Preliminary observations on the coral reef communities in Angria Bank, an isolated carbonate bank in the Northern Indian Ocean

Abstract

Submerged carbonate banks are of significant geological and biological importance and relatively little is known about the biodiversity of these deeper and less accessible habitats. This study provides pilot information on the biodiversity and spatial distribution of the coral reef communities in Angria Bank, a submerged carbonate platform along the central west coast of India. An exploratory survey was carried out in January 2014 to document the habitat characteristics and biodiversity of different reef communities across a gradient from the western to the eastern edge of the Angria Bank. The western zone of the bank comprises rocky and coralline substrates in contrast to the eastern zone which is sandy with calcareous deposits. The overall biodiversity includes 16 genera of corals from 10 families and 82 species of reef fish from 26 families, comparatively lower than the other major reef formations in the Indian Ocean. The study sites between the depths of 25-29 m along the eastern edge of the bank host abundant and diverse coral communities. The macroalgae was equally abundant in three of the five dive sites along the east zone reflecting the homogeneous distribution of reef communities in the Angria bank. Other invertebrates including members of the phylum Porifera, Mollusca, Annelida, Arthropoda, Echinodermata, and Cnidaria account for 28 species. Angria Bank signifies a biodiversity hotspot and these remote habitats hold the potential to serve as a refugium for the shallow reef communities for a range of environmental disturbances. Further research to understand the effect of climate-associated stress on the reef communities of Angria bank is vital to evolve a conservation strategy to sustain the biodiversity and resilience of these communities