title: Drivers and predictions of coral reef carbonate budget trajectories.
abstract: Climate change is one of the greatest threats to the long-term maintenance of coral-dominated tropical ecosystems, and has received considerable attention over the past two decades. Coral bleaching and associated mortality events, which are predicted to become more frequent and intense, can alter the balance of different elements that are responsible for coral reef growth and maintenance. The geomorphic impacts of coral mass mortality have received relatively little attention, particularly questions concerning temporal recovery of reef carbonate production and the factors that promote resilience of reef growth potential. Here, we track the biological carbonate budgets of inner Seychelles reefs from 1994 to 2014, spanning the 1998 global bleaching event when these reefs lost more than 90% of coral cover. All 21 reefs had positive budgets in 1994, but in 2005 budgets were predominantly negative. By 2014, carbonate budgets on seven reefs were comparable with 1994, but on all reefs where an ecological regime shift to macroalgal dominance occurred, budgets remained negative through 2014. Reefs with higher massive coral cover, lower macroalgae cover and lower excavating parrotfish biomass in 1994 were more likely to have positive budgets post-bleaching. If mortality of corals from the 2016 bleaching event is as severe as that of 1998, our predictions based on past trends would suggest that six of eight reefs with positive budgets in 2014 would still have positive budgets by 2030. Our results highlight that reef accretion and framework maintenance cannot be assumed from the ecological state alone, and that managers should focus on conserving aspects of coral reefs that support resilient carbonate budgets.
authors.affiliation: Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK f.a.hartley@gmail.com.|UMR 248 MARBEC/UMR250 ENTROPIE, UM2-CNRS-IRD-IFREMER-UM1, Université Montpellier 2, Montpellier, France.
authors.forename: Fraser A
authors.identifier: 0000-0003-2468-8199
authors.initials: FA
authors.lastname: Januchowski-Hartley
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.|ARC Centre of Excellence for Coral Reef Studies, James Cook University, Queensland 4811, Australia.
authors.forename: Nicholas A J
authors.initials: NA
authors.lastname: Graham
authors.affiliation: Department of Parks and Wildlife, Kensington, Perth, Western Australia, Australia.|Oceans Institute, University of Western Australia, Crawley, Western Australia, Australia.
authors.forename: Shaun K
authors.identifier: 0000-0002-4590-0948
authors.initials: SK
authors.lastname: Wilson
authors.affiliation: Centre for Environment, Fisheries and Aquaculture Science, Pakefield Road, Lowestoft NR33 0HT, UK.|School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Jennings
authors.affiliation: Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.
authors.forename: Chris T
authors.initials: CT
authors.lastname: Perry
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D002254:Carbonates / Q000737:chemistry*; D057231:Climate Change; D057894:Coral Reefs; D012750:Seychelles
chemical_list: D002254:Carbonates
keywords: Seychelles; bioerosion; carbonate production; coral bleaching; parrotfish; regime shifts