High Tide Ory Wet Soturated Swash Surf 
Mark Zone Zone Zone Zone Zone 
Figure 12. Components of possible spatial variation in macrofaunal dis- 
tributions on a sandy beach (tidal zonation, X-axis; parallel 
to the waterline, Y-axis; and depth, Z-axis). 
Slight distributional variation with depth (Z-axis) is evident. Macrofauna 
is generally located entirely within the top 10 centimeters of beach substrate. 
All cores were, therefore, made to a constant depth of 15 centimeters. At no 
time during this study did any animals exhibit an avoidance reaction to the 
coring devices. 
Variation in distribution patterns along the length of the beach (Y-axis) 
also occurs. Such variation has been well documented (Meadows, 1965; Saloman, 
1976; Matta, 1977; Leber, 1977), although its cause has been disputed. Some 
claim that aggregations of macrofauna result from purely physical factors 
(Dillery and Knapp, 1970). Regardless of the cause of this variation sampling 
was performed at several transects along the beach in order to minimize the 
effects of such aggregations. 
On any given sample date transects were selected by use of a random number 
table. All numbers not corresponding to actual beach coordinates were dis- 
carded. The random number was then paced out in meters along a base line 
established parallel to the waterline. When the designated transect point was 
reached, one sample unit (three 10-centimeter cores) was taken from each tidal 
zone (high tide mark, wet, saturated, swash, and surf zones; see Fig. 4) along 
the transect from the high tide drift line to the surf zone. On each sample 
date three transects were worked on each beach. This number of transects 
allowed a good statistical evaluation and represented about the maximum amount 
of work that could be performed during the time when the tide was low enough 
to allow access to the intertidal zone. 
Temporal and seasonal variations in macrofaunal distribution on the sandy 
beach have been described by Holland and Polgar (1976), Matta (1977), and Leber 
22 
