Factors Controlling Oxygen Depletion in Ice-Covered Lakes

Winter oxygen depletion rates from four sets of Canadian lakes (prairie, southeastern Ontario, Arctic, and Experimental Lakes Area) differing in morphometry and trophic state, were analyzed. An inverse relationship was found between oxygen depletion rate and mean depth. The effect of lake trophic status on oxygen depletion rate was demonstrable after the influence of basin morphometry was removed by regression of oxygen depletion rate against the sediment area: lake volume ratio. The sediments of eutrophic lakes consumed oxygen about 3 times faster (0.23 g∙m −2 ∙d −1 ) than those of oligotrophic lakes (0.08 g∙m −2 ∙d −1 ), but water column respiration was about the same (0.01 g∙m −3 ∙d −1 ) for both groups of lakes. Data from prairie lakes showed that the winter oxygen consumption was limited by oxygen supply below an average whole-lake oxygen concentration of 3.8 mg∙L −1 . The rate of eddy diffusion near the sediments in ice-covered prairie lakes was 3.72 ± 1.41 × 10 −3 cm 2 ∙s −1 . Implications for lake management during the winter are discussed.Key words: oxygen, depletion, respiration, lakes, ice-covered, winter, sediments, model, consumption