Spawning of fathead minnow prevented Recruitment failure of lake trout Lower limit for Atlantic salmon hatching

Molluscs Opossum shrimp

Smallmouth bass

Atlantic salmon Brook trout

Rainbow trout Lake trout

(Mason 1990). Aluminium also kills a variety of invertebrates, but the progressive concentration of the metal through food chains and food webs ensures that higher level organisms such as fish are particularly vulnerable, and it is possible that fish kills previously attributed to high acidity were, in fact, the result of aluminium poisoning (Park 1987). The mobilization of heavy metals by leaching may also help to reduce fish populations indirectly by killing the insects and microscopic aquatic organisms on which the fish feed. Birds such as herons, ospreys and kingfishers, which feed on the fish, and those such as ducks and other waterfowl, which depend upon molluscs and aquatic insects for their food, also feel the effects of this disruption of the food chain (Howard and Perley 1991).

The fish are particularly vulnerable during the annual spring flush of highly acidic water into the lakes and streams. This is a well-documented phenomenon which causes stress to all organisms in the aquatic environment (Park 1987). All of the areas presently affected by acid rain receive a proportion of their total precipitation in the form of snow. The acids falling in the snow during the winter accumulate on land and on the frozen

Figure 4.10 The age-class composition of samples of the white sucker populations in lakes Skidway (pH 5.0) and Bentshoe (pH 5.9)


The Basic Survival Guide

The Basic Survival Guide

Disasters: Why No ones Really 100 Safe. This is common knowledgethat disaster is everywhere. Its in the streets, its inside your campuses, and it can even be found inside your home. The question is not whether we are safe because no one is really THAT secure anymore but whether we can do something to lessen the odds of ever becoming a victim.

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