RESEARCHARTICLE A Diverse Assemblage of Reef Corals Thriving in a Dynamic Intertidal Reef Setting (Bonaparte Archipelago, Kimberley, Australia) ZoeT.Richards1*,RodrigoA.Garcia2,CardenC.Wallace3,NatalieL.Rosser4,Paul R.Muir3 1 DepartmentofAquaticZoology,WesternAustralianMuseum,Welshpool,WA,6016,Australia,2 Remote SensingandSatelliteResearchGroup,DepartmentofImagingandAppliedPhysics,CurtinUniversity, Bentley,WA,6102,Australia,3 MuseumofTropicalQueensland,FlindersStreet,Townsville,Qld,4814, a11111 Australia,4 SchoolofAnimalBiology,UniversityofWesternAustralia,Crawley,WA,6009,Australia * [email protected] Abstract OPENACCESS Thesusceptibilityofreef-buildingcoralstoclimaticanomaliesiswelldocumentedanda causeofgreatconcernforthefutureofcoralreefs.Reefcoralsarenormallyconsideredto Citation:RichardsZT,GarciaRA,WallaceCC, tolerateonlyanarrowrangeofclimaticconditionswithonlyasmallnumberofspeciescon- RosserNL,MuirPR(2015)ADiverseAssemblageof ReefCoralsThrivinginaDynamicIntertidalReef sideredheat-tolerant.Occasionallyhowever,coralscanbeseenthrivinginunusuallyharsh Setting(BonaparteArchipelago,Kimberley, reefsettingsandthesearecauseforsomeoptimismaboutthefutureofcoralreefs.Herewe Australia).PLoSONE10(2):e0117791.doi:10.1371/ documentforthefirsttimeadiverseassemblageof225speciesofhardcoralsoccurringin journal.pone.0117791 theintertidalzoneoftheBonaparteArchipelago,northwesternAustralia.Wecomparethe AcademicEditor:ChristopherJFulton,The environmentalconditionsatourstudysite(tidalregime,SSTandlevelofturbidity)withthose AustralianNationalUniversity,AUSTRALIA experiencedatfourothermoretypicaltropicalreeflocationswithsimilarlevelsofdiversity. Received:July21,2014 PhysicalextremesintheBonaparteArchipelagoincludetidaloscillationsofupto8m,long Accepted:January1,2015 subaerialexposuretimes(>3.5hrs),prolongedexposuretohighSSTandfluctuatingturbidi- Published:February25,2015 tylevels.Weconcludethetimingoflowtideinthecoolestpartsofthedayamelioratesthese- verityofsubaerialexposure,andthecombinationofstrongcurrentsandanaturallyhigh Copyright:©2015Richardsetal.Thisisanopen accessarticledistributedunderthetermsofthe sedimentregimehelpstooffsetlightandheatstress.Thelowlevelofanthropogenicimpact CreativeCommonsAttributionLicense,whichpermits andproximitytotheIndo-westPacificcentreofdiversityarelikelytofurtherpromoteresis- unrestricteduse,distribution,andreproductioninany tanceandresilienceinthiscommunity.Thisassemblageprovidesanindicationofwhatcor- medium,providedtheoriginalauthorandsourceare credited. alsmayhaveexistedinothernearshorelocationsinthepastpriortowidespreadcoastal development,eutrophication,coralpredatoranddiseaseoutbreaksandcoralbleaching DataAvailabilityStatement:Allrelevantdataare withinthepaperanditsSupportingInformationfiles. events.Ourresultscallforare-evaluationofwhatconditionsareoptimalforcoralsurvival, andtheBonaparteintertidalcommunitypresentsanidealmodelsystemforexploringhow Funding:Thisprojectwasconductedundercontract toINPEXaspartofenvironmentalmonitoringforthe speciesresilienceisconferredintheabsenceofconfoundingfactorssuchaspollution. IchthysGasFieldDevelopmentProject.ZRwas supportedinthewrite-upphaseofthisprojectby WoodsideEnergy.Thefundershadnoroleinstudy design,datacollectionandanalysis,decisionto publish,orpreparationofthemanuscript. CompetingInterests:Thisresearchwasfundedby INPEX,andZRwassupportedinthewrite-upphase PLOSONE|DOI:10.1371/journal.pone.0117791 