Participating organizations (WP leader in bold): P3. IRTA, P4. IOLR and P25. DOR
Task 19.1 Effect of algal type and concentration on larval performance.
Task 19.2 Comparing the selected microalgae type and protocol (Task 19.1) with lyophilized substitute. The selected microalgae from Task 19.1 will be compared with a lyophilized substitute when used to "green tanks" during early grey mullet larviculture. Larval performance will be evaluated in terms of larval growth, survival, rotifer ingestion rate, geometric morphology, whole body composition, maturation of the digestive tract and the incidence of skeletal deformities.
Task 19.3 Determine the effect of co-feeding ciliates and rotifers on digestive tract maturation and enzyme production. This task will address a potential bottleneck in grey mullet larviculture which is that the DT during intensive rearing develops less quickly than those in mesocosm, which would impact on larval growth, skeletal development and metamorphosis.
Task 19.4 Determine when to wean larvae and to feed weaning diet type according to digestive tract maturation and the shift from carnivorous to omnivorous feeding . This study will test weaning diets (WD) varying in protein, carbohydrate and lipid levels at the suggested times for weaning and mode of feeding change (Sub-task 19.1.3). Samples will be sent for analyses for pancreatic, stomach, brush border and cytosol enzymes.
Task 19.5 Testing the improved grey mullet larval rearing protocol in a commercial hatchery. The improved grey mullet larval rearing protocol resulting from Task 19.1 and Task 3.6.1 in the WP Nutrition will be tested at a commercial hatchery. Larval performance will be evaluated in terms of growth and juvenile survival.
Task 19.1 Effect of algal type and concentration on larval performance.
- Sub-task 19.1.1 Determine the effect of algal type and concentration in rearing tanks on larval performance (led by IOLR). The effect of different Nannochloropsis oculata and Isochrysis galbana concentrations will be tested on larval prey ingestion rate, growth, survival, body composition (lipid class, fatty acids, protein, free amino acids), metamorphic synchrony (percent “silvering”) and digestive tract enzyme ontogeny. Previous studies showed that each pair of inter-specific Nannochloropsis oculata and Isochrysis galbana algal concentrations gave the same turbidity in the larval rearing tanks.
- Sub-task 19.1.2 Determine if the benefit of algal addition to rearing tanks due to background lighting or other factors that contribute to larval performance. The selected Nannochloropsis oculata and Isochrysis Galbana concentrations, from the first two studies, will be tested against a Kaolite (clay) treatment having the same turbidity as the algal treatments to determine if the benefit of the selected algal concentration is due only to its background lighting effect on rotifer ingestion rate or other factors that contribute to larval performance.
Task 19.2 Comparing the selected microalgae type and protocol (Task 19.1) with lyophilized substitute. The selected microalgae from Task 19.1 will be compared with a lyophilized substitute when used to "green tanks" during early grey mullet larviculture. Larval performance will be evaluated in terms of larval growth, survival, rotifer ingestion rate, geometric morphology, whole body composition, maturation of the digestive tract and the incidence of skeletal deformities.
Task 19.3 Determine the effect of co-feeding ciliates and rotifers on digestive tract maturation and enzyme production. This task will address a potential bottleneck in grey mullet larviculture which is that the DT during intensive rearing develops less quickly than those in mesocosm, which would impact on larval growth, skeletal development and metamorphosis.
Task 19.4 Determine when to wean larvae and to feed weaning diet type according to digestive tract maturation and the shift from carnivorous to omnivorous feeding . This study will test weaning diets (WD) varying in protein, carbohydrate and lipid levels at the suggested times for weaning and mode of feeding change (Sub-task 19.1.3). Samples will be sent for analyses for pancreatic, stomach, brush border and cytosol enzymes.
Task 19.5 Testing the improved grey mullet larval rearing protocol in a commercial hatchery. The improved grey mullet larval rearing protocol resulting from Task 19.1 and Task 3.6.1 in the WP Nutrition will be tested at a commercial hatchery. Larval performance will be evaluated in terms of growth and juvenile survival.
