Marine Ecosystems

Home , Abyssal plain, Brine pool, Hydrothermal vent, Kelp forest, Rocky shore

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Marine ecosystems occupy specific areas within the ocean. Some are productive near- shore regions, including estuaries, salt marshes, and mangrove forests. Others appear to be completely barren, like the ocean floor. The hydrosphere connects all freshwater and saltwater systems. The high salt content (salinity) and global circulation make marine ecosystems different from other aquatic ecosystems. Other physical factors that determine the distribution of marine ecosystems are geology, temperature, tides, light availability, and geography. Marine ecosystems include: abyssal plain (deep sea coral, whale fall, brine pool), Antarctic, Arctic, coral reef, deep sea (abyssal water column), hydrothermal vent, kelp forest, mangrove, open ocean, rocky shore, salt marsh and mudflat, and sandy shore. Some of these regions are very productive. Others are in constant darkness where photosynthesis cannot occur. Some marine ecosystems go through extreme changes in temperature, light availability, oxygen levels, and other factors on a daily basis. Others are fairly stable and only change slightly at different seasons. The organisms that inhabit marine ecosystems are as diverse as the ecosystems themselves. They must be highly adapted to the physical conditions of the ecosystems in which they live.

The Abyssal Plain ecosystem is one of the least explored regions of the Earth. The abyssal plain runs along the ocean floor between the base of a continental rise and a mid-ocean ridge. The abyssal plain is a harsh environment located at depths between 3,000 and 6,000 meters (10,000–20,000 feet). Little to no light reaches the abyssal plain. High pressures, extreme cold, low oxygen levels, and scarce food availability also characterize this ecosystem. Despite these harsh conditions, research has shown that the abyssal plain can include several different communities of organisms. These include deep sea corals, whale falls, and brine pools.

Deep (cold) water coral communities are distributed globally from coastal Antarctica to the Arctic Circle. They are in the bathypelagic zone and not typically found below 2,000 meters (6,600 feet). They are made up of hard corals, black and horny corals, and soft corals, including gorgonians. Like warm tropical reefs, the hard corals in deep water develop a reef structure that supports a highly diverse community of fish, crabs, urchins, and worms. Unlike warm reefs, however, they lack symbiotic algae (zooxanthellae) because they are in such deep, cold, and often dark water. This is why deep water corals are typically suspension feeders, capturing plankton and organic matter (detritus) out of the water column.

page 1 National Geographic Society © 2011 www.education.nationalgeographic.com/ www.education.nationalgeographic.com/ species. decreasing packicethreatens afragileAntarctic ecosystemthatissodependentuponasingle chain reaction throughout theentire foodweb.Researchers worrythatglobalwarmingand less phytoplanktonisavailable.Withoutenough algaetoeat,krillcandieof Colder wintersmeanmore packiceandmore algaemats.Thisisgoodforthekrillwhen krillfeedonphytoplanktonandalgaematsundertheice. to supportthefoodweb.Inturn, whales, seals,penguins,albatross, petrels, fish,andsquiddependonthepresence ofkrill an estimated500milliontonsofkrill.Krillis the mostabundantanimalinworld.Antar one keyspecies—krill.Krillare planktonicshrimp-likecreatures. Oceancontains TheSouthern array ofmarineorganisms. TheAntarctic foodwebisthesimplestonEarthandbased However, research hasshownthatAntarctic watersare highlyproductive andsupportadiverse zero to24hoursinasingleday. Theseconditions maketheAntarctic aharshenvironment. to icecoverandextremely coldtemperatures. Sunlightexposure intheAntarctic rangesfrom The communities offish,crustaceans,andbacteria. are usedaschemicalenergy forsurrounding musselbeds.Thebedsthensupport the surfaceofabyssalplain.Thebrinepoolcontainshighlevelsmethanegasthat than thesurrounding abyssaloceanwater. Themore densewatersinks,formingpoolson because ofextremely highsalinitiesthatmakethebrinepoolwatermuchmore dense shorelines. Theyare likesmalllakes.Theycanformwithinthesurrounding oceanwater Brine pools community developmentcanlastforseveralyears. consumed forenergy byotherorganisms. Thissuccessionoffeedersandwhalefall by chemosyntheticbacteriatomakeorganic matter. Thatorganic mattercanthenbe As bacteriaincrease anddecomposethewhale,sulfurchemicalsare released andused and othermollusksfeedonthebonesorganic matterinthesurrounding sediment. (hagfish, certaincrabs)are thescavengersthateatsofttissue.Thenworms,snails, are similartohydrothermal ventandseepcommunities.Afterawhalefalls,thefirstfeeders development ofcomplexanimalcommunitiesandfeedingrelationships. Inthisway, they communities supplyorganic matter(upto160tonsfrom onewhale)andleadtothe zone. Thiszoneisusuallysparselypopulatedandminimallyproductive, butwhalefall shelves andthedeepocean.Whalefallcommunitiesare foundintheabyssopelagic their migratoryroutes andfeedinggrounds. Theseregions tendtobealongcontinental sea floor. Whalefallscanexistbelowanywaterswhere whalesare found,especiallyalong A Antarctic whale fall ecosystem of the Southern Oceanwasoncethoughttoberather barren ecosystemoftheSouthern due are areas ontheseafloor(abyssopelagiczone)thathavedistinctsurfacesand communityiscreated whenadeadwhalesinksandtransportsnutrientstothe Marine Ecosystems f andcreate a ctica’s page 2

