INFLUENCE OF TEMPERATURE ON ROUTIN METABOLIC RATES OF SUBANTARCTIC TELEOSTS

F. A. VANELLA; J. CALVO

Berichte zur Polar- und Meeresforschung / Reports on Polar and Marine Research. Extended Abstract of the IBMANT / ANDEEP International Symposium & Workshop

Alfred-Wegener-Institut

Lugar: Bremerhaven; Año: 2005 vol. 507 p. 96 - 97

1618-3193

The influence of temperature on metabolic activity of poikilotherms varies according to the evolutionary history of each species. Subantarctic notothenioids are exposed to wider variations in temperature than those encountered in the Antarctic, the ancestral environment of the group. In this study the influence of temperature on the routine metabolic rate of Sub-Antarctic Teleosts was described and the results were compared with routine metabolic rates of species with different geographical distributions, exploring the existence of Metabolic Cold Adaptation (MCA).Oxygen consumption (VO2R) was determined as an estimate of the routine metabolic rate for the following subantarctic Notothenioids: Paranotothenia magellanica, Patagonotothen sima, Eleginops maclovinus, Harpagifer bispinis and the Zoarcidae Austrolycus depressiceps. Because of the allometric ratio between live mass and metabolic rate, a general design of repeated measurements was followed. Each specimen was acclimated at a temperature of 10ºC for ten days in a respirometric chamber.  After VO2R was measured, the temperature was lowered 1ºC per day until to reach 4ºC.  This temperature was maintained for ten days before determining VO2R.  The same procedure was followed for the determination at 2ºC. E. maclovinus did not tolerate prolonged confinement; therefore an independent sample design was followed. The VO2R and live mass of each fish showed positive correlation (p < 0.05) in all species and temperatures tested. Lowering the temperature from 10 to 2ºC produced a significant reduction (p < 0.05) of VO2R values with a Q10 (10-2) varying between 5.5 and 19. At temperatures of 2 ºC (Figure 1) both Sub-Antarctic notothenioids and the zoarcid species studied showed VO2R values 2 or 3 times lower than those of Antarctic species with similar habits living at temperatures near or below 0ºC. Temperature affected VO2R differently depending on the living habits of the species studied.  Between 10 and 4ºC, the oxygen consumption rate for the sluggish, benthic A. depressiceps descended more than that of the more active notothenioids.   Between 4 and 2ºC the VO2R of E. maclovinus (benthopelagic) and H. bispinis (benthic) descended more than the VO2R of P. magellanica (pelagic) and P. sima. We can conclude that the metabolic rates of these species of subantarctic fish do not present MCA.  However, this metabolic adjustment may be present in other polar teleosts.