Sewage-Contaminated Streams Produce Bigger, Faster Mosquitoes in...Atlanta?

When I saw this headline from a recent story, "Sewage-contaminated streams breed bigger and faster mosquitoes', I thought, "Must be from a developing country - maybe in South Asia or sub-Saharan Africa." After all, the story, sent to me by colleague Robert Adamski, was published in Sindh Today, a Pakistani online publication.

Imagine my surprise when I discovered that the work was done in metropolitan Atlanta by an Emory University researcher.

It was also the kind of story that evoked a "Tell me something I don't know" response, but I have to admit I had never seen any work like this.

From the story:

According to a report in Discovery News, over a 16-week study period last summer, Luis Fernando Chaves, an ecologist at Emory University in Atlanta and colleagues sampled water quality and mosquito larvae from two streams – one that receives contaminated overflows and one that doesn’t – in the Atlanta area.

In every sample they collected from the contaminated stream, they found mosquito larvae. In a clean stream, on the other hand, larvae showed up less than 10 percent of the time.

In a follow-up experiment, the researchers grew mosquitoes in containers that held either normal tap water or polluted water.

The polluted tanks were full of ammonia phosphates, which are abundant in sewage and are known to feed the bacteria and microorganisms that mosquitoes eat.

So the mosquitoes love sewage-contaminated streams because they have more food and fewer predators - fish are less likely to live in such polluted streams.

An earlier study by the Centers for Disease Control and Prevention found that bigger floods led to more mosquitoes – particularly Southern house mosquitoes, which are a known carrier of West Nile virus.

The latest research helps explain why.

“We’ve known for a while that it’s likely that these combined sewage overflows were creating not only a mosquito problem but a West Nile problem,” said Rosmarie Kelly, a public health entomologist at the Georgia Department of Community Health in Atlanta.

So whether you live in Atlanta, Bangkok, or Nairobi, watch out for those sewage-laden streams.

“What it means for people is that we need to push to have cleaner streams in cities.” -- Luis Fernando Chaves, lead author 

Comments

[Fasterthanthem.com]

A bigger or faster mosquito would be a state bird LOL

[J]

This contradicts common opinion that mosquitoes cannot survive in polluted water. Do I have to change my opinion? What does the literature say?

[PAUL F MILLER]

Thank you, Michael, Forgive me if it may appears that I am trying to be difficult, truly I am not. I was attempting to be "rhetorical" in my questioning and prior posting.

Yes, BOD, along with COD, TSS, MLSS and host of other tests are utilized by science and industry to define sewage or wastewater and to ascribe some level of contamination or pollution.

I suppose I should have phrased my query to ask ... how much BOD, COD, TSS, MLSS in what quantity of water is necessary before we describe it as polluted or contaminated. Those of us in this industry can toss around values, but does the man-in-the-street honestly comprehend what they mean...? Do we honestly know how much BOD, etc is too much and at what level will it begin to negatively impact human health...?

My experience is people want facts, provided to them impartially, in an open, honest, timely disclosure forum. Equally they want to know what they can do to make what they put into their body's health giving as opposed to health taking.

This, I feel, is information which has been either willfully or via neglect withheld from John Q Public, at least in Arizona, I can only hope it may be provided in other areas of our nation.

Respectfully submitted,

[Michael]

Hi, Paul.

Thanks for your comment.

Sewage effluent contamination is generally measured as BOD, which stands for Biochemical (or Biological) Oxygen Demand. It is an indication of how much dissolved oxygen, in mg/L (milligrams per liter), would be required to oxidize (destroy) the organic waste in the water. A high BOD value means more contamination with organic matter than a low value.

1-2 mg/L indicates very clean water; once you get above 8-10 mg/L, you know there is a pollution source nearby. Untreated sewage can have BOD values of several hundred mg/L of oxygen.

Hope this helps.

See: http://en.wikipedia.org/wiki/Biochemical_oxygen_demand

http://www.water-research.net/glossary.htm

[PAUL F MILLER]

Reading this post I find I am inclined to ask if anyone can point me in the direction to where I might find our universal definition of ..."sewage-contaminated-water" ...?

It strike me like so many terms we use, its meaning is based solely upon the writer's intention in that moment. And I too, in my own writing fall into that mode.

As I paused to reflect I found the words attributed to the late Chief Seattle to resonate ... ""Whatever befalls the earth befalls the sons of the earth. Man did not weave the web of life: he is merely a strand in it. Whatever he does to the web, he does to himself."

Respectfully submitted for consideration