Meeting Abstract

64.1  Monday, Jan. 6 08:00  Changing environmental variability in a changing climate: the effects of thermal variation on growth rates and energy flow through an intertidal community MILLER, LP*; ALLEN, BJ; DENNY, MW; Hopkins Marine Station, Stanford University; California State University, Long Beach; Hopkins Marine Station, Stanford University millerlp@gmail.com

Increasing average air and sea temperatures have the potential to drive great changes in populations and communities, but global circulation models also predict substantial changes in temperature variability through time. Unfortunately, our current knowledge about the effects of increasing climatic variation on natural ecosystems is generally quite poor. In highly productive rocky intertidal communities, increasing temperature variability, particularly during low tide, has the potential to strongly impact the survival and productivity of many species at different trophic levels, particularly those already living near their thermal tolerance limits. At our central California field site, we implemented a set of field experiments to manipulate low tide temperature variability for a suite of microalgal and herbivorous grazing limpet species. By manipulating the thermal conductance between experimental plates and the rock surface, we altered the daily temperature range of a microhabitat without significantly affecting mean temperatures. High thermal variability treatments experienced more frequent and more intense heat stress events, similar to what is predicted in global circulation models. Coupled with intensive sampling of microhabitat thermal conditions and estimates of energetic costs for limpets under varying temperature conditions, we show that an increasing frequency of high temperature events, even without increases in average temperature, could negatively impact the growth of microalgae and limpet species, but that effects also differ with species identity.