Identifying the Influence of Ocean Acidification on the Calcification Rates of Different Functional Groups on Coral Reefs

Purpose - Coral reefs are complex adaptive ecosystems that rely on the biogenic construction of calcium carbonate structure by calcifying organisms. The rate of net ecosystem calcification (NEC) is ultimately determined by the different types of benthic calcifiers present, including corals, calcifying algae, foraminifera, and other calcifying taxa. The goal of this research project is to compare how the calcification of different species (coral, crustose coralline algae, and Halimeda) is influenced by ocean acidification. Method – The organisms used in this study (P. astreoides, CCA, and Halimeda) were collected in the Florida Keys and were maintained at the Mote Marine Laboratory, Elizabeth Moore International Center for Coral Reef Research and Restoration (IC2R3). Each organism was isolated for two hours in an incubation chamber filled with either ambient water (pH ~8.0) or acidified water (pH ~7.7) and placed in a water bath/aquarium tank to maintain a constant temperature throughout the incubation. Calcification rates of each organism were determined using the alkalinity anomaly method. This technique accurately estimates calcification rates while only requiring one measurement: total alkalinity. Results – The organisms incubated in acidified water have lower rates of calcification than the organisms incubated in ambient water. Additionally, light incubations have higher calcification rates than dark incubations. Conclusion - The alkalinity anomaly method is a significantly less invasive technique for determining calcification rates. It eliminates coring the organisms which can leave them more vulnerable to disease and predation. More experiments like this will help future scientists in identifying how we can combat ocean acidification and its direct influence on calcification