Metabolic responses of Nephrops norvegicus to progressive hypoxia
Department of applied biology, the University of Hull, Kingston upon Hull, HU6 7RX, England
Accepted: 27 January 1998
This work studied some of the metabolic responses of Nephrops norvegicus to a progressive reduction in water oxygen tension (PwO2) at 12 °C. Experiments were designed to simulate water quality conditions that may occur during the trade of live crustaceans. Oxygen consumption rates and ammonia efflux rates were found to be constant over a wide range of PwO2 values (20.4-5.9 kPa). A similar result was found for the difference between post-branchial and pre-branchial oxygen concentrations (20.4-2.6 kPa), obtained from a separate experiment. Anaerobic pathways, however, were activated after PwO2 reached 6.3 kPa, as blood lactate and glucose concentrations increased from 1.24 ± 0.08 and 1.17 ± 0.19 (T0 values) to 10.55 ± 8.99 and 3.63 ± 0.89 mg · 100 mL−1 respectively. N. norvegicus was able to maintain blood pH levels at relatively constant values despite a drop in water pH levels and the accumulation of lactate observed at low PwO2. Heart rates also remained stable during PwO2 reductions, but scaphognathite beat rate increased considerably, probably as an attempt to maintain steady weight-specific oxygen consumption rates. N. norvegicus appeared to be well adapted to cope with progressive hypoxia as may occur during holding and transportation procedures.
Key words: Hypoxia / metabolism / Nephrops norvegicus
© Elsevier, IRD, Inra, Ifremer, Cemagref, CNRS, 1998