1. Estuaries: Where Rivers Meet the Sea
Chapter 12
Estuaries: Where Rivers Meet the Sea

4. Estuary
Semi-enclosed areas where fresh water and seawater meet and mix
Close interaction between land and sea
Among the most productive environments on earth
Among the environments most effected by humans
Many cites are located along them (NY, London, Tokyo)

5. Importance of Estuaries
Nurseries of the sea – used by many species for nesting and breeding
Most of the fish and shellfish we eat complete part of their lifecycle here (salmon, herring, oyster)
Used for recreation, jobs, and homes
Of the 32 largest cities 22 are located on estuaries

6. Filter out sediments and pollutants from rivers and streams before they flow into the ocean providing cleaner water for humans and marine life

7. Estuaries are interconnected with the world ocean and with major systems and cycles on Earth.
Estuaries are dynamic ecosystems with tremendous variability within and between them in physical, chemical, and biological components.
Estuaries support an abundance of life, and a diversity of habitat types.

8. Estuaries – One of the most Threatened ecosystems on earth
Coastal development
Introduction of invasive species
Overfishing
Dams
Global climate change (sea level rise)

9. Living in an Estuary

10. Organisms of the estuary
Most estuarine organisms are marine species that have developed the ability to tolerate low salinities
Euryhaline – organisms that can tolerate a wide range of salinities – most estuarine organisms are
Stenohaline – tolerate a narrow range in salinity

11. Dealing with Osmosis
Osmoconformers – body fluids change with the salinity
Osmoregulators – keep the salt concentration of their body fluids more or less constant

12. Types of Estuarine Communities

13. Consist of few species
Species present are in large numbers

14. Open Water – when tide is in
Water is murky – turbid
Lots of food – plankton
Fish move in

15. Mudflats – at low tide Organisms – infauna
Problems – predation, desiccation, temperature changes, salinity changes

18. Salt Marshes
Dominated by grasses
Temperate and subarctic regions

23. Mangrove Forests Tropical equivalents of salt marshes
Dominated by Mangroves (trees)
tropical regions