What’s the scoop on cyanobacteria?

What’s the scoop on cyanobacteria?

The good, the bad, and the ugly

Cyanobacteria have been getting a lot of press recently, reflecting concern about the risk of exposure to these potentially dangerous bacteria. Fortunately, to date, we have not detected any cyanobacteria in Pemaquid, Bristol Mills or Biscay ponds, where we initiated monitoring this summer.

Cyanobacteria are so named for their striking color, which also led to their common (though misleading) name, blue-green algae. Though they are microscopic and typically unicellular, they can sometimes grow into large colonies and form thick mats that are visible to the naked eye.

They are also the oldest known fossilized organism and are more than 3.5 BILLION years old. The fact that they are still around, essentially unchanged, qualifies them as living fossils! Critically important in shaping the course of evolution, cyanobacteria have made great contributions to the earth’s history. The oxygen that much of life on earth depends upon was first generated by cyanobacteria during the Archaean and Proterozoic eras.

Cyanobacteria also contributed greatly to the evolution of plants. The chloroplast with which plants make energy for themselves is actually a cyanobacterium living within the plant’s cells. Sometime in the late Proterozoic, or in the early Cambrian, cyanobacteria began to take up residence within certain eukaryote cells, making food for the eukaryote host in return for a home. These eukaryotic cells evolved specialized organelles and became the plants of today.

If these accomplishments are not impressive enough, cyanobacteria have other serious skills to include on their résumé. They can:

  • fix atmospheric nitrogen
  • decompose organic wastes and residues
  • detoxify heavy metals and pesticides
  • catalyze nutrient cycling
  • suppress growth of pathogenic microorganisms in soil and water
  • serve as important source of nutrients and biofuels (and much more).

When to be cautious

Some cyanobacteria can produce dangerous toxins. And certain conditions can cause them to reproduce quickly in fresh water, creating a potential health risk. Called Cyanobacterial Harmful Algal* Blooms, or CyanoHABs, these events of particular concern in water that is used for drinking or where people or dogs are swimming.

Cyanobacteria aggregation

An aggregation of cyanobacteria in a pond in Germany. It’s important to note not all aggregations look like this, and there’s no way of knowing whether dangerous toxins are present without testing the water in a lab.

When the toxins are present, exposure can occur by deliberate or accidental ingestion, contact with skin, or inhalation (for example of water spray while showering). Pets can also be exposed by licking toxins off their fur. Exposure to contaminated water through any of these methods can cause symptoms ranging from a rash to severe illness and, in rare cases, death.

If you see visible floating mats or scum in the water, or if the water appears murky – exercise caution. For more information about the status of your favorite swim spot, or if you have any concerns, contact your town office.

What you can do to protect water quality

So how do we protect our waters from cyanobacteria blooms? Just like fertilizing your garden, if you fertilize the water with nutrients – whether they orignate from goose poop, run-off from septic systems (most will produce nutrients even when functioning properly), lawn fertilizers, or pet waste – algae and bacteria will flourish.

Here are a few things anyone who lives on or near the water can do to reduce nutrient run-off into streams, ditches, marshes, ponds, lakes and the ocean:

  1. Pick up and dispose of pet waste, a common source of excess nutrients and bacteria
  2. Implement landscaping strategies that increase groundwater filtration before water enters the pond or lake
  3. Install rain barrels to reduce runoff
  4. Make sure your septic system is serviced regularly
  5. Incorporate native vegetation, rather than manicured lawns, around pond and lake banks
  6. Allow natural vegetation to grow near the water’s edge, forming a buffer of at least 15 feet deep
  7. Move grass clippings and leaves far from the water from to prevent decomposition in or around ponds and lakes
  8. Use phosphorus-free fertilizers and detergents to limit nutrient-rich runoff

*Again, the label “algal” is misleading, as cyanobacteria are not algae.

– Chains of cyanobacteria by James Golden at Argonne National Laboratory, CC BY-NC-SA 2.0, via Flickr
– Cyanobacteria aggregation by Christian Fischer, CC BY-SA 3.0, via Wikimedia Commons