Effects of ocean acidification on coralline algae in the context of multiple drivers of climate changeBiology & Ecophysiology

Christopher Cornwall^{1, 2}, Denisa Berbece^{1, 2}, Holly Koch¹, Erik Krieger³

¹Te Herenga Waka Victoria University of Wellington, New Zealand, ²University of Otago, New Zealand, ³King Abdullah University of Science and Technology, Saudi Arabia

Multiple climate change drivers are manifesting in our oceans simultaneously. Ocean acidification reduces the calcification rates of calcareous taxa and alters dissolved inorganic carbon uptake for photosynthesis in all seaweeds, while ocean warming and increasing frequencies, durations and intensities of marine heatwaves cause physiological stress to many marine species. Ocean acidification can be classified as a multiple driver, with changes in HCO3-, H+, CO2 and possibly CO32- all having physiological ramifications for various seaweed species. I will give an overview of insights gained over the last four years of manipulation experiments with coralline algae in Aotearoa New Zealand, drawing on examples from other temperate regions where possible. Here I focus on the identification of generalities in their physiological responses to ocean acidification in the context of changes in other environmental drivers.