. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 170 M. I. LATZ AND R. B. FORWARD. 0 Decrease from acclimation salinity (%0) FIGURE 3. The minimum salinity decrease necessary for reversing the sign of phototaxis. Per cent response (ordinate) of positive (solid dot-solid line) and negative (open dot-dashed line) phototaxis to a stimulus of WrrT2 500-nm light upon various salinity decreases from the acclimation salinity (abscissa) by Stage I (A) and IV (B) zoeae acclimated to 2Q'/(r and Stage I (C) and IV (D) zoeae acclimated to 10/rr. Ra
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 170 M. I. LATZ AND R. B. FORWARD. 0 Decrease from acclimation salinity (%0) FIGURE 3. The minimum salinity decrease necessary for reversing the sign of phototaxis. Per cent response (ordinate) of positive (solid dot-solid line) and negative (open dot-dashed line) phototaxis to a stimulus of WrrT2 500-nm light upon various salinity decreases from the acclimation salinity (abscissa) by Stage I (A) and IV (B) zoeae acclimated to 2Q'/(r and Stage I (C) and IV (D) zoeae acclimated to 10/rr. Random swimming in the positive (solid circles) and negative (open circles) directions was determined with no stimulus present. The average sample size for each point was: (A) = 77; (B) =65; (C) =95; and (D) =80. Vertical testing Experiments with light entering the column from above resembled the down- ward-directional aspect of natural light conditions and examined the effect of salin- ity changes on vertical distributions under this irradiation regime. Those with light entering the column vertically from below had two objectives. The first was to further clarify the role of a negative phototaxis in establishing vertical dis- tributions upon sudden exposure to salinities below the acclimation salinity. The second was to determine whether the positive phototaxis or negative geotaxis is the dominant behavioral response during the ascent observed upon exposure to salinities above the acclimation salinity. The vertical distribution of larvae is age-dependent. In acclimation salinity sea water, Stage I zoeae (Fig. 4) are dispersed throughout the vertical column, although slightly more are present in the lower half (light from above 67%, darkness 68% ; no significant difference). Stage IV zoeae, however, are positioned lower in the column (Fig. 5). In darkness, essentially all larvae (97%) were found in the lower half of the column, while 85% of those irradiated from above were so dis
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
