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Aquatic Ecosystems. Chapter 7 Environmental Science. Section 7.1. Freshwater Ecosystems. Freshwater Ecosystems. Temperature , sunlight , oxygen , and nutrients are factors that determine where organisms live. A main factor is salinity .
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Aquatic Ecosystems Chapter 7 Environmental Science
Section 7.1 Freshwater Ecosystems
Freshwater Ecosystems • Temperature, sunlight, oxygen, and nutrients are factors that determine where organisms live. • A main factor is salinity. • Salinity is the amount of dissolved salts the water contains.
Characteristics of Aquatic Ecosystems • Planktonare organisms that cannot swim; they drift. • Phytoplanktonare drifting plants that provide most food. • Zooplankton are drifting animals.
Aquatic Organisms Nekton Benthos • Are free-swimming organisms, like fish, turtles, and whales. • Are bottom-dwelling organisms, such as mussels, worms, and barnacles.
Life in a Lake Lakes Zones of Lake or Pond • Littoral Zoneis near the shore and aquatic life is diverse and abundant. • Littoral Zone is where most plants are found: like reeds and cattails. • Benthic Zone is the bottom of the pond or lake which is inhabited by decomposers, insect larvae, and clams.
How Nutrients Affect Lakes • Eutrophication: an increase in the amount of nutrients in an aquatic ecosystem. • Leads to algal blooms and reduced amounts of oxygen. • Other aquatic organisms suffocate and die. • Eutrophication is accelerated by run-off.
Freshwater Wetlands Description of a wetland: • Areas of land that are covered with fresh water for at least part of the year. • They act as filters when they absorb and remove pollutants. Environmental Functions: • They control flooding by absorbing extra water when rivers overflow. • They provide homes for many species and trap carbon.
Marshes Description of a marsh: • Occur on low, flat lands and have little water movement. • Attract migratory birds • Salinity varies Adaptations: • Organisms adapt to the range of salinity
Swamps Description of a swamp: • Occur on flat, poorly drained land, often near streams. • Mangrove trees are found in saltwater swamps. • Many amphibians in freshwater swamps • Alligators are the top predator of swamps
Human Impact on Wetlands • Many wetlands were drained and filled in for development. • Example: Florida Everglades • Laws protect wetlands and prohibit wetland destruction.
Rivers Description of a river: • Headwaters: cold and full of oxygen • Flows downward: warmer, wider, slower, more vegetation and less oxygen. Factors that impact a river: • Pollution is killing river organisms • Dams change the river ecosystem.
Section 7.2 Marine Ecosystems
Estuaries Description of an estuary: • An area in which fresh water from a river mixes with salt water from the ocean. • It forms a nutrient trap making estuaries very productive. Adaptations of organisms: • Plant and animals must be able to adapt to changing salinity and water levels.
Threats to Estuaries • Used as solid waste landfills. • Used for building sites • Sewage, industrial waste, and agricultural run-off
Salt Marshes vs. Mangrove Swamps Salt Marshes Mangrove Swamp • Are where rivers deposit their load of mineral-rich mud. • Clams, fish, birds. • Nursery for shrimp, crabs, fish • Absorb pollutants • Mangroves have above ground root systems. • Found in tropical and subtropical zones. • Protect coastline from erosion
Coral Reefs • Are limestone ridges built by tiny coral animals called coral polyps • Highly diverse ecosystems but fragile • Fish, snails, clams, sponges • Shallow, clear tropical seas
Threats to Coral Reefs • Can’t get too cold or too hot • Coral bleaching leads to coral death • Global warming, oil spills, run-off, over-fishing leading to more coral reef destruction
Oceans • Shallow, coastal watersis where most ocean life is found • Open oceanis one of the least productive ecosystems (lacks sunlight) • Ocean floorconsists of dead organisms, decomposers and filter feeders
Threats to Oceans • Pollution • Run-off • Overfishing • Trawl nets
Arctic and Antarctic Ecosystem Arctic Antarctic • North Pole • Most food comes from ocean • Plankton, fish, birds, whales, and seals • Only continent not colonized • South Pole • Plankton is base of food web. • Fish, whales, and penguins.
