title: Hibernation in freshwater turtles: softshell turtles (Apalone spinifera) are the most intolerant of anoxia among North American species.
abstract: Softshell turtles (Apalone spinifera) were submerged at 3 degrees C in anoxic or normoxic water. Periodically, blood PO(2), PCO(2), pH, plasma [Cl(-)], [Na(+)], [K(+)], total Ca, total Mg, lactate, glucose, and osmolality were measured; hematocrit and body mass determined; and blood [HCO(3)(-)] calculated. On day 14 of anoxic submergence, five of eight softshell turtles were dead, one died immediately after removal, and the remaining two showed no signs of life other than a heartbeat. After 11 days of submergence in anoxic water, blood pH fell from 7.923 to 7.281 and lactate increased to 62.1 mM. Plasma [HCO(3)(-)] was titrated from 34.57 mM to 4.53 mM. Plasma [Cl(-)] fell, but [K(+)] and total Ca and Mg increased. In normoxic submergence, turtles survived over 150 days and no lactate accumulated. A respiratory alkalosis developed (pH-8.195, PCO(2)-5.49 after 10 days) early and persisted throughout; no other variables changed in normoxic submergence. Softshell turtles are very capable of extrapulmonary extraction of O(2), but are an anoxia-intolerant species of turtle forcing them to utilize hibernacula that are unlikely to become hypoxic or anoxic (e.g., large lakes and rivers).
authors.affiliation: Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA. scott_reese@brown.edu
authors.forename: S A
authors.initials: SA
authors.lastname: Reese
authors.forename: D C
authors.initials: DC
authors.lastname: Jackson
authors.forename: G R
authors.initials: GR
authors.lastname: Ultsch
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D004777:Environment; D005618:Fresh Water / Q000737:chemistry; D006605:Hibernation; D000860:Hypoxia / Q000503:physiopathology*; D007101:Immersion; D010100:Oxygen / Q000032:analysis; D013045:Species Specificity; D014426:Turtles / Q000235:genetics / Q000502:physiology*
chemical_list: D010100:Oxygen