. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 518 D. NEUMANN AND F. HEIMBACH. U 20 2 8 TIME OF DAY 20 FIGURE 9. Temperature fluctuations in two habitats of different depths in Kviturdvikpollen near Bergen, western Norway in relation to tides and darkness (= black horizontal bar) on 10-8- and 11-8-76 (days of spring tide). The upper temperature curve was recorded at a depth of m mean level (corresponding with the boundary between sub- and eulittoral), the lower one at a depth of m. There had been sunny calm weather for several days. The maximum air temperatures a
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 518 D. NEUMANN AND F. HEIMBACH. U 20 2 8 TIME OF DAY 20 FIGURE 9. Temperature fluctuations in two habitats of different depths in Kviturdvikpollen near Bergen, western Norway in relation to tides and darkness (= black horizontal bar) on 10-8- and 11-8-76 (days of spring tide). The upper temperature curve was recorded at a depth of m mean level (corresponding with the boundary between sub- and eulittoral), the lower one at a depth of m. There had been sunny calm weather for several days. The maximum air temperatures at Bergen Airport were 21° and 18°C with wind forces m/s. other as in experiment 1 (Fig. 10), a normal semilunar emergence rhythm resulted with a peak of about 30% emerged midges at day 8 or 9 of the semi-monthly cycle, as was usual in this standard program with 6 h turbulence per tidal cycle (start of turbulence at midnight on day 1, 18-20°C LD 12:12). A specific reinforcement of the synchronization by the tidal temperature cycles could not be detected (compare Figs. 8 and 10). An irregular distribution of emerging midges resulted in experiment 4 (Fig. 10) when the tidal temperature increases always coincided with the start of the 6-h turbulence signal. In view of natural conditions in the intertidal zone, this was an unrealistic program because in nature the beginning of an inundation with increasing mechanical disturbances by breakers and a temperature rise at low water time differ by several hours. The experiment clearly demonstrates that in such a phase relationship of both tidal factors a mutual repression of their synchronizing effects must have occurred. The two other experiments with intermediate phase relationships of both factors (no. 2 and 3 in Fig. 10) resulted in a deviating entrainment of the semilunar emergence rhythm, with a small tendency for a delayed peak in number 2, and an even weaker synchronization in number Please note that these images are
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