Harmful Effects of Acid Rain on Fish Populations
Acid rain is destructive to the environment. The term acid rain is a generic term for any precipitation from the atmosphere that has a higher than normal acidic range. There can be acid snow as well as acid dew or fog. The high levels of acid can attack many species of fish, local wildlife, and trees.
Acid precipitation happens from an increase of the hydrogen ions being absorbed into water molecules, making the pH balance more acidic. When acid precipitation effects habitats with a low buffering capacity the habitat cannot cope with the high acidity and the organisms are affected dramatically.
When we say buffer we are referring to the bicarbonate and carbonate ions; these are found in areas with large amounts of sedimentary rock (specifically limestone). They have the ability to remove the hydrogen ions and make them nonreactive carbonic acid.
Some lakes such as Lake George, which is located in the Adirondack Mountain Region of New York, near the Vermont border. Have a unique composition of the limestone deposits in the lake structure that can help neutralize any acid rain that falls in or around the lake. However, Mother Nature does not always provide this protection and some other nearby by lakes and streams struggle to survive. For example just north of Lake George; Indian lake has an acidic ph of 5.47; this means that it is on its way to levels that can be detrimental to game fish populations.
Head waters of streams are particularly vulnerable because they have little sedimentary input and a low buffering capacity, they often already run a bit acidic; so any introduction of acid can be devastating. Acid can build up in the snow pack and enter the stream during the spring thaw, bombarding the stream with a turbo shot of acid.
These head waters are usually where we will find brook trout. The only species of trout that is truly native to the east coast United States. This makes the threat of contamination all that much more important; to those who are trying to maintain the native fish populations.
The effect of acid rain on aquatic habitats limits or eradicates fish populations because of less fruitful spawning seasons, the lack of food, and from disease.
Emissions from industry are a large contributor to the problem, however; any burning of fossil fuels will contribute to the release of carbon dioxide, sulfur dioxide and nitrogen oxides into the atmosphere. Theses all react with water molecules to create acid.
A neutral pH balance is 7.0 anything below this is considered to be acidic. The levels of pH that are critical to fish populations are 5.0 down to 4.0 and any level of aluminum above .3mg/l. Why did we mention aluminum? Well that is because acid during heavy rain falls and snow pack can liberate aluminum from the areas that surround the water and introduce it to the fish’s habitat in large amounts.
These critical levels of acid and aluminum can devastate fish and invertebrate (i.e. mayflies) populations because they can cause an increase of mucus on their gills. The mucus then causes the fish to suffocate. The same effect has been found in mayfly nymphs captured by researchers. This is significant because if the mayfly populations die off, than the brook trout and other fish will lose their primary food source.
Acid precipitation also has an effect on lakes. Many lakes that have become polluted by acid rain can no longer maintain pH levels suitable for the game species of fish, such as trout, bass, and salmon. This leaves the lake inhabited by trash species like bullhead and suckers, if inhabited at all.
The future of our fish populations are threatened by acid precipitation and other environmental issues, which we will discuss in future posts. As anglers we can do our part by limited our use of fossil fuels and by keeping our water bodies and the areas surrounding them clean.
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