What are the basic needs of aquatic biota? CO 2 O 2 Sunlight Nutrients- food & minerals
What factors influence the availability of those basic needs? Substances dissolved in water- Nitrates, phosphates, potassium, O 2 Suspended matter- (silt, algae) can affect light penetration Depth Temperature Rate of flow Bottom characteristics (muddy, sandy, or rocky) Internal convection currents Connection to or isolation from other aquatic ecosystems.
Freshwater Ecosystems Usually 0.005% salt –Some exceptions: Great Salt Lakes- 5-27% salt Dead Sea- 30% salt Moving water- high elevations; cold; high O 2 ; trout; streamlined plants Standing water- lower elevations; warmer; less O 2 ; bass, amphibians; cattails, rushes
How is a lake stratified and what lives in each level? Epilimnion- upper layer of warm water; high light & O 2 ; ex: water striders, phyto- & zooplankton, fish Thermocline (mesolimnion); middle layer; medium light & O 2 ; ex: phyto- & zooplankton, fish Hypolimnion- lower layer of cold water; lower light & O 2 ; ex: fish Benthos- bottom level; no light & little O 2 ; ex: anaerobic bacteria, leeches; insect larvae Littoral- near the shoreline; cattails, rushes, amphibians, etc.
Transitional Communities ESTUARIES Where freshwater dumps into ocean Brackish (less salty than seawater) Has rich sediments that often form deltas Productive & biodiverse Organisms adapted to varying levels of salinity as tide ebbs & flows “Nursery” for larval forms of many aquatic species of commercial fish & shellfish
Transitional Communities WETLANDS Land saturated at least part of the year Swamps- have trees like bald cypress; high productivity Marshes- no trees; tall grasses; high productivity Bogs/Fens- may or may not have trees; waterlogged soil with lots of peat; low productivity –Fens- fed by groundwater & surface runoff –Bogs- fed by precipitation Bog Fen Marsh Swamp
Importance of Wetlands Highly productive- get lots of sunlight, ↑ plants = ↑ animals Nesting, breeding ground for migratory birds Slows flooding by absorbing runoff Silt settles, making water clearer & nutrient rich Trap & filter water Natural chemical rxns neutralize and detoxify pollutants Gives H 2 O time to percolate thru soil & replenish underground aquifers. Threats- artificial eutrophication (see slide 13), draining, sedimentation via construction “Nature’s Septic Tank”
Marine Ecosystems SHORELINES Rocky coasts- great density & diversity attached to solid rock surface Sandy beaches- burrowing animals Threats- due to hotels, restaurants, homes on beach, more plant life destroyed, destabilizing soil, susceptible to wind & water erosion Insurance high; danger of hurricanes, erosion Build sea walls to protect people but changes & endangers shoreline habitat
Marine Ecosystems BARRIER ISLANDS Low, narrow offshore islands Protect inland shores from storms Beauty attracts developers = developers destroy land New coastal zoning laws protect future development
MARINE ECOSYSTEMS CORAL REEFS Clear, warm shallow seas Made up of accumulated calcareous (made of calcium) skeletons of coral animals Formation depends on light penetration. Have a symbiotic relationship with algae Very diverse, abundant (rainforests of sea) Threats- destructive fishing (cyanide & dynamite to stun fish), pet trade; about 3/4ths have been destroyed
What factors can alter aquatic ecosystems? Natural Succession- normal cycle of pond becoming forest Artificial Succession- humans add N & P to water via fertilizer & sewage causing succession to happen faster = EUTROPHICATION
What factors can alter aquatic ecosystems? Humans! –Find food –Recreation –Waste disposal –Cooling of power plants –Transportation –Dams, canals
Biomes Which biome has the largest total area? The smallest total area? Which biome has the highest % of undisturbed habitat? Which biome has the lowest % of undisturbed habitat? Which biome has the highest % human dominated habitat? Which biome has the lowest % human dominated habitat?
Landscape- geographic unit with a history that shapes the features of the land and organisms in it. Landscape ecology- the study of how landscape structure affects the abundance and distribution of organisms. Does not just focus on “untouched nature”
LANDSCAPE ECOLOGY Uses geographical information systems (GIS) to map patch size, type and configuration to create 3-D maps These maps assist land planners in analyzing land use patterns
LANDSCAPE ECOLOGY Focus on how neighboring communities of a landscape interact
RESTORATION ECOLOGY Chapter 10
RESTORATION ECOLOGY Repair or reconstruct ecosystems damaged by humans or natural forces Growing field of science People are now being held responsible for their actions- restoring wetlands & habitat for endangered species Before After
The 5 “R’s” of Restoration Ecology 1.Restoration- manipulation of nature to re-create species composition & ecosystem processes as close as possible to the state they were in before humans interfered. Before After
The 5 “R’s” of Restoration Ecology 2.Rehabilitation- to bring an area back to a useful state for human purposes rather than a truly natural state. - reverse deterioration if can’t be restored fully 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.
The 5 “R’s” of Restoration Ecology 3.Remediation- process of cleaning chemical contamination from a polluted area by physical or biological methods to protect human & ecosystem health - Incinerate soil contaminated with oil - use special bacteria to clean up oil spills in water (bioremediation) This is like an artificial wetland- wastewater comes in, settles, roots cleanse the water
The 5 “R’s” of Restoration Ecology 4.Reclamation- techniques used to restore the shape, original contour and vegetation of a disturbed site - Surface Mining Control & Reclamation Act (SMCRA) requires mining operations to restore the open pit mines they create to natural state. Before After
The 5 “R’s” of Restoration Ecology 5.Re-creation- attempts to construct a new biological community on a site so severely disturbed that there is virtually nothing left to restore. - often must build a wetland elsewhere to make up for the one destroyed by developer - Read story of Army Corp of Engineers & Florida Everglades restoration
Preservationists vs. Restorationists Preservationist- don’t start destructive projects in the first place. Preserve nature- “you can’t always fix what you broke” Restorationists- you are never going to be able to save every bit of land. Who says changes we make in restoring ecosystems is unnatural? Are we members of the community or separate from it? Should we use our creative energies to try to improve nature, or should we leave well enough alone?
Tools of Restoration Prairies- collect native prairie grasses from graveyards and plant in abandoned farm fields to reestablish native grasslands Remove alien species- like nature center; hunting goats on Galapagos Walk away from ecosystem & let recover naturally- N. & S. Korea after the Korean War
Restoration Ethics 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? Should you improve on nature? Where do you find plants for restoration? Do you take from small population nearby or find larger population farther away? Is there more than one natural state? What is the history of the area? Since humans are part of nature, whatever changes we make to landscape also are natural. Is that true? Can we use nature to solve human problems? Read story on page 121 about Arcata, California’s artificial wetland project. Canal in China Before Canal in China After Notice plants used as filtering system
Ecosystem Management How can we have progress and still maintain the environment? Aldo Leopold was one of the pioneers on his Sand County farm US Forest Services, Bureau of Land Management, National Park Service all adopted versions of ecosystem management Previously, these agencies used their lands for commercial or recreational uses & did not focus on wildlife habitats, endangered species, etc.