February25,2015 1/17 DiverseIntertidalCoralsoftheKimberley ofthisprojectbyWoodsideEnergy.Thisdoesnot Introduction altertheauthors'adherencetoallPLOSONE Reefcoralstolerateonlyanarrowrangeofenvironmentalconditions;hencewidespreadcoral policiesonsharingdataandmaterials. bleachingevents coupledwithland-useimpacts,haveresultedinrapidandprogressivedegra- , dationofcoralreefhabitats[1],[2].Today,onethirdofcoralspeciesfaceanelevatedriskofex- tinction[3]andthosecoralslivinginintertidalnearshorehabitatsareparticularlythreatened [4].Inadditiontodirectanthropogenicimpacts(i.e.habitatmodification,pollution,dredging, over-harvesting),intertidalcoralcommunitiesmustwithstandmultipleabioticstressorsin- cludingemersionduringlowtide,fluctuatingtemperature,lightandwindconditions,physical damagefromwaves,andsedimentandfreshwaterinundation[5–7].Theseimpactsmaybe rapidandpronouncedinshallowreefcommunities[8],[9],henceintertidalfringingreefcoral communitiesareincreasinglyimpoverished[10]andoftenonlythehardiestcoralssurvivein theintertidalzone[11–13]. Scleractiniancoralsarecriticalcomponentsofthecoralreefecosystem,providingthestruc- turalframeworkofreefs;theycontributetoprimaryproduction,nutrientrecycling,andpro- videmicrohabitatandafoodsourceforawidediversityofcoralreeforganisms[14].Hence, resourcemanagersurgentlyneedeffectivestrategiestomitigatetherisksimposedoncoralsto safeguardcoralreefecosystems[15],[16].Onepromisingapproachistoidentifyexistingcoral communitiesthatarehardenedtoclimaticextremesandtodeterminehowthesecommunities toleratestress[17].Todate,onlyasmallnumberofpopulationsofarestrictedsubsetofspecies havebeenshowntotolerateclimaticstress(e.g.AcroporahyacinthusinOfuIslandLagoon, AmericanSamoa[18];backreefcommunitiesintheWesternCaribbean[19];andcoralcom- munitiesinthePersian/ArabianGulf[20]). Inthisstudyweexaminethespeciescompositionanddiversityofreef-buildingcoralsgrow- ingonintertidalfringingreefflatsacrossthreeislandgroupsintheBonaparteArchipelago, Kimberley,northwesternAustralia.Wecomparetheenvironmentalconditionsandspeciesdi- versityoftheseintertidalcommunitieswiththoseofothershallowfringingreefcommunities aroundAustralia,anddiscusshowsuchahighdiversityofcoralissustainedinthisdynamic andsevereenvironmentalsetting. Methods EthicsStatement Allnecessarypermitswereobtainedforthedescribedfieldstudies.Acoralcollectionpermit wasobtainedfromtheWesternAustralianFisheriesDepartment,PermitNumber—SPA01/07. StudySites TheBonaparteArchipelagoislocatedinnorthwesternAustralia(Fig.1)andispartofthe KimberleyBioregion[21].TheKimberleyconsistsofmanyislandarchipelagoswithfringing reefs,platformreefs,submergedbanksandoffshoreatolls[22].Lowenergy,macro-tidalcondi- tionscharacterizetheregionandthetidally-drivencurrentstogetherwithshelfpositionand thedistancefromriversandestuariesinfluencesthelevelofturbidity[23]. FieldSurveys Inthisstudyscleractiniancoralbiodiversitywasrecordedat23sitesacrosstenislands(North andSouthMaretI.,WestMontalivetI.,EastMontalivetI.,WalkerI.,PatriciaI.,BerthierI., AlbertI.,TurbinI.,SuffrenI.)fromthreeislandgroups(Maret,BerthierandMontelivet)inthe BonaparteArchipelago(Fig.1,TableAinS1File).Saltwatercrocodiles(Crocodylusporosus) frequentthesereefsanddivingwasprohibitedunderworkplacesafetyregulations,henceonly PLOSONE|DOI:10.1371/journal.pone.0117791 February25,2015 2/17 DiverseIntertidalCoralsoftheKimberley