Pteropod occurrence in relation to aragonite compensation depth - An example from Carlsberg Ridge(Indian Ocean)

Morphological characteristics of twenty pteropod species were examined to u nderstand the ecological significance of pteropods of the Carlsberg Ridge i n Indian Ocean, Faunal assemblage indicates a warm water tropical environme nt which is associated with well-known centre of winnowing action. The char acteristic pteropod assemblage such as Cuvierina columnella, Cavolinia infl exa, Diacria trispinosa Cavolinia globulosa, Limacina inflata and Creseis v irgula suggests a closer tie with the upwelling off Somali coast. The natur e of aragonite compensation depth (ACD) and its variation due to the change of oceanographic condition was reflected by the pteropod. These pteropods occur below the expected bathymetric level of aragonite compensation depth as per the available literature. This study reveals the possible hydrotherm al activity in the area which is also supported by the brown to dark brown colouration of the biota within the pelagic sediments.