BIO Seminar: Brian Tsukimura

Transduction of physiological stress through species interactions: Temperature variations effects on reproduction

Speaker: Professor Brian Tsukimura, California State University, Fresno, CA

Host: Associate Professor emeritus Jens T. Høeg, Marine Biology Section

Microclimatic variation has emerged as an important driver of many ecological and evolutionary processes. Fine-scale thermal variation was measured in a common, species-rich, but rarely studied habitat with respect to temperature: the airspaces under rocks on intertidal zone boulder shores. We investigated effects of thermal variation using physiological, behavioral, and demographic data on the porcelain crab Petrolisthes cinctipes. Demographic measurements showed clear body size trends, with large crabs underrepresented in the high intertidal zone. Size-dependent and temperature-dependent aerobic metabolism was calculated for P. cinctipes in the intertidal zone based on our observed temperature distributions and found that metabolic expenditure for small crabs is similar between the high and low intertidal zones, but that large crabs should expend less energy in the high intertidal zone due to depressed aerobic metabolism in air. We also measured size-dependent heat tolerance and behavioral heat avoidance and found that large crabs are more heat sensitive. Thermal stress may force redistribution into cooler environments, which may threaten the fitness of its congener, P. manimaculus, through decreased reproductive output (yolk protein production), measured by ELISA. Increased densities and thermal stress increased vitellin reactive material in P. manimaculus. These data suggest that the relocation of P. cinctipes into the lower intertidal can cause interspecific species interactions that are stressful for P. manimaculus at high densities, leading to resorption of oocytes. Interactions between fine-scale temperature variation and size-dependent thermal biology can have important consequences for the ecology of species, and is likely to influence how populations respond to changing conditions.