Nuisance Algae?

I recently saw the attached cartoon (thank you Sidney Harris) that put my creative juices flowing.


Toxic Warning Cartoon

It touched one of my “hot buttons”. Concurrently I encountered in two professional water journals, written by two well respected lake authorities, articles using the term “nuisance algae”, when the writers were talking about cyanobacteria, aka, blue-green algae (toxic algae). Examples: (1) “Most nuisance and harmful algae are opportunistic and can grow rapidly when ”normal” algae (green algae) are slow to develop…” (2)”Excess phosphorous in lakes causes nuisance algae – too much, too toxic or too yucky – and a long-standing paradigm in managing nuisance algae is to reduce excess phosphorous…” Why are we writing (talking) in such casual language in professional (technical) journals? Are we trying to hide something or confuse the readership and the general public?

Will the signs that currently read:

 “WARNING” High Levels of Toxic Algae have been reported.                                                This lake is closed to boating, swimming, fishing…

Now read:

 “SLIGHT WARNING” What used to be Toxic Algae have been reported,                                       But they now are merely NUISANCE ALGAE!!! ?

Anyone who knows me knows that one of my hot buttons is a casual use of the word algae when they are actually talking about cyanobacteria. Additionally, HABs (Harmful Algal Blooms) should be more accurately designated as cyanoHABs when referring to fresh water ponds, lakes and reservoirs, because there aren’t any fresh water Green Algae HABs.

Here’s the deal. There are two basic groups of organisms that co-exist in our fresh water impoundments, Green Algae (Chlorophyta) and Cyanobacteria (Cyanophyta). To complicate it, there are other microorganisms that also co-exist in our ponds, lakes and reservoirs, such as diatoms, bacteria, protozoans, euglenoids, and zooplankton. The following chart will help to explain the differences between Green Algae and Cyanobacteria:

Cyano-Chloro Chart

And the bottom line is: In fresh water impoundments Green Algae are the most important oxygenators and a critical part the food chain. Cyanos, on the other hand, are less important as oxygenators and food chain necessity. Cyanos are very problematic because of the blooms, toxins, and taste and odors they produce. We should always be distinguishing Cyanophyta from Chlorophyta when talking about nuisance algae. Can you say cyanobacteria?


In reality, all microorganisms serve a purpose in a water ecosystem, but it is sometimes difficult to understand the importance of cyanobacteria in our municipal, recreational and agricultural waters. In the big picture they have been very important. Cyanobacteria have been around for perhaps 3 and 1/2 billion years, and it is hypothesized that they were the original oxygenators of our planet. In contrast, Green Algae have been around for only about 500 million years. That is a huge difference and it shows what great survival strategists cyanobacteria are. Saltwater species of Cyanobacteria and Green Algae are still important oxygenators of our oceans and the earth.