Respiratory responses to hypoxia in relation to mode of life of two erythrinid species (Hoplias malabaricus and Hoplias lacerdae) |
| |
| Authors: | F. T. Rantin,A. L. Kalinin,M. L. Glass,&dagger M. N. Fernandes |
| |
| Affiliation: | Department of Physiological Sciences, Federal University of São Carlos, Po. Box 676 São Carlos, SP, Brazil;Department of Physiology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, 14049, Ribeirão Preto, SP, Brazil |
| |
| Abstract: | Predominantly, Hoplias malabaricus inhabits stagnant O2 poor environments, whereas Hoplias lacerdae occurs in well-aerated streams. The present study evaluates the influence of mode of life on O2 uptake and gill ventilation in equally-sized (300 g) specimens of this genus at 25° C. Comparing the species, H. lacerdae was characterized by the highest O2 uptake and gill ventilation combined with a relatively higher cost of breathing and a lower O2 extraction. Both species substantially increased ventilation in response to hypoxia with the difference that H. malabaricus exclusively augmented tidal volume, whereas H. lacerdae also increased breathing frequency. |
| |
| Keywords: | critical O2 tensions gill ventilation cost of breathing ambient hypoxia erythrinids Hoplias |
|
|
