1. Rivers and Streams
Maddie Dahlberg

2. Productivity
The overall productivity of rivers and streams is significantly lower than estuaries (the most productive aquatic ecosystem). They produce around 2,200 kilocalories per square meter a year.

3. Major Life Forms
Macroinvertebrates, such as water insects (mayflies, stoneflies, and caddisflies), crawfish, and mussels, are very common in rivers and streams. Larger animal species include beavers, fish (trout, rockfish, minnows, etc), watersnakes, turtles/terrapins, and several species of amphibians. In larger and wider rivers, birds such as ducks, geese, herons, and occasionally seagulls can found in and around the river. Almost all of the plant life found in and around rivers and streams is SAV (sub-aquatic vegetation) and algae, or grasses, shrubs, and sometimes trees found on the banks.

4. Limiting Abiotic Factors
Abiotic factors include dissolved oxygen, excessive nutrients/pollution (usually fertilizer and waste running of), pH, temperature, and location. Dissolved oxygen is important because without it, aquatic animals will not be able to breathe and the river or stream will become a dead zone. Location and temperature go hand-in-hand, as do location, pH, and excessive nutrients. If a river or stream is in a colder place, the water's temp will be colder. Also, rivers and streams cutting through limestone will have a more basic pH, and those running through or near farmland will have more run-off nutrients and will either be more acidic or basic.

5. Special Features
Rivers and streams flow north to south ending in a larger body of water, like an ocean or bay; the only known river that flows south to north is the Nile River in Egypt and Sudan, which empties into the Mediterranean Sea. The rushing water causes sediment to be loosened and carried further downstream. A prime example of this is the Grand Canyon in Arizona; the Colorado River has eroded the surrounding rock away over time and formed the canyon. Rivers can also be freshwater or have brackish water (a mixture of saltwater and freshwater). At the beginning of a river, the water is fresh while at the delta, the water is usually ranges from brackish to saltwater.

6. Plant Adaptation
In wider rivers, plants, algae, and phytoplankton usually make their homes in the shallower water because the water is clearer and sunlight can reach the river bottom easier. In streams, algae and phytoplankton is the common plant life, as the water clarity allows more sunlight to reach the bottom, and the water is too shallow to support larger aquatic grasses.

7. Animal Adaptation
In rivers with a faster flowing current, fish have more streamlined bodies (pun slightly intended) and will hide to behind rocks to conserve energy. Beavers will build dams and lodges in the river to protect themselves from enemies and to keep warm in the winter. In areas like central Pennsylvania, rivers are more are basic due to the amount of limestone present. While most fish would consider those rivers to be stressful, trout thrive in them.

8. Sources
   Miller, G. T., Jr. (1975). Living in the Environment (15th ed.). Belmont, CA: Wadsworth Pub. Co.
   What Lives in our Streams. (n.d.). Retrieved October 23, 2017, from
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