Southern New England Habitats II: Tidal Marsh

• Definititon: Tidal marshes develop in the quiet water, low Definititon: Tidal marshes develop in the quiet water, low energy environments behind barrier beaches at places where energy environments behind barrier beaches at places where freshwater streams enter the ocean. Such mixing zones freshwater streams enter the ocean. Such mixing zones between fresh and salt water are between fresh and salt water are estuariesestuaries. They are subject . They are subject to daily tidal inundation.to daily tidal inundation.

• Physical environment: Tidal marshes also are an extreme Physical environment: Tidal marshes also are an extreme environment, in that organisms living in them must tolerate environment, in that organisms living in them must tolerate tidal fluctuation and water salinity.tidal fluctuation and water salinity.

• Diversity: As with beaches, richness of terrestrial species may Diversity: As with beaches, richness of terrestrial species may be low, because few species possess the adaptations necessary be low, because few species possess the adaptations necessary to survive this environment. The density of these species may to survive this environment. The density of these species may be high, however. Even marine species must contend with be high, however. Even marine species must contend with environments that are periodically flooded and that show wide environments that are periodically flooded and that show wide swings in water salinity.swings in water salinity.

Topography: the Low Salt Marsh

• The area above the mid-tide level is the first to be extensively The area above the mid-tide level is the first to be extensively vegetated by terrestrial plants. Near the mouth of estuaries, vegetated by terrestrial plants. Near the mouth of estuaries, this tidal water is highly saline, and tidal salt marshes develop.this tidal water is highly saline, and tidal salt marshes develop.

• The predominant species in this zone is a tall, coarse grass- salt The predominant species in this zone is a tall, coarse grass- salt marsh cord grass (foreground).marsh cord grass (foreground).

• Below the mid-tide level, mudflats are exposed at low tide.Below the mid-tide level, mudflats are exposed at low tide.

• In New England, most low marsh occurs at the seaward edge of In New England, most low marsh occurs at the seaward edge of tidal marshes and along tidal creeks, such as the one in the tidal marshes and along tidal creeks, such as the one in the photo.photo.

High Salt Marsh

• Above the high tide level is a region flooded only several times Above the high tide level is a region flooded only several times a month by “spring” tides (tides associated with the full and a month by “spring” tides (tides associated with the full and new moon).new moon).

• This high marsh is vegetated by a finer, tussock-forming This high marsh is vegetated by a finer, tussock-forming grass- salt meadow cord grass.grass- salt meadow cord grass.

• Much of the surface of New England salt marshes is covered Much of the surface of New England salt marshes is covered by high marsh.by high marsh.

Salt PannesSalt Pannes

• Low spots on the surface of the high marsh may fill with tide Low spots on the surface of the high marsh may fill with tide water, which is then trapped in them. water, which is then trapped in them.

• As the water evaporates, it becomes As the water evaporates, it becomes hypersalinehypersaline, creating , creating conditions which few plant species tolerate.conditions which few plant species tolerate.

• A stunted form of salt marsh cord grass grows in these areas, A stunted form of salt marsh cord grass grows in these areas, as does the fleshy-stemmed saltwort and various types of as does the fleshy-stemmed saltwort and various types of algae.algae.

• Numerous invertebrates may be found in pannes, and these Numerous invertebrates may be found in pannes, and these are a valuable food source for species like migratory are a valuable food source for species like migratory shorebirds.shorebirds.

Upper Marsh

• In areas with greater microelevations (elevations inches In areas with greater microelevations (elevations inches above those of lower parts), tidal flooding becomes even less above those of lower parts), tidal flooding becomes even less frequent.frequent.

• In these regions, plant species like spike grass and black In these regions, plant species like spike grass and black grass (actually in the rush family; visible in the center of grass (actually in the rush family; visible in the center of this slide) predominate.this slide) predominate.

Upland Border

• The upland border of tidal marshes are still less frequently The upland border of tidal marshes are still less frequently affected by tidal flooding- usually only during wind-driven affected by tidal flooding- usually only during wind-driven storm tides.storm tides.

• They are characterized by salt-tolerant herbaceous species They are characterized by salt-tolerant herbaceous species like switchgrass (foreground) and woody shrubs like high like switchgrass (foreground) and woody shrubs like high tide bush and groundsel tree (white flowered shrub).tide bush and groundsel tree (white flowered shrub).

Profile of a Southern New England Salt Marsh

Adaptations

• To inhabit the salt marsh, plants and animals have developed mechanisms to cope with environmental conditions.

• The sharp-tailed sparrow (above) has kidneys that remove excess salt from its tissues.

• The saltwort (left) has fleshy stems that helps to dilute salts in its tissues.

Brackish and Freshwater Tidal

Marshes• Water salinity steadily

drops upstream along estuaries, although tidal action may extend inland many miles.

• When water is slightly salty, brackish tidal marshes dominated by reeds and cattails develop (below right).

• Further upstream, freshwater tidal marshes dominated by bulrushes, pickerelweed and water horsetail develop (above right).