Factors to Nutrient Supply in Naturally-Developing Marshes
David Osgood
Measurements of subsurface water dynamics support the idea that regular flushing of the marsh, via tidal action over time, supplies a much greater amount of nutrients than are measured at any one time. The more productive zones of one such marsh are positioned lower in the intertidal zone and receive 1.8 times more nitrogen than less productive zones in the same marsh when factoring in nutrient supply from tidal action. This work demonstrates that important factors to nutrient supply in naturally-developing marshes include a sufficiently conductive substrate, adequate slope, and proper elevation relative to tidal range. With consideration of these factors, a marsh should begin development with more than adequate levels of plant production to evolve into a mature, self-sustaining marsh. (Accepted, Estuaries.)
High Salinity in Temperate Mid-Atlantic Marshes
Marcio Santos
Salinity as high as 140 parts per thousand has been found in temperate mid-Atlantic marshes.
Detailed subsurface surveys at the Virginia Coast Reserve LTER research site reveal plumes of hypersaline waters, owing to their high density, that sink through the island sand mass. Such hypersalinity is detected as deep as 9 meters. High salinity at the junction between the high marsh and the terrestrial landscape that are generated during the summer evaporation season are thus ephemeral in that salts are sequestered at depths.
Plant and Animal Communities in Five Overwash Salt Marshes
John Walsh
In a study of five marshes, ranging in age from about 3 to 125 years of age, the similarities and differences observed in the plant and animal communities provide a space-for-time substitution that chronicles the story of the evolution of overwash salt marshes. Marsh grass and most of the invertebrate fauna (i.e., fiddler crabs and some snails) decrease dramatically in number as these marshes age, whereas predatory crabs and a common mud snail increase in number significantly. (Ph.D. dissertation work in progress.)