Aquatic ecosystems (2)


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Aquatic ecosystems (2)

  2. 2. What are the basic needs of aquatic biota? <ul><li>CO 2 </li></ul><ul><li>O 2 </li></ul><ul><li>Sunlight </li></ul><ul><li>Nutrients- food & minerals </li></ul>
  3. 3. What factors influence the availability of those basic needs? <ul><li>Substances dissolved in water- Nitrates, phosphates, potassium, O 2 </li></ul><ul><li>Suspended matter- (silt, algae) can affect light penetration </li></ul><ul><li>Depth </li></ul><ul><li>Temperature </li></ul><ul><li>Rate of flow </li></ul><ul><li>Bottom characteristics (muddy, sandy, or rocky) </li></ul><ul><li>Internal convection currents </li></ul><ul><li>Connection to or isolation from other aquatic ecosystems. </li></ul>
  4. 4. Types of Aquatic Ecosystems <ul><li>Freshwater Ecosystems </li></ul><ul><ul><li>Standing Water- lakes & ponds </li></ul></ul><ul><ul><li>Moving Water- rivers & streams </li></ul></ul><ul><li>Transitional Communities </li></ul><ul><ul><li>Estuaries </li></ul></ul><ul><ul><li>Wetlands- bogs/fens, swamps, marshes </li></ul></ul><ul><li>Marine Ecosystems </li></ul><ul><ul><li>Shorelines </li></ul></ul><ul><ul><li>Barrier Islands </li></ul></ul><ul><ul><li>Coral Reefs </li></ul></ul><ul><ul><li>Open Ocean </li></ul></ul>
  5. 5. Freshwater Ecosystems <ul><li>Usually 0.005% salt </li></ul><ul><ul><li>Some exceptions: </li></ul></ul><ul><ul><ul><li>Great Salt Lakes- </li></ul></ul></ul><ul><ul><li>5-27% salt </li></ul></ul><ul><ul><ul><li>Dead Sea- 30% salt </li></ul></ul></ul><ul><li>Moving water- high elevations; cold; high O 2 ; trout; streamlined plants </li></ul><ul><li>Standing water- lower elevations; warmer; less O 2 ; bass, amphibians; cattails, rushes </li></ul>
  6. 6. How is a lake stratified and what lives in each level? <ul><li>Epilimnion- upper layer of warm water; high light & O 2 ; ex: water striders, phyto- & zooplankton, fish </li></ul><ul><li>Thermocline (mesolimnion); middle layer; medium light & O 2 ; ex: phyto- & zooplankton, fish </li></ul><ul><li>Hypolimnion- lower layer of cold water; lower light & O 2 ; ex: fish </li></ul><ul><li>Benthos- bottom level; no light & little O 2 ; ex: anaerobic bacteria, leeches; insect larvae </li></ul><ul><li>Littoral- near the shoreline; cattails, rushes, amphibians, etc. </li></ul>
  7. 7. Transitional Communities <ul><li>ESTUARIES </li></ul><ul><li>Where freshwater dumps into ocean </li></ul><ul><li>Brackish (less salty than seawater) </li></ul><ul><li>Has rich sediments that often form deltas </li></ul><ul><li>Productive & biodiverse </li></ul><ul><li>Organisms adapted to varying levels of salinity as tide ebbs & flows </li></ul><ul><li>“ Nursery” for larval forms of many aquatic species of commercial fish & shellfish </li></ul>
  8. 8. Transitional Communities <ul><li>WETLANDS </li></ul><ul><li>Land saturated at least part of the year </li></ul><ul><li>Swamps- have trees like bald cypress; high productivity </li></ul><ul><li>Marshes- no trees; tall grasses; high productivity </li></ul><ul><li>Bogs/Fens - may or may not have trees; waterlogged soil with lots of peat; low productivity </li></ul><ul><ul><li>Fens- fed by groundwater & surface runoff </li></ul></ul><ul><ul><li>Bogs- fed by precipitation </li></ul></ul>Bog Fen Marsh Swamp
  9. 9. Importance of Wetlands <ul><li>Highly productive- get lots of sunlight, ↑ plants = </li></ul><ul><li>↑ animals </li></ul><ul><li>Nesting, breeding ground for migratory birds </li></ul><ul><li>Slows flooding by absorbing runoff </li></ul><ul><li>Silt settles, making water clearer & nutrient rich </li></ul><ul><li>Trap & filter water </li></ul><ul><li>Natural chemical rxns neutralize and detoxify pollutants </li></ul><ul><li>Gives H 2 O time to percolate thru soil & replenish underground aquifers. </li></ul><ul><li>Threats- artificial eutrophication (see slide 13), draining, sedimentation via construction </li></ul><ul><li>“ Nature’s Septic Tank” </li></ul>
