Friday, November 08, 2013

Culprit in mysterious elk deaths found: It's pond scum

Sounds like something that will become more likely with global warming.

http://www.nbcnews.com/science/culprit-mysterious-elk-deaths-found-its-pond-scum-8C11564450


Benjamin Radford LiveScience
Nov. 8, 2013

A hunter stumbled upon a bizarre sight on a 75,000-acre ranch north of Las Vegas, N.M., on Aug. 27: the remains of more than 100 dead elk. Livestock deaths are not unusual, but so many animals dying off, and doing so in what seems to be under 24 hours, was puzzling to scientists.

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Through science and further testing of elk tissue samples and water samples, the real killer has finally been found: pond scum. Or, more specifically, a neurotoxin produced by one type of blue-green algae that can develop in warm, standing water.

A bloom of this alga can be devastating to wildlife. "In warm weather, blooms of blue-green algae are not uncommon in farm ponds in temperate regions, particularly ponds enriched with fertilizer," according to a classic toxicology reference book, "Casarett and Doull's Toxicology: The Basic Science of Poisons" (McGraw-Hill Professional, 2013). "Under these conditions, one species of alga, Anabaena flos-aquae, produces a neurotoxin, anatoxin-A, which depolarizes and blocks acetylcholine receptors, causing death in animals that drink the pond water. The lethal effects develop rapidly, with death in minutes to hours from respiratory arrest."

In other words, the elk herd suffocated to death, unable to breathe. And the fast-acting toxin explains the animals' strange, sudden deaths. In this case, the algae appeared not in ponds, but in three fiberglass livestock watering tanks not far from where the elk died.

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The algae-produced neurotoxin is similar to curare, the famous toxin found in poison-tipped arrows used by South American Indian tribes. Though anatoxin-A can be deadly to other animals, including dogs and cattle, reports of human deaths are rare. New Mexico ranchers have been advised to sanitize their livestock tanks to prevent further wildlife deaths.

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