The Effects of Artifical Enrichment of a Lake

Abstract

A Tasmanian highland lake of low natural productivity was enriched by the addition of a mixture of chemicals. The first application, to the mud, stimulated the existing stunted aquatic vegetation to produce a prolific growth; a later application, broadcast over a portion of the lake, had the additional effect of increasing phytoplankton and zooplankton.

Concurrent with the growth of plants there was a marked increase in the total numbers of epiphytic fauna.

Fish living in the lake at the time of enrichment showed a marked increase in growth rate, and others released later showed a similar response.

It is tentatively concluded that phosphorus was the element responsible for the stimulus to the growth of plants and plankton. It is shown that an unproductive lake of this type can, by suitable enrichment, be rendered capable of carrying a stock of fish.