Southern New England Habitats II: Tidal Marsh Definititon: Tidal marshes develop in the quiet water, low energy environments behind barrier beaches at places where freshwater streams enter the ocean. Such mixing zones between fresh and salt water are estuaries. They are subject to daily tidal inundation.Definititon: Tidal marshes develop in the quiet water, low energy environments behind barrier beaches at places where freshwater streams enter the ocean. Such mixing zones between fresh and salt water are estuaries. They are subject to daily tidal inundation. Physical environment: Tidal marshes also are an extreme environment, in that organisms living in them must tolerate tidal fluctuation and water salinity.Physical environment: Tidal marshes also are an extreme environment, in that organisms living in them must tolerate tidal fluctuation and water salinity. Diversity: As with beaches, richness of terrestrial species may be low, because few species possess the adaptations necessary to survive this environment. The density of these species may be high, however. Even marine species must contend with environments that are periodically flooded and that show wide swings in water salinity.Diversity: As with beaches, richness of terrestrial species may be low, because few species possess the adaptations necessary to survive this environment. The density of these species may be high, however. Even marine species must contend with environments that are periodically flooded and that show wide swings in water salinity.

Topography: the Low Salt Marsh The area above the mid-tide level is the first to be extensively vegetated by terrestrial plants. Near the mouth of estuaries, this tidal water is highly saline, and tidal salt marshes develop.The area above the mid-tide level is the first to be extensively vegetated by terrestrial plants. Near the mouth of estuaries, this tidal water is highly saline, and tidal salt marshes develop. The predominant species in this zone is a tall, coarse grass- salt marsh cord grass (foreground).The predominant species in this zone is a tall, coarse grass- salt 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 tidal marshes and along tidal creeks, such as the one in the photo.In New England, most low marsh occurs at the seaward edge of tidal marshes and along tidal creeks, such as the one in the photo.

High Salt Marsh Above the high tide level is a region flooded only several times a month by “spring” tides (tides associated with the full and new moon).Above the high tide level is a region flooded only several times a month by “spring” tides (tides associated with the full and new moon). This high marsh is vegetated by a finer, tussock-forming grass- salt meadow cord grass.This high marsh is vegetated by a finer, tussock-forming grass- salt meadow cord grass. Much of the surface of New England salt marshes is covered by high marsh.Much of the surface of New England salt marshes is covered by high marsh.

Salt Pannes Low spots on the surface of the high marsh may fill with tide water, which is then trapped in them.Low spots on the surface of the high marsh may fill with tide water, which is then trapped in them. As the water evaporates, it becomes hypersaline, creating conditions which few plant species tolerate.As the water evaporates, it becomes hypersaline, creating conditions which few plant species tolerate. A stunted form of salt marsh cord grass grows in these areas, as does the fleshy-stemmed saltwort and various types of algae.A stunted form of salt marsh cord grass grows in these areas, as does the fleshy-stemmed saltwort and various types of algae. Numerous invertebrates may be found in pannes, and these are a valuable food source for species like migratory shorebirds.Numerous invertebrates may be found in pannes, and these are a valuable food source for species like migratory shorebirds.

Upper Marsh In areas with greater microelevations (elevations inches above those of lower parts), tidal flooding becomes even less frequent.In areas with greater microelevations (elevations inches above those of lower parts), tidal flooding becomes even less frequent. In these regions, plant species like spike grass and black grass (actually in the rush family; visible in the center of this slide) predominate.In these regions, plant species like spike grass and black grass (actually in the rush family; visible in the center of this slide) predominate.

Upland Border The upland border of tidal marshes are still less frequently affected by tidal flooding- usually only during wind-driven storm tides.The upland border of tidal marshes are still less frequently affected by tidal flooding- usually only during wind-driven storm tides. They are characterized by salt-tolerant herbaceous species like switchgrass (foreground) and woody shrubs like high tide bush and groundsel tree (white flowered shrub).They are characterized by salt-tolerant herbaceous species like switchgrass (foreground) and woody shrubs like high 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).