Geographic variation of the physiological response to overwintering in the painted turtle (Chrysemys picta)

We compared the physiological responses of latitudinal pairings of painted turtles submerged in normoxic and anoxic water at 3 degrees C: western painted turtles (Chrysemys picta bellii) from Wisconsin (WI) versus southern painted turtles (Chrysemys picta dorsalis) from Louisiana (LA), Arkansas (AR), and Alabama (AL), and eastern painted turtles (Chrysemys picta picta) from Connecticut (CT) versus C. p. picta from Georgia (GA). Turtles in normoxic water accumulated lactate, with C. p. bellii accumulating less than (20 mmol/L) the other groups (44-47 mmol/L), but with relatively minor acid-base and ionic disturbances. Chrysemys picta bellii had the lowest rate of lactate accumulation over the first 50 d in anoxic water (1.8 mmol/d vs. 2.1 for AR C. p. dorsalis, 2.4 mmol/d for GA C. p. picta, and 2.5 mmol/d for CT C. p. picta after 50 d and 2.6 mmol/d for AL C. p. dorsalis after 46 d). Northern turtles in both groups survive longer in anoxia than their southern counterparts. The diminished viability in C. p. dorsalis versus C. p. bellii can be partially explained by an increased rate of lactate accumulation and a decreased buffering capacity, but for the CT and GA C. p. picta comparison, only buffering capacity differences are seen to influence survivability.