GONZALEZ, Yessy M; WALKENHORST, Holly; HATCH, Kent; Brigham Young Univeristy; Brigham Young University; Brigham Young University: The Effect of Current Velocity on the Critical Oxygen Tension of Rana pipiens

Many amphibians utilize cutaneous gas exchange when submerged in water. Critical oxygen tension is the minimum amount of dissolved oxygen necessary to sustain metabolic processes. It is often assumed that cutaneous respiration is limited primarily by the ability of oxygen to diffuse through the skin. However, the boundary layer around a submerged amphibian can be an even greater impediment to the absorption of oxygen through the skin. The boundary layer is the layer of still water surrounding the organism through which oxygen must diffuse before it reaches the skin. The thickness of the boundary layer is determined by the rate at which the water flows past the amphibian. Preliminary evidence suggests that parts of the stream where the frogs are found are poorly oxygenated. Therefore, we determined whether water flow velocity affects the critical oxygen tension in the frog by placing the frog in a chamber with different flow velocities. We also monitored the behavior of Rana pipiens. Our results suggest that current velocity, by reducing the boundary layer, can effectively reduce the critical oxygen tension for amphibians in lotic systems.