. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 570 A. KLAPOW \\IKMI the position of the high tide waterline was recorded ( July 5 through |ulv 17). The most obvious feature of these distributions is a movement of the population to progressively higher levels on the beach during weeks prior to both new and full moon (as the spring tides approached) and to lower levels on the beach (hiring weeks following new and full moon (as the neap tides approached). The position of the zonal band appears to have retained the same position rela- tive to the high tide washline as th
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 570 A. KLAPOW \\IKMI the position of the high tide waterline was recorded ( July 5 through |ulv 17). The most obvious feature of these distributions is a movement of the population to progressively higher levels on the beach during weeks prior to both new and full moon (as the spring tides approached) and to lower levels on the beach (hiring weeks following new and full moon (as the neap tides approached). The position of the zonal band appears to have retained the same position rela- tive to the high tide washline as the washline changed during the spring-neap cycle, resulting in a fortnightly shift in zonation. The amplitude of this movement is, however, somewhat different in the two cycles shown in Figure 1, although D4TE JUNE 1970 17 19 21 23 Z5 27 5 7 9 II 13 15 17. SPRING TIDES NEAP TIDES SPRING TIDES NEAP TIDES FULL MOON SPRING TIDES FIGURE 1. Semimonthly changes in the position of the Excirolana zone. The relative abundance of isopods in 3 meter sections of a continuous 25 cm wide transect across the zonal range, is indicated by each histogram. Transects were taken at two-day intervals on Scripps Beach. The width of the black bars indicates the relative abundance of isopods in each of the 3 meter long sections of each transect, expressed as a percentage of the total population. The dashed lines indicate the level of the beach reached by high tides during the interval be- tween consecutive transects. This level was determined on July 5th to July 17th by observing the position on the beach where the previous trench had been obscured by wave wash. tide heights on corresponding days in each cycle were similar. This appears to be the result of the truncation of the distribution during the first cycle (June 19 to July 3) by the presence of Scripps seawall. The wave wash on spring tides struck the seawall which effectively stopped any further shoreward movement. This is somewhat atypical for
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
