Introduction and Approach
AcknowledgementsTheauthorswouldliketothankColleenHarpold andKathyMier forhelpingwithfiguresandanalysis.StudycollaborationandfundingwereprovidedbytheU.S.DepartmentofInterior,BureauofOceanEnergyManagement.
Therecommendations andgeneral contentspresented inthisposterdonotnecessarily represent theviews orofficialposition oftheDepartment ofCommerce, theNational OceanicandAtmosphericAdministration ortheNationalMarineFisheries Service.
Spatial And Temporal Variability of Zooplankton Community Structure In The Chukchi Sea (2010-2012)Adam Spear1, Jeff Napp1, Janet Duffy-Anderson1, Sigrid Salo2, and Phyllis Stabeno21 Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, 7600 Sand Point Way N.E., Seattle, Washington 98115. [email protected], [email protected], [email protected] Pacific Marine Environmental Laboratory, NOAA, 7600 Sand Point Way N.E., Seattle, Washington 98115. [email protected], [email protected]
Figure 2. ColoredsymbolsindicatemooringmeasurementslocatedoffIcyCape(Figure1).BlackcirclesindicateBeringstraitmeasurements.VolumetransportwasbelowaveragefromMarch- Mayin2012;averageandaboveaverageMarch- May2011.Nodatafor2010.AnnualmeantransportthroughBeringStraitwashigher2010- 2011than2012(Woodgateetal.,2015).Collectively,resultsindicatethatdespiteaboveaverageflowtotheNEjustpriortoandduringthesamplingperiod,overallflowwasreducedin2012,suggestinginfluenceofsouthern-originwaterandcolderconditionsin2012.
Figure 3. Satellite-tracked30mdepthdrifters(2012).Thecoloroftheline(seekeybelowtheplot)reflectsSST(°C).Driftertrajectories(July–October)illustrateadvectionthroughBeringStrait,acrosstheChukchiShelf,intoBarrowCanyonandtheBeaufortGyre.Topleftinsetillustratesgeneralizedcurrentflow.
Figure 1. SeaIce.PercentcoverageonAugust2,2010(top),2011(middle),2012(bottom).2012wasalowericeyearintheChukchiSeaoverall,buttherewasmoreiceinthesamplingregionatthetimeofthesurveysinthatyearcomparedto2010&2011.Oceantemperatures(notshown)indicatecolderconditionsin2012andcorroborateseaiceobservations.
Figure 4. Watermassdesignations.Circlehalvesindicatesurface(tophalf)andbottom(bottomhalf),respectively.PresenceofAlaskaCoastalWater(ACW)wassignificantin2010andwasnotconstrainedtothenearshore.MeltWater(MW)andWinterWater(WW)weremoreprominentin2012.Remainingwatermassabbreviations:BSSW,BeringSeaShelfWater;SW,SiberianCoastalWater.
ChangesunderwayintheUSArcticareunprecedented;thephysicalenvironmentisexperiencingincreasesintemperature,progressivedeclinesinseaiceconcentration,earlierspringiceretreat,anddelayedfalliceformation.Thisphysicalrestructuringisexpectedtopropagatethroughtheecosystem,andincludechangesinprimary,secondaryanduppertrophiclevelproduction.AspartoftheChukchiAcoustic,Oceanographic,andZooplankton(CHAOZ)project,aseriesofbio-oceanographicresearchsurveysintheUSChukchiSeawereconductedinsummerin2010,2011,and2012tocharacterizethephysicalenvironmentandexaminebiologicalresponse.SurveyswereconductedinAugustofeachyear(30DAS)andcollecteddataonwatercolumnproperties(CTD),oceanographiccurrents(moorings,satellite-trackeddrifters)seaicepresenceandextent,andzooplanktonpreybase(Tuckertrawls).Physicaldatawereanalyzedandevaluatedrelativetospatialandtemporalpatternsofzooplanktoncommunitystructuring(multivariateclustering,PRIMER-E)toevaluatetheinfluenceofbottom-upforcingonsecondaryproduction.
Figure 5. Zooplanktoncommunityclusteranalysis.Zooplanktonassemblagesinthenorth(dk green)in2010and2011werecharacterizedbylarvaceans,cnidarians,cirripedia,Pseudocalanus spp.,andOithona spp.In2012,adissimilarnorthernassemblagewasnoted(dk red)withlowernumbersofmostoftheabovespeciesandmoreCalanus glacialis,anarcticcopepod.Greaterheterogeneityinthespeciesassemblagesin2012reflectstheadditionalcomplexityincirculation.In2010theinfluenceofACWwasnotedbyanassemblage(dk bluecircles)characterizedbygreaternumbersofcladocerans andthecosomata,andfewerlarvaceans.
Table 1. Meanabundances(No.m-3)ofmajortaxa.Thecoldyear(2012)hadhighermeanabundancesoflargercopepods(Calanus glacialis)andgammarid amphipods.2010&2011hadhighermeanabundancesofsmallcopepodsandlarvaceans.Thewarmestyear(2010)hadthehighestabundanceofcalyptopis stageeuphausiids.Aretheselarvalstageeuphausiids aresultofreproductionintheChukchi,oraretheyadvectedfromthenorthernBeringSea?
IcyCapePt.Lay
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Figure 6. TransportDuration.Cumulativetime(d)ofzooplanktontransportfromSt.LawrenceIslandtothenortheastChukchiusingknowncurrentspeedsfrommooredADCPmeasurements.Greencirclesindicateestimatednumberofeuphausiid calyptopis .ResultssuggesteuphausiidreproductionintheChukchiduringwarmeryears,giventhenumberofdaysforparticletransportfromthenorthernBeringSea,andthedevelopmentratesofThysanoessa spp (Teglhus etal.,2015).
Conclusions1. Physicalconditionsweredifferent
amongthethreeyears(warm‘10&‘11,cold‘12)andareattributedtodifferentialtransportofwaterfromthemainsources,andthepresenceofseaiceandmeltwater.
2. Stronginterannual andspatialvariabilityofzooplanktoncommunitystructurewasinfluencedbywatermassproperties.
3. Warmyearshadahigherabundanceofsmallerzooplanktonandpresumedlocalreproductionofeuphausiids.
4. Inthecoldyear,withdecreasedBeringStraittransport,thezooplanktoncommunitystructureovertheshelfwasmoreheterogeneouswithincreasedabundanceoflargespecies.
Results
Total Transport from SW to NE by Month 2010-2015
PosterNo.HE44A-1493
ReferencesTeglhus,F.W.,Agersted,M.D.,Akther,H.,&Nielsen, T.G.(2015).Distributions andseasonal abundances ofkrilleggsandlarvaeinthesub-ArcticGodthåbsfjord, SWGreenland.MarineEcologyProgressSeries.
Woodgate,R.A.,Stafford,K.M.,&Prahl,F.G.(2015).ASynthesis ofYear-roundInterdisciplinaryMooringMeasurementsintheBeringStrait(1990-2014)andtheRUSALCAyears(2004-2011)
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