Effects of Nutrient Loading, Elevated Temperature, and Ocean Acidification on Crustose Coralline Algae

Abstract

Rising temperatures, ocean acidification, and chronic eutrophication all contribute drastic functional changes to tropical shallow water reef ecosystems. “Business-as-usual” carbon dioxide emission scenarios predict atmospheric concentrations of CO2 will nearly double by the end of this century. The increased absorption of CO2 in ocean surface waters contributes to lower pH and lower carbonate saturation states. This acidification raises concern as to whether marine calcifying organisms could successfully continue to build their skeletons under future conditions. The development of crustose coralline algae (CCA) is a vital component of the coral reef environment that supports the function and growth of the reef ecosystem. CCA provide settlement cues for invertebrate and coral larvae while also acting like cement, holding reef structure together. My research focused on investigating the possible synergistic effects that rising temperatures, ocean acidification, and chronic eutrophication could have on the growth rates of CCA. The experiment was held over 24 days during the summer of 2015, exposing groups of CCA nubbins to a variety of environmental stressors. Overall, no significant effects were observed to have changed the growth rates of CCA, possibly suggesting that these marine calcifiers are capable of acclimating to rapid climate change, at least for short periods of time.