. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 218 B. J. BARBER KT AL T E M P E R A T U R E 35 30 25 20 15 10. M A R A P R M A Y J U N J U L 1987 A U G S E P O C T N O V Figure 1. Weekly mean water temperature at the experimental site, lower Delaware Bay, as calculated from the regression ot daily air temperature at Cape May, New Jersey, on water temperature readings from 1978 to 1980 and 1985 to 1988. native and inbred) from Long Island Sound. On the other hand, the null hypothesis was accepted in the two com- parisons involving inbred and native groups having the same
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 218 B. J. BARBER KT AL T E M P E R A T U R E 35 30 25 20 15 10. M A R A P R M A Y J U N J U L 1987 A U G S E P O C T N O V Figure 1. Weekly mean water temperature at the experimental site, lower Delaware Bay, as calculated from the regression ot daily air temperature at Cape May, New Jersey, on water temperature readings from 1978 to 1980 and 1985 to 1988. native and inbred) from Long Island Sound. On the other hand, the null hypothesis was accepted in the two com- parisons involving inbred and native groups having the same site of origin (LIN-L1I and DBN-DBI), indicating that the timing of gonadal maturation cycles was similar for native stocks and inbred strains within each site of origin. Discussion There were distinct differences in the timing of gonadal development and spawning of both native stocks and inbred strains between the Long Island and Delaware Bay sites of origin. Oysters in the Long Island groups initiated gonadal growth, achieved maximal gonadal development, and began spawning about one month earlier than oysters in the Delaware Bay groups. Additionally, both Delaware Bay groups exhibited a protracted period (about three months) of partial spawning and redevelopment. The sta- tistical comparison of gonadal area indices reinforced the observations reported in this study and those of Ford el al. (1990). Time (elapsed days) had the same effect on gonadal area index for the LIN and LII groups and for the DBN and DBI groups, but not for any between-lo- cation comparison. Thus, the timing of gonadal devel- opment differed significantly between the Long Island and Delaware Bay locations. These differences were main- tained in the Long Island inbred strain, even after six generations (23 years) in Delaware Bay, demonstrating that there are genetically determined differences in en- vironmental criteria necessary for the initiation or com- pletion of a particular gametogenic event at these
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