The Secret Life of The Ocean
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Transcript of The Secret Life of The Ocean
CONTENTS
Introduction 01
Taxonomy: 06
01NanoplanktonicFlagellates 09
02Cnidarians 09
03PhylumRotifera 11
04Polychaeta 11
05MarineGastropods 13
06Chaetognatha 13
07Tunicates 13
08Cladocera 15
09Krill 15
10InsectLarvae 15
11Copepods 17
LivinginGroups: 18
Apaptations 19
NightSwimming 20
CommunitiesofZooplankton 21
Colphon 24
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Zooplanktonarethetinyanimalsthatfloataroundonthesurfaceoftheoceanandfeedonthemicroscopicplantsthatmakeupthephytoplankton,oroneachother.Theyaresosmallthattheycannoteasilybeseenandsoformostpeopletheydon’tevenexist.Butwhatwouldhappeniftheydidn’t?
Wehavecluesfromthefossilrecord.AttheendofthePermiantherewasahugeextinctioneventthattookoutanestimated95%ofalllivingspeciesatthetime.Again,attheendoftheCretaceous,therewasanothermassiveextinctioneventwhichtook
outnotonlyallthedinosaursbutmanyotherspeciesaswell,includingthemajorityoflargemarinespecies.ThecausesoftheseextinctioneventsarestilldebatablealthoughthereisstrongevidenceforameteorstrikeattheendoftheCretaceous.Whatdoesseemevidentisthatwholeecosystemscollapsedbecausethefoodchainscollapsed.Whentheplantsandanimalsatthebottomofthefoodchaindiedintheirmillionsorevenbillions,animalsfurtherupthefoodchaindiedoutforlackoffood.Eveniftheysurvivedtheinitialcatastrophe,theystarvedintheyearsofdearthfollowing.
Thisiswhatwouldhappentothemarineecosystemsifsomethingweretohappentothezooplankton.Evennow,thiscanbeseeninthephenomenonknownasElNino,whenthecurrentsoffSouthAmericachange.NormallythereareareasofupwellingoffPeruwherenutrient-richcoldwatersrisetothesurface,whichleadstoplanktonbloomswhichfeedthefish.WhenanElNinoeventoccurs,thecurrentschange,theupwellingdoesnotoccur,theplanktonbloomsfailandthefisheitherstarveormoveelsewhere.Otheranimalssuchaspenguinsandsealsarealsoaffectedandmanychicksand
INTRODUCTIONBy Marine Biologist M. E. Skeel
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pupsunluckyenoughtobeborninsuchyearswillstarve.
Halfthewhalesoftheworldarebaleenwhalesandtheyaretotallydependentuponphytoandzooplanktonfortheirfood.Thesewhalesaremigratory,goingtowarmtropicalwaterstoraisetheirbabies.ThentheytravelgreatdistancestoareasofupwellingincolderwaterssuchastheSubantarcticConvergencewhereplanktonthriveonrisingnutrients.Ittakesmillionsofplanktonicorganismsineachmouthfultosustainahumpbackwhale.Tosustainanentirepopulationofeven
onespeciesofbaleenwhalestakesbillionsofplanktoneveryyear.Eachwhalehastoeatenoughtosustainitselfnotonlyforthesixmonthsoffeedingbutafurthersixmonthsoftravel,breedingandchildrearinginnutrientandfood-poortropicalwaters.
Arephytoplanktonenoughtosustainthewhales?Apparentlynot.Whattheyneedarekrill;millionsandmillionsoftinycrustaceansthatresembleshrimp.TheseanimalsarethebasisoftheentireAntarcticfoodchain,supportingthefish,thesharks,penguins,sealsandwhales.Removethesetiny
animalsandpotentiallytheentireecosystemwouldcollapse,withdireconsequencestoalltheselifeforms.
Soarethezooplanktonoftheworld’soceansinanydanger?Itdoesn’tlooklikewearegoingtobehitbyameteoranytimesoonbutthereisadangerclosertohome:ourselves.Aswedepletetheoceansofthelargerfish,wearefishinglowerandloweronthefoodchain.Nowlargefactoryshipsarebeginningtotakekrill.Someofitgoesforfertilizersandalotofitendsupinpetfood.Afewpeoplearemakingalargeprofitonthese
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tinyanimals.Butifweoverfishthezooplanktoncommunities,weriskthecollapseoftheoceansecosystemsandthenwewillfindoutjusthowimportantzooplanktonare.
