Abstract
The effect of diet (made from either animal or plant material) on the partitioning of energy in
small (8–16 mm test diameter (td)) and large (29–37 mm td) Psammechinus miliaris was examined.
Diet significantly affected ingestion, digestion and growth of both size groups. Assimilation rates of
the different types of feed varied and they supported differential development of the body parts.
Urchins fed on an algal diet showed poorer absorption efficiency, assimilation, gonadal and somatic
growth than individuals fed on an artificial sea urchin diet (mixed plant and animal material) or on
the animal based diets. Small urchins fed on a diet of salmon food utilised proteins as the primary
energy source rather than carbohydrates or lipids as indicated by low O/N atomic ratios, and salmon
diet promoted a higher energetic investment in reproductive development in both size classes. A
negative energy balance resulted when large urchins were fed on the algal diet. Energy losses due to
ammonia excretion were negligible and the metabolic losses of assimilated energy, measured as
oxygen consumption, were between 0.2% and 1.5% with the different diets. A diet made of mussel
flesh stimulated ingestion, gave the highest assimilation rates and best overall growth performance.
Such detailed information should assist in the design of diets for the cultivation of sea urchins.
D 2004 Elsevier B.V. All rights reserved.
Keywords: Energy budget; Echinoid; Diets; Sea urchin; Psammechinus miliaris
0022-0981/$ - see front matter D 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jembe.2003.12.002
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