Paleoecology and paleoenvironment of an unusually depauperate Pleistocene coral reef of the Aramda Reef Member, Gujarat, Western India

Coral reefs are highly diverse ecosystems comprising a wide range of organisms that build and inhabit them. Understanding the ecological complexity and evolutionary dynamics of these ecosystems necessitates data of both the reef-building and reef-associated fauna. However, a comprehensive understanding of the structure and composition of coral reefs and associated fauna across space and time remains limited, even from the highly diverse Western Indo-Pacific (WIP) biogeographic region. In this study, we reconstruct the paleoecology and paleoenvironment of a Late Pleistocene tropical coral reef, exposed along western India of the WIP Realm, by analyzing the reef’s geomorphological architecture and paleoecology of the reef-building corals and associated fauna. Our results reveal that the Indian fossil reef was a fringing reef, dominated primarily by non-acroporid, massive, and encrusting merulinid corals, and lacked vertical and/or ecological succession, unlike other Pleistocene reefal ecosystems globally. The ARM reef was spatially patchy and was short-lived (i.e., ~ 200–1000 years) which led to a depauperate faunal assemblage compared to coeval coral reefs that spanned longer times. Reefal diversity was also constrained as the reef developed under a high-energy and low-to-moderate detritus setting. We finally estimate the regional sea level fluctuations, using various lithological, faunal, and archaeological proxies, and infer that the lowstand associated with the Last Glacial Maximum at ~ 20 kyr contributed to the reef's short-lived nature and eventual demise.