. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 30 m TJ 20 m DO 10 DO m O NDJFMAMJJASO 1983 1984 FIGURE 2. Reproductive cycles of Geukensia demissa during 1983-84, from a low tidal population (Site I. Up-Clambank: •), and a high tidal population (Site 2, Ely Creek: O). Mean values of total GVF for approximately 25 individuals are plotted each month. Vertical lines indicate the standard error of the mean. Asterisks indicate significant differences (P < ) between the two sites. Seasonal variation in surface water temperature (•) at Bread and Butter Creek (see Fig. 1)
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 30 m TJ 20 m DO 10 DO m O NDJFMAMJJASO 1983 1984 FIGURE 2. Reproductive cycles of Geukensia demissa during 1983-84, from a low tidal population (Site I. Up-Clambank: •), and a high tidal population (Site 2, Ely Creek: O). Mean values of total GVF for approximately 25 individuals are plotted each month. Vertical lines indicate the standard error of the mean. Asterisks indicate significant differences (P < ) between the two sites. Seasonal variation in surface water temperature (•) at Bread and Butter Creek (see Fig. 1). Each point represents a single mea- surement of temperature. stant and low GVF values from November to March, after which a rapid increase of GVF occurred, reaching a peak of about by June (Fig. 2). By late April, no animals with sexually undifferentiated gonads were found. The increase of mean GVF closely followed the pattern of increasing water temperature in North Inlet, showing a significant (P < ) and positive correlation (r = ). This population maintained relatively high values of GVF for about four months (May to early Au- gust). The highest GVF value was observed in August (), and spawning probably took place in this month and proceeded through September. It is possible that another spawning event of lesser intensity occurred at this site in June, which is supported by the observation of a significant (P < , Tukey a-posteriori test) decline of about 20% in the mean GVF values between June and July. At the high tidal site, mussels exhibited a different reproductive cycle (Fig. 2). Gametogenesis started later, possibly between May and June. A rapid increase of GVF occurred between June and September, reaching an apparent peak of about in September. Spawning occurred in September, shortly after gametogenic de- velopment (Fig. 2). Since information on the reproductive condition of this popula- tion was available only from June to Octob
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
