title: Bleaching drives collapse in reef carbonate budgets and reef growth potential on southern Maldives reefs.
abstract: Sea-surface temperature (SST) warming events, which are projected to increase in frequency and intensity with climate change, represent major threats to coral reefs. How these events impact reef carbonate budgets, and thus the capacity of reefs to sustain vertical growth under rising sea levels, remains poorly quantified. Here we quantify the magnitude of changes that followed the ENSO-induced SST warming that affected the Indian Ocean region in mid-2016. Resultant coral bleaching caused an average 75% reduction in coral cover (present mean 6.2%). Most critically we report major declines in shallow fore-reef carbonate budgets, these shifting from strongly net positive (mean 5.92 G, where G = kg CaCO3m-2yr-1) to strongly net negative (mean -2.96 G). These changes have driven major reductions in reef growth potential, which have declined from an average 4.2 to -0.4 mm yr-1. Thus these shallow fore-reef habitats are now in a phase of net erosion. Based on past bleaching recovery trajectories, and predicted increases in bleaching frequency, we predict a prolonged period of suppressed budget and reef growth states. This will limit reef capacity to track IPCC projections of sea-level rise, thus limiting the natural breakwater capacity of these reefs and threatening reef island stability.
authors.affiliation: Department of Geography, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4RJ, United Kingdom.
authors.forename: C T
authors.initials: CT
authors.lastname: Perry
authors.affiliation: Department of Geography, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4RJ, United Kingdom.
authors.forename: K M
authors.initials: KM
authors.lastname: Morgan
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000254:growth & development* / Q000502:physiology*; D002254:Carbonates / Q000032:analysis*; D057894:Coral Reefs; D007195:Indian Ocean Islands; D009792:Oceans and Seas; D013696:Temperature
chemical_list: D002254:Carbonates