A laboratory energy budget for the ormer Haliotistuberculata L.

Abstract

Each component of the energy budget (ingestion, egestion,somatic growth, reproductive investment, respiration, excretion, and mucus production) was measured for Haliotis tuberculata L. held at 15°C in a 12-h light: 12-h dark regime. Ulva lactuca L. was used as the food source throughout, and the budget was assessed over the whole size range of the animal. Ingestion rates ranged from 1.94 to 997.2 cal·animal −1·day −1 in 0.01 to 50 g dry wt (3.71 × 10 −3 to 17.3 g dry flesh wt) animals, respectively. The major component of the energy budget was somatic growth (37.5% of I) in a 0.01-g dry wt animal while it was respiration (31.1% of I) in a 50-g dry wt animal. Mucus production formed a large part of the budget (from 23.3% of I in a 0.01-g dry wt animal to 29.l% of I in a 50-g dry wt animal). Scope for growth, I − ( E + R + U + M), was calculated as ranging from 24.5% of ingestion in a 50-g dry wt animal to 36.8% in a 0.01-g dry wt animal. Each component was measured independently and allometric relationships with animal dry weight calculated. Exponents ranged from 0.60 (somatic growth) to 1.06 (reproductive investment). The calorific value of food was 3419 cal·g dry wt −1 and for faeces was 2817 cal·g dry wt −1. Absorption as a percentage of ingestion in terms of dry weight ranged from 78% for 95-mm length animals (50 g dry wt) to 81% in 6-mm animals (0.01-g dry wt −1). Gross and net growth efficiencies ( K 1 and K 2) were calculated on an energy basis and both were logarithmically related to animal dry weight.