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Abstract
Ruditapes decussatus is a species of importance to aquaculture. For hatcheries to consistently produce spat it is essential to develop broodstock conditioning techniques. Food and temperature are the main factors that regulate the timing and rate of energy storage and reproduction in bivalves. This study was designed to evaluate the effects of different diets and temperatures on reproductive output of R. decussatus and express the evolution of the different lipid classes during sexual maturation. Broodstock clams were conditioned at 20 ± 1 °C under four nutritional regimes: unfed, two mono-specific diets, Isochrysis galbana clone T-ISO and Chaetoceros calcitrans and, a mixture of these microalgae. Another group of clams was conditioned at 22 ± 1 °C and was fed the same mixture of microalgae. Gametogenesis, energy storage and spawning success were all influenced by the nutritional value of the diet received, as evidenced by the differences in reproductive effort among the single and combined supplemental diets. Temperature must be carefully managed to improve the reproductive conditioning of bivalves: high temperature throughout gametogenesis shortens the time to full ripeness but does not produce better reproductive output. The combination diet at 20 ± 1 °C is best for R. decussatus broodstock conditioning.
Acknowledgements
The authors are grateful to João Maurício Teixeira who was in charge of the broodstock and larval maintenance. Gratitude is also extended to J. White for revising the English and to two anonymous reviewers for valuable comments.