Meeting Abstract
21.4 Saturday, Jan. 4 14:15 Physiological responses of the porcelain crab Petrolisthes cinctipes to simultaneous exposure to increased variability of pCO2, temperature and emersion PAGANINI, A*; MILLER, NA; STILLMAN, JH; San Francisco State University; San Francisco State University; University of California Berkeley paganini@sfsu.edu
Intertidal zone organisms experience daily, dramatic, fluctuations in temperature and pH. These fluctuations are expected to increase along the California coast under future climate scenarios. How intertidal organisms respond to variability in temperature and pH has not been previously examined, even though an accurate understanding of how coastal organisms will respond to ocean warming and acidification must include consideration of realistic current and future levels of habitat variability. We investigated performance of the porcelain crab, Petrolisthes cinctipes, under interactive conditions of variation in temperature and pH. Adult P. cinctipes were exposed to three temperatures during a simulated daytime low tide (11°C, spikes to 25°C or 30°C), or were held submerged at 11°C. At night the crabs in each treatment were exposed to three pH levels: constant pH (8.1), or pH spikes to 7.6, or 7.15. Following two weeks of acclimation, we measured respiration rates at 11°C and 18°C and upper thermal limits of cardiac performance (CTmax). Metabolic depression was observed in crabs that experienced aerial daily heat spikes, and the depression was stronger in low pH acclimated individuals when measured at 18°C. CTmax was elevated with acclimation temperature, and the elevation was higher under low pH acclimation, suggesting elevated basal maintenance costs. Our results indicate that there are interactive effects of pH and temperature variability on the temperature sensitivity and thermal limits of these intertidal zone crabs, and that the combination of low pH with elevated temperature causes a metabolic state that is likely not ecologically sustainable for these crabs.
