2000 Volume 55 Issue 2 Pages 53-61
Abstract: We studied the community structure of mobile epifauna on the seagrass Enhalus acoroides at a subtidal seagrass bed in Thailand to examine whether the abundance and community structure of the epifauna are affected by (1) the position within the seagrass patches, and (2) the seagrass patch sizes. We collected mobile epiphytic animals on E. acoroides at the center and the periphery of large (>3.6m2 in area) patches, and from small (<1.1m2) patches. The most dominant animal was a grass shrimp, Latreutes sp., followed by several species of gammarid amphipods, a polychaete and gastropods. Species richness, the total number of individuals and the number of the eight major species did not differ significantly between the center and periphery of the large patches. The density of Latreutes sp. was significantly smaller in the large patches than the small patches. Turbellaria spp. were also less common in the large pathces. In contrast, the density of a chaetognath (Spadellidae sp.) tended to be higher in the large patches. Species richness, total animal density, and the densities of other dominant animals did not differ significantly between large and small patches. These findings demonstrate that the position within E. acoroides patches has only a minor effect on the abundance and diversity of the epifaunal community, whereas the size of patches has a larger effect on the epifauna. It was also suggested that the response of mobile epiphytic animals to seagrass patch structure is scale-and species-specific.
