Saltmarsh
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A walkway for people over a salt marsh. |
A
salt marsh is a type of
marsh found in the
intertidal transition between land and ocean. They are dominated by
halophytic herbaceous plants. They are also called
tidal marshes or
saltings. 'Ing' is a word of Nordic origin, meaning 'meadow' and saltings made quite rich cattle pasture which was also free of
liver fluke (
Fasciola hepatica and others). Care should be taken not to confuse 'salting' with 'saltern', which is a salt-house. Salterns were found among salt marshes and are places where
brine is evaporated to produced salt.
The water is
saline, and both the water table level and salinity are dependent on tides. Salt marshes develop on depositional coasts where tidal action is relatively gentle and erosion no more than intermittent and light enough to allow vegetation to take hold. They are common on
low-energy coasts such as
estuaries, enclosed bays, and the land sides of
barrier islands and strips.
The
sediment in salt marshes is delivered not constantly, as in other types of marshes, but cyclically, owing to the tides. As would be expected at the coast, the sediment is rich in sand, shells, and organic material from the ocean.
Plant species diversity is low, since the flora must be tolerant of salt, complete
submersion, and anoxic mud substrate. The most common salt marsh plants are
glassworts (
Salicornia spp.) and the
cord grasses (
Spartina spp.), which have worldwide distribution. They are often the first plants to take hold in a
mudflat and begin its
ecological succession into a salt marsh. Their shoots lift the main flow of the tide above the mud surface while their roots spread into the substrate and stabilize the sticky mud and carry oxygen into it so that other plants can establish themselves as well. Plants such as
sea lavenders (
Limonium spp.),
plantains (
Plantago spp.), and varied
sedges and
rushes grow once the mud has been vegetated by the
pioneer species.
The flora of a salt marsh is differentiated into levels according to the plants' individual tolerance of salinity and water table levels. Vegetation found at the water must be able to survive high salt concentrations, periodical submersion, and a certain amount of water movement, while plants further inland in the marsh can sometimes experience dry, low-nutrient conditions.
Salt marshes are quite photosynthetically active and are extremely productive habitats. They serve as depositories for a large amount of organic matter, and are full of decomposition, which feeds a broad food chain of organisms from bacteria to mammals.
In wintertime the saltmarsh looks more open than in summer. More space is seen between reeds as snow falls between them. The water partly freezes, which makes it look rather spectacular.
In warmer climates, salt can be produced by solar energy so that the French equivalent of the salt marsh, the
marais salant has come to be envisaged primarily as an industrial plant, though classified as a form of agriculture, known in French as
saliculture. For this aspect of the salt marsh, see also
Salt evaporation pond.
*
Geography resource for schools*
Salt Marsh Nature Center located in the
Marine Park section of Brooklyn, New York, USA
