. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. UPSTREAM AND DOWNSTREAM CAPTURE 555 10 20 50 _60_ 90 100 +6- + 3- i ; O '-3H A, A A. 10 20 30 SECONDS 40 SO 60 70 80 90 100 FIGURE 3. (A) Fluctuations in current velocity and direction (positive values are toward the east- northeast, and negative values are toward the west-southwest) in the microhabitat ofOligometra serripinna. (B) Fluctuations in current velocity and direction in a laboratory flume with surging flow (positive values are in the predominant direction, and negative values are for the relatively brief inter
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. UPSTREAM AND DOWNSTREAM CAPTURE 555 10 20 50 _60_ 90 100 +6- + 3- i ; O '-3H A, A A. 10 20 30 SECONDS 40 SO 60 70 80 90 100 FIGURE 3. (A) Fluctuations in current velocity and direction (positive values are toward the east- northeast, and negative values are toward the west-southwest) in the microhabitat ofOligometra serripinna. (B) Fluctuations in current velocity and direction in a laboratory flume with surging flow (positive values are in the predominant direction, and negative values are for the relatively brief intervals of reversed flow). Each filled circle marks a point in the flow cycle where a brine shrimp cyst was captured. interval of s). Motion in the predominant direction was recorded as positive, and motion in the reverse direction was recorded as negative. During the same 100-s interval, one third of a single O. serripinna arm, with 20 pinnules (10 on each side), was recorded with a second video system, a duplicate of the first. The arm was re- corded (at position B in Fig. 2) in side view a few degrees off the perpendicular to provide a foreshortened view of the pinnules on either side. RESULTS AND DISCUSSION Figure 3A plots fluctuations in current speed and direction near slack tide in the microhabitat ofOligometra serripinna. During the 100-s period, there were 10 con- spicuous reversals in current direction, most "negative flow" periods lasted about 2 s and reached speeds of approximately 3 cm/s. The results of the laboratory flume surge experiment are shown in Figure 3B, which places cyst capture in the context of fluctuations in current speed and direction. During the 100-s period, 41 cysts were captured during the cumulative 70 s that flow was in the predominant direction (, downstream captures), and 10 cysts were cap- tured during the cumulative 30 s that flow was in the reverse direction (, upstream captures). The video recordings showed that all th
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
