Ch. 7 Aquatic Ecology

Transcription

1 Ch. 7 Aquatic Ecology 1.Coral Reefs: the aquatic equal to the tropical rain forests 2.The two major aquatic life zones A. saltwater or marine (estuaries, coastlines, coral reefs, coastal marshes, mangrove swamps, ocean over the continental shelf, deep ocean) B. freshwater (lakes, ponds, streams, rivers, inland wetlands) 3.Aquatic Life Zone Organisms A. plankton weak swimming, free-floating a. phytoplankton photosynthetic cyanobacteria, algae; producers b. nanoplankton recently discovered c. zooplankton nonphotosynthetic primary consumers (herbivores) B. nekton strong swimming consumers (fish, turtles, whales) C. benthos bottom dwelling creatures (barnacles, oysters, worms, lobsters) D. decomposers (bacteria) break down organic compounds into simple nutrients. 4. Properties of Water A. buoyancy-provides physical support B. limited fluctuation in temperature-reduces risk of freezing or overheating C. nutrients- soluble and readily available

2 5. Factors that limit aquatic life at different depths (surface, middle and bottom layers) A. temperature B. access to sunlight C. dissolved oxygen content D. availability of nutrients 6. Saltwater Life Zones A. Oceans 1. 71% of earth's surface 2. currents distribute solar heat and waste 3. regulate the earth's climate 4. two major life zones: a. coastal zone 10% of ocean area; 90% of all marine species b. open sea 90% of ocean area

3 B. Estuaries and Tidal Ecosystems 1. Estuary partially enclosed area of coastal water 2. seawater mixes with freshwater C. Coastal Wetlands 1. Areas of coastal land covered all or part of the year by salt water. a. buffer against damage and erosion during storms

4 D. Mangrove Swamp 1. dominated by salt-tolerant trees or shrubs (mangroves) 2. protect coastline from erosion and reduce damage from typhoons and hurricanes E. Rocky and Sandy Shores 1.Intertidal Zone shoreline area between high and low tides a. stressful area for organisms; must cope with waves, being left high and dry

5 2.Barrier Beaches/Sandy Shores a. first line of defense against the ravages of the sea 3.Barrier Islands a. long, thin, low offshore islands of sediment running parallel to the shore b. protect the mainland by dispersing the energy of c. F. Coral Reefs 1. form in clear, warm and shallow coastal waters of the tropics and subtropics ;most biologically diverse life zones

6 7. Human Impacts on Coastal Zones A. two-thirds of world's population lives within 100 miles of a coast B. 10% of coral reefs are dead; 30% in critical condition; 30% are threatened; 30% are stable. C. Beach Erosion 8. Open Sea A. Divided into three zones based on sunlight penetration: 1. Euphotic where photosynthesis occurs; low nutrient levels; high DO levels 2. Bathyal dimly lit; no photosynthesis 3. Abyssal dark; very cold; v. little DO; high nutrient level on ocean floor 9. Freshwater Life Zones A. about 1% of Earth's surface water; 41 % of world's known fish species B. Lentic standing bodies of water lakes, ponds and inland wetlands C. Lotic flowing bodies of water streams and rivers 10. Aquatic Life Zones in Freshwater Lakes

7 A. Lakes depression caused by glaciation, crustal displacement and volcanic activity 1.Zones defined depth and distance from shore a. Littoral Zone -shallow area near shore b. Limnetic Zone -the open sunlit water surface layer away from the shore c. Profundal Zone -deep open water; too dark for photosynthesis d. Benthic Zone - bottom of the lake B. How Plant Nutrients Affect Lakes 1. Lakes are classified according to their nutrient a. Oligotrophic Lake 1. poorly nourished, newly formed lakes b. Eutrophic Lake 1. well nourished, older lakes c. Mesotrophic Lakes most lakes fall somewhere between the two extremes of oligotrophic and eutrophic C. Seasonal Changes in Temperate Lakes 1. Thermal stratification of deep lakes in northern climates. resist mixing because (in summer) warmer less dense water is on top. 2. Epiliminon upper layer of warm water with high levels of DO 3.Hypoliminon lower layer of colder, denser water with low level of DO 4. Thermocline - middle layer where water temperature changes rapidly with increased depth

8 11. Freshwater Streams and Rivers A. Watershed / drainage basin the land area which delivers water to larger streams 12. Freshwater Inland Wetlands A. Lands covered with fresh water all or part of the time B. include marshes, prairie potholes, swamps, mud flats, floodplains, bogs, wet meadows, wet arctic tundra

9 13.Seasonal wetlands covered only part of the year 14. Human Impacts on Inland Wetlands A. They are drained, dredged, filled in or covered over as a result of agriculture, mining, forestry, oil and gas extraction, highways, urban development B. Only 8% of remaining inland wetlands are under federal protection C.Mitigation Banking wetlands can be destroyed if equal areas of the same type of wetland are created or restored