Gilbert Tige

Ostrea angasi acclimatization to French coasts

Abstract Following losses of the European flat oyster Ostrea edulis due to epizootic diseases in France, an acclimatization experiment was conducted with hatched juveniles of O. angasi . Major mortalities were rapidly noted in the cultures and attributed to a haplosporidian ( Haplosporidium sp.) to which O. angasi was very sensitive. This species also contracted Bonamia and Marteilia parasites of O. edulis .

Solving parasite-related problems in cultured molluscs

Abstract A review of the economic impact of disease caused by various pathogens underlines the need for further research on molluscan pathology. In France, recent problem with Bonamia required the introduction of a strategy to limit the effect of the disease. The strategy was developed in collaboration with the authorities and the oyster farming professionals. Their own part in the definition and the settlement of measures was very important. The plan pointed out the weaknesses of the measures presently available in limiting the consequences of an epizootic. The authors recommend complementary prophylaxes which need various disciplines and illustrate the results to date. We conclude by pointing out research areas that require high priority in future work.

Study of a haplosporidian (Ascetospora), parasitizing the Australian flat oyster Ostrea angasi

Considering the epizootics which affect the French stock of flat oysters, Ostrea edulis (Grizel, 1985), trials to introduce an Australian oyster, Ostrea angasi, have been undertaken. The spat produced in a hatchery from breeders imported from Australia were reared in the south ofBrittany and in Normandy (Bougrier et al., 1986). Following mass mortalities (65% of individuals) a haplosporidian was observed in this species. Sporogenesis of the parasite was studied using Iight and electron microscopy.