Fig1.MapofstudysitesintheBonaparteArchipelago,Kimberley,Australia.Individualdotsindicatesurveysiteswithinthethreemainislandgroups— Berthier(green),Maret(blue)andMontalivet(purple).SitenamesanddetailsarelistedinTableAofS1File. doi:10.1371/journal.pone.0117791.g001 theintertidalhabitatwasexamined,duringlowspringtidesof1stSeptember–20thOctober 2007.Approximately240m2ofinnerandouterreefflatandreefcresthabitatwassurveyedat eachsiteandallcoralspeciesencounteredwereidentifiedinsituorcollectedfor lateridentification. Coraldiversitywassurveyedusingarapidecologicalassessmentmethodology.Todeter- minetherelativefrequencyofspeciesoccurrence,allspeciesateachsitewereclassifiedinto oneofthefollowingfivecategoriesofabundance:Category1–rare(1–2colonies);Category2– infrequent(3–5colonies);Category3–frequent(6–20colonies);Category4–common(21–50 colonies);andCategory5–dominant(51ormorecolonies).Sinceaccuratein-situIDofmany coralspeciesisnotpossiblewecollectedsmall(5–8cm)skeletalsampleswhichwerebleached ina3%hypochloritesolutionovernightandthenair-driedandreturnedtothelaboratoryfor ID.Identificationswerecarriedoutwithcomparisontoknownandtypespecimensinthe QueenslandMuseumcollectionaccordingto:[24]forAcroporaandIsopora;[25]forFungii- dae;[26]forPsammocora;[27],[28]forLobophylliidae,Merulinidae,Montastraeidaeand Diploastraeidae;and[29]foralltaxathathavenotbeenrevisedrecently.Moreover,thehigher- leveltaxonomicclassificationsusedinthisstudyreflecttheclassificationslistedintheWorld RegisterofMarineSpecieshttp://www.marinespecies.org/asofSeptember2014.Newdistribu- tionrecordswereverifiedbydiscussionwithJENVeronandwithcomparisontotheCoralsof PLOSONE|DOI:10.1371/journal.pone.0117791 February25,2015 3/17 DiverseIntertidalCoralsoftheKimberley theWorlddatabase:http://www.coralsoftheworld.com.Specimenshavebeendepositedwith theQueenslandMuseum. Analyses ToexaminetheadequacyoflocalsamplingattheBonaparteArchipelago,aspeciesaccumula- tioncurvewascalculatedusingthe“specaccum”functionofthe“vegan”libraryinRwithjack- knifedstandarderrorshttp://www.r-project.org/. Toassesstheproportionofcoralspeciesfromourstudynotnormallyfoundintheintertidal zone,welookedforintertidalvssubtidalrecordsforthesamespeciesintheMuseumofTropi- calQueenslanddatabase(>28,000specimen-basedrecords).Tocomparethediversity observedintheintertidalzoneintheKimberleywiththatseeninothermoretypicalreefloca- tions,westandardizedtheareasurveyedto100m2andcomparedthiswithasemi-quantitative estimateofthelevelofdiversityrecordedelsewhereintheNEIndianOceantotheNWPacific Ocean(seeTableBinS1File). AresemblancematrixbasedonBray-Curtissimilaritieswasconstructedusingsquare-root transformedabundancedatafromthe23sitesusingPRIMER-Ev6[30].AgglomerativeCLUS- TERanalysiswasusedtogroupthesitesaccordingtothesimilarityincoralassemblagecompo- sitionusinggroupaveragelinkagedistances.WeusedKrustal’snon-metricmultidimensional scaling(MDS)analysistovisualizethevariationbetweensitesasa2-Dplot. PhysicalVariables HourlytidalpredictionsforNorthMaretI.(BonaparteArchipelago,Kimberley,Australia); (ScottReef,OffshoreAtoll,Kimberley);BarrowI.(Pilbara,WesternAustralia);LizardI. (NorthernGreatBarrierReef,Australia)andDentI.