The analysis by Maina et al. is a nice example of applied modeling which could result in real conservation gains for coral reef ecosystems. Models of this type are a critical component for planning future marine protected areas (MPAs) in an age of growing environmental uncertainty. Modeling climate change variables at various spatial and temporal scales is essential if we hope to create future MPAs where corals have the best possible chance of survival. While coral bleaching is a serious and immediate threat to corals globally, the authors did not incorporate one of the most ominous environmental threats coral reefs face in a changing climate. The omitted threat is ocean acidification, a process whereby the oceans are absorbing anthropogenic CO2 at an unprecedented rate, which reduces the pH of seawater and most importantly the concentration of carbonate ions in seawater. Carbonate ions are the building blocks for calcification and as oceans acidify, corals are expected to build weaker skeletons (a process similar to osteoporosis in humans) and/or grow at slower rates. The threat to coral reefs from ocean acidification has been the subject of numerous peer reviewed research papers and books spanning more than 15 years ([Smith and Buddemeier, 1992], [Gattuso et al., 1998], [Kleypas et al., 1999], [Kleypas et al., 2001], [Kleypas et al., 2006], [Langdon et al., 2000], [Langdon et al., 2003], Leclercq et al., 2000 N. Leclercq, J.-P. Gattuso and J. Jaubert, CO2 partial pressure controls the calcification rate of a coral community, Global Change Biol. 6 (2000), pp. 329–334. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (54)[Leclercq et al., 2000], [Leclercq et al., 2002], [Marubini et al., 2001], [Marubini et al., 2003], [Guinotte et al., 2003], [Buddemeier et al., 2004], [Langdon and Atkinson, 2005], [Hoegh-Guldberg et al., 2007] and [Veron, 2008], and others). Slower growth rates and fragile skeletons are not conducive to reef growth and some estimates predict erosion will outpace net reef accretion as early as 2050 in some regions of the world’s oceans (Hoegh-Guldberg et al., 2007).
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Guinotte J. M. & Buddemeier R. W., 2008. Comment on “Modelling susceptibility of coral reefs to environmental stress-using remote sensing data and GIS models”, authors Maina, Venus, McClanahan, and Ateweberhan. Ecological Modelling 218(3-4):400-402. Article (subscription required).
