Marine Biology 109, 191-195 (1991) Marine ............ Biology @ Springer-Verlag 1991 Temperature and metabolic rate in sedentary fish from the Antarctic, North Sea and Indo-West Pacific Ocean * I.A. Johnston 1,2 A. Clarke 3 and P. Ward 1,3 Department of Biology and Preclinical Medicine, Gatty Marine Laboratory, University of St. Andrews, Fife KY16 8LB, Scotland 2 Pacific Ocean Research Foundation, 74-425 Kealakehe Parkway, 15 Kailua-Kona, Hawaii 96740, USA 3 British Antarctic Survey, Natural Environment Research Council, Madingley Road, Cambridge CB30ET, England Date of final manuscript acceptance: February 1, 1991. Communicated by J. Mauchline, Oban Abstract. Resting metabolic rate (I2o2Ero~t~) was measured in demersal stages of the teleost Notothenia neglecta Ny- belin from the South Orkney Islands, Antarctica, from 1985 to 1987. The relationship between 1/o2 ~ ,tl and body mass (Mb) conformed to the general rrelationship 1) o =a Mb b, where a is a proportionality constant an~lErl)~t]s the scaling exponent IZo2 (mg 02 h- 1) was -}- . [restl found to scale to Mb (°'s2-°'°1~ in the summer (Novem- ber to April, 1.6 to 1 850 g, n=56) and to Mb (°'v6-+°°13) in the winter (May to October, 0.9 to 1 850 g, n=57) (values of b are means 4- SD). Although the scaling expo- nents were significantly different (P<0.01), l?o~ E ~ was similar in the juvenile stages of summer- and ~winter- caught fish matched for body mass. The effects of activity on oxygen consumption was studied using a Brett respirometer. Adult stages had a factorial aerobic scope for activity (1~o2 : I2o~ ~ ~i) of 5.7, which is similar to that reported fo~demersa~l°flsh from temperate latitudes. The effects of temperature on resting metabolism was investigated in fish with similar sedentary lifestyles from the North Sea (Agonus cataphractus and Myoxocephalus scorpius) and the Indo-West Pacific (Paracirrhites forsteri, P. arcatus, Neocirrhites armatus and Exallias brevis). Extrapolated values of Vo~E~o~tj for the tropical species approached zero at 5 to 10 °C. For a standard 50 g fish, l?o~E~o,~ for the tropical species at 25 °C was in the range 3.4 to 4.4 mg 02 h- 1, compared with 1.3 mg 0 2 h-1 for Notothenia neglecta at its acclimation tempera- ture. Thus, the maximum metabolic rate of sedentary tropical species at 24 °C is likely to be 2 to 4 times higher than in N. neglecta at 0°C. This suggests that the energy available for sustained activity (l?o~ t -l~o~ ~ ~ ) is sig- nificantly lower in cold- than in warm°-%vater fis~. * Please address all correspondence to Professor Johnston at the Gatty Marine Laboratory Introduction The Antarctic marine ecosystem has cooled gradually over 20 m. yr and is thought to have been at or below 0 °C for 3 to 5 m.yr (Kennett 1977, Clarke 1983). Antarctic fish and invertebrates show numerous resistance adapta- tions which enable them to live at temperatures far below the lethal limit of temperate and tropical species (John- ston 1990). However, in spite of the long period of adap- tation to cold conditions, such diverse processes as devel- opment and escape swimming responses occur more slowly in polar than in temperate and tropical organisms (Bosch et al. 1987, Johnston 1990, Johnston et al. 1991). Early work on fish metabolism suggested that resting metabolic rates were elevated at low temperatures in po- lar relative to temperate and tropical species, a phe- nomenon referred to as "metabolic cold adaptation" (Scholander et al. 1953, Wohlschlag 1960, 1962, 1964 a, b). However, both the observational basis and the underlying concept of metabolic cold adaptation have subsequently been criticised (Holeton 1973, 1974, Clarke 1980). In particular, some of the high values for oxygen consumption in Antarctic fish reported in the early liter- ature probably reflect the effects of handling stress (Hole- ton 1974, Forster et al. 1987). The great majority of pre- vious studies have concerned the endemic sub-order Notothenioidii, which comprises around 50% of all Antarctic fish species (Andriashev 1987). All Notothe- nioidii lack a swim bladder, and the majority of species are demersal and sedentary as adults (Andriashev 1987). A serious problem with past comparisons of the meta- bolic rate of Antarctic with warmer water fish is that most of the data for the latter are for active freshwater species. The main aim of the present study was to measure resting metabolic rate in Antarctic, temperate and tropi- cal fish with similar sedentary lifestyles in order to assess any constraints on metabolism imposed by low-tempera- ture environments. Since maximum metabolic rates de- termine behavioural capacities, we have also determined Vo2Em.x~ in the demersal Antarctic species Notothenia ne-