. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. TIDAL RHYTHM IN MYTILUS 357 they were brought back to the laboratory along with a sample of local M. edulis attached to the same piling at the same inter-tidal height, which served as controls for the experimental animals. Study of the activity pattern (at 9 and 14° C.) revealed a prompt shift in the rhythm to synchronize with the local tidal cycle and «- I '3 + 5 I 0 TJ ^-5 A .A . O / 0-0 f V V v v \ 24 6 12 Apr. 27 18 24 6 Mrs. Apr. 28 FIGURE 5. Record of rate of water propulsion in M. edulis from Barnstable Harbo
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. TIDAL RHYTHM IN MYTILUS 357 they were brought back to the laboratory along with a sample of local M. edulis attached to the same piling at the same inter-tidal height, which served as controls for the experimental animals. Study of the activity pattern (at 9 and 14° C.) revealed a prompt shift in the rhythm to synchronize with the local tidal cycle and «- I '3 + 5 I 0 TJ ^-5 A .A . O / 0-0 f V V v v \ 24 6 12 Apr. 27 18 24 6 Mrs. Apr. 28 FIGURE 5. Record of rate of water propulsion in M. edulis from Barnstable Harbor on Cape Cod, after having been kept for one week at + ft. in the inter-tidal at Corona del Mar, California, and of the control. Upper graph for M. edulis transplanted from Barnstable Harbor, and lower graph for mussels from pilings at Corona del Mar, California, serving as control. Dotted line indicates the local tidal cycle. there is found to be good agreement between the transplanted east-coast mussels and the local controls (Fig. 5). They continued to keep in phase with the local tidal cycle for a period of over three weeks in the laboratory. DISCUSSION A marked tidal rhythmicity of rate of water propulsion is exhibited by popula- tions of Mytilus occurring under a great variety of environmental conditions and persists in the laboratory for long periods (over four weeks) in phase with the tidal cycle of their natural environment, independent of a wide range of temperature (9 to 20° C.) and varying conditions of light and darkness. That it exhibits the same frequency in populations from high and low inter-tidal levels and even in sub-tidal populations (30 ft. deep) and that it persists in the laboratory, in phase with the tidal cycle outside, for long periods under constant conditions, demonstrate the intrinsic (or endogenous) nature of the rhythm. It is most interesting that such a rhythm is evident in populations from the underside of floats (and hence not subject
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
