1. Freshwater Ecosystems
Chapter 7
Aquatic Ecosystems
Section 1
Freshwater Ecosystems
Ms. Mandel
Environmental Science

2. Learning Targets
I can describe the characteristics that are used to differentiate between the different types of aquatic ecosystems.
I can differentiate between the different types of freshwater ecosystems.

3. Aquatic Ecosystems
What factors determine which organisms live in the different aquatic ecosystems?
Salinity
Amount of dissolved salts in the water
Temperature
Sunlight
Can only reach certain depths
Oxygen
Amount of DO (dissolved oxygen)
Nutrients

4. Groups of Aquatic Organisms
Plankton
Drifters
Phytoplankton – plants
Zooplankton – animals
May be microscopic or macroscopic (jellyfish)

5. Nekton
Free-swimming organisms (fish, turtle, whales)

6. Benthos Bottom dwelling (mussels, worms, barnacles)
Many live attached to hard surfaces

7. Do Aquatic Ecosystems Contain Decomposers?
Yes
Bacteria
Fungi (microscopic)
Marine worms
Echinoderms
Sea urchins
Starfish
Sea cucumbers

8. Freshwater Ecosystems

9. Freshwater
A little more than 3% of all the water on the Earth is fresh water.
Most is locked up in icecaps and glaciers.

10. Freshwater Rest is found in lakes rivers wetlands soil
rock layers below surface
in the atmosphere

11. Lakes

12. Structured Into Zones Littoral zone Near shore Great biodiversity
Plants rooted in mud, but leaves above water

13. Benthic zone Bottom of lake Very little light
Inhabited by decomposers, insect larvae & clams

14. How Do Nutrients Affect Lakes?

15. Eutrophication Increase in amount of nutrients in an aquatic ecosystem
Leads to overgrowth of algae and plants
Bacteria that feed on algae increase and use up dissolved O2 in lake
Lack of O2 kills organisms that need it
Is a natural occurrence, but can be increased by run-off of sewage, fertilizers or animal waste

16. Freshwater Wetlands

17. Covered with fresh water for at least part of the year
bog
marsh
swamp
Acidic soil, contains dead plant material, mosses and carnivorous pants
Contain non-woody plants
Dominated by woody plants

18. Environmental Functions of Wetlands
Filtering water
Flood protection
Buffers shoreline from erosion
Provide spawning grounds for animals
Habitat for rare, threatened & endangered species
Recreational areas

19. Human Impact on Wetlands
Drained, filled and cleared for farms or development
FL Everglades used to cover 8 million acres and now only cover 2 million acres
Today - Laws and the federal gov’t protect many wetlands

20. Rivers

21. Where do they originate?
Snow melt runoff
Glaciers
Is a river the same from where it starts to where it ends? No
River – Old Age
River – Youth Age

22. Life in a River Mosses Trout Minnows Crowfoot (plant) Catfish Carp
Insect larvae
Phytoplankton
Zooplankton
Etc

23. Rivers in Danger
People use water from rivers for drinking, irrigating and in manufacturing.
People dispose of garbage and sewage
Dams alter the ecosystem they are in
Pollution releases toxins into the water killing species and making fish unsuitable to eat

24. Learning Target Checkpoint
What is the difference between a lake, freshwater wetlands and rivers?