Some observations on the respiration of the American oyster Crassostrea virginica (Gmelin).

The Krogh syringe and some analytical improvements by Pomeroy and Kirshman in the Winkler method for oxygen analysis were combined with the direct method of measuring the pumping rates of the oyster to obtain data on oxygen uptake at various pumping rates. When pumping at a rate of 25 liters per hour an oyster may consume as much as 50 mg of oxygen per hour. The rate of oxygen removal from the water in mg per liter per ml of shell cavity plotted against pumping rates is parabolic. When the hourly work output for various pumping rates are compared with a theoretical curve, it is found that the oyster can pump water at approximately 10 liters per hour with a maximum efficiency of 10 per cent. An oyster with a shell cavity of 40 ml can pump over 40 liters per hour but at this rate efficiency falls to less than two per cent. Some unknown carbohydrate-like substances are removed from the water in quantitites commensurate with the oxygen uptake. The role of algae in the energy budget of the oyster as reflected by oxygen uptake is discussed, and certain points relative to the production of extracellular carbohydrates by algae are considered.