In situ measurement of survival and growth of Lophelia pertusa in the northern Gulf of Mexico

Growth rates of Lophelia pertusa were directly measured using stained coral fragments, deployed in situ for more than 1 yr on small transplant units. Survival of the fragments was quantified after deployment (1) within dense coral areas (high coral) and (2) on exposed bare substrate (no coral) in the same area as the reef. Samples of L. pertusa were collected from Viosca Knoll (430 to 520 m depth), northern Gulf of Mexico in July 2004, stained with Alizarin red, photographed and secured onto transplant units for redeployment. The transplants were recovered in September 2005 and percent polyp survival, growth (mm of linear extension) and number of new polyps were recorded. Survival was high (>90%) for all transplant units and the average linear growth rate observed (similar to 3.77 and 2.44 mm yr(-1) for high coral and no coral sites, respectively) fell at the lower end of the published range for this species. There was no significant difference between any of the survival or growth parameters between sites. The stain bands on the coral sections illustrated double growth centers, which introduces an additional level of complexity when assessing growth through lateral banding patterns. Growth rates of L pertusa have been inferred using various direct and indirect methods; however, this study represents the first direct measurement of in Situ growth for this species.