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Salt marshes are some of the most unique and important ecosystems in the United States, however,
it is only as of late that their importance is being fully understood. Currently, human threats
to salt marshes exist, yet hopefully, a continually increasing understanding will allow us to
better protect and preserve these marshes. Unfortunately, much damage has already been done;
up through the mid 70's, approximately 35% of these valuable wetlands were written off as
wasteland, and drained in order to make them "useful." Salt marshes are found along the
coasts of the United States, where they form an important interface and transition zone
between freshwater rivers and the oceans that they flow into. Salt marshes can be found
at mouths of rivers flowing into the ocean, but also in other sheltered areas, such as
behind barrier islands, where they play an important role in local ecology. As the
illustration on this slide shows, salt marshes are usually slightly above mean sea level,
often in large wetland areas fed by tidal creeks. Here, above a layer of sand, in a muddy
layer of nutrient rich sediment and soil, much of the marsh's vegetation grows (NOAA #12 p.1).
Estuaries depend greatly on the primary production that takes place in salt marshes, most of which comes directly from the lush salt marsh vegetation. Grasses in marshes originally gain their high nutrient content from waters from rivers and oceans washing over the grasses and depositing nutrient rich sediment. In terms of primary production, only a very small amount of the actual grasses are consumed while they are alive. Upon death, however, the grass is decomposed by fungi and bacteria until it becomes detritus. During this process, the protein content of the dead grass is nearly doubled. Tides move this nutrient rich decomposed grass "sludge" to other parts of estuaries and from there, they provide the basis for the food chain (Arcata). (graphic: www.ocean.udel.edu/courses/mast200/Lecture22/sld044.htm)
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