  10. 10. Marine Ecosystems <ul><li>SHORELINES </li></ul><ul><li>Rocky coasts- great density & diversity attached to solid rock surface </li></ul><ul><li>Sandy beaches- burrowing animals </li></ul><ul><li>Threats- due to hotels, restaurants, homes on beach, more plant life destroyed, destabilizing soil, susceptible to wind & water erosion </li></ul><ul><li>Insurance high; danger of hurricanes, erosion </li></ul><ul><li>Build sea walls to protect people but changes & endangers shoreline habitat </li></ul>
  11. 11. Marine Ecosystems <ul><li>BARRIER ISLANDS </li></ul><ul><li>Low, narrow offshore islands </li></ul><ul><li>Protect inland shores from storms </li></ul><ul><li>Beauty attracts developers = developers destroy land </li></ul><ul><li>New coastal zoning laws protect future development </li></ul>
  12. 12. MARINE ECOSYSTEMS <ul><li>CORAL REEFS </li></ul><ul><li>Clear, warm shallow seas </li></ul><ul><li>Made up of accumulated calcareous (made of calcium) skeletons of coral animals </li></ul><ul><li>Formation depends on light penetration. </li></ul><ul><li>Have a symbiotic relationship with algae </li></ul><ul><li>Very diverse, abundant (rainforests of sea) </li></ul><ul><li>Threats- destructive fishing (cyanide & dynamite to stun fish), pet trade; about 3/4ths have been destroyed </li></ul>
  13. 13. What factors can alter aquatic ecosystems? <ul><li>Natural Succession- normal cycle of pond becoming forest </li></ul><ul><li>Artificial Succession- humans add N & P to water via fertilizer & sewage causing succession to happen faster = EUTROPHICATION </li></ul>
  14. 14. What factors can alter aquatic ecosystems? <ul><li>Humans! </li></ul><ul><ul><li>Find food </li></ul></ul><ul><ul><li>Recreation </li></ul></ul><ul><ul><li>Waste disposal </li></ul></ul><ul><ul><li>Cooling of power plants </li></ul></ul><ul><ul><li>Transportation </li></ul></ul><ul><ul><li>Dams, canals </li></ul></ul>
  15. 15. Biomes <ul><li>Which biome has the largest total area? The smallest total area? </li></ul><ul><li>Which biome has the highest % of undisturbed habitat? </li></ul><ul><li>Which biome has the lowest % of undisturbed habitat? </li></ul><ul><li>Which biome has the highest % human dominated habitat? </li></ul><ul><li>Which biome has the lowest % human dominated habitat? </li></ul>
  17. 17. LANDSCAPE ECOLOGY <ul><li>Landscape- geographic unit with a history that shapes the features of the land and organisms in it. </li></ul><ul><li>Landscape ecology- the study of how landscape structure affects the abundance and distribution of organisms. </li></ul><ul><li>Does not just focus on “untouched nature” </li></ul>
  18. 18. LANDSCAPE ECOLOGY <ul><li>Uses geographical information systems (GIS) to map patch size, type and configuration to create 3-D maps </li></ul><ul><li>These maps assist land planners in analyzing land use patterns </li></ul>
  19. 19. LANDSCAPE ECOLOGY <ul><li>Focus on how neighboring communities of a landscape interact </li></ul>
  20. 20. RESTORATION ECOLOGY Chapter 10
  21. 21. RESTORATION ECOLOGY <ul><li>Repair or reconstruct ecosystems damaged by humans or natural forces </li></ul><ul><li>Growing field of science </li></ul><ul><li>People are now being held responsible for their actions- restoring wetlands & habitat for endangered species </li></ul>Before After
  22. 22. The 5 “R’s” of Restoration Ecology <ul><li>Restoration- manipulation of nature to re-create species composition & ecosystem processes as close as possible to the state they were in before humans interfered. </li></ul>Before After
  23. 23. The 5 “R’s” of Restoration Ecology <ul><li>Rehabilitation- to bring an area back to a useful state for human purposes rather than a truly natural state. </li></ul><ul><li>- reverse deterioration if can’t be restored fully </li></ul>These people in Africa are trying to use rocks to create a sort of wind break to prevent wind erosion of their soil. The soil will never be like it was but it will hopefully be usable.
