Oxygen consumption by adults of the Southern hemisphere lampreyGeotria australis in air

Abstract

Adults of the lamprey Geotria australis are capable of surviving and taking up considerable volumes of oxygen when in humidified air. This accounts for their ability to leave water, move through moist vegetation and up and over dam walls, and thereby overcome barriers to their upstream migration. Immature adults of G. australis, which had been on their spawning run for 3–4 months, survived for at least 30 hr and without apparent discomfort in humidified air at 15°C during a light/dark/light regime paralleling field conditions. The mean hourly rate of oxygen consumption of these lampreys stabilised at c. 48 μl.gm−1.hr−1 during the light phase, but then rose during the dark phase and remained at c. 66 μl.gm−1.hr−1, before declining during the second light phase to a level similar to that in the initial light phase. The mean standard rate of oxygen consumption in air and in light, based on the minimal values recorded for individual animals during the period when their oxygen consumption was low and stable, was 33.6 μl.gm−1.h−1, which is virtually identical to the standard rate of oxygen consumption of immature adult G. australis, measured previously in water and light at the same temperature. However, the above mean rate for standard oxygen consumption in air is significantly less (P < 0.001) than the mean rate of 50.4 μl.gm−1.hr−1, determined in the same manner in air during those periods at night when oxygen consumption was high and stable. At the end of the spawning run, when maturity is attained, the mean standard rates of oxygen consumption of male and female G. australis in air and light at 15°C were 32.8 μl.gm−1.hr−1 and 22.6 μl.gm−1.hr−1, respectively. © 1996 Wiley-Liss, Inc.