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Metabolic Thermal Compensation by Rainbow Trout: Effects on Standard Metabolic Rate and Potential Usable Power
Author(s) -
Evans David O.
Publication year - 1990
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1990)119<0585:mtcbrt>2.3.co;2
Subject(s) - rainbow trout , metabolic rate , usable , compensation (psychology) , fishery , rainbow , biology , zoology , fish <actinopterygii> , computer science , endocrinology , physics , optics , psychology , world wide web , psychoanalysis
Metabolic models of thermal acclimation of fishes are generally based on routine rates of oxygen consumption and, therefore, are confounded by metabolic changes due to variation in random activity. My objectives were to describe the amount, direction, and time course of change in the standard metabolic rate of rainbow trout Oncorhynchus mykiss while the fish acclimated to warm and cold temperature, and to account for the energy costs of random swimming. Rainbow trout (100–250 g) were acclimated to 10 and 20°C and tested at 10, 15, and 20°C. Random activity and oxygen consumption were monitored at acclimation temperatures immediately after acute temperature exposures and, in some cases, for several days after temperature changes. Random swimming activity and standard metabolic rate were strongly influenced by both recent thermal history and acute temperature exposure. The initial activity response depended on the extent of the temperature change, and included an orthokinetic reaction when the new temperature deviated widely from the final thermal preferendum. During acclimation, standard metabolic rate was adjusted independently of the direct kinetic effect of temperature in a manner corresponding to partial metabolic compensation. The result was a 53% reduction in standard metabolic rate during warm acclimation (10 to 20°C) and a 35% increase during cold acclimation (20 to 10°C. The time course of warm and cold metabolic acclimation over the 10–20°C range was about 96 h. Analysis of data for rainbow trout and other salmonids indicated that warm and cold metabolic acclimation resulted in increased scope for activity, the latter being equivalent to the maximum sustained usable power – i.e., power that is available for ancillary and discretionary activities. Conservation and budgeting of power output to maximize the availability of usable power appears to be the essence of capacity adaption, not simply stabilization of metabolic function as has often been suggested.