Marine Organisms on Acid: Effects of Ocean Acidification on Marine Biodiversity

Ocean acidification could affect many marine organisms and cause profound ecological shifts. The biological
responses to ocean acidification have been measured across a range of taxa, but this information exists as case
studies and has not been synthesized into meaningful comparisons among functional groups. We used
meta-analytic techniques to explore the variation in biological responses to ocean acidification, and found
significant variation in the sensitivity of marine organisms. Calcifying organisms generally exhibited larger negative
responses than non-calcifying organisms across numerous response variables, with the exception of crustaceans,
which calcify but were not negatively affected. Calcification responses varied significantly among organisms using
different mineral forms of calcium carbonate. Organisms using one of the more soluble forms of calcium carbonate
(high-magnesium calcite) can be more resilient to ocean acidification than less soluble forms (calcite and
aragonite). Additionally, there was variation in the sensitivities of different developmental stages, but this variation
was dependent on the taxonomic group. Our analyses suggest the biological effects of ocean acidification are
generally large and negative, but the variation in sensitivity among organisms has important implications for
ecosystem responses.