Deadly bloom

Algal bloom in Lake Erie, Kelley's Island. October 16, 2011. Photo: T. Joyce, NOAA GLERL. Photo from:

Algal bloom in Lake Erie, Kelley’s Island. October 16, 2011. Photo: T. Joyce, NOAA GLERL. Photo from:

Growth can be kind of a mixed bag. Developmentally, spiritually, behaviorally, as human beings growth can be an obtainable ideal that is reached with time and (sometimes) effort. However, there can be such a thing as too much growth. In the case of an algal bloom, too much growth is causing a lot of trouble, for life in the water and on land.

Algal Blooms and Nutrient Pollution

For example, consider the picture of Lake Eerie to your left. The green that you’re seeing in the water is known as an algal bloom. Algal blooms occur in water when nutrients, such as nitrogen and phosphorous, feed algae causing it to grow excessively.

Nutrients are material that support growth and when there are an immoderate amount of nutrients in the water or air, it’s known as nutrient pollution. Nutrient pollution can come from a variety of sources such as runoff from fertilized fields or lawns, animal waste, sewage treatment plants or emissions from automobiles.

According to the EPA, some algal blooms can emit toxins, which can cause health problems, such as skin rashes and stomach aches, for people that come in contact with them.

But the trouble doesn’t end there. As the algae begins to decompose it begins to consume oxygen in the water, creating a condition known as hypoxia, making the area uninhabitable for fish and other aquatic life.

“Almost all organisms on earth need oxygen,” said Dr. Jill Baron, a research ecologist for the United States Geological Survey. “When you take the oxygen away you smother the organism. Shrimp and fish and shellfish cannot live in low oxygen water. They just die.”

In addition to being deadly for fish, hypoxia is costly for those who rely on these areas as a food source. On the Gulf Coast, there is an area of hypoxic water, known as a dead zone, which reoccurs every year. This occurs when nutrients runoff into the Mississippi River Basin and flow out to Gulf of Mexico. The National Oceanic and Atmospheric administration reported that last year’s Gulf dead zone measured 5,840 square miles.

Unfortunately, dead zones are not uncommon. As of 2008, there were more than 400 reported dead zones in the world, according to a paper published in Science by Robert Diaz and Rutger Rosenberg.


As for solutions, Baron says that efforts to harvest or poison the algae will make for a cosmetic change, but will not remove the excessive nutrients in the water.

In order to prevent the damaging effects of nutrient pollution, such as algal blooms, one must reduce the input from its sources, such as fertilizer runoff from agricultural crops and lawns.

“One part of reducing nutrient losses from croplands is to add fertilizers at the right time and in the amount so that they get used in a way where it isn’t as likely to run off,“ Baron said, “No farmer wants to buy nitrogen fertilizer to just to wash it down river.”

As for automobiles exhaust, “It’s becoming less prominent as a source because cars are getting cleaner,” Baron said.

If you’re interested in learning more about nutrient pollution and solutions for preventing it, the EPA has a website about this issue.

If you would like to learn more about hypoxia and dead zones, check out this link from the Mississippi River Gulf of Mexico Watershed Nutrient Task Force.


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