© 2011 National Geographic Society www.education.nationalgeographic.com/ pressures, extreme cold,lowoxygenlevels,andscarce foodavailability. Thedeepseaisless The deepseaisaharshenvironment. Itischaracterizedbylittle-to-no lightpenetration,high (13,000–20,000 feet).Thisecosystemcontains 98percent ofalltheliving spaceonEarth. is below200meters(656feet).Itincludesthe abyssalzonebetween4,000and6,000meters The action from storms. factors includeincreased temperatures andnutrientrunoff, decreased waterclarity, andwave are fragilesystemsandtheirhealthorgrowth canbeimpactedbyseveralfactors.These world’s reefs containover4,000different fishspeciesandhundreds ofcoralspecies.Corals also provide spawning,nursery, refuge, andfeedingareas formanymarineorganisms. The are hometoeverythingfrom spongesandjelliestooctopus,mantarays,sharks.They of yearsold.Coralreefs are oneofthemostbiologicallydiverseecosystemsinworldand (zooxanthellae) livewithinthetissuesofreef-building corals.Somecoralreefs are thousands Reef-building coralpolypsdivideastheygrow, forminglayeruponlayer. Symbioticalgae andstaghorn. brain corals,pillarplateandbranchingcoralslikeelkhorn are responsible forcreating thestructure ofthereef. Commontypesofstonycoralsinclude and tree corals.Stony, orreef-building, coralsproduce calciumcarbonateskeletonsand include theseafans,whips,andplumes.True softcoralsincludeblack,mushroom, are colonial.Colonialcoralscontainthousandsofpolyps.Examplesflexiblesoft and are madeupoftinyanimals,calledpolyps.Somecoralscontainasinglepolypbutmost Some coralscanliveincolder, deeperwaters. Coralscanbeclassifiedashard (stony)orsoft, ocean. Theseareas are atlatitudesbetweentheTropic andTropic ofCapricorn ofCancer. Coral Reefs impacts. ecosystem thatisvulnerabletothreats from climatechange,decreased icecover, andhuman The Arctic ecosystemcontainshighlyadaptedspeciesandacomplexfoodweb.Itisfragile organisms supportanumberofArctic predators, includingbirds, foxes,seals,andpolarbears. jellies, andfishare foundinthewatercolumnbetweenArctic seafloorandice.These macrophytes (large algae)are alsofound.Phytoplankton,copepodsandotherzooplankton, sponges, mollusks,crabs,andanemones.Inshallowerdepthswher web. TheArctic seaflooriscomprisedofnumerous invertebrates,includingseastars,worms, and channelsoftheiceatice-waterinterface.TheyformbaseAr ice, andalongtheseabed.Worms, copepods,bacteria,andphytoplanktonlive withinpores thrive there. Arctic oceanspeciesare distributedthroughout thewatercolumn,within of lightandyear-round icecover. Adiversearrayofhighlyadaptedorganisms interactand The Deep Sea Arctic ecosystem of the northern polarregion ecosystemofthenorthern ischaracterizedbyextreme seasonality primarilyoccurthroughout thewarmtropical andsubtropical regions ofthe (abyssalwatercolumn)ecosystemcoversthe vastzoneofopenoceanthat Marine Ecosystems e sunlightisavailable, ctic food page 3

