The ecological impact of beach nourishment with dredged materials on the intertidal zone at Bogue Banks, North Carolina ecologicalimpact00reil Year: 1983 High Ttd# brr Mark Zon« W«f Salurfll«<l Zone 2on« 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
The ecological impact of beach nourishment with dredged materials on the intertidal zone at Bogue Banks, North Carolina ecologicalimpact00reil Year: 1983 High Ttd# brr Mark Zon« W«f Salurfll«<l Zone 2on« 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 intertid
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