1. KEY CONCEPT Freshwater ecosystems include estuaries as well as flowing and standing water.

2. Estuaries are dynamic environments where rivers flow into the ocean.
An estuary is a partially enclosed body of water.
mixture of fresh water with salt water
Chesapeake Bay
Louisiana bayous

3. Estuaries are highly productive ecosystems.
Estuaries provide a protected refuge for many species.
birds migration
spawning grounds
Estuaries are primarily threatened by land development.

4. Freshwater ecosystems include moving and standing water.
A watershed is a region of land that drains into a body of water.
Ecosystems may be different along a river’s course

5. Wetlands are among the most productive ecosystems.
provide a home for many species
filter dirty water
renew underground water supply
Some animals have adaptations suited to the freshwater they inhabit.

6. Ponds and lakes share common features.
Freshwater bodies are divided into three zones.
littoral zone
Shoreline, lots of light, warm water
limnetic zone
Open water, lots of fish
benthic zone
Bottom, little sunlight,
decomposers

7. All lakes “turn over” periodically.
Turn over happens due to changes in density.
In both autumn and spring, surface water flows downward and bottom water flows upward.
The upwelling brings up nutrients.