© 2011 National Geographic Society www.education.nationalgeographic.com/ food websincludeseveral fishspecies,numerous invertebrates(snails,crabs,lobster, sea provide aprotected andbiomass-richhabitatthatsupportsacomplexfoodweb.Kelpforest inches) perday. Theyare oneofthemostproductive anddynamicmarineecosystems.They that prefer clearandcold,nutrient-richwaters.Theycangrow asmuch50centimeters(20 several understorykelpspecies.Kelpspecies are seaweedsorbrown macroalgae (large algae) dominated bytwocanopy-formingkelpspecies (giantkelpandbullkelp).Theyalsocontain meters (6to90feet).Theyare oftencalledunderwater“forests” becausetheyare layered and coastsofthe PacificOcean,fromtoAlaska,atdepthsof227 eastern Baja California Kelp Forests process drivestheentire hydrothermal ventfoodweb. bacteria-like organisms (archaea)chemicalenergy turn from theventsintouseableenergy. This or plants,butprimaryproductivity occursthrough chemosynthesis.Thisprocess occurswhen ecosystems around theworld.Nolightisavailabletosupportphotosynthesisbymarinealgae even fish.Hundreds ofspeciesanimalshavebeenidentifiedinthehydrothermal vent include severalspeciesofbacteria,tubeworms,giantmussels,crabs,lobster ecosystems supportfamiliar, yetuniqueand specifically-adaptedlifeforms. Vent organisms is theunderwatermountainchainthatwindsitswayaround theglobe.Hydrothermal vent meters (7,000feet).Theyare concentratedalongtheMid-OceanRidge.TheRidge found inboththePacificandAtlanticOceansatanaverageunderwaterdepthofabout 2,100 composed ofcompoundsincludingbarium,calcium,andsilicon.Hydr composed mostlyofiron andsulfide.The“whitesmokers” release acooler, lightermaterial hydrothermal vents.Thehottestofthevents,called“blacksmokers,”spewadark“smoke” rich water. Thisventwatercanreach temperatures ofupto750°F. There are twotypesof Hydrothermal Vents that there are manymore deepseaorganisms lefttobediscovered. of thedeepsea.Itisdifficulttoaccessandexplore thedeepsea.However, scientistsbelieve flexible bodystructure (siphonophore, dumbooctopus)sotheycanhandlethehighpressures also helpsthemcommunicatewithspeciesoftheirownkind.Manyor silver orbioluminescentusetheircolorationtofrightenconfusepr silver, red, ortranslucentincolor(siphonophores, jellies,mysidshrimp).Organisms thatare strong senseofsmell(fish).Manyfishandinvertebrateshide from predators bybeingblack, bioluminescence (combjellies,squid,anglerfish)orhavelarge eyes(squid,octopus)anda the deepsea.Inorder to“see”inthedarkandfindfoodmates,manyorganisms use down from upperlayersoftheocean.Severalorganisms are well-adaptedtosurvivein results inafoodwebthatdependsondeadorganisms andorganic matter(detritus)sinking productive andpopulatedthanothermarineecosystems.Thelackoflightforphotosynthesis are coastalhabitatsfoundworldwide.Theyare mostabundantalongtherocky are fissures (openings)intheoceanfloorwhich releasehot,mineral- Marine Ecosystems edators. Theircoloration ganisms haveasoft, othermal ventsare , octopus,and page 4

