A new paper in Coral Reefs by lead author and SE Climate Science Center funded researcher, Ilsa Kuffner, posts results from a study exploring the systematic measurements of calcification of the coral, Siderastrea siderea. Systematic measurement of coral calcification is important for quantifying potential impacts from ocean acidification, warming, and/or deteriorating water quality on corals. Additionally, ocean acidification is occurring against a background of increases in sea surface temperature (SST) and changes in water quality stemming from land-use change. It is critical to start measuring calcification rates in a systematic way now, particularly at subtropical latitudes where conditions fluctuate seasonally, so that we can understand how changing ocean chemistry and temperatures are affecting calcifying organisms today and predict possible changes in the future.
Coral reefs are degrading on a global scale, and rates of reef-organism calcification are predicted to decline due to ocean warming and acidification. Systematic measurements of calcification over space and time are necessary to detect change resulting from environmental stressors. We established a network of calcification monitoring stations at four managed reefs along the outer Florida Keys Reef Tract (FKRT) from Miami to the Dry Tortugas. Eighty colonies (in two sequential sets of 40) of the reef-building coral, Siderastrea siderea, were transplanted to fixed apparatus that allowed repetitive detachment for buoyant weighing every 6 months. Algalrecruitment tiles were also deployed during each weighing interval to measure net calcification of the crustose coralline algal (CCA) community. Coral-calcification rates were an order of magnitude greater than those of CCA. Rates of coral calcification were seasonal (summer calcification was 53 % greater than winter), and corals in the Dry Tortugas calcified 48 % faster than those at the other three sites. Linear extension rates were also highest in the Dry Tortugas, whereas percent area of the coral skeletons excavated by bioeroding fauna was lowest. The spatial patterns in net coral calcification revealed here correlate well with Holocene reef thickness along the FKRT and, in part, support the ‘‘inimical waters hypothesis’’ proposed by Ginsburg, Hudson, and Shinn almost 50 yrs ago to explain reef development in this region. Due to the homogeneity in coral-calcification rates among the three main Keys sites, we recommend refinement of this hypothesis and suggest that water-quality variables (e.g., carbonate mineral saturation state, dissolved and particulate organic matter, light attenuation) be monitored alongside calcification in future studies. Our results demonstrate that our calcification monitoring network presents a feasible and worthwhile approach to quantifying potential impacts of ocean acidification, warming, and/or deteriorating water quality on the process of calcification.
I. B. Kuffner, T. D. Hickey, J. M. Morrison. Calcification rates of the massive coral Siderastrea siderea and crustose coralline algae along the Florida Keys (USA) outer-reef tract, Coral Reefs, June 8, 2013. DOI 10.1007/s00338-013-1047-8. Published via Open Access through Springer-Verlag.