Bleaching and recovery patterns of corals in Palk Bay, India: An indication of bleaching resilient reef

Frequency and severity of coral bleaching events increased in recent years affecting the recovery and resilience of corals. In this study, influence of bleaching and recovery patterns of corals on the resilience potential of Palk Bay reef was assessed over a period of two years 2013 and 2014. Individual coral colonies of five different genera were tagged and monitored for their bleaching and recovery pattern during 2013 and 2014. Variation in the bleaching and recovery response among different coral genera were quantified and compared. Also, sea surface temperature (SST) and photosynthetically active radiation (PAR) were monitored simultaneously and compared. Results showed an increase in the intensity of SST and PAR in 2014 compared to 2013. Correspondingly, the average percentage of severely bleached corals was also high in 2014. Favites and Leptastrea spp. were more sensitive, being the first to bleach. Whereas, Porites spp. exhibited a delayed response to bleaching as the SST rose above 30 ∘C. Cyphastrea spp. and some colonies of Leptastrea spp. were unresponsive to bleaching and remained healthy. The recovery process also varied, as the Favia and Favites spp. recovered under environmental conditions in which the Porites spp. still continued to bleach. Subsequent surveys revealed complete recovery of all coral colonies without any post-bleaching mortality. Results of this study indicated that an increase in the intensity of bleaching conditions did not have any significant impact on the survivability of corals on a reef which is dominated by stress-tolerant coral species. This may enhance the resilience potential of the Palk Bay reef by ensuring the presence of healthy live corals, which in turn contributes to the functional diversity of the reef and its resistance to the future disturbances.