© 2011 National Geographic Society www.education.nationalgeographic.com/ of theocean.Currents alsohelpsomeanimals migrate andallowotherstodistributetheir the baseofopenoceanfoodweb.Open oceancurrents carrynutrients todifferent parts found intheopenocean.Large populationsofplanktondriftalongonoceancurrents andform to dominate,invertebratespeciesactuallymake upover95percent of theanimalspecies fish alsoplayanimportantpartinthisecosystem. Althoughthemegafaunaar and seaturtlestomicroscopic planktonandsmallschoolingfish.Sea birds andlarge migratory open oceanorganisms rangesfrom megafauna,orlarge animals likesharks,whales,dolphin, a highlydiverseanddynamicecosystemthat containsawidevarietyoflife.Thediversity 200 meters(656feet)ofwater. Thisdistinguishesitfrom thedeepseaecosystembelow. Itis encompasses theentire watercolumn.Theopenoceanzonegenerally refers totheupper volume oftheworldocean.Itextendsfrom theedgeofcontinentalshelfoutward and Open Ocean throughout theworld. but coastaldevelopmentandpollutionhavedestroyed significantamountsofmangrove habitat fisheries withinandadjacenttomangroves. Mangroves oncecovered vastareas ofcoastlines, ocean, sandyshores) asadults.Thismakesmangrove ecosystemsavitalpartofmaintaining also asanurseryground. Theywillthenmigratetoothermarineecosystems(coralreefs, open fish, andbirds. Manyoftheseorganisms usethemangrove forprotection andfeeding, economically importantorganisms, snails,mussels,crabs, includingalgae,sponges,barnacles, and shellfish.Themangrove forest provides acomplexhabitatformanyecologicallyand serve asasubstrate(placeofattachment)fornumerous speciesofsponges,tunicates,algae, and nutrientsfrom reaching nearbyseagrassandcoralreef ecosystems.Theprop roots also decreasing waterflow. Thisallowssedimentstoaccumulate.prevents excesssediment serve manyimportantfunctions.Theystabilizetheshoreline byabsorbingwaveactionand partially exposednetworkofroots (prop roots) thatgrow downfrom theirbranches.Theirroots are foundclosesttothewater’s edge.They are oftensubmerged inshallowwaterwithathick, them obtainoxygenandrelease excesssalt.Redmangroves are themostsalt-tolerantand mangrove andare foundfartherfrom thewater’s edge.Theyhavespecialadaptationstohelp red, black,andwhitemangroves. Blackandwhitemangroves are lesssalt-tolerantthanthered South America,Africa,theMiddleEast,Asia,andOceania.TheU.S.onlyhasthr different speciesofmangrove trees throughout thetropical andsubtropical zonesofNorthand are locatedinshallow, low-oxygensandyormuddyareas alongshorelines. There are over80 Mangrove in salinityandtemperature. productivity andbiomass.Theyare vulnerabletowaveaction,increased turbidity, andchanges stars, seaurchins, worms),andlarge mammals(sealions).Kelpforests havehighlevelsof ecosystems are comprised of salt-tolerant, woody mangrove trees and shrubs. They isthelargest marineecosystem.Itcontainsapproximately 65percent ofthe Marine Ecosystems e large andseem ee species: page 5

