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Lesson 6.3 Aquatic Ecosystems

Lesson 6.3 Aquatic Ecosystems. 75% of Earth’s surface is covered by water. What are the basic needs of aquatic life?. CO 2 O 2 Sunlight Nutrients- food & minerals. Describing Aquatic Ecosystems. Salinity: Amount of dissolved salt present in water Salt water, fresh water, or brackish

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Lesson 6.3 Aquatic Ecosystems

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  1. Lesson 6.3 Aquatic Ecosystems 75% of Earth’s surface is covered by water.

  2. What are the basic needs of aquatic life? CO2 O2 Sunlight Nutrients- food & minerals

  3. Describing Aquatic Ecosystems • Salinity: • Amount of dissolved salt present in water • Salt water, fresh water, or brackish • Photosynthesis: • Light availability • Depth & water clarity • Flowing or standing water • Zones: photic, aphotic, benthic

  4. Types of Aquatic Ecosystems Freshwater Ecosystems Standing Water- lakes & ponds Moving Water- rivers & streams Transitional Communities Estuaries Wetlands- bogs/fens, swamps, marshes Marine Ecosystems Shorelines Barrier Islands Coral Reefs Open Ocean

  5. Freshwater Ecosystems Usually 0.005% salt Some exceptions: Great Salt Lakes- 5-27% salt Dead Sea- 30% salt Moving water- high elevations; cold; high O2; trout; streamlined plants Standing water- lower elevations; warmer; less O2; bass, amphibians; cattails, rushes

  6. Freshwater Ecosystems: Ponds, Lakes, Inland Seas • Horizontal zones: littoral and limnetic

  7. How is a lake stratified and what lives in each level? Epilimnion- upper layer of warm water; high light & O2; ex: water striders, phyto- & zooplankton, fish Thermocline (mesolimnion); middle layer; medium light & O2; ex: phyto- & zooplankton, fish Hypolimnion- lower layer of cold water; lower light & O2; ex: fish Benthos- bottom level; no light & little O2; ex: anaerobic bacteria, leeches; insect larvae Littoral- near the shoreline; cattails, rushes, amphibians, etc.

  8. Freshwater Ecosystems: Wetlands Lesson 6.3 Aquatic Ecosystems • Areas of land flooded with water at least part of the year • Marshes, swamps, bogs, and fens • Prevent flooding, recharge aquifers, filter pollutants, and provide habitats.

  9. Freshwater Ecosystems: Rivers and Streams Lesson 6.3 Aquatic Ecosystems • Bodies of surface water that flow downhill, eventually reaching an ocean or inland sea • Watershed: area of land drained by a river and its tributaries • Characteristics, such as dissolved oxygen, temperature, water speed, organisms, and others, change from source to mouth.

  10. Estuaries • Where river flows into the ocean or an inland sea • Prevent flooding and soil erosion as well as provide habitats. • Coastal estuaries • brackish; organisms must tolerate wide salinity and temperature ranges • home to salt marshes & mangrove forests Everglades, Florida, wetlands Did You Know?Salt marshes and mangrove forests are two of the most productive ecosystems on Earth.

  11. Oceans Lesson 6.3 Aquatic Ecosystems • Currents are driven by water temperature and density differences, wind, and gravity. • Surface winds and heating generate vertical currents that transport nutrients and oxygen. • Horizontal ocean zones: intertidal, neritic, open ocean • Vertical ocean zones: photic, aphotic, benthic Did You Know?If the water in the oceans evaporated, a 60 m (200 ft) deep layer of salt would be left behind.

  12. Ocean Ecosystems • Intertidal: Highly diverse; extreme range of temperature, moisture, and salinity • Neritic: Productive kelp forests and coral reefs provide habitats and help protect shorelines from erosion. • Open ocean: Low productivity due to low light penetration; phytoplankton base of food chain; deep sea organisms and hydrothermal vent communities Did You Know?Over 90% of ocean water on Earth is in the open ocean zone.

  13. What factors influence the availability of those basic needs? Substances dissolved in water- Nitrates, phosphates, potassium, O2 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.

  14. 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

  15. 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 Swamp Marsh Bog Fen

  16. 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 H2O time to percolate thru soil & replenish underground aquifers. Threats- artificial eutrophication (see slide 13), draining, sedimentation via construction “Nature’s Septic Tank”

  17. 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

  18. 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

  19. 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

  20. 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

  21. What factors can alter aquatic ecosystems? Humans! Find food Recreation Waste disposal Cooling of power plants Transportation Dams, canals

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