Seasonal Metabolic Compensation in Sympatric Seatrout: Adaptation to the Estuary

Abstract

Abstract The standard metabolic rates of spotted seatrout Cynoscion nebulosus and sand seatrout Cynoscion arenarius were compared at different seasonal temperatures. During early summer at 25 C, when spatial overlap of the two species in Texas estuaries is greatest, their metabolic ratees were similar. At 15 C in winter, the metabolic rate of spotted seatrout was twice that of sand seatrout: 50 and 25 mg O2˙kg−1 hour−1, respectively. At peak summer temperatures of 30 C, the metabolic rate of spotted seatrout was less than that of sand seatrout: 124 and 170 mg O2˙kg−1 hour−1, Spotted seatrout are permanent residents of estuaries, but sand seatrout migrate out to the Gulf of Mexico in late summer and overwinter there. Greater metabolic compensation on the part of spotted seatrout may be an adaptation to year-round exploitation of the estuarine habitat, which has more extreme temperatures than offshore waters.