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

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)

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

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

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.

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

Living in an Estuary

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

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

Types of Estuarine Communities

Consist of few species Species present are in large numbers

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

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

Salt Marshes Dominated by grasses Temperate and subarctic regions

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