How does acid rain affect lakes, rivers and streams?
Lakes that have been acidified cannot support the same variety of life as healthy lakes. As a lake becomes more acidic, crayfish and clam populations are the first to disappear, then various types of fish. Many types of plankton-minute organisms that form the basis of the lake’s food chain-are also affected. As fish stocks dwindle, so do populations of loons and other water birds that feed on them. The lakes, however, do not become totally dead. Some life forms actually benefit from the increased acidity. Lake-bottom plants and mosses, for instance, thrive in acid lakes. So do blackfly larvae. Not all lakes that are exposed to acid rain become acidified. In areas where there is plenty of limestone rock, lakes are better able to neutralize acid. In areas where rock is mostly granite, the lakes cannot neutralize acid. Unfortunately, much of eastern Canada-where most of the acid rain falls-has a lot of granite rock and therefore a very low capacity for neutralizing acids.
