Evaluation of coralline algal diversity from the Serravallian carbonate sediments of Little Andaman Island (Hut Bay), India

Palaeodiversity of coralline algae has been studied from the Serravallian carbonate sediments outcropping in the Little Andaman Island (Hut Bay). Little Andaman is the southernmost island of the Andaman Group, situated between South Andaman and Car Nicobar. The algae described in the present case study have been recovered from the fossiliferous limestone samples of Hut Bay Limestone Quarry belonging to the Long Formation and examined by means of thin-section microscopic analysis. Shannon–Weaver index has been applied for measuring the degree of algal diversity. A total of nine coralline algal genera, including three geniculate and six non-geniculate algae have been reported with the statistical data indicating a fairly conducive benthic environment. This is supported by the presence of a considerable number of growth-forms characterizing the concerned coralline algal taxa. The limited occurrence of taphonomic signatures observed in the algal thalli further strengthens the interpretation of a conducive environment. Greater diversity and abundance of benthic foraminifera present in close proximity to the coralline algae have resulted in possible failure of the latter in attaining higher levels of diverse assemblages. Factors of mild environmental disturbances, hydrodynamic conditions, and substrate availability also supposedly played a major role in determining the diversity of coralline algae.