Can we clean up, stop, or end harmful algal blooms?

No, but there are ways to lessen the effects of harmful algal bloom events.

A harmful algal bloom outbreak on Lake Erie viewed from space

Imagery of the Western Lake Erie harmful algal bloom from September 26, 2017. The scum shown here near downtown Toledo stretched all the way to Lake Ontario. This photo is from Landsat-8 (a NASA/USGS satellite).

Harmful algal blooms — often referred to as HABs for short — occur when algae produce toxic or harmful effects on people, fish, shellfish, marine mammals, birds, or other aquatic organisms. Blooms occur in marine and freshwater environments throughout the world, with damaging ecological, social, and economic effects. So why can’t we clean up the algae and take care of this problem? Unfortunately, the answer is not so simple. Harmful algal blooms are a natural process. There are records of HABs from early European colonists arriving to Florida in the 1500s. However, research points to an increase in the frequency and intensity of algal blooms in modern times due to environmental changes caused by humans.

There are many examples of human activities that contribute to HABs: runoff from agriculture, dissolved chemicals introduced into water supplies via rainfall or irrigation, and effluent from sewage treatment plants all contribute to excess amounts of nutrients in our waterways. These nutrients are food for algae. In housing developments, for example, retention ponds are a common place to see freshwater HABs. All this runoff ends up in the water system, eventually making its way to the ocean.

One of primary missions of NOAA's National Centers for Coastal Ocean Science is to empower communities to take action on HAB issues by developing detection tools and forecasts. NCCOS is involved in mitigating harmful algal blooms in a number of different ways and through several legislative measures. For example, the Harmful Algal Bloom Hypoxia Research and Control Act provides NOAA with a legal mandate to study HABS, to mitigate their effects, and to provide early warning for when and where blooms will occur. NOAA partners with other organizations throughout the country, as well, to support research through three funding opportunities:

  1. The Ecology and Oceanography of Harmful Algal Blooms program provides funding for universities and other groups to look at the ecology and oceanography of HABS.

  2. The Monitoring of and Event Response to Harmful Algal Blooms program focuses on a practical approach to methods for testing technologies to detect toxins in the cells of the algae and characterize their abundance.

  3. The Prevention, Control and Mitigation of Harmful Algal Blooms program focuses on what can be done to prevent people from coming into contact with HAB affects, to better inform the public and to provide more directed early warning products for harmful algal blooms.

Harmful algal bloom resources, frequently asked questions, and regional information are available via the National Ocean Service HAB portal.

Did you know?

Less than one percent of algal blooms actually produce toxins. Not all algal blooms are harmful, and some may actually be beneficial. Phytoplankton are microscopic algae that form the base of the marine food web, and therefore, all other life in the ocean relies on them. Blooms can also be good indicators of environmental changes not only in the water, but also on land.

More Information

Search Our facts
Get Social
Last updated:
10/30/19

Author: NOAA

How to cite this article

Contact Us