Enhanced surveillance of shellfish mortality to improve early detection and investigation of outbreaks of exotic or emerging infectious diseases: An example of a mass mortality outbreak of mussels, France 2014.

This paper explores the relevance and feasibility of enhanced surveillance of mussel-related mortality based on regular telephone interviews of a key informant in a farming community. Based on qualitative analyses of data collected through semi-structured interviews, this method of participatory disease surveillance enabled the retrieval of high quality data during an outbreak of mussel mortality which occurred in Pertuis Charentais, France, in 2014. The findings illustrated that such an enhanced surveillance approach compared with the institutional shellfish health surveillance system could improve the early detection of outbreaks of mussel mortality by one week. This approach enabled a detailed description of the outbreak, showing higher incidence proportion in the Northern water bodies. It also captured relevant data for hypothesis generation for further outbreak investigations, integrating a global view of the health and disturbance of the coastal marine ecosystem. However, to be effective and sustainable, this flexible approach requires a pre-existing knowledge of the structure of the information network of the farmers' community. Such a community-based enhanced surveillance could increase the reactivity of the entire system to enable the earliest possible and most appropriate interventions to protect shellfish populations against exotic or emerging infectious diseases. This would also help to improve the vigilance of mussel farmers and foster their commitment, which is an essential element for sustainable shellfish health surveillance.

Pearl formation: persistence of the graft during the entire process of biomineralization.

Most bivalves species of the genus Pinctada are well known throughout the world for production of white or black pearls of high commercial value. For cultured pearl production, a mantle allograft from a donor is implanted into the gonad of a recipient oyster, together with a small inorganic bead. Because of the dedifferentiation of cells during the first steps of the host oyster's immunological reaction, so far the fate of the graft and its exact role in the process of pearl formation could not be determined via classical histological methods. Here we report the first molecular evidence of the resilience of the graft in the recipient organism by showing that cells containing genome from the donor are still present at the end of pearl formation. These results suggest the existence of a unique biological cooperation leading to the successful biomineralization process of nacreous secretion in pearl formation.

Spatio-temporal variation in the genetic composition of wild populations of pearl oyster (Pinctada margaritifera cumingii) in French Polynesia following 10 years of juvenile translocation.

Abstract The genetic impact of the cultural practice of spat collection and translocation between genetically distinct stocks of black-lipped pearl oyster, Pinctada margaritifera cumingii, was studied by comparing samples collected in the 1980s and 2000s from seven atolls in French Polynesia. An amova revealed homogenization of the previously genetically distinct wild stocks of Tuamotu-Gambier and Society archipelagos (the indices of genetic differentiation among archipelagos and among populations within archipelagos, respectively, Phi(CT) and Phi(ST), decreased from 0.032* and 0.025*, respectively, to 0.006(NS) and 0.007(NS)). These results suggest high success of spontaneous reproduction in farms, probably due to the very high density of cultivated pearl oysters, and underline the importance of genetic monitoring of future hatchery produced stocks.