Air-exposure of settled Jasus edwardsii at 17˚C
initially halved oxygen consumption, doubled ventilation frequency and reduced
heart rate. During 8 h emersion, oxygen uptake partially recovered,
ventilation remained elevated and heart rate was restored. Haemolymph
PCO2 increased fourfold, despite
the hyperventilation. Branchial gas exchange, initially impaired in air, may
improve as the gills drain. Partial anaerobiosis was indicated by elevation of
haemolymph [lactate-] to 4.2 mmol
L-1. Although haemolymph pH decreased ~0.3 units over 8
h, a base excess compensated all of the metabolic and part of the respiratory
acidosis. On return to water, oxygen consumption initially increased to
>2.5 times pre-emersion rates while ventilation and heart rates increased
further. Most respiratory variables returned to pre-emersion levels within 8 h
of re- immersion, but oxygen consumption and heart rate remained elevated for
24 h. The excess oxygen consumption over resting rate during 24 h recovery in
water indicated a metabolic cost of 8 h emersion equivalent to 10 h resting
metabolism in water. These responses contrast with better acid–base
compensation previously reported for undisturbed
Homarus gammarus in air and worse tolerance of
air-exposure by Panulirus argus
Changes in the ATPase activity of insect fibrillar flight muscle during sinusoidal length oscillation probed by phosphate-water oxygen exchange.
