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Life in Water

Life in Water. Chapter 3. The Hydrologic Cycle. Over 71% of the earth’s surface is covered by water: Oceans contain 97%. Polar ice caps and glaciers contain 2%. Freshwater in lakes, streams, and ground water make up less than 1%. Solar heating and gravity are major forces.

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Life in Water

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  1. Life in Water Chapter 3

  2. The Hydrologic Cycle • Over 71% of the earth’s surface is covered by water: • Oceans contain 97%. • Polar ice caps and glaciers contain 2%. • Freshwater in lakes, streams, and ground water make up less than 1%. • Solar heating and gravity are major forces.

  3. The Hydrologic Cycle (interactive) Net Movement and Processes: * Evaporation from oceans * Atmospheric transport to land and condensation. * Precipitation onto land. * Gravity flow back to Ocean. - Run off to surface waters (lake & streams) - Infiltration to groundwater Transpiration and evaporation on land takes place but on average it is less than precipitation, so water enter streams and groundwater.

  4. The Hydrologic Cycle • Turnover time (residence time) is the time required for the entire volume of a reservoir to be renewed (replaced). • Atmosphere 9 days • Rivers systems 12-20 days • Groundwater 300 years • Oceans 3,100 years • Glaciars & ice-caps 16,000 years

  5. Marine Oceans and seas Coral reefs and kelp forests Intertidal shores: rocky or soft bottom. Estuaries, salt marshes and mangrove forests Inland Waters Ponds and lakes Streams and rivers Wetlands Groundwater Aquatic Biomes

  6. Properties to consider • Water Movement • Temperature • Light • Salinity • Nutrients • Oxygen • Human influence

  7. Oceans and SeasGeography of Ocean Basins • Major Ocean Basins: • Pacific is oldest & largest (180 million km2) • Indian is smallest (75 million km2) • Atlantic is in between (106 million km2) • Depth: • Average about 4000 m • Deepest trench is > 10,000 m deep

  8. Oceanic Circulation

  9. Deep Blue Sea – Structure • Littoral Zone (intertidal zone): Shallow shoreline. • Neritic Zone: Coast to continental shelf break. • Oceanic Zone: Beyond continental shelf.

  10. Deep Blue Sea - Structure • Benthic: Habitat on bottom of ocean. • Pelagic: Habitat off the bottom of the ocean. http://www.oceansalive.org/

  11. Deep Blue Sea - Physical Conditions • Light • Approximately 80% of solar energy striking the ocean is absorbed in first 10 m. None below 600 m, yet oceans are ≈4000 m on average. • Temperature • Sunlight increases velocity of water. • Rapid motion decreases density, thus warm water floats on top of cooler water. • Thermocline: Layer of water through which temperature changes rapidly with depth. • Creates thermal stratification.

  12. Ocean Phytoplankton Biomass as Chlorophyll http://www.ccpo.odu.edu/~arnoldo/ocean405/globalcolor.gif

  13. http://topex-www.jpl.nasa.gov/aviso/text/general/discover/images/arrow.gifhttp://topex-www.jpl.nasa.gov/aviso/text/general/discover/images/arrow.gif

  14. Deep Blue Sea - Chemical Conditions • Salinity • In the open ocean, salinity varies from about 34 ppt to 36.5 ppt. • Lowest salinity occurs near equator where precipitation exceeds evaporation. • Highest salinity occurs in subtropics where evaporation exceeds precipitation.

  15. Deep Blue Sea - Chemical Conditions • Oxygen • A liter of air contains about 200 ml of oxygen at sea level, while a liter of seawater contains a maximum of 9 ml of oxygen.

  16. Deep Blue Sea - Biology • Photosynthetic organisms are limited to upper epipelagic zone (euphotic zone). • Phytoplankton and zooplankton. • Due to size, oceans contribute 1/2 of total photosynthesis in the bioshpere. • Chemosynthesis occurs near undersea: • hot springs • cold seeps

  17. http://www.njscuba.net/biology/img/phytoplankton.gif http://www.njscuba.net/biology/img/zooplankton.gif

  18. Deep Blue Sea - Human Influences • For most of human history, vastness of oceans has acted as a buffer against human intrusion. • New human-induced threats: • Overharvesting • Dumping • Sediment and Nutrients

  19. http://www.whalersdiveclub.org/webpages/whalers_photo_gallery.htmhttp://www.whalersdiveclub.org/webpages/whalers_photo_gallery.htm

  20. Coral Reefs and Kelp Forests • Reefs and kelp beds both grow in surface waters with sufficient light for photosynthesis. • Both limited by temperature. • Currents deliver oxygen and nutrients, and remove waste products. • Biological productivity may depend on flushing action. • Reefs and kelp beds among most productive and diverse ecosystems.

  21. Marine Shores • Inhabitants of intertidal zone are adapted to amphibious existence. • Differential tolerances to periodicity of air exposure leads to zonation of species. • Due to increased accessibility, intertidal zones are experiencing increasing human exploitation.

  22. Intertidal Zonation

  23. http://www.clarku.edu/departments/biology/biol201/jlagliva/Nahant,%2520Intertidal%2520zonation.jpghttp://www.clarku.edu/departments/biology/biol201/jlagliva/Nahant,%2520Intertidal%2520zonation.jpg

  24. Estuaries, Salt Marshes, and Mangrove Forests • Estuaries are found where rivers meet the sea. http://ccmaserver.nos.noaa.gov/images/estuary.jpg

  25. Estuaries, Salt Marshes, and Mangrove Forests • Salt Marshes and Mangrove Forests are concentrated along low-lying coasts. • Transistion between land and sea • All driven by ocean tides and river flow. • Transport organisms, nutrients, oxygen, and remove wastes. • Extremely vulnerable to human intrusion.

  26. http://www.edc.uri.edu/restoration/html/gallery/saltmarsh.htmhttp://www.edc.uri.edu/restoration/html/gallery/saltmarsh.htm

  27. Mangrove http://www.stevesbasement.com/mangroveforestA2.jpg

  28. Salt Marshes and Mangrove Forests

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