. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MIGRATION RHYTHMS OF LARVAL CRABS 149 consisted of 14 h of light alternating with 10 h of dark, instead of the 12 h:12 h cycle previously used (Cronin and Forward, 1979). In contrast to the results of that work, no rhythmicity was indicated, either statistically or by visual inspection of the data (Fig. 6, Table II). Essentially random movements of the center of the larval population occurred. Neuse River: Field-caught late-stage zoea larvae Larvae were collected in an identical way to the first-stage Neuse River larvae. Fou
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MIGRATION RHYTHMS OF LARVAL CRABS 149 consisted of 14 h of light alternating with 10 h of dark, instead of the 12 h:12 h cycle previously used (Cronin and Forward, 1979). In contrast to the results of that work, no rhythmicity was indicated, either statistically or by visual inspection of the data (Fig. 6, Table II). Essentially random movements of the center of the larval population occurred. Neuse River: Field-caught late-stage zoea larvae Larvae were collected in an identical way to the first-stage Neuse River larvae. Four replicates were performed (Fig. 7); there was some statistical evidence in two of them of circadian rhythmicity (experiments 821 and possibly 822, Table II). However, the form of the circadian pattern is difficult to recognize in the figures, and all the graphs reveal considerable random movement. DISCUSSION Larvae of the estuarine crab Rhithropanopeus harrisii are known to possess endogenous rhythms of vertical migration by the time they attain the third zoeal stage (Cronin and Forward, 1979). The period lengths of these rhythms can ap- proximate the period of either the tidal cycle or the diel cycle, depending on the prior entrainment regime and the larval source. We designed the experiments de- scribed in this paper to answer the questions of whether these rhythms are expressed early in larval life and whether it is possible for larvae to become entrained to oo 05 -C "o. Q 15 Exp 821. 5O Hour 100 00 05 . fi 15 Exp 822. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983. Woods
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
