Temperature and photoperiod drive Crassostrea gigas reproductive internal clock

Abstract

This study examined the gametogenic cycle of Crassostrea gigas in controlled conditions over one year, with a focus on the initiation of gametogenesis. This work analysed also the role of temperature and photoperiod in the regulation of oyster reproduction. Broodstock were maintained in natural (NC), accelerated (AC) and perpetual winter (WC) conditions of temperature and photoperiod, with feeding ad libitum. Qualitative and quantitative analyses of the reproductive pattern were performed using biometric measurement approach, sex ratio determination, histology and a gonad filling index. Each experimental treatment led to different strategies for growth and resource allocation. The gametogenic cycle, appeared entirely modulated, accelerated or delayed, by coupled temperature/photoperiod parameters. Temperature played a key role in gonial mitosis regulation. Gonia proliferation was set off and sustained by winter temperature (8-11 °C) whatever the physiological state of oysters. Maturation of germ cells appeared to be a function of temperature and could proceed at low temperature, while ripe oysters were obtained at 8 °C in winter conditioning. The three conditioning methods used in this study, allowed the production of gametes throughout the year, including in the autumnal resting period. Moreover, stocks of ripe oysters could be maintained at low temperature during several months to produce spat when desired for aquaculture production.

Seasonal variation in reproductive activity and biochemical composition of flat oyster (<em>Ostrea edulis</em>) in the Homa Lagoon, Izmir Bay, Turkey

“…According to Okumus et al (1998), fluctuations in the CI and MY have important implications for cultivation and harvesting strategy. Meat quality and biochemical composition in bivalves primarily depends on food, environmental parameters (mainly temperature) (Brown and Hartwick 1988, Austin et al 1993, Fabioux et al 2005 and reproductive activities (Chávez-Villalba et al 2007). In this study, MY and CI ranged from 2.69% to 12.29% and from 5.21% to 20.42%, respectively.…”

The reproductive cycle of the oyster Crassostrea gasar

“…An experimental study of C. gigas under winter conditions found high values of the CI. These high values resulted from the absence of spawning (Fabioux et al, 2005).…”

Local scale variation in the reproductive pattern of the southern geoduck, Panopea abbreviata (Bivalvia: Hiatellidae), in Patagonia

“…Between the external factors, temperature has been documented as a main factor that control the reproductive processes, as the initiation of the reproductive cycle, the maturation of germ cells and spawning (Giese 1959, Ruiz et al 1992, Fabioux et al 2005.…”