Effects of Dietary Carbohydrate on Weight Gain and Gonad Production in Small Sea Urchins, .

In experiment 1, juvenile sea urchins (n = 80, 0.088 ± 0.001 g wet weight and 5.72 ± 0.04 mm diameter) were held individually and fed one of three semi-purified formulated diets (n = 16 individuals treatment). In the diets, protein was held constant (310g kg dry, as fed) and carbohydrate level varied (190, 260, or 380 g kg dry, as fed). Wet weights were measured every 2 weeks. Total wet weight gain was inversely proportional to dietary carbohydrate level and energy content of the respective diet. In experiment 2, sea urchins (5.60 ± 0.48g wet weight, n= 40) fed 190 g kg carbohydrate consumed significantly more dry feed than those fed 260 g kg, but not more than those fed 380 g kg carbohydrate. Based on differential feed intake rates, sea urchins that consumed more feed also consumed higher levels of protein and had the highest weight gain. Consequently, protein content and/or protein: energy ratio may be important in determining feed utilization and growth among sea urchins in this study. The average digestible energy intake was approximately 70 kcal kg body weight day, suggesting daily caloric intake of juvenile is lower than in shrimp and fish.