Temporal variation in the specific dynamic action of juvenile New Zealand rock lobsters, Jasus edwardsii

Abstract

To enhance the on-growing of Jasus edwardsii in culture, it is important to understand the feeding physiology of juveniles. In crustaceans, there is a loss of energy and an increase in oxygen consumption (specific dynamic action or SDA) associated with feeding. The present research measured the SDA of juvenile J. edwardsii fed either in the morning or at night held at 15 °C. Closed box respirometry was used to measure oxygen consumption (MO 2) and ammonia excretion in juvenile lobsters. Juveniles exhibited a nocturnal rhythm in both MO 2 and ammonia excretion. The factorial rise in MO 2 (1.58±0.03 times) for lobsters fed in the morning was significantly less than lobsters fed at night (1.80±0.01 times). Lobsters fed in the morning had a significantly shorter SDA (30±1.2 h) response compared to lobsters fed at night (36±1 h). Energy loss as a result of digestion was less for lobsters fed in the morning. Therefore, if juvenile J. edwardsii are fed in the morning, they could optimise the energy content of the meal and this could result in increased growth.