Interactive effects of diet and temperature on reproductive conditioning of Argopecten purpuratus broodstock

Adult specimens of Argopecten purpuratus, obtained from Culture Centers of Tongoy Bay (Region IV, North of Chile), were conditioned at two temperature s, 16 degrees C and 20 degrees C, and three different diets: a mixture of p ure microalgae, microalgae mixed with lipids and microalgae mixed with carb ohydrates. Daily food supply was 6% of dry biomass. Three replicate tanks w ere assayed for each treatment. The progress of gonadal recovery was follow ed by periodic determination of gonadic index and histological analysis dur ing three months. Gonadal recovery was slower for the animals conditioned a t 20 degrees C than for those at 16 degrees C. Recovery was poorest for the animals fed pure microalgae at 20 degrees C. The highest percentages of ma ture animals, at the end of the experiment, were obtained for the animals c onditioned at 16 degrees C and the maximal value was obtained for those fed microalgae-lipids. This diet also rendered the best result for scallops ma intained at 20 degrees C. All scallops conditioned at 16 degrees C responde d to spawning induction; the poorest response was for individuals condition ed at 20 degrees C and fed pure microalgae. The percentage fertilization of gametes from the different treatment broodstocks did not differ but the pe rcentage of larvae D survival was much higher for those from scallops condi tioned at 16 degrees C and fed pure microalgae or microalgae-lipids. These results indicate that temperature affects gametogenesis and that enriched l ipid diets may improve the conditioning of bivalve broodstock. (C) 2000 Els evier Science B.V. All rights reserved.