(Whitsundays,CentralQueensland,Aus- tralia)(seeTableCinS1Fileforco-ordinates)wereobtainedfromtheNationalTidecentreof theAustralianBureauofMeteorologyfortheyears2002–2014http://www.bom.gov.au/ oceanography/projects/ntc/ntc.shtml.Theaverageproportionaloccurrenceoftidalamplitude peryear(2002–2014)at1mintervals(±SD)wasplottedtocomparethedistributionoftidal amplitudesbetweenregions.Theproportionaloccurrenceofspringlowtides((cid:1)2m)athourly intervalsforNorthMaretI.wasalsoplottedtoillustratetimeofdayandlengthoftimeintertid- alcoralsareexposedtoairduringdifferentlunarphases(2002–2014). ToprovideenvironmentaldataweusedsatelliteimagerycapturedbytheMODerateresolu- tionImagingSpectroradiometer(MODIS)onboardNASA’sAquasatellite.Thissensorcaptures imageryatmanyspectralbandsfromthevisibletothefarinfrared(http://modis.gsfc.nasa.gov/ about/)onaneardailyrepeatcycle.Empiricalalgorithmsarethenappliedtothespectralinfor- mationtoderivegeophysicalparameterssuchasseasurfacetemperature(SST)[24]andthedif- fusedown-wellingattenuationcoefficient{K (490nm),[31].Weobtainedeightdayaveraged d globaldataat4kmspatialresolutionofSSTandK (490nm)fromhttp://oceandata.sci.gsfc. d nasa.gov/MODISA/Mapped/8Day/4km/fromJuly2002toJune2014.TheSSTdataovera 12km×12kmregionaboutacoordinateof125.0°E/14.3750°Swereaveragedateachtime stamptoobtainaSSTtimeseriesforNorthMaretI.Thesameapproachwasusedtoobtainav- erageSSTestimatesfortheotherfourlocationsandco-ordinateslistedinTableCinS1File. K (490)isameasureofthelightpenetrabilityinthewatercolumnandassuchisaproxyfor d turbidity,wherehigherK (490)valuespertainstolesserpenetrationoflightintothewatercol- d umnandhencegreaterturbidity.TheoperationalMODISK (490)algorithmreliesonalog- d transformedratiobetweentheremotesensingreflectanceat488and547nmandhasbeen validatedforoceanicwaterswithnegligiblebottomreflectance[32],[33].Overopticallyshallow waterssuchasincoralreefs,thelargecontributionofbottomreflectancetotheabove-water PLOSONE|DOI:10.1371/journal.pone.0117791 February25,2015 4/17 DiverseIntertidalCoralsoftheKimberley radiancescanover-estimateparametersthatrelyonthisspectralratio[34],[35].Tominimize thiseffecttheK (490)valuesweretakenoveradjacentdeep-waterregionsforeachlocationand d averagedtoobtainatimeseriesforeachlocation.Thesevaluesshouldthereforebeinterpretedas theaverageminimumturbidityateachlocation.Lastly,weconductedaseriesofone-wayANO- VA’stotestthenullhypothesisthatthereisasignificantdifferencebetweentheSSTandK (490) d time-seriesvaluesbetweenNorthMaretI.,andScottReef,BarrowI.,LizardI.andDentI. ResultsandDiscussion SpeciesDiversity Basedonaskeletalcollectionof506coralsfrom23intertidalsites,wedocument225speciesof hardcoralfrom60generaoccurringinthenorthernsectoroftheBonaparteArchipelago (TableDinS1File).SevenofthesespeciesarenewlyrecordedfromWesternAustralia(Gonio- porafruitcosa,Gonioporanorfolkensis,Isoporacrateriformis,Lobophylliaflabelliformis,Lobo- phylliaserratus,Platygyraacuta,Stylaraeapunctata)andthisstudyextendstheirdistribution rangefromIndonesiaandtheNWPacifictoincludetheeasternIndianOcean. Ourstudyprovidesarobustrepresentationoftheobservedlocalspeciesrichness(seespe- ciesaccumulationcurve—FigureAinS1File);howeverthisestimateisconservativebecause weonlypresentdatapertainingtospeciesrecordsthathavebeensubstantiatedwithareference skeletalspecimen.Furthermore,intertidalcoralcommunitiescontainasubsetofthelocaldi- versity(70–90%)[13],[36]henceweestimateafurther23–68speciescouldbeexpectedifsub- tidalhabitatsweresurveyedbutfurthercollectioneffortsarerequiredtoverifythis. Bycomparingthecurrentintertidalrecordswithover28,000specimen-baseddepthdistri- butionrecordsintheMuseumofTropicalQueenslandwedocument34speciesintheintertidal