Effects of pH variability on the intertidal isopod, Paradella dianae

Ecological and evolutionary effects of anthropogenic climate change are influenced by the response of individual organisms and populations to environmental variability. Environmental conditions are predicted to become more variable with global climate change and oceans will become more acidic as increasing amounts of atmospheric CO 2 are dissolved in seawater. Species such as the isopod Paradella dianae living in the intertidal are naturally subjected to large environmental variation and may therefore have high acclimation potential to increased acidity and more pronounced pH fluctuations. Here, we use P. dianae to experimentally test whether organisms that are naturally exposed to variable environmental conditions can withstand elevated pH fluctuations. We observed physiological and behavioral differences between animals under stable, low pH conditions and fluctuating, low pH levels. Fluctuating pH conditions influenced survival, oxygen consumption, harassment response, and swimming speed of isopods differently relative to stable pH conditions, suggesting that variable environments can produce different effects than constant environments.