Bonaparte Archipelago, Kimberley, Australia

17 Pages·2015·3.28 MB·English

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
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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
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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
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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
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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,
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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
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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
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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
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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?
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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