The respiration of some animals from the Profundal Zone of a lake

Abstract

1. The oxygen consumption of some profundal and other muddwelling animals was studied in relation to varying periods of starvation, varying temperatures and varying oxygen content of the water. This oxygen uptake corresponds to moderately active, not to a basal, metabolism. 2. In the oligochaetes starvation did not depress the oxygen consumption but sometimes an increase of consumption was observed during the experiments, presumably caused by an increase of activity. In the case of Pisidium casertanum the oxygen consumption may be slightly depressed by starvation, but no distinct decrease occured in Corethra flavicans and Procladius sp. In Chironomus anthracinus there was no marked influence of starvation. 3. The curve relating oxygen consumption to a gradually increased temperature was found to be less steep than Krogh's curve in Chironomus anthracinus and to correspond with Krogh's curve in Lumbricillus rivalis and Pisidium casertanum. The slope was, however, more steep than Krogh's curve in Tubifex tubifex and T. barbatus, Ilyodrilus hammoniensis, Corethra flavicans and Procladius sp. It ought to be emphasized that the results relate to active respiration and short-term experiments. A comparison has been made between the present results and similar ones from experiments with other freshwater invertebrates (Table V, p. 35). 4. It was found that the respiration had three main types of relation to oxygen content of the water: (a) one type has nearly the same oxygen consumption from air-saturation to c. 1\12–5% oxygen, where there is a distinct critical point of oxygen content below which a marked decrease of consumption occurs, (Tubifex tubifex, Tubifex barbatus, Ilyodrilus hammoniensis and Chironomus anthracinus). The critical points are at a low oxygen concentration, a quarter of air-saturation or still lower. (b) a second type has a decreasing consumption from air-saturation to 4–6% oxygen, and then a still more marked decrease (Lumbricillus rivalis, Procladius, and Pisidium casertanum). (c) a third has an oxygen consumption decreasing gradually to the lowest values (Corethra flavicans).