bio 111 marine and coastal ecosystems week7

8/2/2019 Bio 111 Marine and Coastal Ecosystems Week7

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Marine and Coastal Ecosystems


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Ocean covers most of the earth's surface


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amount of O2 in the

water is strongly affected

by photosynthesis andcell respiration

most of the O2 produced

by photosynthesis in the

ocean is released to the

atmosphere

50% of the world's

oxygen comes from

phytoplankton and algae!


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Water flows in complex currents atdifferent levels of depth


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the ocean neverrests

currents move andmix ocean waters

currents transportheat, nutrients,

pollutants, andorganisms

ocean circulationalso affects theearth's climate andtherefore, allhabitats on land


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Deep water circulation

the ocean is a three

dimensional habitat major current maps

only show circulationat the surface - not

greater depths surface water is

partially isolated fromdeeper waters bydifferences in density

because the densestwater sinks, theocean is stratified(layered)

warm water floats ina shallow "lens" ontop of cooler water

sudden changes in

temperature oversmall depth intervalscalled thermoclines


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The Great Ocean Conveyor

after water masses leave

the surface they sink toa depth determined bydensity

to sink all the way to the

bottom of the ocean,surface water mustbecome very dense (coldand salty)

main places wheresurface waters reach thebottom are in the

Atlantic Oceans

after sinking, water

spreads through theAtlantic to other oceanbasins

eventually rises to the

surface again and flowsback to the Atlantic

this circulation is part ofa global pattern knownas the Great OceanConveyor - mixes theearth's oceans on a

4,000 year cycle


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Great Ocean Conveyor


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Effects of the Great Ocean Conveyor

small variations in the conveyor circulation canproduce dramatic changes in weather patternsaround the world

larger changes may even bring on ice ages

note: keep this in mind for our unit on globalwarming


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Why are there tides?

main cause of tides isthe gravity of the moonand sun acting on theocean

the tidal bulges are

largest, and thereforethe tidal range isgreatest, when themoon and sun are in

line and acting together this happens at the

new and full moons

when the moon andsun at pulling at rightangles the bulges andtidal range are smallest

this occurs when the

moon is in quarter


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some oceanzones support

more life thanothers

the upper,sunlit layers

are mostproductive

called thephotic zone


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Vertical movement of water affectsmarine ecosystems

nutrients are neededto supportproductivity in thephotic zone

nutrient rich watersare carried to thesurface nearcontinental margins

process is calledupwelling

upwelling zones occurwhere winds blow thesurface water awayfrom the borders ofthe continents

deeper, nutrient richwater rises to fill inthe gaps


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Upwelling


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The world's most productivefisheries are in upwelling zones

shrimp boats Mississippi

coast


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Examples of marine

ecosystems with highproductivity and biodiversity

Satellite image of chlorophyll concentration


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Satellite image of chlorophyll concentration(indicates areas of high productivity)

high shown ingreen,orange, red

note: highestphytoplankton

concentrationin areas ofhighernutrientavailability

(along coastsand inupwellingzones)


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Coral reefs

coral reefs are the

external skeletonsof tiny marineanimals called

coral polyps the intricate reef

structure supportsenormous

biodiversity


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Coral structure

coral polyps

live brain coral

brain coral skeleton ofcalcium carbonate


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microscopiczooxanthellae (algaeliving within the coraltissues) help coralsbuild reefs byproviding extraenergy fromphotosynthesis

although corals getmost of theirnutrition from thezooxanthellae, theyare also predators

catch small animalswith their tentacles,in a similar way to

jellyfish (close

relatives)

note: keep the zooxanthellae inmind for our discussion of coralbleaching


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looking up from below you can see thefishes school above the reef - I included itbecause it's a pretty cool photo and a goodexample of reef productivity


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Great Barrier Reef 1600 miles long!


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Estuaries: where rivers meet the sea

salinity variesdramaticallyfrom place toplace

most have asandy or softmud bottom

nutrientscarrieddownriver fromthe land

Chesapeake Bay aerial view


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Estuaries are tremendously productiveand home to large numbers of organisms

wild riceplants in thePatuxent River(tributary to theChesapeakeBay)


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Salt Marshes

salt marshes are

grassy areas thatborder estuaries andextend inland fromthe mudflats


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Marsh ecosystems

salt marshes are

subject to extremechanges in salinity,tides, and temperature

communities aredominated by a fewhardy grasses andother salt tolerant

plants

very high primaryproduction

marsh plants trap

and use nutrientswashing off the land(and help preventnutrient pollution)

contributes to theproductivity of thebordering estuaries


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Zonation of salt marsh plants

M f t


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Mangrove forests mangroves are

denseforests of

trees adapted tolive in theintertidal zone

as with salt marsh

plants, mangroveshave differenttolerance to saltwater immersionat high tide

different speciesof mangroves livein zones based onthe level of tidal

flooding

mangrove forestsPuerto Ricoaerial view


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seaweeds, sponges,oysters, and lots ofother types of

organisms liveattached to the rootsof the red mangrove

view above water

view underwater


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75% of all shelteredtropical shores wereonce fringed with

mangroves provided protection

from flooding ofcoastalcommunities,nurseries for fishes,nutrient traps, etc.

human activitieshave destroyedmuch of theseforests around the

world

sprouting mangrovesFlorida Keys


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Pollution threatens marine resources

nets and plastic debrisendanger wildlife

oil pollutionaccumulates from

hundreds of spills peryear

toxic pollution enteraquatic ecosystems

example: mercuryreleased by burningcoal for electricity


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Pollution threatens marine resources

excess nutrients

cause algal blooms nutrients released

from over-fertilization ofagricultural andresidential lands,food processingwaste, sewage

treatment, cattleand chicken feedlots etc.

i i bl


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marine species are renewable resources,but they can be overexploited

piles of oyster shells


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over 70% of allmarine commercial

fisheries are fullyexploited ordepleted

modern,

industrialized fishingoverexploits notonly the targetspecies, but other

species that are notwanted (bycatch)


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Aquaculture

raising marine animalssimilar to farm animals

applies to both freshwater and marine

species if use non-polluting

and sustainablemethods, can take

pressure offoverexploited marinespecies

overexploitation - notice thesmaller size of the fish in thetuna market

bio 111 marine and coastal ecosystems week7

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