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ScienceDaily: Amphibians as Environmental Omen Disputed

pete

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Just thought in was an interesting notion about the "canary in the coal mine" analogy for amphibians in the environment...

ScienceDaily (Nov. 30, 2009) — Amphibians, for years considered a leading indicator of environmental degradation, are not uniquely susceptible to pollution, according to a meta-analysis to be published in Ecology Letters.

After a review of over 28,000 toxicological tests, researchers from the University of South Dakota, Yale University and Washington State University are challenging the prevailing view that amphibians, with their permeable skin and aquatic environment, are particularly sensitive to environmental threats and, as such, are "canaries," or predictors of environmental decline.

"The very simple message is that for most of the classes of chemical compounds we looked at, frogs range from being moderately susceptible to being bullet-proof," said David Skelly, professor of ecology at the Yale School of Forestry & Environmental Studies and a member of the research team. "There are lots of other kinds of environmental threats that have led to their decline, including habitat conversion, harvesting for food and the global spread of the Chytrid fungus, which is mowing down these species in its path."

Read more.
 

blueberlin

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But... that amphibians are not uniquely susceptible is sort of the whole point of environmental awareness, isn't it?

The imagery of bullet-proof frogs is amusing.

-Eva
 

lexmiller

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So if the amphibians are disappearing in areas then there must be something worse than bullets mixing it up out there. Whenever you tamper with the water an amphibian lives in or near you are going to affect its physiology.

Yes I agree that not everything kills amphibians...they are actually a lot more hardy than most people think, but that's the point. Fish and other creatures taht depend on water in ways OTHER than for drinking are often the first to die when something goes wrong with the water.

I know we basically all agree, so I guess I am preaching to the choir.
 

paris

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problem is they don't say what sort of tests they did. common tox tests I know of are called LD50's, essentially they determine how much of a compound (Dose) is Lethal enough to kill 50% of the animals tested (acute toxicity). These tests usually are 48 hours or less. The main fallacy here is that if something doesn't kill you in that time it is safe. Tests for bioaccumulation are less done since more time($) is involved, and chronic toxicity and combined toxicity are not addressed. Also since (many) amphibians go through development twice (embryo & metamorphosis) then they have a greater risk of effect-not just possibly lethal (direct or indirect) but also developmental. This also does not take into account bioactive compounds that though not directly toxic may have a knock-on effect due to the changes they induce. many tests are also only done on 1 stage, btw. We just did a test on B. cognatus with a fungicide 'Headline'. We not only did it on metamorphs that were field collected, but also on tadpoles we bred in the lab, and then on the siblings of those tadpoles once they morphed.
 
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