Chapter 7 Environmental Science 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 Plankton are organisms that cannot swim; they drift. Phytoplankton are drifting plants that provide most food. Zooplankton are drifting animals.

Aquatic Organisms Benthos Nekton 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 Zone is 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.

Time for a reading quiz

Section 7.2 Marine Ecosystems

Description of an estuary: 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 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 waters is where most ocean life is found Open ocean is one of the least productive ecosystems (lacks sunlight) Ocean floor consists of dead organisms, decomposers and filter feeders

Threats to Oceans Pollution Run-off Overfishing Trawl nets

Arctic and Antarctic Ecosystem Only continent not colonized South Pole Plankton is base of food web. Fish, whales, and penguins. North Pole Most food comes from ocean Plankton, fish, birds, whales, and seals

Time for reading quiz