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Zooplankton aretinyanimalsfoundinalloceanzones,particularlythepelagicandlittoralzonesintheocean,butalsoinponds,lakes,andrivers.They are a key component of marine ecosystems.
ZOOPLANKTON:(zoh-plankton)
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Zooplanktonsareclassifiedbysizeandbydevelopmentalstage.Sizecategoriesinclude:picoplanktonthatmeasurelessthantwomicrometers,nanoplanktonmeasurebetweentwoto20µm,microplanktonmeasurebetween20µmupto200µm,mesoplanktonmeasurebetween0.2mmupto20mm,alsomacroplanktonmeasurebetween20mmto200mm,andthemegaplankton,whichmeasureover200mm(almost8inches).Therearetwocategoriesusedtoclassifyzooplanktonbytheirstageofdevelopment:meroplanktonandholoplankton.Meroplanktonsareactuallylarvaethateventuallychange
TAXONOMYInformation by marinebio.org
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intoworms,mollusks,crustaceans,coral,echinoderms,fishes,orinsects.Holoplanktonremainplanktonfortheirentirelifecycle,andincludepteropods,chaetognaths,larvaceans,siphonophores,andcopepods.
Meroplanktonandholoplanktonarecomponentsofalmosteverytaxonomicgroup.However,themostcommon
planktonareprotists,nanoplanktonic
flagellates,cnidarians,ctenophores,
rotifers,chaetognatha,veligerlarvae,
copepods,cladocera,euphausids,
krillandtunicates.Protistsproduceenergybyphotosynthesisandformthe
baseofmarinefoodwebsasprimaryproducers.Protozoaarealsoprotistsandaresimilartoanimals.Protozoamakeupahugepartofmicroandnanozooplankton,suchasamoebas,ciliates,andflagellates.Theseanimalsdonotphotosynthesizeenergy.SomeamoebassuchasthoseclassifiedasForaminiferaandActinopodahavehardskeletons,usuallylargerthan2millimetersindiameter,thathelpformdeep-seasediment.
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01 02Zooplanktonalsoincludethenanoplanktonicflagellatesthathelpkeepbacteriapopulationsundercontrol.Theyarecharacterizedbyeitheralongtailusedforswimming(flagellates)orbyhair-likestructurescalledcilia(ciliates).Somedinoflagellateshaveanet-likestructurecalledaprotoplasmicnet—usedtocaptureandeatpreythataretypicallylargerinsizethanbacteria.Somedinoflagellatespeciesarealsoresponsibleforharmfulfishkillsandtheinfamousredtides.Ciliatesarecapableofcatchingbacteria,otherprotistsandphytoplankton.
Mixotrophsareanamazingorganismthatarehalfplantandhalfanimal.Mixotrophshavetheabilitytoingestotherorganismsthroughphagocytosis(phago:“toeat”+cytosis:“cells”=theprocessofengulfingothercellsforingestion)butalsocontainfunctionalphotosyntheticstructures.
NANOPLANKTONIC FLAGELLATES
Cnidariaisaphylumthatcontainsthecolonialsiphonophoresandthescyphozoans—alsoknownasthetruejellyfish.Bothoftheseanimalsarepredatorsandhavestingingtentacles.Theyarenotfoundofteninfreshwaterandintheoceantheyinhabitthelayersclosertothesurface.CombjelliesorctenophoreswerepreviouslyclassifiedunderCnidariabuthaverecentlybeendistinguishedfromotherjellyfishbecausetheylackthecharacteristicstingingcellsofotherjellyfishknownasnematocysts.Combjellieskeepcopepodzooplanktonlevelsincheckthroughpredation.
CNIDARIANS
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03 04PHYLUM ROTIFERA
Thereareabout2,375speciesofrotifersinfreshwaterandonly125intheocean.Mostoftherotifersarenon-motile(notabletomove)butabout100speciesareholoplanktonic.Theyusuallyeatbacteria,detritus,otherrotifers,algaeorprotozoa.Rotifersarehighlyefficientreproducers.Theyareabletoreproduceasexually(withoutamate)whenenvironmentalconditionsaregood,andsexuallywhenenvironmentalconditionsarestressful.Thisabilityallowsrotiferstoconserveenergyingoodconditionsandadapttotheirenvironmentinstressfulconditions.Adaptationispossiblethroughsexualreproductionbecauseavarietyof
offspringareproduced,allowingtheindividualsbestsuitedtotheenvironmenttosurvive.
