Oregon Sea Grant

Since the Industrial Revolution, surface ocean pH has declined due to the input of anthropogenically derived carbon dioxide, termed ocean acidification. Examinations of phytoplankton physiology in the face of changing pH are becoming more important as anthropogenically-driven pH decreases in the surface ocean progress (termed ocean acidification). Previous research has shown that phytoplankton response to acidification are highly variable, with some taxa showing improvement and some showing marked deterioration. The ability to maintain homeostasis of intracellular pH is an important adaptation for phytoplankton to continue to thrive under changing conditions; increased energy production has been shown to mitigate the negative effects of acidification.

This dissertation examines the effect of steady state and changing pH environments on the internal pH, esterase activity, and photosynthetic efficiency (the latter two parameters are involved with energy production or utilization) of the marine phytoplankton species, Isochrysis galbana. This work presents new links between cellular energy balance in phytoplankton and environmental pH response, providing valuable data regarding microalgal adaptation to changing ocean pH as ocean acidification progresses.