The relative importance of parental nutrition and population versus larval diet on development and phenotypic plasticity of Sclerasterias mollis larvae

Abstract

The relative importance of parental diet/population and larval diet were examined on egg, growth, morphology and biochemistry of Sclerasterias mollis larvae. Adult S. mollis were fed one cockle (Austrovenus stutchburyi) per two animals each week, as a low diet, or two cockles per animal each week, as a high diet. The experiment was run for one year. In addition, two field populations (Otago inshore and offshore) with dissimilar nutritional status (based on the gonad index) were selected. Otago inshore starfish had higher gonad indices and assumed to have better nutritional status. The low and high diet laboratory starfish produced eggs with similar characteristics. Eggs from the low diet laboratory parents had the highest carbohydrate concentration. The eggs from the field parents had higher fertilization rate and lower carbohydrate concentration than eggs from the laboratory parents. The Otago inshore starfish had smaller eggs with a lower carbohydrate concentration than the starfish from Otago offshore. Parents from the laboratory or the field had significant effects on larval growth, morphological phenotypic plasticity (measured by the body length relative to the body width) and development rate. Larvae from Otago offshore parents had highest growth and morphological phenotypic plasticity. Larvae from the low diet laboratory parents and those from Otago inshore had the highest development rate. Larvae from low diet laboratory parents had the highest carbohydrate concentration. Neither the parents nor the larval diet had a significant effect on larval mortality. A higher concentration planktonic diet resulted in higher growth, morphological phenotypic plasticity and development rate. Parents were however more important than larval diet on growth and phenotypic plasticity of the larvae. This study showed that parental nutrition has an important effect on growth, morphological phenotypic plasticity and body composition of S. mollis larvae. The nutritional status of the parents does not influence the larvae through a change in the egg size, protein, lipid, carbohydrate and energy content.