The Oceans

An overview

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A quick oceans tour

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Marine ecosystems

• Cover 70% of the Earth’s surface.• List as many different marine ecosystems as

you can.

Marine ecosystems: Estuaries

• Estuaries: fresh water from river mixes with ocean

• Rich in nutrients• Wetlands form in

shallow areas

Estuaries

• • Salt marsh• Estuaries: very

productive ecosystems• What does that mean?

– Make lots of biomass– Lots of plant

growth/m2

– Nurseries for fish, crustaceans

Estuaries

• Coastal• Partly enclosed• One or more rivers

flow into them• Water is brackish—

ranges from fresher upstream to saltier where estuary grades into the ocean.

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Klamath River estuary

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Estuaries

• Value– Aquatic nurseries– Protected harbors– Fishing, other

recreation– Habitat for non-aquatic

animals, such as bald eagles, shorebirds

• Threats– Many near populated

areas• May be filled

– Pollutants• Sewage• Runoff from rivers

Intertidal zone

• Florida salt marsh• Tidal creek running

through it• Whole region is tidal,

meaning affected by the daily tides

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Intertidal zone

• Means: ``region between the tides’’

• Constant change

• Intertidal Zone

Marine ecosystems: mangrove swamps

• Coastal areas• Mangrove trees

grow partly submerged

• Protect coasts from erosion, especially during storms

• Tsunami of ‘04

Mangrove swamp

• Roots hold sediment• Habitat for

thousands of animal species, such as shrimp

• In South America and Southeast Asia, mangrove swamps being cleared for shrimp farms

                                                                                    

Coral reefs

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Coral reefs

• Made of animals = coral polyps• Limestone skeletons form the reefs• Thousands of species of fish, plants live among

the corals biodiversity hotspot• Need light for photosynthesis, water within

temperature and salinity range• BUT: in trouble

– People– Warming oceans

Coral reefs

• Individual corals are polyps• Grow together to form large colonies• BUT: grow very slowly, inch or so a year

corals

• ANIMALS• Individual = polyp• Colonies, like reefs, may

have been in existence for thousands of years

• Most corals contain an algae, zooxanthellae symbiotic

                                 

Coral reef distribution

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• Fishing for tropical fish on coral reefs, using explosives. – For pet stores and for restaurants – Philippines

• Also use cyanide– Small amounts stun fish, but continued use can kill coral

Continental shelf

• aqua color

Continental shelves

• Extension of the continents• Shallow (average about 460 ft)

– Significance?• Light reaches much of the shelf• Teaming with life—many important fisheries

Littoral zone

• Nearest the coast• From high water mark to shallow,

submerged areas

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• Pelagic – water• Benthic – bottom• Abyssal – deep• Photic – affected by

light

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Marine ecosystems

• Open ocean: Pelagic– Fish– Marine mammals– Plankton

• Light at surface

Marine ecosystems

• Deep Ocean: benthic zone– Very cold—light doesn’t penetrate– Few if any plants– Bottom feeding organisms

• Starfish, anemones, sponges

Marine ecosystems

• Deepest reaches of the ocean: Abyssal zone– Cold– Dark– High pressure

• In some places: hydrothermal vents spew superheated water

Ocean circulation

• Ocean conveyor

OCEANS

How they workHow we protect them

Oceanography

• Study of the physical ocean• Cover 71% of the Earth• Contains 97 % of its surface water

Ocean water

• 96.5 % H2O by mass• Remainder: various salts• Temperature:

– Warmer near the surface– Deep water (below ~1000 m) is equally cold

• Density:– Colder, saltier water is denser = deep water

Salinity patterns

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Ocean currents

• Water flows horizontally• Causes?

– Surface: wind– Deep: density differences – salinity,

temperature• ocean conveyor

Vertical movements

• Upwelling– Deep, cold water rises to replace surface waters

that flow away– Brings nutrients to surface– Site of rich fisheries

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Marine ecosystems

• Biological diversitydiversity_over_time.pdf

• Coral reefs form in nutrient poor waters

• Nutrients tied up in living things

• Nutrients tightly recycled

Coral Bleaching

• Corals expel the single-celled algae normally living in their tissues

• Related to global warming

Episodes of coral bleaching

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Marine ecosystems

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