marine mammals as ecosystem sentinels · oceans sustainability unit 3 figure 5. gray whale...
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Figure1.Graywhaleapproachesfishingpangatointeractwithhumans.Image:SanIgnacioLagoon,BajaCalifornia,2006,MichelleKinzel.
Figure2.Graywhalespyhoppingtoviewsurroundingarea.Image:MichelleKinzel,2006.
MarineMammalsasEcosystemSentinels
Scientistswhostudyclimatechangeconsidervariousfactorsandenvironmentalvariablesinordertoassessthenatureanddegreeofchangescorrelatedwithachangingclimate.Physicalgeographersandchemicaloceanographersstudychangesinoceantemperatures,increasingamountsofcarbondioxideinseawater,risingsealevelsandotherphysicalparameterswhenassessingclimatechange.
Biologistsandecologistsexaminethebehaviorpatternsandresponsesoforganismsandsearchforpossiblelinkagesorcorrelationstoclimatechangeparameters.Foreachofthesixexamplesbelow,youaretoidentifytheevidenceprovidedforeachstudy,aswellasdeterminetheinterpretationofferedthatexplainshowtheevidenceisrelatedtopotentialclimatechange.Theevidenceispresentedasexamplesofchangesinthedistributionorbehaviorofgraywhales,andtheinterpretationisahypothesisorpossibleexplanationofhowtheseobservedchangesrelatetoclimatechange.Thegraywhaleisthusconsideredtobeamajorindicatorofenvironmentalchangesintheecosystemandcanbelabeledasanecosystemsentinel.Scientistssearchforlinkagesbetweengraywhalebehaviorsandclimatechangevariablesinoceansystems.
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Figure3.Graywhaleglobaldistribution,showinghigherlatitudefeedinggroundsandlowerlatitudebreedinggroundsalongthePacificCoastofNorthAmerica.ImageCredit:"Cypron-RangeEschrichtiusrobustus"byOwnwork.LicensedunderCCBY-SA3.0viaWikimediaCommons.
Foreachofthefourstudiesyouareprovided,youneedtoidentifytheexampleofchangeindistributionorbehaviorofthegraywhales.Thesechangesrepresentthefactsorobservations.Thenusetheinformationprovidedwiththatexampletodeterminethescientificinterpretationrelatedtothewhales’change,notinghowtheobservationsorfactscouldbeattributedchangesintheatmosphere,biosphere,andhydrosphere.
ScientificStudy1)Between1967and1999,scientistsmonitoringthemigratorymovementsofwhalesattwolocationsalongthePacificCoastofNorthAmerica,GraniteCanyonandPointVicente,observeda6–8daydelayinthesouthboundmigrationofthegraywhalepopulation.TheoverallmediansightingdateshiftedfromJan.8before1980toJan.15after1980.ThisshiftinmigrationcoincideswiththeNorthPacific“regimeshift”thatoccurredinthe1970s.Aregimeshiftisdescribedasa“majorreorganizationofbiotainthePacificNorthwest”andisdirectlyrelatedtothePacificDecadalOscillation.Thewatertemperatureitselfdoesnotinfluencethe
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Figure5.GraywhalemigratoryroutealongthePacificCoastofNorthAmerica.MapCreatedbyMichelleKinzel,2007.
whales,butduetofeedbackloopsinthesystem,thechangesinthehydrosphereareaffectingthepreyavailabilityanddelayingthejourneysouthformanywhalesinthepopulation.
Figure4.ThePacificDecadalOscillation(PDO)isalong-termoceanfluctuationofthePacificOceanwithcoolandwarmphasesoscillatedevery20–30years.Image:CreativeCommonsPermission,https://sealevel.jpl.nasa.gov/science/elninopdo/pdo/
ScientificStudy2)GraywhalesexhibitedresponsesinbehaviortotheextremesofwarmElNinoandcoolerLaNinaoceanicconditionsintheirsouthernrange.Inthebreedinggrounds,therewasadeclineinthepresenceofmother-calfpairsbyhalfandadelayinpeakoccupancyfollowingthewarmElNinoof1997–1998inSanIgnacioLagoon,BajaCalifornia.ThisalterationofbehaviorwasrelatedtothechangeinpreyavailabilityforpregnantgraywhalesduringtheElNinoyear.WithreducedamountsofpreyavailablecausedbythewarmerElNinowaters,thefemalegraywhalesproducedfewercalvesandtooklongertoreachthebirthinglagoons(delayinpeakoccupancy).Thisincreasein
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temperatureandincreaseinpreycreatesaresponseinthegraywhales,anexampleofapositivefeedbackloop.
Figure6.ElNinoisadisruptionoftheocean-atmospheresystemwhichcausesoceantemperaturestoincreasebyafewdegrees.ImageCredit:JPL,http://www.jpl.nasa.gov/imagepolicy/,CreativeCommonsLicensed.
