Reproductive cycle and gonadial changes in the New Zealand rock oysterCrassostrea glomerata

Abstract

The annual reproductive cycle and the cyclical changes in the gonad of the New Zealand rock oyster, Crassostrea glomerata (Gould, 1850), during the breeding period of 1970-71 and 1971-72 have been described. The gonad passes through an intermediate phase, after a post-spawning period, when sex is indeterminate. Gametogenesis begins in July and August, but follicles ripen mostly during the spring months of October and November. Maximum development is seen in November, and nearly all oysters are in spawning condition in December and January. Major spawning takes place in January or February depending upon water temperature, and spawning continues until the end of March. Larvae may be found in the-plankton until late in the season, to the end of April or even May. Following spawning, gonadial regression sets in, with leucocyte infiltration and phagocytosis of residual gonial cells. A greater percentage of oysters more than 1 y old are females. The majority of oysters of age 1 y and below are males.

Hermaphroditism and sex reversal in the four common oviparous species of oysters from the coast of Karachi

“…0 .4-1 .0% in C. virginica (Needler, 1942 ;Kennedy & Battle, 1963) and 0 .26-3 .0% in C . gigas (Katkansky & Spark, 1966) and the same species from other coasts (0 .05% in C. madrasensis, Rao, 1953 ; 0 .75% in S. glomerata, Dinamani, 1974; 2 .9% in S . cuccullata, Awati & Rai, 1931 ; from the coasts of Madras, New Zealand and Bombay respectively) .…”

“…gigas (Katkansky & Spark, 1966) and C . (Saccostrea, Stenzel, 1971) glomerata (Dinamani, 1974) from the coast of temperate regions, which oysters have an annual reproductive cycle . From the tropical region hermaphrodites are reported in C .…”

Long-term and transgenerational effects of nonylphenol exposure at a key stage in the development of Crassostrea gigas. Possible endocrine disruption?

“…Similarly, in studies of other species from Pakistan (C. rivularis, C. madrasensis, Saccostrea glomerata and S. cucculata), only 0.06% true hermaphroditism has been recorded (Asif 1979). In C. glomerata, 0.7% hermaphroditism has been recorded (Dinamani 1974), in S. commercialis 0.32% (Cox et al 1996), and in C. rhizophorae 0.5% (Nascimento et al 1980). Likewise, studies of the Pacific oyster C. gigas have also shown a relatively low incidence of hermaphroditism for yearling oysters, ranging between 0 and 1.1% recorded at a variety of different sites in Japan, the USA and Canada (Amemiya 1929, Berg 1969.…”

“…Within the genus Crassostrea, there is typically a preponderance of male oysters in the first year of a cohort (protandry) (Amemiya 1929, Needler 1932a,b, Coe 1934, 1938, 1943, Menzel 1951, Kennedy & Battle 1964, Dinamani 1974, Andrews 1979, Mackie 1984, Paniagua-Chavez & Acosta-Ruiz 1995, Guo et al 1998). This may be because sperm are energetically cheaper to produce than eggs, which have substantial yolk reserves (Russell-Hunter 1979).…”

The reproductive cycle in the population of Saccostrea cuccullatta (Born) from the coast of Karachi, Pakistan

“…gigas, Berg, 1969) . The absence of inactivity of the gonads is also reported in S. glomerata from the coast of New Zealand (Dinamani, 1974) . However, a loss of sexuality in a low percentage of the population is observed during late autumn and winter .…”