. Annual program report, 1990. Acidic Precipitation in Ontario Study; Acid precipitation (Meteorology); Acid pollution of rivers, lakes, etc; Acid rain. Ciliate abundance and biomass did not appear to be affected by liming. Species composition changes are being investigated. The population of Mysis relicta increased two-fold after liming and remained high throughout the study period. This may have had important implications for the lake trout, for which this is a favourite prey. Lake trout growth rates increased significantly in Trout Lake beginning the year after liming. Other nearby lake tro
. Annual program report, 1990. Acidic Precipitation in Ontario Study; Acid precipitation (Meteorology); Acid pollution of rivers, lakes, etc; Acid rain. Ciliate abundance and biomass did not appear to be affected by liming. Species composition changes are being investigated. The population of Mysis relicta increased two-fold after liming and remained high throughout the study period. This may have had important implications for the lake trout, for which this is a favourite prey. Lake trout growth rates increased significantly in Trout Lake beginning the year after liming. Other nearby lake trout populations did not exhibit increased growth rates (Figure 20). Ructuations in the abundance and growth rates of other species of fishes in Trout Lake did not show consistent trends. Summary & Conclusions Liming was successful in increasing the pH and alkalinity of both lakes for a limited period, determined primarily by the lake flushing rate. Aluminum was reduced from potentially toxic levels in the more acidic lake and while levels increased slowly, they did not return to preliming levels at the same rate as the pH and alkalinity. The improved water quality in both lakes had effects on the biota. In the acid lake these effects were most dramatic as lake trout could be reintroduced into the system. Many of the other changes seen in the ecological community in previously acidic Bowland Lake were in response to the addition of lake trout rather than dircctiy attributable to improved water chemistry. In Trout Lake, where there were no documented signs of stress on the lakes ecosystem prior to liming, shifts occurred in the phytoplankton and zooplankton communities species composition and in the abundance of Mysis. The increase in Mysis may have been responsible for an increase in the growth rate of lake trout after liming. While successful recruittnent of lake trout in Bowland Lake has been documented, no information is yet available regarding the rates of success of indi
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Keywords: ., bookauthorontarioministryoftheenvironment, booksubjectacidpollu
