Auburn University researcher comments on dangers of toxic blue-green algae

Article body

Dr. Alan Wilson, a professor in Auburn University’s School of Fisheries, Aquaculture and Aquatic Sciences in the College of Agriculture, comments on the recent deaths of pets related to poor water quality, specifically freshwater algal blooms.

What is blue-green algae and what makes it toxic?

Blue-green algae (more formally called cyanobacteria) are a large, morphologically and functionally diverse group of photosynthetic bacteria that are found everywhere on the planet, including lakes, oceans, deserts and tundra. Blue-green algae are chemically rich and are capable of producing many chemicals, including compounds that make drinking water taste muddy (i.e., off-flavors) or toxins that can harm pets, aquatic organisms like fish and other animals. Not all blue-green algae produce toxins. Moreover, not all blue-green algae with the ability to produce toxins (i.e., have molecular machinery; also called toxigenic) always produce toxins.

Toxin production in blue-green algae can be caused by changes in environmental factors, such as temperature, available nutrients, salinity or interactions with other organisms, or the life-cycle of the organism. For example, when blue-green algae die, they rupture allowing their internal contents, including toxins, to enter surrounding water. Thus, to have a toxic blue-green algal bloom, it is necessary to have abundant toxigenic blue-green algae that are producing toxins. Toxin exposure thresholds have been around for many years (for example, the World Health Organization’s Toxic cyanobacteria in water and Guidelines for safe recreational water environments), however the U.S. Environmental Protection Agency recently announced recreational exposure advisories for several blue-green algal toxins.

What types of bodies of water does it affect?

Blue-green algae are found in all kinds of ecosystems around the planet but tend to be most abundant—and problematic—in nutrient-rich, warm, freshwater lakes, reservoirs, rivers and ponds. Blue-green algal blooms along the coast are generally rare because of high salinity, however these events have recently been observed along the Gulf Coast due to an unusually heavy and long-lasting release of freshwater from the Mississippi River through the Bonnet Carré spillway in Louisiana. Although not blue-green algae, red tides are well-known toxic algal blooms of another group of phytoplankton (i.e., dinoflagellates) in coastal systems that can harm marine fish and mammals.

Like true plants, blue-green algae need a few things to thrive, including water, sunlight, carbon dioxide and nutrients commonly found in garden fertilizer, such as phosphorus and nitrogen. Of these requirements, nutrient inputs and availability are likely the easiest to manage. With that said, managing blue-green algal blooms is not easy.

Several great online resources exist to educate the public about blue-green algal blooms, including from U.S. EPA and Centers for Disease Control and Prevention.

My colleagues and I are organizing the biannual U.S. Symposium on Harmful Algae in beautiful Orange Beach, Alabama, Nov. 3-8 and it will be a great opportunity for everyone who is interested in algal blooms, including academics, industry professionals, teachers, legislators and the general public, to learn from U.S. experts.

What precautions should people take for themselves and for their pets or livestock?

Generally, I discourage people to let their children, pets or livestock get into green waterbodies, especially during the warm summer months or when blue-green algal scum is present. We have plenty of beautiful, clear and safe recreational waterbodies around the state to enjoy. There is no need to risk anyone’s health by recreating in water during a blue-green algal bloom.

If you do find yourself or your pet in a blue-green algal bloom, rinse with tap water immediately and do not let your pet lick their fur where mats of algal material could concentrate toxins. Moreover, the U.S. EPA recently released some advice about keeping pets safe during blue-green algal blooms.

Can you tell by looking at the water if it is safe?

Yes, with a bit of training, it is certainly possible to identify some blue-green algae from the pond bank. For example, the colonial blue-green alga, Microcystis, can form thick scums that are often times John Deere green in color. It is possible to see individual colonies of Microcystis with the naked eye since they can get fairly large (i.e., 1 mm). Other blue-green algae, like Aphanizomenon or Dolichospermum (name recently changed from Anabaena), can form scums, but their appearance from shore will look different (i.e., see some pictures of blue-green algal blooms). Some blue-green algae, like Cylindrospermopsis, don’t typically form scums even when abundant. There are other kinds of algae, including euglenoids, tiny plants, including duckweed, or even tree pollen that can form scums and look like blue-green algal blooms. So, not all green waterbodies are dominated by blue-green algae, but it is a safe bet to be wary of nutrient-rich, green ponds in Alabama in the summer.

I have led several workshops where I have trained academics, agency scientists and aquaculture farmers how to identify blue-green algae and recently analyzed water samples for the general public, water utilities, state agencies and zoos concerned about harmful algal blooms. If anyone is worried about their favorite waterbody, they can connect with me at

What are the symptoms for people and animals?

Blue-green algae are chemically diverse, including many toxins and off-flavor compounds. The known toxins produced by blue-green algae include hepatotoxins (e.g., microcystin), neurotoxins (e.g., anatoxin-a) or dermal toxins (e.g., lyngbyatoxin). Exposure routes include ingestion, inhalation and direct contact. Since people and pets can vary in their sensitivity to blue-green algal toxins, symptoms of exposure to these compounds vary but can include diarrhea, vomiting, stumbling, loss of appetite, muscle twitching, rashes, allergic reactions and even death in extreme cases. There are a variety of great online resources produced by U.S. EPA for pet owners or by the World Health Organization for recreational users.

Auburn University is a nationally ranked land grant institution recognized for its commitment to world-class scholarship, interdisciplinary research with an elite, top-tier Carnegie R1 classification, life-changing outreach with Carnegie’s Community Engagement designation and an undergraduate education experience second to none. Auburn is home to more than 30,000 students, and its faculty and research partners collaborate to develop and deliver meaningful scholarship, science and technology-based advancements that meet pressing regional, national and global needs. Auburn’s commitment to active student engagement, professional success and public/private partnership drives a growing reputation for outreach and extension that delivers broad economic, health and societal impact.