Thesetinyanimalsarequiteuniquebecausetheydemonstrateincrediblecomplexityincomparisonwithorganismsofasimilarsize.Thedistinguishingfeatureofarotiferisitscorona,acollectionofciliashapedlikeawheelaroundtheheadendoftheorganism.Astheciliamove,theycreateacurrentwhichsucksinfoodfortherotiferandhelpsittonavigate.
POLYCHAETA
ThePolychaetaorpolychaetesareaclassofannelidworms,generallymarine.Eachbodysegmenthasapairoffleshyprotrusionscalledparapodiathatbearmanybristles,calledchaetae,whicharemadeofchitin.Polychaetameans“many-bristled”(asopposedtotheOligochaetawhichare“few-bristled”),andindeedthepolychaetesaresometimesreferredtoasbristleworms.Morethan10,000speciesaredescribedinthisclass.Commonrepresentativesincludethelugworm(Arenicolamarina)andthesandwormorclamwormNereis.
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05 06 07ThechaetognathaorArrowwormsaremostlyholoplanktonicandareabundantworldwide.Thesetransparentwormsareapproximately3cmlongandhavefinsonthesidesoftheirbodies.
MARINE GASTROPODS
Anothertypeofzooplanktonincludethelarvaeofbenthicmollusksusuallyfoundincoastalwaters,suchasmarinegastropodsincludingheteropodsorpteropods.
CHAETOGNATHA TUNICATES
Sometunicatesareplanktonic,suchastheholoplanktonicclassesAppendiculariaandThaliasia.Botharefilterfeeders;Appendiculariaconsumessmallfoodparticlesusingamucousfilter.Othertypesoftunicatesarebenthicandareonlyplanktonicduringtheirlarvalstages.
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08 09 10CLADOCERANS
Claudoceraarefoundincoastalwaters.Theyswimusinganantenna,likecopepods,butinsteadofusingtheirfirstantenna—theyusethesecondantenna.Theyappeartohavetwosectionstotheirbodybutit’sonlyanillusioncausedbyafoldedoutershell.Cladoceranseatphytoplanktonandotherzooplankton.Likemanyspeciesofzooplankton,cladoceransmigratetothesurfaceatnight.Thisisreferredtoas“diurnalmigration”.
KRILL (Euphausia superba)
INSECT LARVAE
ThelarvaeofthemidgeChaoborusistheonlywidelyknowninsectlarvaeclassifiedasplankton.Chaoboruscomesupduringthenighttofloatwithotherplanktonandeatsmanytypesofzooplanktoninlakes.
Krill,classifiedunderEuphausids,arefoundallovertheworld.Theycanbe3cmlargeandareanimportantsourceoffoodformanytypesofwhales.Incoldwaters,krilloftenfeedondiatoms,atypeofphytoplankton.Inwarmerwatertheyeatotheranimals.
(Phylum Arthropoda, Subphylum Crus-tacea, Order Copepoda)
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11Mostmacrozooplanktonarecopepodsfoundinmarineandfreshwaterecosystems.Copepodsswimusinganantennaandfrontalstructuresontheirbodies.Theyeatphytoplanktonanddetritus,andoccasionallyotherzooplanktonsmallerinsize.
COPEPODS(Phylum Arthropoda, Subphylum Crus-tacea, Order Copepoda)
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Allspeciesofplanktonhavebeenforcedtodevelopcertainstructuraladaptationstobeabletofloatinthewatercolumn.Adaptationsinclude:flatbodies,lateralspines,oildroplets,floatsfilledwithgases,sheathsmadeofgel-likesubstances,andionreplacement.Theflatbodyandspinesallowsomespeciesofplanktontoresistsinkingbyincreasingthesurfaceareaoftheirbodieswhileminimizingthevolume.Allotheradaptationskeepplanktonfromsinkingquicklytothebottom.Zooplanktonhavealsoadaptedmechanismstodeterfish(theirheaviestpredator)including:
transparentbodies,brightcolors,badtastes,redcoloringindeeperwater,andcyclomorphosis.Cyclomorphosisoccurswhenpredatorsreleasechemicalsinthewaterthatsignalzooplankton,suchasrotifersorcladocerans,toincreasetheirspinesandprotectiveshields.
