Upload
raisie
View
44
Download
0
Tags:
Embed Size (px)
DESCRIPTION
The Oceans. An overview. A quick oceans tour. Marine ecosystems. Cover 70% of the Earth’s surface. List as many different marine ecosystems as you can. Estuaries: fresh water from river mixes with ocean Rich in nutrients Wetlands form in shallow areas. Marine ecosystems: Estuaries. - PowerPoint PPT Presentation
Citation preview
The Oceans
An overview
•
A quick oceans tour
•
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.
•
Klamath River estuary
•
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
•
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
•
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
•
•
• 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
•
•
• Pelagic – water• Benthic – bottom• Abyssal – deep• Photic – affected by
light
•
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
•
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
•
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
•
Marine ecosystems
•