Aquatic Biodiversity notes - Chapter6:AquaticBiodiversity...

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Chapter 6: Aquatic Biodiversity I.Aquatic Environments The Water Planet: Saltwater and Freshwater Saltwater and freshwater aquatic life zones cover almost three­fourths of the earth’s surface. Water covers about 71% of the earth’s surface. Major types of organisms found in aquatic environments are determined by the water’s salinity. Salinity­ the amounts of various salts such as sodium chloride (NaCl) dissolved in a given volume of water. Aquatic life zones are classified into two types: Saltwater/marine­ estuaries, coastlines, coral reels, coastal marches, mangrove swamps, and oceans. Freshwater­lakes, ponds, streams, rivers, and inland wetlands What kinds of Organisms Live in Aquatic Life Zones? Aquatic systems contain floating, drifting, swimming, bottom­dwelling, and decomposer organisms. Plankton­ weakly swimming, free­floating organism Phytoplankton/plant plankton­ algae Zooplankton/animal plankton­ primary consumers(herbivores) that feed on phytoplankton and secondary consumers that feed on other zooplankton Ultraplankton­ extremely small photosynthetic bacteria may be responsible for 70% of the primary productivity near the ocean surface. Nekton­ strongly swimming consumers such as fish, turtles, and whales Benthos­ bottom dwellers such as barnacles and oysters that anchor themselves to one spot, worms that burrow into sand or mud, and lobsters and crabs that walk about on the bottom Decomposers­ that break down the organic compounds in the dead bodies and wastes of aquatic organisms into simple nutrient compounds for use by aquatic producers. Life in Layers Life in most aquatic systems is found in surface, middle, and bottom layers. Important environmental factors: Temperature, access to sunlight for photosynthesis, dissolved oxygen content, and availability of nutrients Euphotic zone­ upper layer through which sunlight can penetrate. At lower depths oxygen levels fall because of aerobic respiration by aquatic animals and decomposers and because less oxygen gas dissolves in the deeper and colder water than in warmer surface water In shallow waters in streams, ponds, and oceans, ample supplies of nutrients for primary producers are usually available. In the open ocean, nitrates, phosphates, iron, and other nutrients often are in short supply and limit net primary productivity (NPP) II. Saltwater Life Zones Why Should We Care About The Oceans? The world’s oceans provide many important ecological and economic services.
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The Coastal Zone: Where Most of the Action Is The coastal zone makes up less than 10% of the world’s ocean area but contains 90% of all marine species. Coastal zone­ the warm, nutrient­rich, shallow water that extends from the high­tide mark on land to the gently sloping, shallow edge of the continental shelf(the submerged part of the continents).
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  • Fall '11
  • Meador
  • Biodiversity, human activities, Aquatic Life Zones, life zones, plant nutrients, freshwater life zones, excess plant nutrients

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