1. Chapter 7 Environmental Science
Aquatic Ecosystems
Chapter 7
Environmental Science

2. Section 7.1
Freshwater Ecosystems

3. 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.

4. Characteristics of Aquatic Ecosystems
Plankton are organisms that cannot swim; they drift.
Phytoplankton are drifting plants that provide most food.
Zooplankton are drifting animals.

5. Aquatic Organisms Benthos Nekton
Are free-swimming organisms, like fish, turtles, and whales.
Are bottom-dwelling organisms, such as mussels, worms, and barnacles.

6. 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.

7. 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.

8. 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.

9. 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

10. 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

11. Human Impact on Wetlands
Many wetlands were drained and filled in for development.
Example: Florida Everglades
Laws protect wetlands and prohibit wetland destruction.

12. 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.

13. Time for a reading quiz

14. Section 7.2
Marine Ecosystems

15. 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.

16. Threats to Estuaries Used as solid waste landfills.
Used for building sites
Sewage, industrial waste, and agricultural run-off

17. 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

18. 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

19. 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

20. 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

21. Threats to Oceans
Pollution
Run-off
Overfishing
Trawl nets

22. 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

23. Time for reading quiz