title: Measuring oxygen uptake in fishes with bimodal respiration.
abstract: Respirometry is a robust method for measurement of oxygen uptake as a proxy for metabolic rate in fishes, and how species with bimodal respiration might meet their demands from water v. air has interested researchers for over a century. The challenges of measuring oxygen uptake from both water and air, preferably simultaneously, have been addressed in a variety of ways, which are briefly reviewed. These methods are not well-suited for the long-term measurements necessary to be certain of obtaining undisturbed patterns of respiratory partitioning, for example, to estimate traits such as standard metabolic rate. Such measurements require automated intermittent-closed respirometry that, for bimodal fishes, has only recently been developed. This paper describes two approaches in enough detail to be replicated by the interested researcher. These methods are for static respirometry. Measuring oxygen uptake by bimodal fishes during exercise poses specific challenges, which are described to aid the reader in designing experiments. The respiratory physiology and behaviour of air-breathing fishes is very complex and can easily be influenced by experimental conditions, and some general considerations are listed to facilitate the design of experiments. Air breathing is believed to have evolved in response to aquatic hypoxia and, probably, associated hypercapnia. The review ends by considering what realistic hypercapnia is, how hypercapnic tropical waters can become and how this might influence bimodal animals' gas exchange.
authors.affiliation: Department of Biosciences, The Faculty of Mathematics and Natural Sciences, University of Oslo, P. O. Box 1066, 0316 Oslo, Norway.
authors.forename: S
authors.initials: S
authors.lastname: Lefevre
authors.affiliation: Zoophysiology, Aarhus University, Department of Bioscience, C. F. Møllers Allé 3, 8000 Aarhus C, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Bayley
authors.affiliation: UMR 9190 Centre for Marine Biodiversity Exploitation and Conservation, Université Montpellier 2, Place Eugène Bataillon, 34095 Montpellier cedex 5, France.|Department of Physiological Sciences, Federal University of São Carlos, SP, Brazil.
authors.forename: D J
authors.initials: DJ
authors.lastname: McKenzie
mesh_terms: D000388:Air; D000818:Animals; D005399:Fishes / Q000378:metabolism*; D000860:Hypoxia; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D012119:Respiration; D014867:Water
chemical_list: D014867:Water; D010100:Oxygen
keywords: intermittent-closed; oxygen consumption; respiratory partitioning; respirometry