As news spread, some conspiracy-minded folk soon speculated about links to animal mutilations, UFOs or even the dreaded Hispanic vampire el chupacabra.
Pond scum of death 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 algae 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."