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Chapter 7 Environmental Science
Aquatic Ecosystems Chapter 7 Environmental Science
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Freshwater Ecosystems
Lakes and Ponds Wetlands Rivers Factors affecting which organisms live in freshwater ecosystems Temperature Sunlight Oxygen Nutrients
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Aquatic Ecosystem Organisms
Plankton Organisms that float near the surface Two types Phytoplankton – produce most food for ecosystem Zooplankton – microscopic animals Nekton Free-swimming organisms Fish, turtles, whales Benthos Bottom-dwelling organisms Mussels, worms, barnacles Decomposers Break down dead organisms
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Lakes and Ponds Layers of a Lake Littoral zone Benthic zone
Top layer near the shore Nutrient rich Plants are rooted in mud Plants make energy from photosynthesis Depend on sunlight Benthic zone Bottom of the lake Bacteria lives here No sunlight reaches this layer Dead organisms are consumed by decomposers
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Lakes and Ponds, cont. Eutrophication Increase of nutrients
Occurs when a large amount of plant growth in a lake or pond Increases amount of bacteria Bacteria uses up oxygen Eventually not enough oxygen for organisms Runoff can accelerate eutrophication Sewage, fertilizers, animal wastes
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Freshwater Wetlands Areas of lands covered in water for at least part of the year Two types – marshes and swamps Environmental Functions Absorb and remove pollutants Control flooding by absorbing extra water Provide homes for wildlife Prevent against erosion Provide recreational areas for fishing, etc. Provide breeding grounds for fish and shellfish
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Marshes Occur in low, flat lands Have little water movement
Plants root in sediment under water Reeds, rushes, cattails Water birds have adapted to marshes Heron – spearlike beak to grab fish Ducks – flat beak to sift through water for fish Kinds of marshes according to salinity Brackish marshes – slightly salty water Salt marshes – saltier water
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Swamps Flat, poorly drained land near streams Types of swamps
Mangrove swamps In warm climates near the ocean (salt water) Freshwater swamps Ideal environment for amphibians Swamps attract birds and reptiles Wood ducks, alligators
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Human Impact on Wetlands
Wetlands were considered wastelands where insects breed Humans drained the wetlands for this reason Important roles now recognized Purifiers for wastewater Flood prevention Habitats for wildlife Most states have laws against the destruction of wetlands
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Rivers Many begin from snow melt in mountains
Cold, full of oxygen, fast moving River flows down the mountain Becomes wider, warmer, slower, less oxygen A river changes depending on the land and climate it is flowing through
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Rivers in Danger Industries polluting the water Runoff from land Dams
Kills organisms Makes fish inedible Runoff from land Puts pesticides in the river and sediment Dams Change the ecosystem in and around river
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Marine Ecosystems Costal Wetlands
Areas covered by salt water for all or part of the time Many fish and wildlife live here Absorb excess rain Helps to avoid flooding problems Filter out pollutants and sediments Are recreational areas for boating, fishing, etc
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Estuaries Estuary Area where fresh water from a river mixes with salt water from an ocean Currents form here Cause mud and nutrients to fall to the bottom Marsh grasses will begin to grow here Constantly receiving fresh nutrients Makes it a very productive ecosystem
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Plants and Animals of Estuaries
Rooted plants Sunlight can reach the bottom since water is shallow Nutrient supply is always high Plankton live here Mammals feed on plankton Dolphins, manatees, seals Oysters, clams feed on the plants All organisms that live here can tolerate various levels of salinity
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Threats to Estuaries Ports are built over estuaries
Provides easy access to oceans Usually populated areas surround an estuary Waste is dumped in the estuary Pollutants Sewage Industrial waste containing toxic chemicals Agricultural runoff containing pesticides, fertilizers
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Salt Marshes Develop in estuaries where rivers deposit their load of mineral-rich mud Clams, fish, aquatic birds live here Protects young animals when small Shrimp Crab Fish When older, they migrate to the sea Absorbs pollutants Protect inland areas
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Mangrove Swamps Located along coastal areas of tropical and subtropical zones Mangrove trees are the main plant Protects the coastline from erosion Reduces damage from storms Many animals use as a breeding grounds Sometimes filled with waste and destroyed
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Rocky and Sandy Shores Rocky Shores Sandy Shores
Many plants anchor to rocks Many animals live on the rocks Anemones Mussels Sponges Sandy Shores Dry out when tide goes out Tiny organisms live off of plankton Barrier islands Land that runs parallel to the shore Protect the mainland and coastal wetlands
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Coral Reefs Limestone ridges built by tiny coral animals called polyps
They secrete skeletons of limestone Calcium carbonate Thousands of plants and animals live here Most diverse ecosystem on Earth Live in clear, warm salt water Live in shallow water so sunlight can reach They are predators that never chase their prey Stinging tentacles to capture organisms that float by
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Disappearing Coral Reefs
Corals die if: Water becomes too hot or too cold Fresh water drains into the water near reef Water is too muddy, polluted or too high in nutrients Causes of coral reef destruction Oil spills Sewage Pesticides Silt runoff Overfishing Careless divers Shipwrecks Ships dropping anchor People breaking off pieces
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Oceans Animals Phytoplankton Zooplankton Decomposers
Live where light and nutrients are (shallow water) Have flagella to keep them from sinking deeper Zooplankton Feed on phytoplankton near surface Examples Jellyfish Tiny shrimp Larvae of fish, oysters, lobsters Decomposers Live on bottom of ocean Consume dead organisms
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Threats to the Oceans Pollution Overfishing and nets Industrial waste
Sewage Plant nutrients (fertilizers, etc.) Overfishing and nets Animals can get tangled in nets and die
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Arctic and Antarctic Ecosystems
North and South Poles Large population of plankton Many fish eat the plankton Birds, whales, seals feed on the fish Fish and seals feed the polar bears Antarctic is not populated by humans Mainly used for research purposes
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Section 2 Assignment Page 185 #1-5
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Chapter 7 Review Pages #6-18, 20-26, 29, 34-35
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