Thought you might be interested in this.
SALAMANDER DIE-OFF - USA (UTAH)
A ProMED-mail post
Date: Sat, 10 Jul 1999 22:42:02 -0400
To: ProMED-mail <email@example.com>
From: Marjorie P. Pollack
Source: The Salt Lake Tribune, 10 Jul 1999
The mysterious death last fall of at least 200 tiger salamanders in
Desolation Lake east of Salt Lake City has been linked to a continent-wide
disease infecting these lizard-like creatures. Similar die-offs of tiger
salamanders have been reported in Maine, North Dakota, Saskatchewan and
Arizona, according to a study by the National Wildlife Health Center -- a
federal agency based in Madison, Wis. All of these incidents were caused by
an infection triggered by a virus in the family known as "iridovirus," the
An international team of scientists is preparing a coordinated research
proposal to figure out what is triggering the disease outbreaks in frogs as
well as salamanders. "It is more than likely that multiple factors could be
working on these animals," said James P. Collins, a biologist at Arizona
State University who has been studying the spread of iridovirus in Arizona
salamanders. He suspects most of the causes will be traced back to
environmental problems caused by humans. Cynthia Carey, a researcher at the
University of Colorado, said a goal of the next round of research will be
determining whether die-offs are a normal part of the salamanders' life
cycle. "What we'll find out is whether this is something unusual we need to
be alarmed about, or if it is part of the natural history of salamanders,"
A "health alert" issued in October by the National Wildlife Health Center
urged wildlife officials to report all large die-offs of salamanders to
help scientists trace the spread of the disease. "Whether the recently
identified salamander disease is related to global amphibian declines is
still unknown," stressed the alert. "Salamander die-offs have been reported
previously, but scientists are not sure how common such events may be."
Tiger salamanders, known to scientists as _Ambystoma tigrinum_, are found
throughout much of North America. The subspecies found in Utah, Arizona and
parts of western New Mexico and western Colorado is called the Arizona
tiger salamander. Adults average 6 to 8 inches in length. They usually are
dark black or gray with light yellow spots or bars. They are very common in
Utah, said Gloria Wurst, a professor of zoology at Weber State University
who has studied tiger salamanders in the Monte Cristo area east of Ogden
since 1990. Salamanders can be found in most small lakes and ponds that
don't have fish. That's because fish love to eat salamanders. Salamanders
also readily colonize the stock ponds built for sheep and cattle.
Wurst has seen no problems with the salamanders at her study sites but says
the number of animals in a small pond near the Snowbasin Ski Area appears
to be declining as a result of habitat disruption.
Tiger salamanders begin their lives by hatching from eggs in a pond in the
late spring or early summer. The larvae, which have gills and fins, live in
the pond anywhere from 10 weeks to a year. Most then transform into
lizard-like adults that crawl out of the water and spend the fall and
winter hidden under logs and in burrows on dry land. Adult salamanders
return to the pond the next spring to breed and lay eggs.
The cycle was disrupted by disease last fall at Desolation Lake. Hikers
visiting this popular little lake in Big Cottonwood Canyon noticed dead and
dying salamanders along the shoreline and notified federal biologists. "We
went up on Sept. 1 and there were hundreds of carcasses," recalled Rex
Sohn, a wildlife technician for the U.S. Fish and Wildlife Service. "We
didn't do an adequate count, but I would `guestimate' that we saw 200 to
300 dead salamanders." Eight of the sick animals were captured and sent to
a federal health center in Madison, Wis., where the viral infection was
"Is it a disease that has been around a long time?" asked Sohn. "Has it
become more of a concern because of more human activity in back country? Is
there more human interest in wildlife now so it is being reported? Or is it
a new disease? We don't know."
No one has checked the lake this year, but it is assumed that some of the
adults survived and there still are salamanders in the lake.
Last year's die-off is puny compared to the 26,000 dead salamanders that
Peter Hovingh counted at Desolation Lake in 1985. A scientific paper he and
Kathleen Muriel Worthylake published in the Great Basin Naturalist in 1989
found clear evidence of a bacterial infection in those dying salamanders.
Researchers now wonder whether the animals first were infected by the
iridovirus and then attacked by the bacteria.
Center for Integrated Ag Systems, UW-Madison
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