Benthic communities of mesophotic coral ecosystem off Puducherry, east coast of India

Abstract

The shallow coral reef ecosystems along the Indian coast are being threatened by anthropogenic global ocean warming and increased frequency of coral bleaching in the recent past. Identification and conservation of deeper reef habitats are essential as they serve as a source of larvae and livestock to replenish the shallow reef habitats. Information on the location and spatial extent of the mesophotic coral ecosystems (MCEs) and their biodiversity is poorly known in the continental shelf of the east coast of India. In this study, we have documented the species diversity of MCEs at a depth of 30–40 m off Puducherry along the east coast of India. In total, 12 species of corals, including 5 black corals and 16 octocorals, 4 species of sponges and 31 species of coral-associated benthopelagic fish species were recorded. Subergorgia sp. was the most dominant species of octocorals and found extensively as gorgonian forests. The MCEs reported in this study raise important questions about the origin and connectivity of the coral populations in this region to the other major coral reef ecosystems along the east coast. Understanding the physical processes and hydrographic features around the MCEs, off Puducherry will reveal more information about the distribution and colonization of coral communities and their vulnerability to changes in future.