1. Freshwater Ecosystems
RIVERS

2. Every river is part of a larger system-a watershed, which is the land drained by a river and its tributaries.
Rivers are large natural streams of water flowing in channels and emptying into larger bodies of water.
This diagram shows some common characteristics of a river system.
Every river is different, however, so not all rivers may look exactly like this illustration.

3. What Lives in a River? Organisms have adapted to fast moving water.
Current speed determines what lives in a river or stream.
1. Producers such as algae & moss cling to rocks
2. Consumers: insect larvae hide under rocks
3. Tadpoles use suction disks

4. Parts of a River
RIVER SOURCE, also called the headwaters, is the beginning of a river.
Often located in mountains, the source may be fed by an under- ground spring, or by runoff from rain, snowmelt, or glacial melt.

5. Watershed
A watershed boundary, also called a drainage divide, marks the outer- most limit of a watershed.
A watershed is a tract of land drained by a river and its tributaries.
Anything that affects a watershed may eventually impact its tributaries and river as well as the water body at the mouth of the river.
People's actions within a watershed can affect the overall quality of its rivers.

6. Floodplain
A fully-developed floodplain is relatively flat land stretching from either side of a river, which may flood during heavy rain or snowmelt.
Built of materials deposited by a river, floodplain soil is often rich in nutrients and ideal for growing food.

8. Tributary
A tributary is a smaller stream or river that joins a larger stream or main river.

10. Main River and Meander
The main river is the primary channel and course of a river.
A meander is a loop in a river channel. A meandering river winds back and forth, rather than following a straight course.

13. Mouth of a River
The river mouth is the place where a river flows into a larger body of water, such as another river, a lake, or an ocean.

14. Wetlands
Wetlands are low-lying areas saturated with water for long enough periods to support vegetation adapted to wet conditions.
Wetlands help maintain river quality by filtering out pollutants and sediments, and regulating nutrient flow.
Swamps are an example of a wetland.

18. Delta
A delta is a landform that is created at the mouth of a river where that river flows into an ocean, sea, estuary, lake, reservoir, flat arid area, or another river.
Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river.
Over long periods of time, this deposition builds the characteristic geographic pattern of a river delta.

19. Mobile-Tensaw Delta
The delta is characterized by a large number of distributary rivers, streams, bayous, and creeks which form a maze of waterways.
The delta and adjacent Mobile Bay Estuary comprise one of the largest wetland ecosystems in the United States

20. Fauna of the Delta 126 species of fish
40 species of mammals, including black bears, wild pigs and deer
69 species of reptiles such as alligators and the rare red-bellied turtle
30 species of amphibians
500 species of plants, including swamp lilies, cardinal flowers, butterfly weed, green-fly orchids and the tiny-leaved buckthorn, one of the rarest shrubs in the United States
More than 300 species of birds, including eagles, ospreys, pelicans, herons, kites, owls, warblers, vireos, wrens, egrets and a variety of woodpeckers, including the Pileated woodpecker, which can grow as long as 19 inches and is the largest woodpecker in North America

23. Problems Facing Rivers: Pollution
2 types of pollution that affect rivers:
a. point source pollution
b. nonpoint source pollution