15 5 Estuaries and Freshwater Ecosystems KEY CONCEPT

15. 5 Estuaries and Freshwater Ecosystems KEY CONCEPT Freshwater ecosystems include estuaries as well as flowing and standing water.

15. 5 Estuaries and Freshwater Ecosystems 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 – Florida Everglades

15. 5 Estuaries and Freshwater Ecosystems • Estuaries are highly productive ecosystems. • Estuaries provide a protected refuge for many species. – birds migration-use as refuge from cold weather – spawning grounds-aka “nurseries of the sea” • Estuaries are primarily threatened by land development.

15. 5 Estuaries and Freshwater Ecosystems 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- ex. Colorado River seen below

15. 5 Estuaries and Freshwater Ecosystems • Wetlands are among the most productive ecosystems. – provide a home for many species – filter dirty water – renew underground water supply

15. 5 Estuaries and Freshwater Ecosystems Ponds and lakes share common features. • Freshwater bodies are divided into three zones. – littoral zone-( close to shoreline--similar to oceanic intertidal) – limnetic zone-open water further out from shore – benthic zone-bottom of lake or pond (bacteria live here)

15. 5 Estuaries and Freshwater Ecosystems • 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.