Meeting Abstract
The notion that bimodal breathers (animals that breathe both air and water) obtain O2 from the air and exhale CO2 into the water has been well established in the literature. However, while the majority of supporting experiments tested animals maintained in hypoxic water, the freshwater systems that bimodal breathers inhabit have been reported to be hypercapnic as well. Using a biomodal respirometer, data from three air-breathing species show that when in hypercapnic water, excretion of CO2 into the air signicantly increases and can account for 10% to 70% of metabolically produced CO2 across species. The large variation between species suggests the independent evolution of air-breathing organs and behaviors result in different CO2 respiratory patterns. However, all three species continued to rely on the water for CO2 excretion to some extent when submerged.
