The physiology of overwintering in a turtle that occupies multiple habitats, the common snapping turtle (Chelydra serpentina)

Common snapping turtles, Chelydra serpentina (Linnaeus), were submerged in anoxic and normoxic water at 3degreesC. Periodic blood samples were taken, and PO2, PCO2, pH, [Na+], [K+], [Cl-], total Ca, total Mg, [lactate], [glucose], hematocrit, and osmolality were measured; weight gain was determined; and plasma [HCO3-] was calculated. Submergence in normoxic water caused a decrease in PCO2 from 10.8 to 6.9 mmHg after 125 d, partially compensating a slight increase in lactate and allowing the turtles to maintain a constant pH. Submergence in anoxic water caused a rapid increase in lactate from 1.8 to 168.1 mmol/L after 100 d. Associated with the increased lactate were decreases in pH from 8.057 to 7.132 and in [HCO3-] from 51.5 to 4. 9 mmol/L and increases in total Ca from 2.0 to 36.6 mmol/L, in total Mg from 1.8 to 12.1 mmol/L, and in [K+] from 3.08 to 8.45 mmol/L. We suggest that C. serpentina is tolerant of anoxic submergence and therefore is able to exploit habitats unavailable to some other species in northern latitudes.