Oxygen Depletion and Winterkill Risk in Small Prairie Lakes Under Extended Ice Cover

Abstract

Mean rates of dissolved O2 depletion in 10 shallow eutrophic prairie lakes (area 2.3-27.3 ha, mean depth 1.6-4.2 m), ranged from 0.22-0.34 g/m2 .cntdot. d[day]-1 for nonstratified lakes and 0.32-0.42 g/m2 .cntdot. d-1 for stratified ones. An average rate for all lakes was 0.29 .+-. 0.06 g/m2 .cntdot. d-1. The rates correlated with the lake depth. A method for estimating the winterkill [fish] risk on the basis of initial O2 storage, rate of dissolved O2 depletion and/or the mean or maximum lake depth is proposed.