Effects of acute temperature change on the metabolism and swimming ability of juvenile sterlet sturgeon (Acipenser ruthenus, Linnaeus 1758)

The objective of this study was to provide information on changes in the metabolism and swimming ability of juvenile sterlet sturgeon, Acipenser ruthenus, caused by acutely low or high temperatures. Changes in critical swimming speed (U-crit), oxygen consumption rate (MO2), tail beat frequency (TBF) and tail beat amplitude (TBA) were observed with a Steffensen-type swimming respirometer, an oxygen electrode and a camera at different swimming speeds at three temperatures: 5 degrees C, 15 degrees C, and 25 degrees C. Fish tested at 5 degrees C and 25 degrees C were maintained at 15 degrees C (near optimal) for one week to simulate conditions below a dam. The U-crit value decreased significantly during acute temperature changes at 5 degrees C and 25 degrees C; U-crit was highest near the optimal temperature. Oxygen consumption rate (MO2) increased with the swimming speed at 15 degrees C; however, at 25 degrees C and 5 degrees C, the MO2 decreased with the swimming speed. Both TBA and TBF decreased at 5 degrees C and 25 degrees C compared to values at 15 degrees C. The slopes of the regression lines (TBF/U) at 5 degrees C and 25 degrees C seemed lower compared to 15 degrees C.