Laurel, Md: May 23, 2016-- New
U.S. Geological Survey-led research suggests that even though amphibians are
severely declining worldwide, there is no smoking gun – and thus no simple
solution – to halting or reversing these declines.
“Implementing conservation plans
at a local level will be key in stopping amphibian population losses, since
global efforts to reduce or lessen threats have been elusive,” said Evan Grant,
a USGS research wildlife biologist who led the study published in Scientific
Reports today. “This research changes the way we need to think about amphibian
conservation by showing that local action needs to be part of the global
response to amphibian declines, despite remaining questions in what is causing
local extinctions.”
The evidence shows that though
every region in the United States suffered declines, threats differed among
regions. They include:
Human influence from the
Mississippi River east, including the metropolitan areas of the Northeast and
the agricultural-dominated landscapes of the Midwest
Disease, particularly a chytrid
fungus in the Upper Midwest and New England
Pesticide applications east of
the Colorado River
Climate changes across the
Southern U.S. and the West Coast
Amphibian declines are a global
phenomenon that this new research demonstrates has continued unabated in the
United States since at least the 1960's, and which are occurring even in
protected national parks and refuges. Scientists have broadly linked declines
to environmental factors like climate, human influence such as land-use change,
and contaminants and disease, but have not been able to use actual scientific
data on a large scale to discern causes of the ongoing disappearance of
amphibian populations.
The new study is the first to
test this linkage at a continental scale, and finds that the presence and
intensity of the four main threats – human influence, disease, pesticide
application, and climate change varies substantially across the US. The causes
of the declines are more variable – and more locally driven – across the United
States than had been assumed.
For example, the research
provides evidence that the average decline in overall amphibian populations is
3.79 percent per year, which supports previous USGS-led research findings from
2013 that showed a similar rate of loss, though the new research finds that the
decline rate is more severe in some regions, such as the West Coast and the
Rocky Mountains. If this rate remains unchanged, these species would disappear
from half of the habitats they occupy in about 20 years.
"Losing 3 or 4 percent of
amphibian populations might not sound like a big deal but small losses year in
and year out quickly lead to dramatic and consequential declines,” said USGS
ecologist Michael Adams, a study coauthor and the lead for the USGS Amphibian
Research and Monitoring Initiative, which studies amphibian trends and causes
of declines.
David Miller, a professor at Penn
State University and the lead biometrician in the study, summarized the extent
of the effort. "This study involved a truly comprehensive and
collaborative effort to bring together data from researchers across the United
States,” Miller said. “We combined nearly half a million actual observations of
84 species across 61 study areas to answer questions about the causes of
wide-scale amphibian declines.”
The research, “Quantitative
evidence for the effects of multiple drivers on continental-scale amphibian
declines,” was led by Evan Grant, USGS; David Miller, Penn State University;
Erin Muths, USGS; and 22 others. The study was published in the open-access
journal Scientific Reports.
Contacts
Department of the Interior,
U.S. Geological Survey
Office of Communications and
Publishing
12201 Sunrise Valley Drive
Reston, VA 20192
United States
Phone: 703-648-4460
Hannah M Hamilton, Ph.D.
Public Affairs Specialist
Phone: 703-648-4356
Catherine Puckett
Deputy Press Officer, USGS
Phone: 352-377-2469
Evan Grant
Research Wildlife Biologist
Phone: 413-863-3823
Jeff Mulhollem
Public Relations Specialist
Penn State University
Phone: 814-863-2719
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