Record of a central Indo-Pacific corallimorph in the Lakshadweep atolls and its competition with the hard corals

Abstract

Coral reefs are disappearing worldwide because of mass bleaching, natural disasters, diseases and anthropogenic stressors.This leaves a large area of unutilised substratum, to which other benthic organisms, like corallimorpharians (CMs),anemones and macroalgae, can move in. In this article, we describe, for the first time, the competition for space betweena CM and the hard corals in Kavaratti Atoll in the Indian Ocean. This is the first reported instance of an invasion of CM inthe entire Lakshadweep Islands. The CM Rhodactis bryoides Haddon and Shackleton, 1893, is identified by morphologicaland molecular analysis. The species has not so far been reported from the western Indian Ocean area. We monitored the rateof invasion for six months to figure out the growth rate of CMs. This area did not have any prominent causative factors forCM outbreaks, such as external disturbances and nutrient enrichment. Yet our study showed that CMs are successful in thecompetition for space. More research needs to be done into the biology of this species, how it interacts with other benthicgroups and how the environment facilitates its spread. Keywords: Bioinvasion, Coral reefs, Corallimorpharia, Phase shift, Rhodactis bryoides