Year: 1997
Type: dissertation
Abstract: The circadian rhythm in diving behaviour of captive canvasback ducks Aythya valisineria was measured using radio-telemetry, and indirectly via analysis of underwater feeding activity. The asphyxic ventilatory response then was measured in awake unanesthetized ducks by closed-circuit plethysmography at the times corresponding to maximum and minimum dive activity. 76% of dives occurred at night and nocturnal dives were 37% longer than those performed in the light. The day-night differences in diving behaviour were apparently correlated with day-night differences in respiratory chemosensitivity. The ventilatory response to progressive asphyxia was non-linear, and consisted of an increase in tidal volume with no change in respiratory frequency. Respiratory sensitivity to asphyxia, as reflected by the exponential regression coefficient (the slope of lnV$\sb{\rm I}$ versus (CO$\sb2$)), was lower at night than during the day (P = 0.02). I suggest that underwater exercise performance is facilitated by reduced respiratory chemosensitivity and that the respiratory and behavioural control systems are synchronized by the circadian timing system.
Author: Melanie A. Woodin
Language: English
Subfield: Endocrine and Autonomic Systems
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2729331545