Effects of nutrition on somatic growth and reproductive strategy of the sea urchin Pseudechinus huttoni

Abstract

This study aimed to understand how resource allocation to somatic and gonadal tissues of the sea urchin Pseudechinus huttoni was influenced by nutritional status using several methods. Urchins in the laboratory were fed kelp (Macrocystis pyrifera) four days a week as the low-quality diet group, or a mixture of kelp and cockle flesh (Austrovenus stutchburyi) once a week, as the high-quality diet group. The experiment lasted for one year. The gonad, gut, lantern, test, lantern muscle indices and gametogenic stage were measured at 3 weeks and 6 and 12 months after the start of the experiment. A high-quality diet led to higher gonad (only in females) and gut indices but lower lantern, lantern muscles and test indices. Females allocated a higher percentage of energy to the gonad when fed a high-quality diet but a higher percentage of energy to the test when fed a low-quality diet. Dietary condition had no influence on gametogenic stages; however, the urchins fed a high-quality diet had larger oocytes. The gonadal growth appears not to have priority over somatic growth in P. huttoni and more energy resources are allocated to the test when food is limited.