. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 396 R. C. COCHRAN AND F. ENGELMANN 20 o ^ ..• x- -3 O *_ 1' -X £ 0) o O D-O--D. '• Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Date of Collection of Animals (1970) Dec -o to 100- o o 50 o 3 a aT M FIGURE 1. Annual reproductive cycle of 5. pnrpunttHs, as measured by the percentage of animals that released gametes when cut open (dotted curve) superimposed on the seasonal variation in ocean temperature (solid line) at the same location. Suhtidal ocean temperatures were taken on the dates of collection. similar conditi
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 396 R. C. COCHRAN AND F. ENGELMANN 20 o ^ ..• x- -3 O *_ 1' -X £ 0) o O D-O--D. '• Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Date of Collection of Animals (1970) Dec -o to 100- o o 50 o 3 a aT M FIGURE 1. Annual reproductive cycle of 5. pnrpunttHs, as measured by the percentage of animals that released gametes when cut open (dotted curve) superimposed on the seasonal variation in ocean temperature (solid line) at the same location. Suhtidal ocean temperatures were taken on the dates of collection. similar conditions. The reproductive activity of the two laboratory populations did not differ from that of the field population. Thus long-day photoperiod (T4L:10D) did not inhibit the onset of reproductive activity. It should be men- tioned here that the water temperature (13° C) in the holding tanks was mark- edly lower than that in the field throughout most of this period (Figure 1). Temperature It became apparent during these studies that the annual reproductive cycle of S. [>nrf>nratus from Palos Verdes is inversely correlated with the annual fluctuation of ocean temperature at the same location (Figure 1 ). A rise of water tempera- ture above 17° C coincides with the loss of the ability to spawn. A series of experiments were thus undertaken in order to ascertain whether temperature is indeed the environmental cue for the regulation of the reproductive season of this population. In an experiment begun May 1, 1972, almost all animals maintained at 13° C (the normal winter temperature) and a photoperiod of 14L:10D remained repro- ductively active for nearly two months beyond the date (late June) when animals in the field had become reproductively inactive (Table III). During this experi- ment, for a period of 10 days in late July, the temperature of the general sea water system accidently rose to ° C, while that of the regulated tank reached ° C. Prior to, and afte
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
