A methodological approach to measuring the oxygen consumption profile of six freshwater fish species: implications for determination of the standard metabolic rate.

Procedures for the determination of standard metabolic rate (SMR) are variable and subjective in respirometry. We examined the oxygen consumption profile of six fish species (three salmonids and three cyprinids) in respirometry, and analysed the implications for the determination of SMR. In addition, we used data on Arctic charr (Salvelinus alpinus) and bleak (Alburnus alburnus) to define, how the length of a measuring period affects the determination of SMR and to investigate the temporal consistency of SMR. Fish activity in the respirometer differed between the species and there was a family-specific response to change in illumination. In salmonids, switching off the lights resulted in an increased oxygen consumption rate for hours, whereas in cyprinids the response was shorter or totally absent. In Arctic charr and bleak, individual oxygen consumption profiles remained unchanged between the consecutive trials. The results emphasize the importance of taking species-specific responses into account when determining SMR. [ABSTRACT FROM AUTHOR]