Coral Mortality in the Gulf of Mannar, Southeastern India, Due to Bleaching Caused by Elevated Sea Temperature in 2016

Abstract

Intensive underwater surveys have been conducted to assess the extent of coral bleaching and subsequent mortality in the Gulf of Mannar between March and October 2016. The extent of bleaching was 23.92%  10.55% during the period between March and June 2016, and the live coral cover was drastically reduced to 22.69  9.07% during October 2016 with a mortality of 16.17  8.46%. Fast-growing coral forms, including the genera Acropora, Montipora and Pocillopora were most affected, not only by bleaching but also by severe mortality. Boulders, including the genera Porites, Favia and Favites were found to be resistant to bleaching. During the bleaching period, water temperature was between 31.2C and 32.6C. The current bleaching is in alignment with the third global coral bleaching event which occurred between 2014 and 2017. Management interventions, including protection and rehabilitation using the native resistant coral species will not only help in the recovery process, but also increase the live coral cover.

Opportunistic spongivore fishes in a reef of Gulf of Mannar, India

“…Coral cover in GoM has been reported as 22.69% after the 2016 bleaching event (Edward et al 2018), but the coral cover at Pattinamaruthoor patch reef was more than 55% as assessed in this study. It could be due to the dominance of fast growing coral genera such as Acropora and Montipora.…”

“…Rapid growth rate of space competitors such as macroalgae and sponges on live corals lead to coral degradation especially after bleaching events. Recent works in GoM report the severity of space competition between corals and other organisms (Raj et al 2006(Raj et al , 2018a(Raj et al , 2019(Raj et al , 2021aMachendiranathan et al 2016;Edward et al 2018). Degradation of coral reefs in GoM would directly mean the degradation of dependant livelihood.…”

“…Corals in GoM have been damaged significantly by various natural and human-induced threats (Edward et al 2008(Edward et al , 2012Samuel et al 2012). The corals of GoM have suffered massive mortalities on account of the coral bleaching incidences in 2010 and 2016 driven by climate change (Edward et al 2012(Edward et al , 2018Raj et al 2021a). Recent studies report that climate-stressed corals of GoM have taken advantage by space competing organisms such as macroalgae and sponges (Raj et al 2006(Raj et al , 2018a(Raj et al , 2019(Raj et al , 2021aMachendiranathan et al 2016;Edward et al 2018).…”

“…The corals of GoM have suffered massive mortalities on account of the coral bleaching incidences in 2010 and 2016 driven by climate change (Edward et al 2012(Edward et al , 2018Raj et al 2021a). Recent studies report that climate-stressed corals of GoM have taken advantage by space competing organisms such as macroalgae and sponges (Raj et al 2006(Raj et al , 2018a(Raj et al , 2019(Raj et al , 2021aMachendiranathan et al 2016;Edward et al 2018). Sponges in particular have been reported to cause significant damage to the recovering corals of GoM (Raj et al 2018a(Raj et al , 2019.…”

Incursion of killer spongeTerpios hoshinotaon the coral reefs of Lakshadweep archipelago

“…Moreover, reports of turf algae being a dominant component in the atolls 17 might indicate towards a faster transition. Globally Elevated SST is a major threat to coral reefs 19 , and the reefs of India 20,21,22 including the atolls 23 are no different. With reports indicating that elevated SST has already depleted the coral ecosystem of Lakshadweep which was evident during 1998 17 , 2010 23 and 2016 19 mass bleaching events, it can provide an opportunity for sponges to invade 24 .…”