By Austen
Verrilli • December 11, 2012, Environmental Monitors (Application and
technology News for Environmental Professionals
When
researchers from the University of Idaho set out to track amphibians, they ran
into a problem.
“One
of the big issues with trying to monitor amphibians is that they can be
difficult to find,” said Katherine Strickler, a post-doctoral researcher of
fish and wildlife resources at UI. “If you are not there at the exact
time, you can miss them.”
So,
Idaho researchers turned to a new method for biologically detecting which
species call a habitat home. They sample bodies of water and test them for
environmental DNA unique to each species of fauna.
Environmental
DNA results from any bit of matter an animal leaves in an ecosystem, from eggs,
to molted skin, to feces or any other cell. Strickler said eDNA persists longer
than regular cell material, giving scientists a greater window for biological
detection.
Collecting
eDNA is less stressful for amphibians, which can hide while scientists peruse
their ecosystem.
The
method is incredibly precise and eliminates false positive altogether, as long
as samples remain uncontaminated. UI researchers sequence DNA specific to one
amphibian and others that are very similar. Then they collect a water sample
from an area where they suspect a particular amphibian would live. Samples
are sterilized so that bacteria don’t break down the DNA.
Researchers
separate and replicate a specific eDNA sequence from the samples and run it
through a sequencing machine to verify a species match.
Researchers
collect their water samples with a simple rig consisting of a vacuum flask,
filter funnel and a Pegasus Athena peristaltic pump.
They
pump four 250 milliliter samples from each body of water. A special filter
binds to any DNA in the sample.
Strickler
said they tested several peristaltic pumps before purchasing the Pegasus model.
“The Pegasus is great because it allows us to filter water a lot more quickly,
a lot more efficiently and it gives us less wear and tear on our bodies,”
Strickler said.
The
pump’s compact design also makes it ideal for sampling in remote locations
where the scientists have to hike-in equipment.
Strickler
and Karen Goldberg, a UI biological research scientist, monitor ecological
areas in military bases under a U.S. Department of Defense grant. They’re
working in southeast Arizona, Washington state and Florida’s panhandle.
So
far they have had success sampling in smaller scale ponds, but they have not
verified if their sampling method will work in large bodies of water.
Eventually
they hope to establish a protocol for eDNA sampling that can be used by other
scientists.
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