Effects of varying calcium/phosphorus ratios in diets fed to juvenile lobsters ( Homarus americanus)

Abstract

1. 1. Juvenile lobsters were fed dry pellet diets with calcium/phosphorus (Ca/P) ratios which varied from 0.37 to 1.91. Animals receiving diets with a Ca/P ratio of 1.01 or below generally had better growth than animals receiving diets with a Ca/P ratio of 1.55 or above. 2. 2. Best growth and survival were shown by animals fed an experimental diet containing a 0.51 Ca/P ratio (0.56% Ca and 1.10% P). These animals achieved a length increase which was 85% of control animals fed live brine shrimp. The weight increase, however, was only 50% of control animals. 3. 3. Mineral determinations were quite variable and statistical analysis revealed no trend in ash, calcium or phosphorus content of carapace or body tissue with respect to diet. 4. 4. Histological studies revealed abnormalities in the endocuticle of animals receiving diets with Ca/P ratio of 1.55 or above.