Influence of Surrounding Medium on Metabolic Rates in Alpine Newts, Ichthyosaura alpestris, during Aquatic Phase
Measuring standard metabolic rates in newts remains a complicated task despite substantial methodological and technological advances in the field. We examined the influence of aquatic versus terrestrial conditions in respirometry chambers on measurements of respiratory gases and motor activity in Alpine Newts, Ichthyosaura alpestris, during their aquatic phase. Aquatic conditions during intermittent respirometry trials biased values of carbon dioxide production more than values of oxygen consumption, which caused marked differences in estimates of respiratory quotient. Placing newts in water increased their motor activity relative to terrestrial conditions during respirometry trials, which made obtaining representative estimates of standard metabolic rates complicated. We conclude that the absence of water, rather than aquatic conditions in respirometry chambers, produces more-accurate metabolic measurements in newts during their aquatic phase.Abstract
Respirometry measurements in newts under aquatic and terrestrial conditions. (A) Oxygen consumption, (B) CO2 production, (C) respiratory quotient (CO2 production/O2 consumption), and (D) the number of activity bouts during respirometry trials in adult Alpine Newts, Ichthyosaura alpestris, under aquatic and terrestrial conditions (18 ± 0.5°C) in a respirometry chamber. Data are summarized using boxplots (median, 5%, 10%, 25%, 75%, 90%, and 95% percentiles). Data points are jittered horizontally to reduce overlap. Differences between means are presented as mean ± 95% CIs.
Contributor Notes