© 2011 National Geographic Society www.education.nationalgeographic.com/ tidal flatsforfeeding. Fish andcrabsmovethrough theflatsathightide.Migratorybirds andpredatory animalsvisit on plankton.Theseburrowing animalsbreathe through tubestogetoxygenfrom thesurface. crustaceans, andclams.Manyoftheseanimals burrow underthemud surfaceandfilter-feed Phytoplankton andzooplanktonare abundantandprovide foodformudsnails,oysters,worms, bayous, barrierislands,andlagoons.Biodiversity inmudflatsislowerthansaltmarshes. nutrients (detritus).Mudflatsare oftenassociatedwithintertidalzones likebays,estuaries, or seagrassmeadows.Theyformwhentides orriversdepositlayersofmud(silt,clay)and as anursery. Mudflatsoftencoverlow-lyingareas betweensaltmarshvegetation,mangroves, vegetation alsoprovides protection andfoodforfish,crab,shrimpthatusetheecosystem Bacteria decomposethedetritusandhelprecycle itbackintothesystemasnutrients.Marsh marshes. Saltmarshplantsprovide acontinuoussupplyofdeadorganic matter(detritus). insects) andaquaticorganisms (algae,turtles,crabs,fish)interactincomplexwayswithinsalt and mudflats.Attheland-seainterface,terrestrial organisms (grasses,birds, raccoons, structural zonesthatformdistincthabitatswithinthesaltmarsh:levees,pannes,pools, trees. Theyare oneofthemostproductive ecosystemsonEarth.Theycontainseveraldifferent Salt marshesare characterizedbysalt-tolerantgrassesandotherlow-lyingplants,butno the organisms inthisecosystemtoadjustchangeswaterdepth,salinity, andtemperature. land andsea.Theyare eitherperiodicallyorcontinuouslysaturatedbysaltwater. Thisrequires Salt MarshesandMudflats humans, birds, cats,rodents thathaveaccesstotherocky shore. shore facesomeotherthreats. Theymustalsoprotect themselvesfrom terrestrial specieslike adapted totheextreme conditionsoftherocky shore ecosystem.Organisms oftherocky including urchins,anemones,seastars,andhares crabs,mussels,barnacles, are well- rocky shores are highlycomplexandbiologicallydiverse.Numerous marineinvertebrates, and waveaction.Sometimesthesechangesoccurmore thantwotimesaday. Tidepoolsand the rocky shore mustbeabletotolerateextreme changesintemperature, salinity, moisture, rocky shore oneofthemostphysicallystressful marineecosystems.Organisms thatlivealong completely exposedtotheair(aerialexposure) andsunlight.Theseabioticfactorsmakethe covered withwateratcertaintimesoftheday. Atothertimes,thesesameareas canbe influences create distincttidalzones.Changingtidescause rocky shore areas tobecompletely Rocky Shore and sparse. circulation) oftheopenoceanare fairlyconsistent,there are areas where lifeisbothabundant eggs throughout theocean.Eventhoughabioticconditions(light,temperature, salinity, ecosystemsare coastalareas withsolidrock substrate(foundation).Strong tidal Marine Ecosystems are low, wet,muddy areas thatlieatthe interfacebetweenthe page 6

© 2011 National Geographic Society www.education.nationalgeographic.com/ humans, birds, cats,rodents thathaveaccesstothem. coastal fisheries.Sandyshore organisms mustprotect themselvesfrom terrestrial specieslike shore ecosystemsplayanimportantrole infilteringseawater, cyclingnutrients,andsustaining stars. Birds andturtlesmigrateusesandybeachesasfeedingnestingsites.Sandy hermit crabs,seaurchins,snails,hares, seagrasses,algae,barnacles, mussels,and them from dryingoutduringlowtide.Examplesofresidential sandyshore speciesinclude type ofenvironment. Theabilitytoburrow inthesandprotects themfrom wavesandprevents vary according tolocalclimateandgeology. Theyallhavespecialadaptationstosurviveinthis ecosystem unstableformanyplantsandanimals.Theorganisms thatinhabitthesandyshore surface layersofthesandyshore are alwaysinmotionfrom wavesandwind.Thismakesthe the beachcomesfrom theweatheringanddecayofrocks, corals,seashells,andminerals.The are exposedshoreline systemsofoneormore sandridgescreated bythewind.Mostsandon are exposedbetweentheextreme highandlowtidemarks.Theyare mostlyflat.Sanddunes Sandy Shores are low-lyingareas oflooselydepositedsand,gravel,orshells.Sandyshores Marine Ecosystems page 7