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Biology | Physiology


Clark Cotton


Dissolved oxygen (DO) concentrations in bodies of water can differ based on geographic location, time of day, or even climate change. Because frogs acquire approximately 20% of their oxygen across the skin, decreases in DO could negatively affect diving behavior by increasing reliance on anaerobic metabolism and formation of lactate. To evaluate this possibility, we measured pulmonary and cutaneous oxygen exchange as well as blood lactate levels before and after a 30-minute dive period under both saturated DO (8.341 ± 0.042 mg/L) and low DO conditions (3.918 ± 0.597 mg/L). Although frogs diving in a low oxygen environment tended to accumulate slightly more lactate, which would indicate a shift toward anaerobic metabolism, the trend was not significant (t(8) = 1.86, p = 0.525). A reduction in cutaneous O2 gas exchange was observed to be significant (t(8) = 1.86, p = 0.0015) following a forced dive. However, cutaneous O2 gas exchange only makes up a miniscule amount of the total pulmocutaneous gas exchange; therefore, would have little effect on lactate accumulation. In conclusion, low DO water does not appear to influence diving behavior or lactate accumulation in a biologically significant way for this species. However, we acknowledge the possibility that low DO water may have a more profound effect during dives of longer durations.