PARENT SESSION
Symposium 23: Body Size, Biophysics and Biological Stoichiometry: From Individual Function to Ecosystem Structure
Organized by: J Sabo and B Enquist
Friday, August 8. 8:30 AM to 12:00 PM, SITCC Chatham Ballroom B.
Living on the edge: Biophysical and biomechanical consequences of body size to intertidal invertebrates.
Helmuth, Brian*,1, Jost, Jennifer1, 1 University of South Carolina, Columbia, SC
ABSTRACT- Coastal environments are among the most physically challenging ecosystems on earth. Forces exerted by crashing waves regularly exceed those imparted by hurricane force winds on land, and fluctuations in body temperature of 20°C or more are not at all uncommon. While researchers have made significant inroads into understanding the consequences of body size and morphology to the frequency of dislodgement and breakage of intertidal invertebrates and algae, only recently have biophysical models been used to unravel similar impacts of body size and shape on intertidal heat flux. We therefore have only a rudimentary understanding of what spatial and temporal patterns of body temperature are in nature. Compared to work in terrestrial habitats, the exploration of how biomechanical and biophysical responses of individuals to environmental forcing scales to the level of populations and communities is still relatively unexplored in intertidal environments. Nonetheless, the unique and often severe environmental conditions in this habitat provide important lessons for how the consequences of body size and morphology change in counterintuitive and often highly nonlinear ways in both space and time. We present a series of models and measurements which explore the consequences of body size to thermal stress of intertidal mussels (Mytilus spp. and Geukensia demissa). Size has little effect on mussel temperature in soft sediment environments, due to the coupling between organism and sediment temperatures. In contrast, the body temperatures of rocky intertidal mussels vary markedly with size, but the relative effect changes with the duration and timing of exposure at low tide. As a result, the impact of body size likely varies with intertidal zonation height and with latitude. Similarly, latitudinal-scale patterns of body temperatures (and hence levels of thermal stress) are species-dependent, and we discuss the implications of these differences to Environmental Stress Models.
Key words: temperature, Intertidal, size, mussel