Experimental Simulation of Winter Anaerobiosis in a Senescent Lake

Abstract

The ability of certain benthic organisms to resist seasonal anaerobiosis in lake bottoms has long excited the curiosity and admiration of biologists. A process analogous to holding one's breath for several enables these forms to thrive in the periodically stagnated ooze of eutrophic lakes, which might otherwise support only micro-anaerobes. Summer stagnation of eutrophic lakes is believed to result in complete absence of profundal oxygen for as long as three months or more. A shorter period of benthic anaerobiosis often occurs during winter stagnation. In more shallow lakes and ponds with soft ooze bottoms the latter stagnation period is far more important. In this type of lake thick ice and a heavy snow-cover effectively shut out the light necessary for photosynthesis; bacterial decomposition and respiration of aquatic organisms exhaust the dissolved oxygen; and very often the entire aquatic habitat becomes anaerobic. Such conditions are often accompanied by spectacular fish-kills. During a study of seasonal population dynamics in a senescent eutrophic lake of this type near Minneapolis (Lindeman, '41), it was believed highly desirable to