0.9 —-<—-=-~-- SHANNON-WEAVER'S DIVERSITY INDEX 
eeovesescersore PIELOU'S EQUITABILITY INDEX 
a SIMPSQN'.S, INDEX OF DOMINANCE 
(57/ vd] |e Naeem Cols Been. arco eocceee aka gcseesetercta ai WML hr arce anes { t crower tl at 
0.6 
VALUES 
0.5 
ee ee <2 
0.4 i 
a 
1 5 10 3 1 
5 cm cm 
17.3 cm 2 86.5 cm 
5 2 5 cm 10 cm box 
173.0 cm 2 226.2 cm 3 985.9 cm g 
NUMBER OF CORES, CORE DIAMETER, AND TOTAL AREA SAMPLED 
BY EACH METHOD 
Figure 11. Measures of macrofaunal community structure per sampling effort 
using various sampling devices (5- and 10-centimeter cores and 
a box). The numbers next to the X-axis represent the number of 
cores treated as one sample; the number just below is the 
interior diameter of the coring device; and the bottom number 
is the total surface area sampled. All cores were taken to a 
depth of 15 centimeters. 
each species. Figure 11 shows no change after three 10-centimeter cores for 
Simpson's (1949) Index of Dominance, and little change for Shannon-Weaver's 
(1963) Index of Diversity or Pielou's (1966) Index of Equitability. Since the 
box method was unwieldy in the swash zone, impossible in the surf zone, and 
very time consuming, the method of sampling selected was three 10-centimeter 
cores taken to a depth of 15 centimeters and treated as one sampling unit. 
Coring was chosen over other sampling methods such as trenching because cores 
represent discrete sampling units and make statistical analysis more meaning- 
ful (Cox, 1976). 
Figure 12 represents a schematic cross section of a typical sandy beach. 
The X-axis indicates distributional variations perpendicular to the waterline 
and is usually related to tidal flux. Faunal zonation due to tidal influence 
has been well documented by Dahl (1953), Cox (1976), and Leber (1977). There- 
fore, each tidal zone was sampled in order to establish a complete concept of 
the distribution of the macrofauna and any changes that may occur with time or 
changing beach configuration. 
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