Meeting Abstract
A key challenge for ecological physiologists is to determine how long and short-term environmental variation will influence organisms in current and future climate scenarios. Bioenergetic models, such as Scope for Growth (SFG), are used to integrate variation in food availability and temperature into changes in organismal biomass. These frameworks do not explicitly consider the costs of structural biomaterials, such as those that play a role in attachment, mechanical defense and other traits critical to an organism’s survival. We hypothesized the production of biomaterials may be influenced by the energetic state of the organism. We developed several SFG models using alternative ‘allocation rules’ that describe how energy might be prioritized among maintenance, growth, and biomaterials in congener marine mussels, Mytilus trossulus and Mytilus galloprovincialis. Mussels produce structural biomaterials called byssal threads to anchor themselves to rocky shores. Byssal thread attachment strength varies annually and is influenced by abiotic conditions. We ask, does byssal thread production depend on mussel energetics? We perturbed mussel energetic state by manipulating food availability and temperature in a mesocosm experiment. We evaluated five alternative models (each with different allocation rules) for their ability to predict the relationship between thread production and tissue growth using Akaike Information Criteria (AIC). Two models were well supported by the data: thread production is proportional to 1) all energy available, or 2) maintenance. This study establishes relationships between soft-tissue and structural material fluxes in mussels, and serves as a model system for incorporating structural materials into bioenergetics models.
