Meeting Abstract
P3.45 Sunday, Jan. 6 Do heating rates matter for measurement of cardiac output in intertidal mussels? ZIPPAY, M.L.*; BURNETT, N.P.; HELMUTH, B.; University of South Carolina, Biological Sciences and Environmental Sustainability Program; University of California, Berkeley, Department of Integrative Biology; Northeastern University Marine Science Center zippay@environ.sc.edu
Most controlled laboratory experiments examining the effects of temperature on the performance of intertidal organisms rely on air temperature as a proxy for body temperature, or conduct measurements in water to simulate aerial temperatures. In such experiments, body temperatures can deviate from air temperatures inside the experimental chamber based on heating method, organism size and behavior, and heating rate. Q10 and other metabolic rate calculations, such as Arrhenius temperature, tend to be based on changes in ambient air temperature and therefore may not correspond to the true changes in the body temperature of the organism. Understanding the metabolic responses of organisms to changes in body temperature provides a better index for comparing climate effects within and among species, especially among intertidal organisms, which experience large fluctuations in body temperature that commonly approach their upper lethal limits. In the present study, we used a non-invasive sensor to measure the cardiac responses of a rocky intertidal bivalve Mytilus californianus and a salt marsh bivalve Geukensia demissa to elevated body temperatures. These intertidal bivalves experience a wide spectrum of heating rates during every low tide. Our preliminary data, suggest that rates of heating have differential effects on cardiac output of experimental organisms of different sizes and species. Since many physiological assessments often overlook realistic heating rates, this index of thermal stress could be more important than previously thought (i.e. magnitude and duration) and should be considered when investigating future climate change impacts on intertidal organisms.
