B. Tue Ecoroaicat Imporrance or A SALT MARSH 
(By B. W. Tripp, Massachusetts Institute of Technology) 
The salt marsh, for the nearly 200 years of our history, has been 
considered wasteland and of little value to man. Except for the earliest 
settlers who used marsh hay for their livestock, we have considered 
the marsh only as an undesirable breeding ground for noxious insects 
and fit only for waste disposal. To be of any value, the marsh needed 
to be “reclaimed.” I intend to discuss a few of the environment- 
biosphere relationships that occur in a salt marsh and to indicate some 
of the vital aspects of marshes that have been ignored. 
A salt marsh is an integral part of the estuarine system which it 
borders. An estuary by definition is a protected, semienclosed bay 
that is open to the sea and is diluted by fresh water derived from land 
drainage. The distinctive characteristics of the estuary make it an 
ideal spot for salt marsh formation. Geologically, the marsh is a 
transitory feature and will eventually transform into upland. Salt 
marshes are formed in sheltered areas behind sand spits and at the 
heads of bays. Material that has been eroded from the continent 
settles out from the water and the bay bottom rises to the low tide 
level (fig. I). At this level, the exposed flat can be colonized by pioneer 
species of plants and in vegetated areas of the mud flat the sedimenta- 
tion rate is accelerated. 
The vegetation causes the marsh to grow vertically upward and 
laterally outward to include the entire area of sediment deposit. As the 
marsh rises, a drainage system develops in the form of creeks which 
follow the previous channels of the bay. The new marsh is regularly 
innundated by the tides, and as the creeks carry the bulk of water in 
and out of the marsh, they are kept open by the scouring action that 
results. We now have a salt marsh—an intertidal plateau of silt and 
sand, covered with vegetation and regularly flooded by the tides. 
This new salt marsh has the appearance of a meadow, as the only 
macro plant is a grass. Two species of the genus Spartina predominate 
in the marsh: S. alterniflora (cord grass), and S. patens (marsh hay). 
Zonation in the marsh is associated with dryness as the tall cord grass 
grows in the wetter, low marsh while the shorter marsh hay grows in 
the upper part of the marsh that is less often innundated by the sea. 
The other marsh plants are less obvious but they are also ecologically 
important and include mud algae and phytoplankton. The marsh is 
also an essential habitat to a large animal population that includes both 
marine and terrestrial species. Waterfowl such as the heron, egret, 
osprey, duck, and rail, can be counted in a wildlife population of 
insects, muskrats, deer, racoons, and skunks. Marine species that call 
the marsh home, are crabs, terrapin, snails, shellfish, and fish (espe- 
cially during the juvenile stages of development). Between the two 
groups of macro flora and fauna we find the bacteria, which also fill a 
critical role in the system (fig. II). The salt marsh ecosystem supports 
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