First record of stonefish metabolism: baseline respiration and spontaneous activity of tropical marine Synanceia verrucosa

Abstract

ABSTRACT For the first time oxygen consumption and spontaneous activity of 16 individuals of stonefish Synanceia verrucosa were determined simultaneously. The experiments were conducted in an intermittent-flow respirometer at 25°C, and salinity (PSU 32). Continuous measurements of fish activity and oxygen consumption were combined in order to calculate routine (RMR) and standard metabolic rate (SMR) and at the same time quantify spontaneous activity. The relationship between RMR and activity was found to be highly significant (P < 0.001). Relative SMR values varied between 24.0 and 54.4 mg O2 h−1 kg wet mass−1 for large (> 500 g) and small (102–394 g) specimens, respectively. Spontaneous activity rates ranged between 4–6 and 40–75 movements h−1 (mean), for large and small specimens, respectively. Absolute SMR for a standard mass of 100 g was calculated to be 3.58 mg O2 h−1, using a wet mass vs. oxygen consumption relationship of SMR [mg O2 h−1] = 0.0643*WM [g] 0.873. The investigated stonefish is so far the most motionless fish found in coral reef/mangrove areas, with activity levels much lower than closely related scorpionfish (Scorpaenidae), and scorpaenids from lower latitudes (e.g. sculpins). SMR of fish in this study was extremely low in comparison with other marine tropical species.