An Investigation into the Impact of Ocean Acidification on the Recruitment, Respiration, Photosynthesis and Calcification of Coralline Algae.

Francesca Alice Hale

Ocean acidification caused by anthropogenic emissions poses a threat to many marine organisms. Coralline algae are thought to be one of the most vulnerable groups to decreasing seawater pH, due to the composition of their calcium carbonate skeletons. This study investigated the effect of ocean acidification on the rates of respiration, photosynthesis and calcification on two species of coralline algae as well as the ability of coralline algae to recruit under acidified conditions. Four pH treatments, (ambient, and three more acidic levels) were used in a block-type experimental design. No significant effect of pH was found for either species on any of the rates investigated, but there were some trends in the calcification rates indicating lower rates in the dark at the lowest pH treatment. The total area new recruits were able to cover was significantly lower at the lowest pH treatment than the two intermediate treatments. These results suggest that ocean acidification may have more of an impact on early life stages of coralline algae and although adults may appear tolerant to ocean acidification, it is important to understand the impacts of low pH on their offspring, throughout their development.