Acid Rain Effects Acid Rain  Elmhurst College
Acid Lake Effects Effects on Forests Acid Rain Solutions  Chemistry Department
Acid Soils and Effects Effects on Buildings    Virtual ChemBook

 pH Limits for Life in Aquatic Plants and Animals


 Small mouth Bass

 Lake Trout

 Brown Trout

 Yellow Perch



 May Fly



Acid Lake Effects

Acidity Effects on Aquatic Plants and Animals:

The amount of acid or pH is extremely critical for all life forms whether outside of the body or inside of individual cells. Larger animals are fairly well protected by skin from changes in acid levels, however inner organs such as digestive, lungs, and reproductive may be effected by changes in pH.

Eggs, sperm, developing young, bugs, insects may be particularly sensitive to small changes in pH.

Ecological Effects:

Changes begin to occur as soon as a lake starts to lose it natural bases or alkalinity.

1. As acids increase there is a large reduction in the number of zooplankton, phytoplankton, mollusks, and small crustaceans.
2. There is a slowdown in the rate of decomposition of dead plants and animals.
3. Fish are directly effected by interfering with their reproductive cycles.
4. A calcium deficiency in fish leads to bone malformation.
5. Fish can suffocate as their gills become clogged with aluminum hydroxide.
6. Songbirds are effected by eating insects contaminated with toxic metals.

Acidity Effects on Salamander Eggs/Embryos:

In water pools of nearly neutral acidity, less than 1 % of the salamander eggs die. In water at pH less than 6, 60 % of the eggs die.The salamander is particularly susceptible to acid snow melting. The salamander breeds in early spring in temporary ponds formed from snow melt and rain. The pH levels may be particularly low in these ponds from the acid shock of the freshly melted acid snow.

In the graphic on the left, compare the normal and abnormal eggs and embryos. In the abnormal eggs (upper right), the oval button on the top which is the nutrient rich yolk, has failed to retract.

In the abnormal embryo (lower right), note the swelling at the top which shows abnormal heart. Posterior is also stunted.

More than 60 % salamanders die which develop in waters with a pH of less than 6. Of those that do survive, many are crippled such as this one with a curved spine. Other also have stunted gills.


Acidity Effects on Baby Trout:

Left - normal - pH 5.5

Top Right - pH 5.0
growth is distorted

Bottom Right - pH 4.6
growth is unrecognizable

As you can see the pH range for having healthy trout is very narrow, with a one pH unit change in pH spelling the difference between disaster. Because the pH scale is logarithmic, a change from pH 5.5 to 4.5 represents a 10 times increase in acidity.

The increase in acidity with the spring snow melt may make a huge difference in the survivability of the aquatic life.