Euroortodoncia (Spain)

In the current study, we used breath-by-breath respirometry to evaluate respiratory physiology under voluntary control in a male beluga calf [Delphinapterus leucas, body mass range (Mb): 151–175 kg], an adult female (estimated Mb = 500–550 kg) and a juvenile male (Mb = 279 kg) false killer whale (Pseudorca crassidens) housed in managed care. Our results suggest that the measured breathing frequency (fR) is lower, while tidal volume (VT) is significantly greater as compared with allometric predictions from terrestrial mammals. Including previously published data from adult bottlenose dolphin (Tursiops truncatus) beluga, harbor porpoise (Phocoena phocoena), killer whale (Orcinus orca), pilot whale (Globicephala scammoni), and gray whale (Eschrichtius robustus) show that the allometric mass-exponents for VT and fR are similar to that for terrestrial mammals (VT: 1.00, fR: −0.20). In addition, our results suggest an allometric relationship for respiratory flow (), with a mass-exponent between 0.63 and 0.70, and where the expiratory was an average 30% higher as compared with inspiratory . These data provide enhanced understanding of the respiratory physiology of cetaceans and are useful to provide proxies of lung function to better understand lung health or physiological limitations.

In the current study we used transthoracic echocardiography to measure stroke volume (SV), heart rate (fH) and cardiac output (CO) in adult bottlenose dolphins (Tursiops truncatus), a male beluga whale calf [Delphinapterus leucas, body mass (Mb) range: 151-175 kg] and an adult female false killer whale (Pseudorca crassidens, estimated Mb: 500-550 kg) housed in managed care. We also recorded continuous electrocardiogram (ECG) in the beluga whale, bottlenose dolphin, false killer whale, killer whale (Orcinus orca) and pilot whale (Globicephala macrorhynchus) to evaluate cardiorespiratory coupling while breathing spontaneously under voluntary control. The results show that cetaceans have a strong respiratory sinus arrythmia (RSA), during which both fH and SV vary within the interbreath interval, making average values dependent on the breathing frequency (fR). The RSA-corrected fH was lower for all cetaceans compared with that of similarly sized terrestrial mammals breathing continuously. As compared with terrestrial mammals, the RSA-corrected SV and CO were either lower or the same for the dolphin and false killer whale, while both were elevated in the beluga whale. When plotting fR against fH for an inactive mammal, cetaceans had a greater cardiac response to changes in fR as compared with terrestrial mammals. We propose that these data indicate an important coupling between respiration and cardiac function that enhances gas exchange, and that this RSA is important to maximize gas exchange during surface intervals, similar to that reported in the elephant seal.

The Parnaíba sedimentary basin western margin geology in the State of Pará, Brazil, indicates that the present basin margin is of a tectonic origin and not its original depositional limit. The Paleozoic section bearing fine sediments are strongly faulted and is covered by an extensive Cenozoic sedimentation probably the last period of tectonic reactivation. To the north, parallel to the Tocantins river, a thick Quaternary sedimentation covers all the preceding formations reaching colossal thicknesses at the mouth of the Amazon river.