Nicholas A. J. Graham from School of Marine Science & Technology, Newcastle University, Newcastle-upon-Tyne, United Kingdom and his other associates from different institutes studying the impact of increasing temperature on coral reef and its dependent component have documented its effect on the coral lives and have sent an alert to the regional authority to take further steps to curb the degrading ecosystem.
As they say in a published paper, “Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the associated effects on fish have not.”
Sensing this they responded to recent and repeated calls to assess the importance of local management in conserving coral reefs in the context of global climate change. According to them, “this information is important, as coral reef fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions and providing crucial ecosystem services to human societies in tropical countries”.
Their assessment of the impacts of the 1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes have spanned 7 countries, 66 sites and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis they have shown that changes in the size structure, diversity and trophic composition of the reef fish community have followed coral declines.
Although the ocean scale integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales, with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas still support high biomass of fish; however, they had no positive affect on the ecosystem response to large-scale disturbance.
This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should be integrated into existing management frameworks and combined with policies to improve system-wide resilience to climate variation and change.
Change in hard coral cover across the region between the mid 1990s and 2005 varied geographically. The changes reported represent the combined effects of coral loss in 1998 and any subsequent recovery to 2005. The greatest declines were apparent through the low latitude island states of Maldives, Chagos, and Seychelles. Kenyan and Tanzanian nationally protected sites experienced moderate declines, while Mauritius and Réunion sustained the smallest declines, and coral cover increased in Kenyan and Tanzanian fished sites.