INFLUENCE OF PREY DENSITY AND DIETARY SUPPLEMENTATIN ON THE LARVAL DEVELOPMENT OF THE BLUE CRAB, Callinectes sapidus

Variation in the number of larval stages is often seen during the development of arthropods. This variation appears to be influenced by environmental factors, genetics and the presence of naturally-occurring chemicals. Polyhydroxybutyrate (PHB), that is produced by micro-organisms as a quorum sensing chemical, has been applied to crustacean aquaculture. In the Chinese mitten crab, Eriocheir sinensis, PHB has shown to enhance larval development.

It is hypothesized that food availability and dietary components may be contributing factors in determining the number of larval stages of the blue crab. To test this hypothesis, the larvae were cultured in 24-well plates and fed on three different live feed diets: high- and low-density diet and high-density-PHB -supplemented diet. The larvae were monitored daily for molting and survival until reaching megalopae. Water was exchanged every two days. Larval stages were determined and confirmed by analyzing photo images of exuvia or larvae. Overall, our data indicate that a high-density-diet enhances larval development by decreasing the number and duration of larval stages. The larvae did not undergo all eight stages, and appeared to skip or combine larval stages before reaching megalopae with a high-density-diet. Additionally, the high-density-PHB-supplemented diet did not alter larval duration but appeared to increase instances of larval stage skipping or combining. Experiments are in progress to confirm these findings and identify which larval stages are likely to be skipped. Additionally, following studies are also in progress with low-density-PHB-supplemented diet to determine if PHB enhances larval development under less favorable conditions.