1. Freshwater Ecosystems

2. Freshwater Ecosystems
The organisms that live in an aquatic ecosystem are determined by the water’s salinity.
Salinity refers to the amount of dissolved salt that the water contains.
The two types of aquatic ecosystems are freshwater and marine ecosystems

3. Freshwater ecosystems
Freshwater ecosystems include lakes, ponds, wetlands, rivers, and streams.

4. Freshwater contains little or no salt, so it has a LOW salinity
Freshwater contains little or no salt, so it has a LOW salinity. Flowing freshwater = rivers and streams Still Freshwater = lakes and ponds

5. Freshwater Organisms
Where organisms live in an aquatic ecosystem depends on sunlight, temperature, oxygen, and nutrients.
Organisms are grouped by their location and by their adaptations.

7. Plankton Plankton make up the first group of aquatic organisms.
They are microscopic drifters and cannot swim against currents. They float on the surface and need sunlight to survive.

8. Phytoplankton
Phytoplankton are microscopic plants that drift in freshwater and serve as food for most aquatic ecosystems.

9. Water Biomes Phytoplankton are important producers in water biomes.
They are the first step in many aquatic food chains

10. Nekton
Nekton are free-swimming organisms, such as squid, sharks, penguins, fish and seals.

11. Benthos
Benthos are bottom dwelling organisms, such as mussels and barnacles. Many benthic organisms live attached to surfaces.

12. Lakes
Larger and deeper than ponds
Plant growth is limited to the shoreline
Sunlight does NOT penetrate to the bottom= no plants after a certain depth!

13. Lakes and Ponds
Sunlight and nutrients influence the type and location of organisms in a pond or lake.

14. Ponds Small, shallow bodies of water
Sunlight penetrates all the way to the bottom
Most completely filled with plant material
Very high amount of nutrients

15. Littoral Zone
A shallow zone in a freshwater habitat where light reaches the bottom and nurtures plants.
Farther from shore, phytoplankton make their own food by photosynthesis.
Cattails, reeds, and pond lilies are rooted in the mud underwater.
Aquatic life is diverse and plentiful
The littoral zone near the shore is rich in nutrients.

16. Benthic Zone The benthic zone is the bottom layer of a pond or lake.
It is so deep and there is too little light for photosysnthesis.

17. Decomposers and bacteria live in this layer where they feed on dead plants and animals that drop down from above.

18. Freshwater Wetlands Swamp Marsh
Freshwater wetlands are covered by water for part of the year.
The two types are marshes and swamps.
Swamp Marsh

19. Marshes contain non-woody plants such as cattails

20. Swamps contain woody plants such as trees and shrubs.

21. Environmental Functions of Wetlands
Trap and filter sediments, nutrients, and pollutants, which protect lakes, reservoirs, and oceans
Reduce flooding and protect farmland and roads
Prevent erosion of shorelines
Provide spawning grounds and habitats
Recreational activities such as fishing and boating

22. Rivers Water moves slower in a river and debris settles on the bottom.
Because of this, rivers tend to have more nutrients and less dissolved oxygen.
nutrients and oxygen