Influence of water temperature on demand-feeding rhythms in sea bass

Under natural environmental conditions, sea bass feeding rhythms are noctur nal in winter and diurnal during the rest of the year. Increasing water tem perature from 22 to 28 degrees C or decreasing it to 16 degrees C had littl e effect on the dual feeding behaviour of sea bass. An 8 : 16 LD photoperio d with low temperature or 16 : 8 LD with high temperature also failed to ch ange the diurnal/nocturnal behaviour of sea bass. In conclusion, sea bass F eeding rhythms did not follow passively the manipulated environmental facto rs simulating summer and winter conditions in the laboratory, which suggest s an endogenous circannual control of the seasonal phase inversion. (C) 199 9 The Fisheries Society of the British Isles.