Respiratory gas exchange in the resting starry flounder, Platichthys stellatus: a comparison with other teleosts.

A wide range of respiratory, ventilatory, and cardiovascular parameters have been recorded under completely resting conditions in the starry flounder (Platichthys stellatus), a generally inactive benthic teleost. The results differ in a number of important respects from those of a previous study on the same species. The present data have also been compared with those reported for the active pelagic rainbow trout (Salmo gairdneri) and for other teleost species. Of particular note in the flounder, relative to the trout, are low arterial and venous PO2's, a low arterial-venous O2 content difference, a low transfer factor and high diffusion gradient for O2 across the gills, a high in vivo blood O2 affinity, a high cardiac output and stroke volume accompanied by a low peripheral vascular resistance, a low ventilation volume, a low ventilation-perfusion ratio, and a low capacity-rate ratio for O2 exchange at the gills. Parameters of CO2 transport and acid-base regulation appear conventional, though blood CO2 contents and lactate concentrations are low. The respiratory strategies of inactive versus active, and benthic versus pelagic teleosts are discussed.