Chapter 16 - Sea urchins in a high CO2 world: Impacts of climate warming and ocean acidification across life history stages

Abstract

Abstract Uptake of anthropogenic carbon dioxide (CO2) is changing seawater chemistry (ocean acidification) causing a reduction in seawater pH and saturation state (Ω) of the CaCO3 minerals needed for calcification and increased organism hypercapnia (pCO2). Ocean acidification and global warming are having negative impacts on sea urchin larvae and adults. As sea urchins calcify in both these life stages, they have been used as a model group to investigate the impacts of climate change on marine species. In general, near-future acidification has a stunting effect on sea urchin growth as seen in smaller larval and adult skeletons, a change largely caused by energetic constraints and reduced Ω. These effects can be reduced by moderate warming and sufficient food supply. Variation in the response to acidification and/or warming within and between species indicates that there is capacity for phenotypic plasticity to adjust to changing climate. The presence of sea urchin populations at naturally acidified habitats indicates resilience to acidification and highlights species-specific and biological system adaptive strategies to life at low pH. We need to identify the sea urchin species that are resilient and their phenotypic plastic responses or genetic adaptations to climatic stressors to understand the echinoid fauna of the future.