Abstract
The changes in global climate, including the observed and predicted changes to ocean chemistry are expected to have significant impacts on the future of coral reefs. A series of laboratory experiments examined the interactive effects of water flow rate, light levels, and decreased pH on the growth of several species of reef cnidarians. Under current water chemistry conditions (pH 8.04), the massive coral species, Montastraea faveolata shows high growth under flow conditions less than 15.7 cm/s. At this flow rate, decreased pH (pH 7.88) had no significant impact on the growth of this species. Under both water chemistry conditions, colonies showed decreased growth under low light conditions. The branching species, Pocillopora damicornis, showed significant decreases in growth, particularly a decreased ability to add complexity under low pH conditions (pH 7.87). The massive, azooxanthellate coral, Tubastraea coccinea showed little growth response to decreased pH. This indicates that branching species are more likely to show negative responses and decreased growth as oceanic pH continues to fall. Aiptasia pallida anemones were smaller and denser in terms of protein make-up under low pH (pH 7.85) conditions than under current water chemistry (pH 8.04) conditions. The information presented here could be used in future conservation efforts.