zonethathavepreviouslybeenrecordedonlyfromsubtidalhabitats(e.g.Echinoporagemma- cea,Stylaraeapunctata,Oulastreacrispata—Fig.2f)(TableDinS1File).Numerousotherspe- cieswerecordedinthisinshorehabitatwereonlypreviouslyrecordedfromoffshoreclear waterhabitats(e.g.Leptastreapruinosa,Astreoporamyriophthalma[29]. ThediversityofhardcoralsinthethreeislandgroupsoftheBonaparteArchipelagowas similarto,orhigherthanasemi-quantitativeestimateofthelevelofdiversityinintertidalor shallowsubtidalhabitats(0–5mdepth)inotherpartsoftheIndo-Pacific(FigureBinS1File). Thelevelofdiversitywassimilartothatestimatedforinshorefringingreefsinthecentralsec- toroftheGreatBarrierReef(i.e.DentI.,BorderI.,Whitsundays)~2decadesago[37]priorto thewelldocumenteddeclineofcoralcoverandconditionoftheinshoremidtosouthernsec- tionsoftheGreatBarrierReef[38–40]. SpeciesrichnesswashighestwithintheMaretgroupandpeakedonthewesternsideof SouthMaretI.(n=158)(Fig.3).AllMaretI.siteshadover120species.Thediversityofcorals atsitesintheBerthiergrouprangedfrom38–127species,whilediversityofcoralsatsiteswith- intheMontalivetgrouprangedfrom42–107species.Thespatialvariationinthecomposition ofcoralassemblagesisclearinthe2DnmMDSplotwhichshowsLittleBruneiBayandS.MOF sitesatMaretI.beingdistinctivefromothersitesinMaretI.(Fig.4).Thereisadegreeofover- lapinthecoralassemblagesacrossthethreeislandgroups,with11ofthesitesgroupingtogeth- erwith60%similarity. Sevenspecieswerelocallywidespread(Pocilloporadamicornis;Symphylliarecta;Acropora hyacinthus,Galaxeaastreata,Coelastreaaspera,LobophylliahemprichiiandStylophorapistil- lata)and33otherspecies,includingfiveAcroporaspecies(A.aspera,A.millepora,A.interme- dia,A.muricataandA.valida),werepresentatmorethan¾ofsitessurveyed.Therewere manyrarespecies,seventeenofwhichwererecordedatasinglesiteonly.Oneofthese, PLOSONE|DOI:10.1371/journal.pone.0117791 February25,2015 5/17 DiverseIntertidalCoralsoftheKimberley Fig2.AhighdiversityofcoralthrivesintheBonaparteintertidalzone.(a)Thicketsofbranching AcroporaasperaandA.muricatadominatetheinnerreefplatformatnorthPatriciaI.,(b)Onlowtidescorals areexposedtoairforuptothreeandahalfhoursatatime,(c)AhighdiversityofAcroporaspeciesthriveon theouterfringingreefplatformatnorthPatriciaI.,(d)Anaggregationofjuvenileandsubadultcorals inhabitingasteepgranitecliff-faceontheeastsideofWalkerI.,(e)Goniastreacoralheadsdominatethe innerplatformatnorth-westPatriciaI.,(f).Oulastreacrispataarareanddistinctivespeciesthatnormally occurssubtidallywasencrustingagraniteboulderontherockyshoreofWalkerI. doi:10.1371/journal.pone.0117791.g002 Lobophylliaserratus,islistedasEndangeredintheIUCNRedListofThreatenedSpecies (www.iucn.redlist.org),andStylaraeapunctataislistedasDataDeficient. ThedistinctivenessoftheBonaparteintertidalcoralassemblageisexemplifiedbythehigh diversityofAcroporaspecieslivingthere(47spp.)(FigureCinS1File).Acroporaareoneof themostthermallysensitiveandthreatenedcoralgenera[3],anditisincreasinglyraretofind diverseandabundantassemblageofAcroporaonintertidalnearshorefringingreefs.Onthe GreatBarrierReefforexample,nearshorereefshavebeenclassifiedas“non-Acroporareefs” [41]duetotherelativepaucityofAcroporaspp.NotonlywasAcroporathemostdiverseofthe PLOSONE|DOI:10.1371/journal.pone.0117791 February25,2015 6/17 DiverseIntertidalCoralsoftheKimberley Fig3.Spatialvariationinthetotalspeciesrichnessrecordedat23sitesspanningthreeislandgroups intheNorthernsectoroftheBonaparteArchipelago.MaretIs.group(bluecolumns);BerthierIs.group (greencolumns)andMontalivetIs.group(purplecolumns). doi:10.1371/journal.pone.0117791.g003 Fig4.Spatialvariationinthecompositionofthecoralassemblagesatthreeislandgroupsinthe BonaparteArchipelago.MaretGroup(bluedots);BerthierGroup(greendots)andMontalivetGroup(purple dots).Kruskal’snon-metricmultidimensionalscaling(nm-MDS),usingBray-Curtissimilarityindexofthecoral assemblageat23sitesbasedonrelativeabundancedata.Linkagesarebasedonweightedpairgroup averagesandellipsesindicatethosesiteswith60%similarityatP<0.001. doi:10.1371/journal.pone.0117791.g004 PLOSONE|DOI:10.1371/journal.pone.0117791 February25,2015 7/17 DiverseIntertidalCoralsoftheKimberley 60generaofscleractiniancoralrecorded(FigureCinS1File),butsixAcroporaspeciesdomi- natedthecommunity(Fig.2a-c).AnabundanceofAcroporaspp.hasbeenreportedfrom otherintertidallocationsintheKimberley(e.g.TurtleReefatTalbotBayandOne-ArmPoint, CapeLeveque,intheWesternKimberley[22])indicatingthisregionmayprovideacriticalref- ugeforthisincreasinglythreatenedgroupofcorals. PhysicalVariables HourlytideheightdatafromNorthMaretI.,showsthesemidiurnalpatternsofthetideswhich oscillateupto8moverspringtides(Fig.5a).Whenthemeanproportionaloccurrenceoftidal heightsforNorthMaretI.iscontrastedwithfourothermoretypicalreeflocations(Fig.5b-e)it isevidenttidalconditionsinthevicinityofNorthMaretI.aremoredynamicandreachampli- tudesupto3mgreaterthanthoseintheothermoretypicalreeflocationswithasimilarlevelof diversity.Duringspringlowtides(i.e.tides(cid:1)2m),coralsgrowingontheintertidalreefplat- formatNorthMaretI.areexposedtotheairforupto3.5hoursatatime(FigureDinS1File). However,animportantphysicalfeatureoftheBonaparteArchipelagoisthatthespringlow tidesoccurintheearlymorning,4am-9am,andlateafternoontoearlyevening,4pm–9pm (Fig.6).Thus,coralsremainsubmergedoverthehottestpartsofthedayandare,bufferedfrom thestressesarisingfromsubaerialexposure.Nevertheless,evenwhencoralsaresubmerged, otherenvironmentalfactorscomeintoplaysuchassea-surfacetemperaturesandturbidity. Eight-dayaverageMODIS-derivedSSTfromJuly2002toJune2014showsthattheaverageSST atNorthMaretI.rangedfrom25.2to34.3°C(Table1).ThemaximummeansummerSSTover thisperiodwas32.2±1.0°CandtheminimummeanwinterSSTwas26.5±1.0°Cencompassinga rangeof5.7°C.The+1°Cbleachingthreshold(sensuNOAACoralReefWatchmethods—see http://coralreefwatch.noaa.gov/satellite/index.php)atNorthMaretI.is33.2°Candourdatasuggest SSTremainedabovethisthresholdfortwo8-dayperiodsinJanuaryandFebruary2013(FigureE inS1File).Whencomparedwithmoretypicalreeflocations(Fig.7)themeanSSTinthevicinity ofNorthMaretI.issignificantlyhigherthanLizardI.,BarrowI.andDentI.butnotsignificantly differentfromScottReef(TableEinS1File).WhileScottReefhassuccumbedtobleachingevents inthepast[43],todatethereisnoevidencetosuggesttheintertidalcoralcommunitiesintheBona- parteArchipelagohaveexperiencedableachingevent(despiteNOAAissuingnumerousbleaching alertse.gMar-Jun2013).Eventhoughthisregionisremote,theBonaparteArchipelagoisintermit- tentlyvisitedbyscientists(WAMuseum,AustralianInstituteofMarineScience,Departmentof Fisheries;CygnetBayResearchStation);touristvesselsandtheAustraliancustomsserviceprovide surveillance.Whilewidespreadbleachingwasbeenreportedacrossalmost2000kmofWestern Australiancoastlineduringthesummerof2010/11[42]thereisnosuggestionthattheinshore Kimberleyreefshaveexperiencedawidespreadbleachingeventtodate. Theeight-dayaverageofK (490)rangedfrom0.03–0.18m-1atNorthMaretI.