected mussels to one of three, triplicate, treatments respectively. Treatments included: “Never” removing byssus, “Weekly” byssus removal, and “Daily” byssus removal. Using statistical analyses, changes in physical measurements (ie. length, width, and height), gonadosomatic index, and condition index were assessed. We identified a low amount of byssus production for mussels in the “Never” treatment, which corresponded to a lesser percent change in length (shell growth) in comparison to the other treatments. Therefore mussels may shift their energetics from producing longer shells and tissue growth toward applying a greater amount of energy in byssus production. Combined with modeling predictions, this information will be useful for aquaculture practices as well as understanding physical changes mussels undergo in response to stressors that impact byssus production.