higher tides than average occur periodically. Spring tides occur approximately fortnightly in 

 conjunction with the new and full moons. The statistical average of these, referred to as mean 

 high water spring (MH WS), has an elevation of 69 cm (2.25 ft) above local mean sea level (MSL) 

 in Little Egg Inlet (U.S. Department of Commerce 1985). Less frequent tidal inundation occurs at 

 even higher elevations at least several times each year. 



The frequency of this flooding controls the kinds of plant species that can survive in an area. 

 Unlike the intertidal areas of the southeastern United States, the salt marshes of New Jersey are 

 predominantiy high marsh. High marsh has been reported to be over seven times more common 

 than low marsh in the state (Spinner 1969). From the standpoint of primary productivity (organic 

 accumulation per square meter), certain high marshes appear to be as productive as low marshes 

 (Nixon 1982). However, the export of produced organic matter is low from high marsh, indicating 

 its productivity values are less important than those of low marsh. 



The marsh wedands in south-central New Jersey are generally divided into transition zones. 

 The most extensive of these zones occurs between (1) the upland and normal monthly tide level, 

 high marsh, which receives weekly flooding, and (2) the low marsh, which tolerates daily 

 flooding. Near local MSL, prolonged inundation inhibits plant growth and the marsh gives way to 

 intertidal sand and mud flats. The most sheltered areas (with the least wave action) contain the 

 muddiest sediments (Hayes and Kana 1976). The upper limit of salt-tolerant plants appears to be 

 at about the 5.0 ft (about 1.5 m) contour shown on USGS topographic maps. This is an 

 important elevation because it represents the lower limit of human development that could occur 

 without altering existing wetlands. The zone below this elevation (delineated on the basis of 

 vegetation types) is a critical area, subject to strict Coastal Zone Management laws of New Jersey. 



The pannes, potholes, and depressions within the marsh are unique habitats and have been 

 investigated in certain East Coast marshes (Redfield 1972). The lack of emergent vegetation has 

 been credited to a lack of favorable sediment characteristics (Redfield 1972). The low circulation, 

 depth, and exposure to temperature or salinity extremes may also be factors preventing marsh 

 colonization of the areas once the topographic features are formed. 



Mosquito ditches affect the ecology of the East Coast marshes, although there is inadequate 

 information on how extreme these effects may be (Daiber 1974). In the New Jersey sites, ditches 

 increase the flushing of the high marsh and may be enhancing the growth of certain species. 

 More important, substantial low marsh composed of tall 5. altemiflora is created along the edges 

 of the ditches. Spoil from the ditches is uncommon, but where it occurs, it provides elevation for 

 the growth of Iva frutescens and other high-marsh transitional species. The depth and sediment 

 characteristics of the ditches limit growth of seagrass or tall S. altemiflora. 



Roads and house lots also affect local marsh ecology. The raised elevations of the roads 

 increase the abundance of high-marsh transitional species, many of which are the dominant 

 roadside vegetation (e.g., Panicum species and Phragmites communis). The lots are covered with 

 material that prevents marsh growth. Sediments from the sand and gravel also enter the nearby 

 marsh and probably influence vegetative growth. 



DATA GATHERING AND ANALYSIS 



Before we could model how the rising seas under the three scenarios would affect the coastal 

 wetlands of south central New Jersey, we needed to determine the types, elevation, and 

 productivity of the plant species currently in the marshes. However, as in the Charleston study, 

 there is little data on the elevation range that contains most of the coastal wedands in New 

 Jersey. For this reason, we surveyed a series of sixteen field transects across representative 

 marshes and tidal flats near Tuckerton. 



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