J. zyxwvutsrqp Fish zyxwvut Biol. zyxwvuts (1980) 16,629-638 zyxwvu Effects of feeding on metabolic rate, and the Specific Dynamic Action in plaice, Pleuronectes platessa L. M. JOBLING* AND P. SPENCER DAVIES Zoology Department, The University, Glasgow, Scotland (Received zyxwvu 14 August 1979, Accepted 27 September 1979) The rate of oxygen consumption of plaice increases after feeding and declines to a resting level after 24-72 h. The maximum increase corresponds to a level which is approximately twice the resting rate of oxygen consumption. This increase corresponds to the Specific Dynamic Action (SDA) and increases in magnitude with increase in food intake. The magnitude is greatest with high protein content diets. The duration of the SDA effect is reduced with increase in temperature and increases with the percentage of protein in the diet. I. INTRODUCTION It is known that the heat output by homeotherms increases after feeding. This was first termed the Specific Dynamic Effect by Rubner (1902) but has subsequently come to be known as the Specific Dynamic Action (SDA) or the calorigenic effect (Garrow, 1974). The effect has been studied in mammals but the biochemical basis of the phenomenon is still not understood. It is now agreed that it is a post-absorptive process and that the energy expenditure for contraction ofgut muscle make a very small contribution (Brody, 1945). In poikilotherms the effect has been observed as a post-prandial increase in the rate of oxygen consumption. This has been observed in molluscs (Crisp et af., 1978), insects (Heiman zyxwvu & Knight, 1975) and Crustacea (Wallace, 1973; Aldrich, 1975; Nelson et af., 1977). In teleosts, a quantitative approach to SDA has been made by Muir & Niimi (1972), Hamada & Ida (1973), Beamish (1974) and Miura et af. (1976), all of whom investigated the effects of different feeding levels on the magnitude of the SDA. The present study was undertaken to assess the effects of both feeding level and the composition of the diet upon the post-prandial stimulation of oxygen consumption in plaice. 11. MATERIALS AND METHODS The experiments were conducted on tank-reared plaice, in the weight range 16-50 zy g, provided by the White Fish Authority Marine Cultivation Unit at Ardtoe, Argyll. Prior to use, the fish were acclimated to laboratory conditions in aquaria maintained at the experimental temperature (10, 15 or 20" C) and during this time they were fed upon live food (Tubvex, Arenicola and Mytihs). The fish were not fed for 48 h before being placed in the respirometer. Measurements of oxygen consumption were made using a continuous flow respirometer, at the experimental temperature (usually lo" C), under continuous illumination. The flow rate through the respirometer chamber was adjusted so that the outflowing water was *Present address: Institut for Fiskerifag, University of Tromse, Troms0, Norway. 629 0022-1 I 12/80/060629+10 $02.00/0 @ 1980 The Fisheries Society of the British Isles