Distribution And Photobiology Ofsiderastrea Radians And Thalassiarntestudinum In Florida Bay, Florida, Usa

摘要

The distribution of Siderastrea radians (Pallas) Blainville and photophysiology of its symbiont in Florida Bay, USA, were examined during annual macrophyte surveys in spring 2006 and 2007. Siderastrea radians was present in five of the 11 sampled basins in areas with little sediment and low abundance of the seagrass Ihalassia testudinum Banks ex Konig. The five basins are located along a northeast-to-southwest transect that also represents a salinity gradient from inshore, predominantly estuarine conditions adjacent to the Everglades, to offshore near-marine salinities adjacent to the Gulf of Mexico. Colony abundance was highest in the basins at the extremes of this physical range, presumably due to higher potential for larval recruitment from external reef source populations. Effective quantum yields, measured in situ by PAM fluorometry, were significantly correlated between S. radians and the dominant seagrass T. testudinum among all five basins where the two species co-occurred, albeit with a 40% reduction in mean yields of S. radians. These findings indicate S. radians may function as an alternative eco-indicator species for regions in Florida Bay where T. testudinum is absent.