Thursday, October 15, 2015

Cyanobacteria: A Primordial Lake Monster

TOS_Blue_Green_AlgaeIt came from the lake. It is a life form nearly as old as life itself. Living peacefully in the depths for eons, it is awakened by humankind’s abuse of the environment. It strikes out with toxins that attack nerves or the liver. Attempts to kill it only make it more toxic.

It sounds like the plot of a 1950s horror movie. But this horror plays out in lakes and ponds across New York, Vermont and New Hampshire on hot, sunny days each summer. This year, a September heat wave extended the season of blue-green algae blooms past Labor Day at Lake Champlain. In the second week of September there were blooms in Missisquoi Bay, a northern, shallow bay of Lake Champlain, and St. Albans Bay, another lake trouble spot. This summer blooms, or suspected blooms, were also reported in Lake Placid, Schroon Lake, Friends Lake.

Blue-green algae blooms appear as dense, green clouds in the water, like pea soup or green paint. They’re unpleasant to swim through, can smell, and can reduce oxygen in the water. They also produce toxins that can make people sick and, in rare instances, kill dogs that ingest them.

Despite the name, blue-green algae are not algae at all but something even more primordial. Blooms are comprised of masses of cyanobacteria, “among the first forms of life that evolved 3.5 billion years ago,” explained James Haney, a biologist who leads a lab at the University of New Hampshire dedicated to studying these organisms.

Cyanobacteria are classified with bacteria because their DNA isn’t neatly packaged inside a nucleus like our own, and they are single-celled. However, cyanobacteria differ from most bacteria in their ability to photosynthesize, that is, make their own food from water, carbon dioxide and sunlight (they also need nutrients, just as plants do). Cyan is a blue-green color, but species in this group can also create blooms that are white, red, or brown.

There are thousands of species of cyanobacteria, but scientists are most familiar with the relatively few that form floating colonies under certain conditions and release toxins. These toxins serve the cyanobacteria in many ways, explained Haney, including, in one case, regulating iron. Cyanobacteria tend to release toxins when they die, so killing them with chlorine may temporarily make matters worse. Boiling kills the cyanobacteria, said Haney, but it won’t destroy the toxin.

Although it’s easy to think of these organisms as a scourge, they’re a natural part of the ecosystem and, in most conditions, exist at lower population levels where you won’t even notice their presence. Typically, they become a problem in response to pollution.

Andrew Schroth, a geologist at the University of Vermont, is studying the water conditions that produce toxic colonies. “What they’ve seen in Lake Erie is that the blooms are driven by how much phosphorus comes into the system during spring runoff, from March to June,” he explained.

Phosphorus is a pollutant from fertilizers, some detergents, manure, and human waste. It feeds the blooms that form in July and August, when the water gets warm. It can linger in water bodies over time.

The phosphorus trigger works differently in Lake Champlain, Schroth said. There, when water is calm enough, phosphorus is released from the sediment. In shallow water, both phosphorus and light are in reach of the cyanobacteria. Add warm water and you have all the ingredients for a population surge – and a cyanobacteria bloom.

In addition to the immediate harms caused by blooms, there may be other effects. Amanda Murby, a doctoral candidate in Haney’s lab, is studying some less familiar cyanobacteria and how their toxins may accumulate in the bodies of animals up the food chain. In this way, the toxins behave “very much like mercury,” said Haney. His lab is studying how the toxins accumulate in loons and is also researching their long-term effects on human health. Schroth, meanwhile, is exploring ways to reduce the phosphorus runoff that causes blooms, which seem likely to increase in the hotter weather and more frequent floods brought on by climate change.

“Cyanobacteria are like bears,” he added. “Both are a natural part of the environment, and become a problem when we feed them.” Reducing phosphorus runoff may not be an ending worthy of a horror movie, but it would be a satisfying conclusion for a natural system thrown out of balance.

Madeline Bodin is a writer living in Andover, Vermont. The illustration for this column was drawn by Adelaide Tyrol. The Outside Story is assigned and edited by Northern Woodlands magazine and sponsored by the Wellborn Ecology Fund of New Hampshire Charitable Foundation:


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4 Responses

  1. Paul says:

    Good article. It is strange that a photosynthetic organism like this that produces oxygen leads to lower oxygen levels in the water.

    These bacteria are what created the atmosphere that we are now mucking up.

  2. Jesse B says:

    Paul, it does seem kind of strange, but to clarify it’s not the cyanobacteria leading directly to lower oxygen. Rather, the dense mats of cyanobacteria actually block out available light which reduces the ability of bottom dwelling plants and algae from producing oxygen. Also when the overabundant cyanobacteria die, they sink to the bottom and decompose that uses up the already depleted oxygen levels.

    National Geographic has an excellent overview on this topic (

  3. For dog owners who frequent waterfront areas with their pets, the Dogs and Harmful Algal Blooms (HAB) information brochure published by New York Sea Grant (NYSG) may be of interest.

    Author Dave MacNeill, a Sea Grant educator based at SUNY Oswego, developed the publication after noticing more and more reports of dogs becoming ill from the algal toxins in the Lake Ontario area. He enlisted the aid of Dr. Karyn Bischoff, a toxicologist at the Cornell University Veterinary College; Dr. Greg Boyer of the SUNY College of Environmental Science and Forestry, who has researched HABs from blue-green algae in upstate lakes to brown tide in Long Island bays; and others.

    Dr. Bischoff notes that “Cyanobacterial poisonings are under-reported in domestic animals because people have not been aware of the problem.”

    The Dogs and Harmful Algal Blooms brochure is online at

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