Projecting Coral Reef Futures Under Global Warming and Ocean Acidification

Abstract

Many physiological responses in present-day coral reefs to climate change are interpreted as consistent with the imminent disappearance of modern reefs globally because of annual mass bleaching events, carbonate dissolution, and insufficient time for substantial evolutionary responses. Emerging evidence for variability in the coral calcification response to acidification, geographical variation in bleaching susceptibility and recovery, responses to past climate change, and potential rates of adaptation to rapid warming supports an alternative scenario in which reef degradation occurs with greater temporal and spatial heterogeneity than current projections suggest. Reducing uncertainty in projecting coral reef futures requires improved understanding of past responses to rapid climate change; physiological responses to interacting factors, such as temperature, acidification, and nutrients; and the costs and constraints imposed by acclimation and adaptation.

Effects of diurnally oscillatingpCO2on the calcification and survival of coral recruits

“…Despite the growing literature addressing the response of corals to OA [7,8,12], to our knowledge, only one previous study has employed a measure of fitness as a response variable for corals exposed to high pCO 2 [34]; this earlier work demonstrated the survivorship of Porites panamensis larvae was unaffected by 861 -950 matm pCO 2 . Additionally, the impacts on corals of diurnally oscillating pCO 2 with a natural-phase relationship-as occurs routinely on shallow reefs [20 -23]-has not previously been considered.…”

“…Some of the most striking examples of these effects are exhibited by scleractinian corals [7], yet despite the negative implications of these trends for coral reef ecosystems [8], progress has been slow in elucidating the mechanisms underlying the response of corals to high pCO 2 [9][10][11].…”

Pacific-wide contrast highlights resistance of reef calcifiers to ocean acidification

“…However, recent studies now indicate more nuanced responses to OA for select reef calcifiers [9], with a compilation of laboratory studies of corals suggesting that coral calcification will decline approximately 10-20% (rather than ceasing) for a doubling of present-day partial pressure of CO 2 (pCO 2 ) [10]. More subtle responses to OA have also been shown in recent studies reporting signs of resistance to OA for some reef calcifiers [11][12][13].…”

Calcareous green alga H alimeda tolerates ocean acidification conditions at tropical carbon dioxide seeps

“…It is becoming apparent that tropical coral reefs in particular are facing major ecological changes in the upcoming decades (Pandolfi et al 2011). An emerging paradigm suggests that marine organisms will be negatively affected by OA.…”