Spatial Preference of Coral Associated Brachyuran Crabs in Gulf of Mannar Marine Biosphere Reserve

Brachyuran crabs associated with the head forming coral Pocillopora spp were accessed for their spatial preference in the islands of Gulf of Mannar Marine Biosphere Reserve (GoMMBR). The inter-branch volume of the corals is positively correlated with the number of associated crabs. The maximum average volume of the coral was observed at Appa Island (516 ml). Comparatively more species diversity and abundance of brachyuran were observed in Mandapam group of islands where maximum number of Pocillopora spp (19 no) was examined for the occurrence of these crabs. Very less coral colonies along with meager cryptofaunal associates were observed in Tuticorin group of islands. This probably indicates the deteriorating status of the coral health. Various natural as well as human disturbances enhanced the decrease in coral cover along with its crab associates.