Freshwater Wetlands I Wetlands A Definition an ecosystem

Freshwater Wetlands

I. Wetlands A. Definition - an ecosystem in which water either covers the soil or is present at or near the surface of the soil for at least part of the year B. Usefulness - productive ecosystems that serve as breeding grounds for insects, fishes and other aquatic animals, amphibians, and migratory birds

C. Formation Form from geological or ecological factors such as: tidal flows, flooding rivers, connections with groundwater, or because they are above aquifers or potholes.

D. Characteristics 1. found all over the world in lowland areas or along rivers, lakes, streams Some 2. Most are temporary and seasonal - occur for a few weeks at a time. 3. Some are always under water.

E. Organisms Present - cattails, rushes, and other tall grass-like plants, bald cypress trees, turtles, otters, alligators, and herons.

II. Role of Wetlands in an Ecosystem A. Prevent flooding by holding water much like a sponge. B. Help keep river levels normal by accepting and releasing water. C. Filtering and purifying the surface water.

III. Wetlands & Water Purification A. Wetlands purify water by filtering out sedimentation, decomposing vegetative matter and converting chemicals into useable form. B. Ability of wetlands to recycle nutrients makes them critical in the earth’s functioning. C. No other ecosystem type is as productive or unique in the conversion process.

IV. Types of Wetlands A. Swamps - slow moving streams, rivers or isolated depressions that host trees and some shrubs. B. Bog 1. a peat-accumulating wetland lacking a direct inflow and outflow of water(water is from precipitation) 2. Grows shrubs, evergreens, and mosses.

C. Prairie Pothole 1. Shallow, bowl-like depressions having variable wetness (not wet year-round) 2. Found in the northern Great Plains. 3. Used for breeding by birds.

D. Marsh 1. an inland area with 1– 6 feet (33– 200 cm) of water 2. contains a variety of grasses, flowers, and bushes 3. Muskrats are common in marshes.

E. Riparian Marsh 1. Marshes along rivers 2. Serve two ecological roles: a. to absorb excess water when river levels are high b. to release needed water when river levels are low. 3. Balancing river levels helps prevent floods and droughts.

4. The straightening and deepening of rivers to enable commerce/trade has caused a loss of riparian marshes. 5. Few riparian marshes are left. 6. It’s believed that the great Mississippi River flood of 1993 was worse due to the loss of riparian marshes.

F. Estuaries 1. Definition - wetland formed where a river meets the sea. 2. Contain a mixture of fresh water and salt water. 3. Affected by the rise and fall of ocean tides. 4. Shallowness allows for photosynthesis to occur. 5. spawning and nursery grounds for commercial fish & shellfish (shrimps and crabs)

6. Food Webs Differ from the Norm a. Most primary producers not consumed by herbivores. b. Organic material enters as detritus. c. Detritus is base of the food web. d. Organisms feeding on detritus: clams, worms, sponges, crayfish, and shrimp

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