Emergence of coral rubble islet near Manoli Island, Gulf of Mannar, India

Abstract

Coral reefs of the Gulf of Mannar region, India, are damaged severely by bleaching events, anthropogenic stressors, coral diseases, and invasive species. The fate of dead corals has not been investigated in this region. In this study, dead corals forming a coral rubble islet was identified about 800 m away from the southeast of Manoliputti Island, Gulf of Mannar. The 50 m-long rubble islet consisted mainly of dead Acroporidae and Faviidae corals. Field observations indicate that the convergence of waves from various directions around the coral rubble islet may be a primary factor in its formation. Current velocity and wind patterns data from satellite support that the collision between wind and current would facilitate the formation of a coral rubble islet. Further studies are required to understand the long-term influence of extreme waves, currents, and longshore drifts on this coral rubble islet's accretion, shape, and shift. The study infers that the instability of the seafloor topography, combined with the vulnerability of Acroporidae and Faviidae corals to hydrodynamic forces, may have led to the substantial generation and accumulation of coral fragments over the past two decades. Thus, further studies on the sediment texture of reef flats and conservation and restoration of these corals are needed urgently to protect coral reefs in the Gulf of Mannar.