Ocean Acidification Reduces Skeletal Density Of Hardground-Forming High-Latitude Crustose Coralline Algae

Crustose coralline algae (CCA) function as foundation species by creating marine carbonate hardground habitats. High-latitude species may be vulnerable to regional warming and acidification. Here, we report the results of an experiment investigating the impacts of CO2-induced acidification (pCO(2) similar to 350, 490, 890, 3,200 mu atm) and temperature (similar to 6.5 degrees C, 8.5 degrees C, 12.5 degrees C) on the skeletal density of two species of high-latitude CCA: Clathromorphum compactum and Clathromorphum nereostratum (CN). Skeletal density of both species significantly declined with pCO(2). In CN, the density of previously deposited skeleton declined in the highest pCO(2) treatment. This species was also unable to precipitate new skeleton at 12.5 degrees C, suggesting that CN will be particularly sensitive to future warming and acidification. The decline in skeletal density exhibited by both species under future pCO(2) conditions could reduce their skeletal strength, potentially rendering them more vulnerable to disturbance, and impairing their production of critical habitat in high-latitude systems.