Some lime-induced changes in lake metabolism

Application of hydrated lime to bog and other dystrophic lakes is thought to stimu- late production at several trophic levels. It enhances the medium for plant growth by increasing: the rate of remineralization of plant nutrients ( Hasler and Einsele 1948) ; the depth of the euphotic zone (Hasler et al. 1951) and the supply of available car- bon dioxide (Hasler et al. 1951, Waters 1957, Waters and Ball 1957). In addition, phos- phate should be conserved in the tropho- genie layer as a result of the removal of iron from suspension. The consequences of phosphate removal by ferric-iron com- plexes are discussed by Einsele ( 1938)) Ohle ( 1937a) and Mortimer ( 1941, 1942). Lakes treated with lime have not re- sponded uniformly owing, perhaps, to the differences in the nature of the lakes and method of treatment. Hasler et al. (1951) and Johnson and Hasler ( 1954) have en- larged the euphotic zone in several instances although the latter workers and Waters (1957) were unable to clear some lakes. Large applications of hydrated lime result in plankton blooms and probably are in- duced by the momentary release of phos- phorus (Waters). But whether the increase in plant production is transferred to all trophic levels is questionable. Johnson and Hasler report no increase in production of rainbow trout following an increase in stand- ing crop of plankton. However, Waters and Ball show an increase in plankton and growth rate of yellow perch. This paper considers some of the direct effects of lime on lake metabolism. A lake previously treated with apparent success was used to test the result of treatment on lake dystrophy and the distribution of iron and phosphorus. Because of its possible significance in achieving and maintaining desired results, a method of application was studied in two other lakes by measuring the efficiency of solution of lime and the degree of retention of the dissolved products. The effect of lime-treatment on the production of planktonic crustacea will be reported elsewhere. Appreciation is extended to the Guido Rahr Foundation for a research grant, to the University of Notre Dame and Rainbo Lodge for facilities, and also to Drs. J. C. Neess, W. R. Schmitz and W. J. Wisby for their helpful suggestions.