Lactate accumulation, glycogen depletion, and shell composition of hatchling turtles during simulated aquatic...

We submerged hatchling western painted turtles Chrysemys picta Schneider, snapping turtles Chelydra serpentina L. and map turtles Graptemys geographica Le Sueur in normoxic and anoxic water at 3 degrees C. Periodically, turtles were removed and whole-body [lactate] and [glycogen] were measured along with relative shell mass, shell water, and shell ash. We analyzed the shell for [Na+], [K+], total calcium, total magnesium, Pi and total CO2. All three species were able to tolerate long-term submergence in normoxic water without accumulating any lactate, indicating sufficient extrapulmonary O2 extraction to remain aerobic even after 150 days. Survival in anoxic water was 15 days in map turtles, 30 days in snapping turtles, and 40 days in painted turtles. Survival of hatchlings was only about one third the life of their adult conspecifics in anoxic water. Much of the decrease in survival was attributable to a dramatically lower shell-bone content (44% ash in adult painted turtles vs. 3% ash in hatchlings of all three species) and a smaller buffer content of bone (1.3 mmol g(-1) CO2 in adult painted turtles vs. 0.13-0.23 mmol g(-1) CO2 in hatchlings of the three species). The reduced survivability of turtle hatchlings in anoxic water requires that hatchlings either avoid aquatic hibernacula that may become severely hypoxic or anoxic (snapping turtles), or overwinter terrestrially (painted turtles and map turtles).