(Table2).The d K (490)valuesrepresentnaturalturbiditylevelsatNorthMaretIsland.Theyareslightlylower d thanthevaluesdetectedatBarrowI.(Pilbara),alocationthathasbeenexposedtoalargemulti- yeardredgingoperation[44],[45](FigureFinS1File)andnotsignificantlydifferentfromDent Island(inshoreWhitsundays,GBR)(TableEinS1File).Thereareseasonaldifferencesinthe K (490)valuesobtainedacrossalllocationswiththehighestturbidityrecordedinWinterat d NorthMaretI.(FigureGinS1File).ItislikelythesimilarityofsummerK (490)valuesacrossthe d locations(Table2)reflectstheeffectsoftropicalcyclonesandmonsoonalstormsonwaterquality. FactorsDrivingDiversity Thefindingsofourpreliminarycomparisonofregionaldiversitysuggestthatthelevelofcoral diversityintheBonaparteintertidalzoneisroughlyequivalentto,orgreaterthanthat PLOSONE|DOI:10.1371/journal.pone.0117791 February25,2015 8/17 DiverseIntertidalCoralsoftheKimberley Fig5.Spatialcomparisonoftidalamplitudeat1mintervals(±SD)from2002–2014.Presentedisthe proportionaloccurrenceoftideheightsfor(a)NorthMaretI.,(b)ScottReef(c)BarrowI.,(d)LizardI,and(e) DentIsland. doi:10.1371/journal.pone.0117791.g005 documentedfromothermoretypicalshallow-waterreefsintheNEIndianOceanandWestern PacificOcean.ItisimportanttonotehoweverthattheenvironmentalconditionsintheBona- parteArchipelagoarefarmoreextremeanddynamicthantheseotherlocations.Hencethe questionmustbeasked,howisthediversityoftheBonapartecommunitybeingsustained whenintertidalcoralcommunitiesallaroundtheworldarebecomingincreasinglyimpover- ishedduetocoralbleachingandsedimentimpacts? PLOSONE|DOI:10.1371/journal.pone.0117791 February25,2015 9/17 DiverseIntertidalCoralsoftheKimberley Fig6.HourlytideheightdataofspringlowtidesforNorthMaretI.from2002–2014.Thelengthsoftime coralsareexposedforeachdaydependsuponthelunarphase(seeFigureDinS1File)andmaximumlow tideexposureoccursinearlymorningandevening. doi:10.1371/journal.pone.0117791.g006 Thereareanumberofpossibleexplanationsforthehighdiversity.Firstly,theBonaparte 0 Archipelagooccursatlowlatitude(~14°24 S)andinrelativelycloseproximitytoIndonesia (~500km)wherethegreatestlevelofreefcoraldiversityisdocumented[46].Whileitiswell knownthatcoraldiversityincreasestowardstheequator[47],[48]thediversityofcoralsoccur- ringintheKimberleyregionhasbeenunder-representedinstudiesofcoralbiogeographyand biodiversity[49].HencetheextentoffaunalconnectivitybetweenIndonesiaandNWAustralia Table1.SummarystatisticsforSSTparametersatNorthMaretI.incomparisontothreeothermoretypicalcoralreeflocations(unit=°C). NorthMaretI. ScottReef BarrowI. LizardI. DentI. MinimumSST 25.193 25.120 21.714 22.147 20.040 MaximumSST 34.350 32.747 32.669 32.013 30.936 AverageSST 29.216 29.170 26.439 26.743 25.414 StandardDeviationSST 1.790 1.623 2.733 2.036 2.619 Max.SummerSSTmean 32.208 31.607 30.114 30.450 29.384 Max.SummerSSTStandardDeviation 0.978 0.692 1.302 0.817 0.732 SummerSSTmean 30.389 30.225 28.570 29.124 28.401 SummerSSTStandardDeviation 1.328 1.113 1.458 0.925 0.941 MinWinterSSTmean 26.504 26.635 22.407 23.808 21.077 MinWinterSSTStandardDeviation 0.962 0.751 0.615 0.789 0.772 WinterSSTmean 27.128 27.283 23.325 24.460 22.110 WinterSSTStandardDeviation 0.989 0.782 0.896 0.792 1.005 Datarelateto8-dayglobalaveragesderivedfromtheMODISaquasatelliteata4-kmspatialresolutionfromJuly2002toJune2014.SeeTableCinS1 Fileforsiteco-ordinates. doi:10.1371/journal.pone.0117791.t001 PLOSONE|DOI:10.1371/journal.pone.0117791 February25,2015 10/17