1. 9.3 Lakes and freshwater wetlands

2. Main Idea
As the Amount of water changes and the amount of sediments increases, lakes can be transformed into wetlands and eventually into dry land.

3. Origins of lakes
Lakes-Bodies of water surrounded by land, form in different ways in surface depressions and in low areas.

4. Ways that lakes can form
Oxbow lake

5. Ways that lakes can form
Stream flow becomes blocked by sediment from landslides or other sources
Other?

6. Ways that lakes can form
Glaciers
as glaciers move they form lakes by gauging out land and leaving behind a surplus of water when they melt.
This is how a majority of the lakes in Michigan including the great lakes formed.
Video

7. Lakes Undergo Change
A lakes water supply is maintained by precipitation, runoff, and underground water sources.
Over hundreds of thousands of years lakes will fill in with sediment and become part of the landscape

8. Eutrophication
Nutrients added to lake by run off from surrounding watershed.
video

9. Freshwater Wetland
Wetland-are of land covered by water for part of the year.
Includes
Bogs
Marshes
Swamps

10. Bogs Non stream fed Receives water from precipitation
Soil rich in sphagnum moss
Breakdown of peat moss creates acids
Very acidic
Supports unusual plant species

11. Bogs

12. Marshes Form along mouths of rivers
Constants supply and nutrients and water
Lush marsh grasses
Abundant wildlife

13. Swamps Low-lying areas near streams
Can develop from marshes that have filled in to support growth of trees and shrubs
As larger trees grow they shade the marsh plants causing them to die.
Old swamps developed 200 million years ago developed in to present day coal reserves.
How is coal formed 7:39

15. Wetlands and Water Quality
Improve water quality
Filtering system that traps pollutants, sediments, and bacteria
Home to an abundance of wildlife

17. Feedback: Fertilizers such as nitrates and phosphates contribute to eutrophication.

18. Feedback: Plants take in carbon dioxide and release oxygen through photosynthesis.

19. Feedback: Wetlands serve multiple purposes at one time, making them valuable natural resources on Earth.

20. Feedback: Eutrophication is a natural process, but it can be sped up with the addition of nutrients, such as those found in fertilizers.