The Effect of Feeding on Growth of the Temperate Coral Oculina arbuscula (2014)
Undergraduate: Hannah Aichelman
Faculty Advisor: Karl Castillo
Department: Environmental Science
Rising atmospheric carbon dioxide concentrations will continue to cause mean global surface seawaters to increase in temperature and decrease in pH. Although previous experimental studies indicate that ocean warming and ocean acidification will continue to compromise coral calcification, uncertainty remains as to the effect of feeding on the skeletal growth response of corals. Indeed, the existing literature reports variable levels of feeding in laboratory-based experiments with few studies accounting for the ambient zooplankton concentration that corals experience in their natural environment. The lack of a standardized feeding metric across these experiments decreases the applicability of the findings and hinders efforts to better understand the calcification response of corals to climate change. The temperate scleractinian coral Oculina arbuscula is found throughout the coast of the mid-Atlantic and southeast United States. This species is considered facultatively symbiotic, existing in a range of forms from zooxanthellate to azooxanthellate. Therefore, O. arbuscula, as with all scleractinian corals, depends not only on photosynthesis of the algal symbiont, but also on heterotrophic feeding which provides nitrogen, phosphorus, and other nutrients not supplied by photosynthesis. Here, six colonies of O. arbuscula were collected at Radio Island in Beaufort, NC and transported to the University of North Carolina at Chapel Hill. Currently underway is a laboratory-based experiment in which four feeding treatments (zero, low, ambient and high) are used to quantify the effects of feeding newly hatched Artemia sp. nauplii on the skeletal growth of O. arbuscula at the current mean annual temperature of 20°C and at the predicted end-of-century summer temperature of 28°C using a buoyant weight method. Ambient zooplankton concentration for this region was determined using a value reported by Fulton (1984). The results