The percentage of deformed mouthparts of some pollution tolerant chironomids are used as an indicator of the severity of PCB / heavy metal pollution. A researcher at a local college (State University of New York (USA) College at Oneonta)has been working on this.

I have collected some chrionomids in a polluted pond (PCB's of 1.1 ppm, Pb, Mercrury, and a witches brew of other heavy metals) that had red heads (like blood midges) and green bodies. I found a note in an article that there are some chironomids in polluted waters that feed primarily on algae which gives them a green appearance. I called these critters "Christmas Chironomids" because of their appearance.

I have not been able to identify them any further.

Ed





On 30 Jun, 2004, at 0:41, Desert Eagle wrote:

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Can someone give me a definition of what a Chironomid is?

Non-biting midge. Chironomus tentans is a well-known representative, often used as a lab animal for testing the toxicity of pollutants to sediment-dwelling organisms (i.e. the larvae). Chironomids are small-to-medium sized diptera, very similar in looks to mosquitos, but without the biting-sucking mouthparts. Size of the adults varies from 2-3 mm to 12-15 mm. These are the midges that can often be seen hovering in extremely large congregations above shorelines.


The larvae and pupae are a staple food of insect-feeding fish in stillwaters and slow-flowing, silt-bottomed running waters.

Henk

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