title: Effect of closed v. intermittent-flow respirometry on hypoxia tolerance in the shiner perch Cymatogaster aggregata.
abstract: This study compares the critical oxygen saturation (O2 crit ) levels of the shiner perch Cymatogaster aggregata obtained using two different methods wherein hypoxia is induced either by the fish's respiration (closed respirometry) or by degassing oxygen with nitrogen (intermittent-flow respirometry). Fish exhibited loss of equilibrium at a higher O2 saturation in the closed respirometry method when compared with the intermittent-flow method. Utilization of closed respirometry yielded O2 crit measurements that were almost twice as high as those obtained with intermittent-flow respirometry. The lower hypoxia tolerance in closed respirometry is consistent with additional stress, caused by a build-up of ammonia and carbon dioxide and a faster rate in dissolved oxygen decline. The results indicate that these two methods of determining hypoxia tolerance in aquatic organisms are not comparable, and that much care should be given to method choice.
authors.affiliation: Scripps Institution of Oceanography, La Jolla, CA 92093-0208, U.S.A.
authors.forename: S
authors.initials: S
authors.lastname: Snyder
authors.affiliation: College of Marine and Environmental Sciences, ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Qld 4811, Australia.
authors.forename: L E
authors.initials: LE
authors.lastname: Nadler
authors.affiliation: University of Aarhus, Aarhus 8000, Denmark.
authors.forename: J S
authors.initials: JS
authors.lastname: Bayley
authors.affiliation: University of Copenhagen, Marine Biological Laboratory, Biological Institute, Strandpromenaden 5, DK-3000 Helsingør, Denmark.
authors.forename: M B S
authors.initials: MB
authors.lastname: Svendsen
authors.affiliation: University of Texas Marine Science Institute, Port Aransas, TX 78373, U.S.A.
authors.forename: J L
authors.initials: JL
authors.lastname: Johansen
authors.affiliation: CNR-IAMC, Istituto per l'Ambiente Marino Costiero, Località Sa Mardini, 09072 Torregrande, Oristano, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Domenici
authors.affiliation: University of Copenhagen, Marine Biological Laboratory, Biological Institute, Strandpromenaden 5, DK-3000 Helsingør, Denmark.
authors.forename: J F
authors.initials: JF
authors.lastname: Steffensen
mesh_terms: D000641:Ammonia / Q000378:metabolism; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D000860:Hypoxia; D010100:Oxygen / Q000502:physiology; D010101:Oxygen Consumption; D010471:Perches / Q000502:physiology*
chemical_list: D002245:Carbon Dioxide; D000641:Ammonia; D010100:Oxygen
keywords: aquatic breathers; critical oxygen saturation level; hypoxic; physiology; respiration; stress