Coral Reef Biodiversity in the Face of Climatic Changes

Abstract

Loss of marine biodiversity seems inevitable in the 21st century. In benthic marine systems, survivors will have to acclimatize to seawater constantly increasing in temperature and evolving chemically, while also needing to out-compete new opportunistic neighbors and possibly facing increased predation pressure. Last but not the least, with a metabolism already pushed to its limits, survivors will have to fight against emerging diseases. Recent studies have shown that thermal stresses on coral reef scleractinians (Vega Thurber et al., 2009), sponges (Webster et al., 2008) and coralline algae (Webster et al., 2010a) induce changes from a balanced, functional associated microflora to a pathogen-dominated one, causing disease before the physiological tolerance limits of the hosts are reached. Changes in water chemistry (loss of bioavailable calcium carbonate due to acidification) and other stress factors (temperature, salinity, oxygen, sedimentation, etc., due to the greenhouse effect or to its climatic consequences) will affect biodiversity and community structure, and in the long term induce disaggregation of limestone scaffolds.