Occurrence of anemonefishes and host sea anemones in Andaman and Nicobar Islands

Abstract

Among the anemonefishes, 13 species under the genus Amphiprion viz., A. akallopisos, A. bicinctus, A. chrysogaster, A. clarkii, A. ephippium, A. frenatus, A. melanopus, A. ocellaris, A. percula, A. perideraion, A. polymnus, A. sandaracinos and A. sebae, and one species under the genus Premnas viz., P. biaculeatus are reported from 14 selected study sites of the coral reef ecosystem of Andaman and Nicobar Islands during 2000-2005. Field observations reveal that the anemonefish are found in association with 10 host sea anemones viz., Cryptodendrum adhaesivum, Entacmaea quadricolor, Heteractis aurora, H. crispa, H. magnifica, H. malu, Stichodactyla gigantea, S. haddoni, S. mertensii and Macrodactyla doreensis. The fishes and their hosts were observed at a depth of 0.5 to 10 m during low tide in the coral reef areas and slopes. The sea anemones such as C. adhaesivum, H. aurora, H. malu, S. haddoni, M. doreensis are often found buried in the sediment or sand and retracted completely when disturbed whereas, H. magnifica, H. crispa, S. gigantea, S. mertensii and E. quadricolor were usually found attached to hard substrata. Among the fish species, melanistic variation was noticed only in A. ocellaris. The surveys show that the numerical abundance of Amphiprion populations from these groups of islands has diminished. Rapid developmental activities in the islands, turbidity, discharge of waste, increase in water temperature and deposition of sand due to tsunami and destruction of natural habitats due to ecological imbalance in the coastal belt are considered as the probable reasons for decrease in population.