M.+Klosinski

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CLIMATE
 * temperature and precipitation are the most important factors that determine which species can survive water temp. sunlight affects amount of oxygen, the most important in fresh water.


 * fresh water environments are very small gurgling brooks to large, slow-moving rivers and strong currents
 * Temperature varies in ponds and lakes seasonally. During the summer, the temperature can range from 4° C near the bottom to 22° C at the top. During the winter, the temperature at the bottom can be 4° C while the top is 0° C (ice).

PLANTS
 * as water tumbles and splashes air from the atmosphere mixes in. the faster the water moves more usually have clearer water and higher oxygen content than slower moving water. plants and algea provide oxygen through photosynthesis
 * 1) **submersed leaves**, which are very thin and narrow, often highly dissected and very flexible
 * 2) **floating leaves**, broader leaves that are firm or leathery but flexible enough to resist tearing by wave action
 * 3) **emersed leaves** (aerial leaves), i.e., similar to typical leaves of terrestrial plants living nearby
 * most nutrients that supports life is washed in form land
 * Plants are very efficient at removing toxins and other nutrients from the water that might be harmful to fish and animals. They help reduce algae and bacterial blooms from clouding the water.
 * plants in fresh water adjust to low salt content
 * Many freshwater plants provide food for aquatic life by dropping fruit and seeds into the water. Herbivorous fish like to dine on tender underwater shoots that are usually highly nutritious.


 * ANIMALS**
 * Eggs are generally placed in shallow water, often in nests where they are fanned, guarded, or rolled around. All these are thought to be adaptations to low oxygen concentrations. In addition, several species of wetland fish are live-bearers which may also be an adaptation to the variable conditions in a wetland.
 * Some fish (gars, bowfins, mudminnows) can absorb air from their air bladders.


 * plant have to have strong roots for in the the river


 * animals increase their breathing at the water's surface


 * most animal depend on fish for food


 * fish depend on plants for oxygen


 * Freshwater animal species are disappearing faster than land or sea animals. 573 freshwater animals in the U.S. are threatened with extinction
 * some animals live at the surface of the water such as frogs


 * Many fish species seen on the Barrier Reef as adults actually started their lives in streams and brackish water estuaries (mixed fresh and salt water).