Data Collection and Analysis 



Each transect was a sample cross section of an area of the marsh. It began at a benchmark 

 located on high ground near a marsh's boundary, and ended at a tidal creek or mud flat, or after 

 covering 300 m (1,000 ft)— whichever came first. The New Jersey Department of Environmental 

 Protection provided three benchmarks. One was Station E55, located within the mainland near 

 the fringing marsh northeast of Tuckerton, where the mean tidal range is 61 cm (2.0 ft). As 

 Figure 3-2 shows, transects T9-T16 were surveyed there. The other two benchmarks were 

 Stations M55 and P55, located along the Great Bay Boulevard marsh, where the mean tidal 

 range is 96.9 cm (3.18 ft). These benchmarks were used for transects T1-T8. 



The dashed line in Figure 3-2 shows how we arbitrarily subdivided the study area into these 

 two primary survey areas to account for the significant variations in tidal range. The indicated 

 subdivision is not exact, since a continuum exists, but it was necessary for scenario modeling, 

 which is described later in the report. These two ranges represent the typical excursion of water 

 levels between mean high water and mean low water. Since they are statistical averages, they can 

 be related to local mean sea level by definition. In other words, mean high water at the Great Bay 

 Boulevard marsh would be 48.5 cm (1.59 ft) above local mean sea level, while mean low water 

 would be 48.5 cm below it. Similarly, in the Tuckerton marsh, mean high water would average 31 

 cm (1.0 ft) above local mean sea level. These tides compare with a mean ocean tidal range of 1.1 m 

 (3.7 ft) in Little Egg inlet. 



Because of the difficulty of wading through very soft muds, we had to limit the length of the 

 transects. Although this biased the sample somewhat, logistics prevented a more rigorous 

 approach. Nevertheless, very detailed information on marsh zonation and boundaries in New 

 Jersey is available on 1:2,400 photo maps prepared by the New Jersey Department of Environ- 

 mental Protection. We used portions of these maps in our study to estimate areal coverage of 

 each marsh type. Budget limitations prevented us from determining all areas by planimetry, so we 

 substituted representative grid squares. 



For each transect, we measured the elevation and distance from the benchmark using a rod 

 and level. Data points were surveyed wherever there was a noticeable break in slope or change in 

 species. Typically, we recorded at least 20 survey points along each transect, with the average 

 distance between points being about 7.5 m (25 ft). Our field team of three people included a 

 biologist who kept parallel notes with the surveyors on the actual species at and between each 

 survey point. Along each transect we collected and tagged samples of species for laboratory 

 typing and verification, noting such information as the elevation of the boundaries between 

 different species. By measuring the length of the transect that a species covered and dividing it by 

 the transect's total length, we computed percentages for the distribution of each species along a 

 transect. 



The demarcation between terrestrial plants and salt-tolerant species can often be abrupt 

 because of a sudden change in slope at that point. Wetland transects commonly consist of a 

 series of low-relief steps between areas of more or less constant elevation, with each step 

 representing the upper or most landward deposit of detritus for a particular tide level. However, 

 we have also observed areas where slopes are almost uniform from highland to tidal flats (Kana, 

 Baca, and Williams 1986). 



Results of Individual Transects 



Table 3-1 summarizes the results of the sixteen transects, dividing them between the 

 Tuckerton marsh's 61 cm (2.0 ft) tidal range and the Great Bay Boulevard marsh's 96.9 cm (3.18 

 ft) range. It presents the principal species observed along each transect, their "modal"— or most 

 common— elevations, the percentage of each transect they covered, and the length of each 

 transect. For example, in transect number 3, short S. alterniflora was found at a modal elevation 

 of 86.9 cm (2.85 ft) and covered 94 percent of the transect. 



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