ScientificStudy3)In1999and2000,graywhaleswererecordedfeedingyear-roundinwatersoffshoreofKodiakIsland,Alaska.Duringthistime,increasingnumbersofwhaleswerefoundfeedinginareastraditionallyconsideredmigratinggrounds,aresponsetolackofpreyinthehigherlatitudesthatresultedfromtheElNino.Thislackoftraditionalpreyitems,benthicinvertebrates,causedthegraywhalestoshifttheirprimarypreyandtheirmainfeedinglocations.Becauseofchangesinthebiosphere,thegraywhaleswerefoundinnon-traditionalfeedingareas.
ScientificStudy4)Themostsurprisingandlastexampleofevidenceofashiftinthegraywhales’behaviorcamefromrecordingsofwhalecallsintheBeaufortSea,locatednorthofAlaska,inthewinterof2003–2004.Seaiceconditionsasnotedfromanalysisofsatelliteimageryfoundicecrackslargeenoughtoprovidebreathingholesforgraywhalesduringwinterconditions.ThisprovidedevidencethatthegraywhalescouldpotentiallyoverwinterinArcticconditions,astheywererespondingtothereductioninseaice.Thechangeinthehydrosphere,orreductioninseaice,elicitedadirectbehavioralresponseinthegraywhales’behavior.
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Figure7.Lifecycleofgraywhaleandmigratorymovementsrepresentedinmapformatandinatimeline.ImagebyMichelleKinzel,2015.
Allscientificstudiescitedfromthefollowingjournalarticle:
Moore,S.E.2008.“MarineMammalsAsEcosystemSentinels.”JournalofMarineMammalogy.89(3)534-540.
MarineMammalsasEcosystemSentinels—Pre-ActivityWorksheets
1)Readthesummaryarticle“GrayWhalesAsEcosystemSentinels”byMichelleKinzel,2015.
2)CompletethefollowingchartbasedontheinformationprovidedinthearticleyoureadforStep1.Forhomework,youonlyneedtocompleteallsectionsofthischart.
Tipsforcompletingthechart:
• ScientificStudy:Summarizetheinformationforeachstationnumberbyprovidingashorttitle-likenameforthescientificstudy.
! Examplesmightinclude“FeedinginJuly,”“CalfProduction,”etc.
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• Observation/Facts:Readthearticleandlistanythingthatcanbecategorizedasanobservationorfact.Lookforexampleswithdatareferences,summariesofthingsseenorrecordedandexamplesofscientificevidence.
! SeeExamplebelowrelatedtoClimateChange
• InterpretationofObservation:Theseareoftenreferredtoasahypothesisandofferanexplanationfortheobservationsandfacts.Thesearealsofactual,butcoverabiggerpicturesummaryoroverarchingdescriptionoftheinformationpresented.Keywordsthatindicateastatementisaninterpretationcouldinclude“coincidedwith,”“attributedto,”“relatedto,”etc.
! SeeExamplebelowrelatedtoClimateChange• LifeCycleMostAffected:Determinefromthesummaryprovidedwhichlifecycleis
affected,migration,feedingorbreeding/calving.
ExampleofScientificStudy,ObservationsandInterpretation.Usethisexampletounderstandhowtoidentifyobservations,factsandinterpretthem.
Figure7.Climatechangestudyexamplesshowingeffectsonecosystemsandspecies.
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ScientificStudy:ClimateChangeinOceansAffectingPolarBears
Facts:1)Oceantemperatureshaveincreased.
2)Reflectiveicedisappears,anddarkerwatersabsorbmoreheat.
3)Arcticseaicemeltsastemperaturesriseinhydrosphereandatmosphere.
4)ewerpolarbearcubsaresurviving.
InterpretationofObservation:Thereducedpolarbearcubsurvivalisattributedtofoodshortagescausedbyreductioninhabitatfrommeltingseaice.Thisisanexampleofanegativefeedbackloop.
Question:Howdochangesinthephysicalenvironmentaffectthebiology(reproductivesuccess)ofpolarbearsintheArctic?
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Table1.Completethistablebasedoninformationfromthearticle.
ScientificStudy/Station
NumberObservation/Facts
InterpretationofObservation/CausalFactors
(Scientificreasonrelatedtoclimatechange)
LifeCycleMost
Affected;Feeding,Migration
orBreeding
1
2
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ScientificStudy/Station
NumberObservation/Facts
InterpretationofObservation/CausalFactors
(Scientificreasonrelatedtoclimatechange)
LifeCycleofGrayWhaleMost
Affected;Feeding,Migration
orBreeding
3
4
Question:Whatphysical(hydrosphericoratmospheric)/environmentalandbiologicalfactorsaffectgraywhales?
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Question:Howdothesefactorsaffectthebehaviorofthegraywhale?Arethesedirectorindirectinfluences?
3)Labelthefollowingmapwithscientificstudynumbers.Usethearticle“MarineMammalsAsEcosystemsSentinels”todeterminewhichgeographiclocationcorrelateswithwhichscientificstudy,1–4.Placethenumberofthescientificstudyonthemapinthetextboxofthecorrectgeographiclocation.
Figure8.RangeofeasternNorthPacificgraywhales,depictingcoastalstudysitesfromwintering/breedingareasoffshoreofMexico,summering/feedingareasextendingfromthePacificNorthwesttoAlaska.MapImageCreatedbyMichelleKinzel,GoogleEarth,2015.