The focus set by scientists was primarily on understanding the trophic capacity of the lagoons, and the ecophysiologic and metabolic capacities of oysters (feeding regime, growth, reproduction,

respiration) as well as its resistance to temperature and high population density stress. The pilot atoll was Takapoto, where a field station allowed running long term in situ experiments. In selected lagoons, a network of stations was set with volunteering farmers to monitor environmental conditions ( Pouvreau and Prasil, 2001). In addition, research on aquaculture practices focused on the processing of oysters and lines to clean epibionts and trophic competitors. The PGRN aimed to disseminate results to farmers by various means: on site training, newsletters in both French and Tahitian, meetings Selleck Nutlin3a etc. The program find more also led to numerous doctoral studies conducted in the new French Polynesia university, and yielded an abundant scientific literature (e.g., Charpy, 1996, Niquil et al., 1998, Zanini and Salvat, 2000, Buestel and Pouvreau, 2000 and Torréton et al., 2002). These papers clarified the dominant planktonic communities, trophic flux and limiting nutrients found in atoll lagoons,

and their variations according to atoll morphology and hydrodynamic regime ( Charpy et al., 1997, Andréfouët et al., 2001b and Dufour et very al., 2001). This first coordinated research, which terminated in October 1999, provided practical advice to farmers to optimize densities, collecting methods, and epibiont clean-ups. It also enhanced knowledge on the biology and ecophysiology of P. margaritifera ( Pouvreau et al., 2000a and Pouvreau et al., 2000b). It clarified the links between Takapoto environment and oyster physiology and sources of food. A major conclusion was that lagoons (at least Takapoto Atoll) were not food-limiting given their current loads of cultivated animals ( Niquil et al., 2001).

In atoll lagoons, organic particles < 5 μm (heterotrophic bacteria, autotrophic bacteria and phytoplankton < 5 μm) generally represented more than 70% of the living carbon biomass whereas particles between 5 μm and 200 μm (protozoan, phytoplankton > 5 μm, appendiculates and metazoan larvae) represent less than 30%. PGRN demonstrated that the low retention efficiency of the dominant < 5 μm planktonic communities by P. margaritifera was largely offset by the efficient grazing of the larger size-fraction plankton and protozoan ( Loret et al., 2000a and Loret et al., 2000b), and by exceptionally high pumping rates ( Pouvreau et al., 1999, Pouvreau et al., 2000c and Yukihira et al., 1998). However, not all aspects of the planktonic food chain were understood, including the role of various zooplankton compartments and the influence of possible competitors.