ADAPTATIONS
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Manytypesofzooplanktonmigratedeeperintothewaterduringthedayandcomeupatnight.Themigrationofspeciesappearstobedependentonlocationratherthanparticularspeciestypes.Allplanktonmigratedifferentlybasedonfactorslikeage,sexandtheseason.Theamountoflightisprobablythemajorfactorintheextentofmigratorybehavior.Itseemsthatzooplanktonmovearoundmostinlowlightandleastinhigherlightsituations.It’spossiblethatzooplanktonmigratetolowerlevelsduringthedaysotheyarelessvisibletopredatorsrelyingonvision.At
night,zooplanktoncansneakuptothesurfaceandsnackonphytoplanktonrelativelysafely.Thelowermetabolismoccurringincolderwatersduringthedaymayalsobeafactorinthemigrationofzooplankton.Thisway,zooplanktoncansaveenergybyfeedinginthecooler,nightwaters.Thefactthatdifferentspeciesofzooplanktonhavevaryingmigrationtimesseemstobetheresultofapartitioningofresources.
NIGHT SWIMMING
Copepods
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Specificspeciesofzooplanktonoccupyparticularmarinehabitats.Eachspeciesisuniquelyadaptedtofactorslikelight,temperature,turbulence,andsalinityinitsenvironment.ZooplanktonononesideoftheGulfStreamaredifferentspeciesfromthoseontheotherside.Thesecharacteristicsofdifferentspeciesofzooplanktoncansometimeshelpscientistsdistinguishonewatermassfromanother.
Zooplanktonarealsosensitivetotheirenvironmentandlikephytoplankton—achangeinzooplanktonconcentrationcanindicateasubtleenvironmental
change.Zooplanktonarehighlyresponsivetonutrientlevels,temperatures,pollution,foodthatisnotnutritious,levelsoflight,andincreasesinpredation.Aswellasprovidinganessentiallinkinthemarinefoodchain(whichisanunderstatement),thediversityofspecies,amountofbiomassandabundanceofzooplanktoncommunitiescanbeusedtodeterminethehealthofanecosystem.
Thereareotherfactorsthatinfluencethedistributionofzooplanktonlikepredation,reproduction,communityinteractionsandtheamountof
COMMUNITIES OF ZOOPLANKTON
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availableresources.Zooplanktoncanalsobepredatorsofalgaeorprotozoacausingthesizesoftheseorganismstochangethroughevolution.Whenlightconcentrationsinborealortemperateareasincreaseinspring,phytoplanktoncommunitiesincreaseinnumber.Becausezooplanktonfeedonsmalerplanktonslikephytoplankton,thenumbersofzooplanktonincreaseinresponseduringthespring.However,thereactionofzooplanktonisdependentonthespeciestypeaswell,sosometimesthezooplanktonnumbersincreaseonlyinthesummerwithotherspikeinthefall.
ZooplanktonarealsoaffectedbylevelsofpH,heavymetals,calcium,andaluminum.Nutrientslikenitrogenandphosphoruswillaffectthepreyofzooplankton(likealgae,protozoaandbacteria),indirectlyaffectingzooplanktonsurvival.Scientistsarestillputtingtogetherpiecesofthezooplanktonpuzzle.Somequestionsincludehownutrientlevelsfoundinalgaecaninfluencethegrowthandbehaviorofzooplankton.Otherquestionsconsideredimportanttomarineandhumanlifeishowtoxinsandpollutionisaffectingthiscruciallinkinthefoodchain.
Chaoborus
23Podon sp
Marinebio.orgReferences
Dinoflagellates-AndrewMacRae,PalynologyatTheUniversityofCalgaryDept.ofGeologyandGeophysicsKrill:ChesapeakeBayProgramZooplanktonProjectZooplanktonEcology-DepartmentofFisheriesandAquaticSciences,UniversityofFloridaRobertW.Sanders,“Zooplankton”,inAccessScience@McGraw-Hill,http://www.accessscience.com,DOI10.1036/1097-8542.756950
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GraphicDesignandSilkscreen
ParsonsTheNewSchoolforDesign
Professors:KatarzynaGruda
WilliamMorrisey
Design:MariaA.Gonzalez
Typefaces:AkzidenzGrotesk
BodoniOldFaceBE.
Software:InDesignCS4
Text:marinebio.org
M.E.Skeel(www.helium.com)
Images:Flickr
GuidetotheMarineZooplanktonof
southeasternAustralia.(http://www.
tafi.org.au/zooplankton/index.html)
COLOPHON
Noctiluca scintillans