Effects of water temperature changes on the endogenous and exogenous rhythms of oxygen consumption in glass eels Anguilla japonica

Abstract

The oxygen consumption rate (OCR) of glass eels Anguilla japonica was measured to determine the effects of water temperature changes on their endogenous and exogenous rhythms. Glass eels were exposed to different water-temperature patterns during simulated 12, 14 and 24 h cycles. The OCR of wild glass eels, freshly collected from estuaries, exhibited a clear endogenous circatidal rhythm while kept in constant darkness at 15 ± 0.1°C. However, if the temperature was varied, the glass eels OCR coincided with the gradually increasing water temperature (∆t = 1°C per 12 or 24 h) in the experimental chamber. This minor variation in water temperature (∆t = 1°C per 12 or 24 h) was significant enough to affect the rhythmicity of the glass eels' OCR. When the glass eels were exposed to a cyclic increase or decrease in water temperature (1°C per 14 h), the OCR peaks displayed a clear rhythmicity at 14 h intervals. The results indicate that the glass eels' OCR is controlled not only by an endogenous circatidal rhythm, but also by exogenous rhythms related to small environmental changes, such as water temperature changes of as little as 1°C. The possible mechanisms underlying these temperature responses are discussed and the implications of the findings for the eco-physiology and metabolic activity rhythms of glass eels are highlighted.

Proximate and Ultimate Control of Eel Continental Dispersal

“…Slight temperature changes may induce phase shifting of endogenous rhythms through alterations of the clock molecular machinery (Rensing and Ruoff 2002). Accordingly, in A. japonica glass eels kept under free-running conditions, a slight temperature change may shift the rhythm of the internal circatidal clock (Kim et al 2002). Such temperature-mediated phase shifting in the internal tidal clock may be one of the processes leading to an inefficient use of tidal streams by glass eels (see Fig.…”

Effects of Water Temperature Changes on the Oxygen Consumption Rhythm in the Japanese eel, Anguilla japonica

“…It is reported that when the glass eels were exposed to a cyclic increase or decrease in water temperature (1℃/14 h), the OCR peaks displayed a clear rhythmicity at 14 h intervals (Kim et al, 2002a). Therefore, our observation of eels' thermal limits which may affect physiological state and the survival of the eels, can offer a meaningful information for appropriation of optimal temperature in the eel culture.…”

“…The relationship between the endogenous rhythm and the environmental factors should be defined to understand physiological and behavioral aspects of this species. However, few data are available on the correlation between water temperature changes and metabolic activity rhythms in adult eels (Kim et al, 2002a). …”

Effect of Yellow Clay on the Oxygen Consumption Rate of Korean rockfish, Sebastes schlegelii

“…2) following the procedures described by Kim et al(1996Kim et al( , 1998Kim et al( , 2002. To obtain the concentration in mg/L, the following formula was used to convert the gas volume under standard conditions, V std , into the gas volume under measured conditions, V R :…”