Blue-green algae get the blame for simply being green

18 August 2013

It must be horribly disconcerting to be erroneously selected out of a police line-up – if you are just there as a ‘filler’.  I wonder if algae and some water plants feel the same way about being identified as being “blue-greens” (= cyanobacteria)?

There have been two sets of press reports this week that have identified, incorrectly, algae and plants as blue-green algae.  While this is often an easy mistake to make, the knock-on effects can be substantial as the public may subsequently make the same mistake.  The first article I will deal with appear in the MailOnline and showed a series of great photos, none of which included blue-green algae.  Rather, the green covering on the water is due to a member of the harmless duckweed family (genus Lemna).  The identification clue is that the green stuff is floating ON the water, not in it.  The second image from the same article shows this more clearly.  Gratifyingly, I noted that a number of the comments submitted had noted that this was indeed not algae.

While we cannot expect the press to be scientifically-correct, we can reasonably expect them to do their homework.  Toxic algae in water resources is a very important issue and there is little leeway for misinformation.

 

Unsightly: Toxic algae blooms seen covering the surface of the Paddington canal basin in London are being blamed on recent soaring summer temperatures

Unsightly: Toxic algae blooms seen covering the surface of the Paddington canal basin in London are being blamed on recent soaring summer temperatures…but its not toxic algae

Sightings: A total of 137 cases of algae have already been reported to the Environment Agency since January, compared with 127 last year

Sightings: A total of 137 cases of algae have already been reported to the Environment Agency since January, compared with 127 last year (but this is not one of them…)

The second article, also originating in the UK, shows “a bloom of blue-green algae that is prevalent this summer” somewhere in East Lancashire (Blackburn Citizen).  Well, UK reporters really should know better as England is one of the countries where blue-green algal blooms and what they look like have received a LOT of attention (think back to the early 1990s and the work done by the NRA after soldiers fell into a bloom of toxic algae while canoeing).  Anywho, this picture (see below) shows a nice bloom of blanket weed, the harmless chlorophyte filamentous alga of the genus Cladophora.

The original caption is incorrect - this is blanket weed (Cladophora), not blue-green algae.

The original caption above is incorrect – this is blanket weed (Cladophora), not blue-green algae.

The two pictures following give an idea of what cyanobacterial surface blooms (blooms can also be on the bottom or in a layer somewhere below the surface, i.e. not directly visible to the naked eye) actually look like – i.e. a paint-like scum that leaves a scum or film on the shoreline and which often discolours to blue-ish when it drys out.

Paint-like patterns formed by blue-green algae (Photo: Bill Harding)

Paint-like patterns formed by blue-green algae (Photo: Bill Harding)

Typical, very dense, blue-green algal scum (Photo: Bill Harding)

Typical, very dense, blue-green algal scum (Photo: Bill Harding)

Next sentence.

 

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