Sunday, June 22, 2008
The beautiful green toxic cyanobacterial pond scum at Madison's B.B. Clarke Beach
Although many of Madison's beaches were open again by Sunday, B.B. Clarke Beach on Spaight Street was still most definitely closed. Not only had the recent flooding caused considerable beach erosion, but the high water still covers most of the beach that remains. And a bloom of toxic pond scum floats above the former beach, fed by runoff nutrients in the water.
Cyanobacteria are great abstract painters. They're best known for the bright turquoise accent colors they use in compositions like this one (click through the photo to Flickr to view large). They look like specs of paint or bright little plastic fragments floating in the water, but they are really clumps of blue-green algae. They're bad news in a lot of ways, as this CDC site makes clear. Adults usually have the sense to steer clear of them (although boaters are warned to check first before getting into the water to launch their boats) -- but children and pets do not. It goes without saying you need to watch young children near water, but also be sure to keep your dogs away from the water if there is any chance it may harbor blue-green algae.
Update: Check below in the Comments for additional remarks left by some well-informed readers about blue-green algae that go into far more detail than my post about what they are, the problems they cause, how humans contribute to them and what can be done about them.