b. Biological Sampling. Three main strategies were employed to obtain 
biological samples: (1) Epipsammic microalgal communities occupying the 
beaches were sampled and identified during four sampling periods. (2) Quan- 
titative sampling of intertidal macrofauna was carried out twice monthly during 
daylight hours at both beaches. (3) At night, a semiquantitative transect 
method was employed at the Fort Macon beach to evaluate the interaction between 
the intertidal, supratidal, and subtidal systems. 
(1) Intertidal Microalgal Sampling. The intertidal flora of the study 
beaches was sampled during the spring, summer, and fall of 1977, and during the 
winter of 1978. The spring sample of 1977 was obtained by coring to a 3-centi- 
meter depth with a 7-centimeter-diameter plastic coring device. The cores were 
taken at 5-meter intervals on a sunny morning at low tide along a transect from 
the previous high tide mark to the surf zone. At least one sample was taken 
from each tidal zone (wet, saturated, swash, and surf; see Fig. 4). The samples 
were placed in plastic bags and transported to the laboratory for microalgal 
analysis. 
The summer, fall, and winter samples were also taken on sunny mornings at 
low tide to evaluate the diatom populations. However, rather than using a 
corer, 1.0-meter-long troughs were scraped from the top 0.5 to 1.0 centimeter 
of sand in a strip 2 centimeters wide. The troughs were dug 4 meters apart 
along a transect from the previous high tide mark to the swash zone. The 
troughing method did not lend itself to sampling in the surf zone, so the surf 
zone sampling was abandoned. The change in method was intended to increase the 
amount of surface area sampled while still keeping the sample size manageable. 
The sand surface has been reported to harbor the greatest amount of microflora 
(Meadows, 1965). 
(2) Intertidal Macrofauna Sampling. Intertidal macrofaunal sampling 
consisted of collecting a series of sediment cores which included organisms. 
These samples were then sieved in the field using a 1-millimeter mesh box 
sieve. The organisms were then handpicked and preserved with 10 percent 
glycerin, 45 percent ethanol, and 45 percent water mixture for transport back 
to the laboratory. 
Sampling was quantitative. An experiment was performed (in triplicate) to 
determine the optimum sampling effort with respect to core diameter and number 
of cores taken. Three different coring devices were tested: a 5-centimeter 
inside diameter (i.d.) clear plastic coring tube, a 10-centimeter i.d. aluminum 
coring tube, and a square wooden box that was 31.4 centimeters on a side. 
Core samples were taken to a 15-centimeter depth in the sand. The effect of 
putting several cores in one sieve box and treating them as one sample was also 
tested. The effect of combining the cores was tested for 1, 5, and 10 cores 
of the 5-centimeter size and 3 cores of the 10-centimeter size. 
Results of those experiments are given in Figures 9, 10, and 11. Figure 9, 
which shows the average number of species collected per sampling effort, indi- 
cates that the optimum sampling effort (the greatest number of species obtained 
with the least work) is ten 5-centimeter cores treated as one sample. Figure 
10, however, shows that the average number of organisms continues to increase 
sharply from ten 5-centimeter cores to three 10-centimeter cores. Indexes of 
community stability are shown in Figure 11. These values take into account not 
only the number of organisms and species, but also the number of organisms of 
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