1. Estuaries

2. 1. What is an estuary?
a partially enclosed body of water where 2 different bodies of water meet & mix.

3. Estuaries
2. Estuaries are formed where fresh water meets & mixes with ocean water.
3. Estuaries are found where rivers meet the sea.
4. Estuaries are found where rivers meet chemically distinct lakes.

4. Estuary Features and Landforms
5. Each estuary includes a variety of habitats. Some may be bordered by marshes.
6. Estuary features such as swamps or lagoons form behind barrier islands and beaches.

5. Estuary Features and Landforms
7. Bays, harbors, sounds, and inlets are all estuaries.
8. Bayous are formed by channels of slow moving water leading from a river or lake.

6. Estuary Features and Landforms
9. Salt marshes form in estuaries in areas protected from high-energy waves.
10. Tidal flats are part of many estuaries. Oyster & clams are harvested here.

7. Estuary Features and Landforms
11. Mangrove forests surround wetland areas in southern estuaries.
12. In mountainous areas, estuaries may be found in seaside fjords.

8. Estuary Life 13. Many types of plants grow in estuaries.
14. Estuaries provide food, shelter, and water to variety of plants and animals.
Plants are not usually termed “residents”

9. Importance of Estuaries
15. Why is an estuary a spawning & nursery grounds for many organisms?
a. Few predators, abundant food, diversity of habitats, high turbidity
b. Filters pollutants from water
c. Buffer to mainland during storms (absorbs excess water)

10. Importance of Estuaries
16. Estuaries are :
a. Food & resting place for migratory birds
b. Source of commercially important species; clams, oysters, blue crabs
c. Food & habitat for many organisms
d. Popular sport & recreation areas; fishing, sailing, swimming

11. 17. Human Impact on Estuaries
a. Landfill – draining & filling in to build homes, etc. (destroys habitat)
b. Mining – for minerals, oil, sand, & gravel
c. Construction – dams/channel dredging (changes spawning migrations, water circulation, & local salinity)
d. Sediments – from construction, dredging, & erosion (increases turbidity which inhibits photosynthesis & smothers gill breathers)
e. Chemicals – pesticides/sewage (decrease species diversity)

12. f. Overharvesting – clams, oysters, mussels, & fish
g. Thermal Pollution – industries use water as coolant; heated water returned to estuary (incr. water temp = decrease O2)

13. Threats to Estuaries

14. Estuaries Additional Details
18. Nutrient-rich river water spills into the estuary and mixes with nutrient-rich ocean water which makes them a productive ecosystem in which organisms raise their young.
19. Large amount of plankton feed small fish, etc.
20. Birds, mammals, & larger fish feed on the smaller fish and plants.
21. Migratory birds rest & breed here.
22. Pollution & rising sea levels threaten most estuaries.
23. North Carolina estuaries are threatened by runoff from urban development & agricultural areas.

15. Estuaries of NC

16. Life in a Transition Zone
Survival in an Estuary
Life in a Transition Zone