  24. 24. The 5 “R’s” of Restoration Ecology <ul><li>Remediation- process of cleaning chemical contamination from a polluted area by physical or biological methods to protect human & ecosystem health </li></ul><ul><li>- Incinerate soil contaminated with oil </li></ul><ul><li>- use special bacteria to clean up oil spills in water (bioremediation) </li></ul>This is like an artificial wetland- wastewater comes in, settles, roots cleanse the water
  25. 25. The 5 “R’s” of Restoration Ecology <ul><li>Reclamation- techniques used to restore the shape, original contour and vegetation of a disturbed site </li></ul><ul><li>- Surface Mining Control & Reclamation Act (SMCRA) requires mining operations to restore the open pit mines they create to natural state. </li></ul>Before After
  26. 26. The 5 “R’s” of Restoration Ecology <ul><li>Re-creation - attempts to construct a new biological community on a site so severely disturbed that there is virtually nothing left to restore. </li></ul><ul><li>- often must build a wetland elsewhere to make up for the one destroyed by developer </li></ul><ul><li>- Read story of Army Corp of Engineers & Florida Everglades restoration </li></ul>
  27. 27. Preservationists vs. Restorationists <ul><li>Preservationist- don’t start destructive projects in the first place. Preserve nature- “you can’t always fix what you broke” </li></ul><ul><li>Restorationists- you are never going to be able to save every bit of land. Who says changes we make in restoring ecosystems is unnatural? </li></ul><ul><li>Are we members of the community or separate from it? </li></ul><ul><li>Should we use our creative energies to try to improve nature, or should we leave well enough alone? </li></ul>
  28. 28. Tools of Restoration <ul><li>Prairies- collect native prairie grasses from graveyards and plant in abandoned farm fields to reestablish native grasslands </li></ul><ul><li>Remove alien species- like privet @ nature center; hunting goats on Galapagos </li></ul><ul><li>Walk away from ecosystem & let recover naturally- N. & S. Korea after the Korean War </li></ul>
  29. 29. Restoration Ethics <ul><li>If habitat was filled with diseased, ugly organisms, should you return it to that state? Should you reintroduce mosquitoes, black flies, leeches, ticks, poisonous snakes? </li></ul><ul><li>Should you improve on nature? </li></ul><ul><li>Where do you find plants for restoration? Do you take from small population nearby or find larger population farther away? </li></ul><ul><li>Is there more than one natural state? What is the history of the area? </li></ul><ul><li>Since humans are part of nature, whatever changes we make to landscape also are natural. Is that true? </li></ul><ul><li>Can we use nature to solve human problems? Read story on page 121 about Arcata, California’s artificial wetland project. </li></ul>Canal in China Before Canal in China After Notice plants used as filtering system
  30. 30. Ecosystem Management <ul><li>How can we have progress and still maintain the environment? </li></ul><ul><li>Aldo Leopold was one of the pioneers on his Sand County farm </li></ul><ul><li>US Forest Services, Bureau of Land Management, National Park Service all adopted versions of ecosystem management </li></ul><ul><li>Previously, these agencies used their lands for commercial or recreational uses & did not focus on wildlife habitats, endangered species, etc. </li></ul>