Influence of feeding regime and temperature on development and settlement of oyster Ostrea edulis (Linnaeus, 1758) larvae

Under controlled conditions of food density and temperature, larval performances (ingestion, growth, survival and settlement success) of the flat oyster, Ostrea edulis, were investigated using a flow-through rearing system. In the first experiment, oyster larvae were reared at five different phytoplankton densities (70, 500, 1500, 2500 and 3500m(3) L-1: approximate to 1, 8, 25, 42 and 58cellsL(-1) equivalent TCg), and in the second, larvae were grown at four different temperatures (15, 20, 25 and 30 degrees C). Overall, larvae survived a wide range of food density and temperature, with high survival recorded at the end of the experiments. Microalgae concentration and temperature both impacted significantly larval development and settlement success. A mixed diet of Chaetoceros neogracile and Tisochrysis lutea (1:1 cell volume) maintained throughout the whole larval life at a concentration of 1500m(3)L(-1) allowed the best larval development of O.edulis at 25 degrees C with high survival (98%), good growth (16mday(-1)) and high settlement success (68%). In addition, optimum larval development (survival 97%; growth 17m day(-1)) and settlement (78%) were achieved at 25 and 30 degrees C, at microalgae concentrations of 1500m(3)L(-1). In contrast, temperature of 20 degrees C led to lower development (10m day(-1)) and weaker settlement (27%), whereas at 15 degrees C, no settlement occurred. The design experiments allowed the estimation of the maximum surface-area-specific ingestion rate {J</mml:mover>Xm<mml:mo stretchy="false">}= 120 +/- 4m(3) day(-1)m(-2), the half saturation coefficient {X-K}=537 +/- 142m(3)L(-1) and the Arrhenius temperature T-A=8355K. This contribution put a tangible basis for a future O.edulis Dynamic Energy Budget (DEB) larval growth model.