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Salt Marshes Salt Marshes • Salt marshes

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Salt Marshes Salt Marshes • Salt marshes Powered By Docstoc
					Salt Marshes
• Salt marshes are coastal wetlands rich in
  marine life. They are sometimes called tidal
  marshes, because they occur in the zone
  between low and high tides. Salt marsh
  plants cannot grow where waves are strong,
  but they thrive along low-energy coasts.
 Where are Marshes Located?
  What are Their Features?
• Salt marshes are transitional areas between land
  and water, occurring along the intertidal shore of
  estuaries and sounds where salinity (salt content)
  ranges from near ocean strength to near fresh in
  upriver marshes.
• Because many salt marshes are influenced by the
  twice daily rise and fall of tides, they are subject
  to rapid changes in salinity, temperature and water
  depth.
• Salinity, frequency and extent of flooding of the
  marsh determine the types of plants and animals
  found there.
• The low marsh zone floods twice daily in most
  UK environments, while the high marsh floods
  only during storms and unusually high tides.
  Animals and plants live in these zones of the
  marsh, depending on how well they can withstand
  the drier conditions of the upper marsh or the wet
  conditions that regularly occur in the lower marsh.
            The Vegetation
• Salt marsh plants are adapted to a harsh,
  semi-aquatic environment and saline soils.
  Species diversity is low. Stout stems, small
  leaves, and physiological adaptations for
  salt excretion and gas exchange characterize
  the inhabitants of the salt marsh, which are
  mostly grasses and low perennial herbs.
• The tangle of marsh plant roots and stems helps to
  stabilize the muddy bottom, as well as to trap
  debris and dissolved nutrients with each tidal
  cycle. Bacteria convert this oasis of detritus into
  food resources for microscopic algae, invertebrate
  larvae, and larger animals. Salt marshes are about
  twice as photo-synthetically productive as corn
  fields and provide critical nursery grounds for
  numerous organisms.
Algae and sea lettuce
a   b

        c
      Species composition and
              zonation
• Species composition and zonation in the salt
  marsh are governed by salinity gradients in
  combination with the amount of intertidal
  exposure.
• Eelgrass, Zostera marina, for example,
  occupies the lowest or most marine zone. It
  cannot tolerate a freshwater environment or
  intertidal conditions that would expose its
  roots to air.
• Cordgrass, Spartina foliosa, occurs in the
  marine-to-terrestrial transition zone,
  characterized by lower salinity and periodic
  exposure to the air. Shoreward, where
  conditions are even drier, species belonging
  to the genus Salicornia are common.
Cord Grass
• On higher ground, where tidal intrusions are
  rare, the wiry, prickly-leaved succulent
  jaumea, Jaumea carnosa, is common, as are
  the bushy shoregrass, Monanthochloe
  littoralis; tall and slender sea arrowgrass,
  Triglochin maritima; and endangered salt
  marsh bird's beak, Cordylanthus maritimus.
Jaumea carnosa
                 Monanthochloe littoralis
                      Cordylanthus maritimus




Triglochin maritima
• The green, wiry-leaved saltgrass, Distichlis
  spicata, is widespread, occurring from the
  middle to high marsh, as well as in dunes
  and on salt flats. An unusual salt marsh
  plant is the orange, parasitic dodder,
  Cuscuta salina. Its tiny, scale-like leaves
  and thread-like stems frequently invade and
  cover large areas of vegetation.
Salt Grass

				
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