| Summary: | Pushingboundariesofrangeandresilience:areviewofrange-‐extensionbyabarrens-‐formingseaurchinScottD.Ling,InstituteforMarine&AntarcticStudies,UniversityofTasmania,Hobart.Tas.7001,Australia;email:Scott.Ling@utas.edu.auThebarrens-‐formingseaurchinCentrostephanusrodgersii(Diadematidae)hasundergonerecentpolewardrange-‐extensiontotheTasmaniancoastline(SEAustralia).Bycompilingfieldobservations(includingSSTspanning>60yrs),broad-‐scalesurveysandmanipulativeexperimentsconductedduringthepastdecade,thisreviewdetailsknowledgeontheresponseofthiskeyseaurchinspeciestoclimatechangeandduallyexploresmultipleprocessesinfluencingtheultimateecologicalconsequenceofcatastrophic-‐shiftfromproductivekelpbedstourchinbarrens,asnowobservedwithintherange-‐extensionregion.Asaresultofchangingregionalclimate,easternTasmaniahasbecomeincreasinglysuitableforCentrostephanuslarvaldevelopmentwiththetimingoftheseaurchinsarrival,age-‐structureandspatialdistributionacrosstheextension-‐regionconsistentwithpatternsinwarmingseatemperaturesandcurrent-‐drivendispersalpotential.Furthermore,consistencyintemperaturedependencyoflarvaldevelopmentpluslackofgeneticdifferentiationofthespeciesacrossitsentirerange,confirmthecriticalroleofchangingclimateindrivingtherange-‐extension.Continuedwarmingpredictedforthisregionwillfavourincreasedlarvalsurvival,promotingongoingpopulationexpansionandultimatelyincreasedlikelihoodofpopulationsreachingsufficientdensitytoaffectwidespreadovergrazing.Assuch,knowledgeofpatternsandmechanismspromotingovergrazingarealsoreviewedforthepurposeofidentifyingkelpbedsatgreatestriskgivenclimatetrends,reefsubstratumtypesandpredatorabundance(chieflyspinylobsters)asinfluencedbyintensefishingpressure.Finally,thisreviewshowshowmanagementofnon-‐climaticlocalscalestressorscanbeusedtoincreaseresilienceofkelpbedsagainstovergrazinggivenlarge-‐scaleclimate-‐drivenincreasesinkeyseaurchinpopulations.
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