What is an estuary? An estuary is a partially enclosed body of water where two different bodies of...
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Transcript of What is an estuary? An estuary is a partially enclosed body of water where two different bodies of...
Estuaries
What is an estuary?An estuary is a partially enclosed body of
water where two different bodies of water meet and mix (e.g. fresh water from rivers or streams and salt water from the ocean, or fresh water from rivers or streams and chemically distinct water of a large lake).
Transition zone between river environments and ocean environments
Subject to both marine influences, such as tides, waves, and the influx of saline water; and riverine influences, such as flows of fresh water and sediment.
The flow of both seawater and freshwater provide high levels of nutrients in both the water column and sediment, making estuaries among the most productive natural habitats in the world.
Turbid watersWaters in estuaries are often turbid and
brackish Turbidity is caused by stirred up sediment
and the influx and withdrawal of organisms such as phytoplankton.
Two main challenges in an estuarySedimentation – Can be problematic for phytoplankton if
sustained, plankton need sunlight to survive, they do not get this if they are submerged in the sediment
Osmoregulation – Osmoregulators Maintain a constant internal water/salt balance even though the
environment is different. Includes freshwater fish, many marine fish, all terrestrial animals OsmoconformersHave internal osmolarity similar to that of the surroundings. Most marine invertebrates, some vertebrates, e.g. sharks• http://www.youtube.com/watch?v=lBbSsUpCRdM
Freshwater fish tend to gain water and loose salt
Marine fish tend to gain salt and loose water
Provide habitats for large number of species – fish nurseries (salmon, sea trout etc). Also feeding grounds for many birds.
Primary producers are phytoplankton which feed on detritus in the water.
Many species of bacteria live in the sediment of estuaries, this can have implications on other sediment dwelling species as they are in direct competition for resources (oxygen).
Common species found in British estuariesMany animal species are found in British
estuaries, these include:arthrop0ds (crustaceans and insects) molluscscnidariansPolychaetesBirdsEchinodermsMany grass, phtyoplankton and seaweed
species
Threats to estuaries6o% of the worlds population live around estuaries and the
coast– Why?22/36 of the worlds biggest cities sit directly on estuaries.
Human threats:Increased sedimentation due to soil erosion up streamOverfishingDrainage of wetlandsEutrophication from nitrates and phosphates – causes algal
blooms etc – results in hypoxia and ultimately dead zonesPollutants including PCB’s plastics and heavy metalsOver management and damming of areas for human
purposes.http://www.youtube.com/watch?v=D1iv37Yn8bg
Task - Each of you have a journal article relating to
estuaries in some form, the journals do not have abstracts. Your job is to write one, it should be between 100 – 200 words.
https://springerlink3.metapress.com/content/v875220495363h23/resource-secured/?target=fulltext.pdf&sid=1xa24bw1tuh4wnjghond2tob&sh=www.springerlink.com
http://www.psparchives.com/publications/our_work/hood_canal/hood_canal/hood_canal_onsite_factor_2.pdf
http://archimer.ifremer.fr/doc/00000/3080/