title: Changing dynamics of Caribbean reef carbonate budgets: emergence of reef bioeroders as critical controls on present and future reef growth potential.
abstract: Coral cover has declined rapidly on Caribbean reefs since the early 1980s, reducing carbonate production and reef growth. Using a cross-regional dataset, we show that widespread reductions in bioerosion rates-a key carbonate cycling process-have accompanied carbonate production declines. Bioerosion by parrotfish, urchins, endolithic sponges and microendoliths collectively averages 2 G (where G = kg CaCO3 m(-2) yr(-1)) (range 0.96-3.67 G). This rate is at least 75% lower than that reported from Caribbean reefs prior to their shift towards their present degraded state. Despite chronic overfishing, parrotfish are the dominant bioeroders, but erosion rates are reduced from averages of approximately 4 to 1.6 G. Urchin erosion rates have declined further and are functionally irrelevant to bioerosion on most reefs. These changes demonstrate a fundamental shift in Caribbean reef carbonate budget dynamics. To-date, reduced bioerosion rates have partially offset carbonate production declines, limiting the extent to which more widespread transitions to negative budget states have occurred. However, given the poor prognosis for coral recovery in the Caribbean and reported shifts to coral community states dominated by slower calcifying taxa, a continued transition from production to bioerosion-controlled budget states, which will increasingly threaten reef growth, is predicted.
authors.affiliation: Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, EX11 1RP, UK c.perry@exeter.ac.uk.
authors.forename: Chris T
authors.initials: CT
authors.lastname: Perry
authors.affiliation: Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, EX11 1RP, UK.
authors.forename: Gary N
authors.initials: GN
authors.lastname: Murphy
authors.affiliation: School of Environment, The University of Auckland, Private Bag 92019, Auckland, New Zealand.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Kench
authors.affiliation: Department of Geography and Department of Biology, Memorial University, St. John's, Newfoundland, Canada A1B 3X9.
authors.forename: Evan N
authors.initials: EN
authors.lastname: Edinger
authors.affiliation: School of Earth and Environmental Sciences, James Cook University, Queensland 4810, Australia.
authors.forename: Scott G
authors.initials: SG
authors.lastname: Smithers
authors.affiliation: School of Marine Sciences, University of Maine, Darling Marine Centre, Walpole, Maine 04573, USA.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Steneck
authors.affiliation: Marine Spatial Ecology Lab, School of Biological Sciences, University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Mumby
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000254:growth & development / Q000382:microbiology / Q000502:physiology*; D002119:Calcium Carbonate / Q000378:metabolism*; D017691:Caribbean Region; D057894:Coral Reefs; D017753:Ecosystem; D011157:Population Dynamics; D012617:Sea Urchins / Q000502:physiology
chemical_list: D002119:Calcium Carbonate
keywords: Caribbean; Diadema; bioerosion; carbonate budgets; coral reefs; parrotfish