The Effects of Lime Application to Acid Bog Lakes in Northern Michigan

To investigate the observed correlation between alkalinity and productivity of lake waters and to test the use of lime in bog lakes to increase biological productivity, lime application was made to two, acid, soft-water, colored bog lakes in the upper peninsula of Michigan. Lime application was made twice to each of the two lakes, once in the summer under thermally stratified conditions and once in the autumn under nearly homothermous conditions, by pumping a lime-water mixture into the surface waters. Total rate of lime application was 100 pounds per acre-foot in each lake. The summer lime applications resulted in raising the pH and increasing alkalinity, total hardness and conductivity in the epilimnion only. The autumn application resulted in similar effects in the lower hypolimnion, because of sinking of the denser lime solution to the bottom where because of its greater density it did not later mix with upper layers. Lime application did not decrease the organic colloidal color. Total phosphorus was greatly increased in the bottom waters of one treated lake which originally was low in total phosphorus but there was no significant increase in the bottom waters of the other treated lake where total phosphorus concentrations were originally high. Total phosphorus also increased temporarily in the epilimnion of one lake following the summer application. A bloom of nannoplankton (Microcystis aeruginosa) was observed in one lake following the release of epilimnial phosphorus. Chemical data indicated that because of the presence of higher bicarbonate concentrations, the nannoplankton utilized carbon dioxide at a rate which may not have been possible without lime application. In both lakes the following summer, significantly higher standing crops of net phytoplankton were observed (principally of Dinobryon sertularia). Increases in standing crop of zooplankton also occurred the year following lime application.