Cardiac function and critical swimming speed of the winter flounder (Pleuronectes americanus) at two temperatures

摘要: Abstract Using Transonic® flow probes and a uniquely designed swimming flume, we directly measured cardiac parameters ( Q , output; S V stroke volume; f H heart rate) in winter flounder Pleuronectes americanus) before during critical swim speed U crit ) tests at 4 10 °C. Resting averaged 9.8 ml min −1 kg 0.5 (1.0 g ventricle 21 beats °C 15.5 (0.95 34 values of 2.13, 0.91 2.35, for respectively). Cardiac output, increased by approx. 170%, 70% 60% both temperatures the test. However, generally reached near maximal levels almost immediately upon remained these until (0.65±0.06 bl s 0.73±0.07 °C). This rapid rise function to did not appear be result stress alone, as only fell slightly when were swum 75 speeds which they appeared comfortably. Our results suggest that have been significantly overestimated flatfishes, “lift-off”/slow is energetically expensive. Furthermore, show maximum resting volume (per ventricle) are extremely high compared with other teleosts.