Feb. 11, 2015
Contact:
Dave Edmark, Division of Agriculture Communications
479-575-6940 / dedmark@uark.edu
Water mites – more to them than meets the eye
Fast facts:
 Water mites can be bioindicators of water quality
 Research team is documenting water mites’ diversity in U.S. and Canada as
part of five-year National Science Foundation grant
FAYETTEVILLE, Ark. – If you’re swimming in pristine waters, chances are you’re
surrounded by a high diversity of water mite species. If you’re in less than pristine
waters, there might be even more water mites around, but fewer species of them. Ashley
Dowling wants to find how and where they’re thriving.
The lowly water mite, with a diameter of about 3 mm or less, can be found in a
variety of waters: standing, flowing, shallow or deep. If the surface of a stream dries up,
they can often be found in a gravel riverbed. “If there is water, there might be mites,”
said Dowling, an associate professor of entomology at the University of Arkansas
System Division of Agriculture.
“Their influence on the structure and dynamics of aquatic communities is
significant but underappreciated,” said Dowling, “One of the things we’re looking at is
water mites as bioindicators of water quality.” But Dowling emphasized that his research
team must first document water mites’ diversity in the U.S. and Canada. After that is
accomplished, the stage will be set for using the data to determine water mites’ role as
water quality bioindicators.
Dowling, his co-investigator Andrea Radwell of the entomology research faculty
and his research team are looking at this in a big way. He’s about halfway through a five-
year National Science Foundation grant of more than $725,000 to study the diversity of
water mites in North America and train new specialists in water mite biology. It takes
years to gather and analyze the data from different parts of the country, but the picture is
coming together.
The water mite looks like a small aquatic spider. Sometimes it’s a parasite that
lives off insect hosts, and then it can become a predator on other small arthropods.
Evaluating the quality of freshwater streams is a major concern in Arkansas and
elsewhere. The presence of three insect groups has been considered by scientists as an
indicator of a stream’s quality. The insects are large and easy to identify, but the smaller
water mites take the task to another level. Researchers in Europe have noticed that
water mites are more sensitive to changes in water quality.
“If phosphorous or nitrogen levels change a little bit, the mites tend to react faster
than the aquatic insects that are commonly used,” Dowling said. “The problem with mites
is that they are much, much smaller. But they’re extremely easy to identify once you
have some tools at your disposal.”
Further development of those tools is part of this project’s mission. Dowling
explained that because North American water mites have not been explored in depth as
in Europe, they can’t be used for water quality assessment. “If you go to any given
stream, you really have no idea what to expect in terms of what should be there if it’s a
healthy stream or what it would look like if it were a contaminated stream.”
So Dowling’s team has been traveling to learn more about streams in different
parts of the country and examine the diversity of water mites present. “Typically we
sample what we consider some of the highest quality streams because in our project
we’re looking for diversity,” he said. “We may be building the baseline for what a high
quality stream is. Then we can monitor that and see how it changes.”
Certain water mites are already known to thrive in poor quality streams, and any
such stream probably doesn’t have a diverse representation of water mites as a high
quality stream would. The research team is exploring further to find out the level of water
mites’ diversity in streams that are at varying levels of degradation.
“We want to see how those stream communities change so you can catch it early
as opposed to waiting until it’s completely polluted,” Dowling said.
The researchers are traveling coast to coast over the five years of the grant and
are seeking to produce definitive monographs and data on the Torrenticolidae, the most
common and abundant water mite family in U.S. and Canadian streams.
They’ve been to the northern Rockies, the Pacific Northwest and Alaska. In 2015
they’ll visit Florida and Georgia. They chose these locations because those areas are
the parts of North America that haven’t already been covered by two veteran water mite
researchers: Ian Smith, a Canadian in his 70s, and Dave Cook, an Arizona scientist in
his 90s. These two leaders in the field are both winding down their activity and Dowling
notes that points to a need to prepare a new generation of water mite research
specialists.
Two Ph.D. candidates and one master’s student are working with Dowling on the
project. One of them, Whitney Nelson, a doctoral student, joined the effort as an
ecologist who didn’t have much experience with water mites. She aspires to an
academic career and the work has raised her interest.
“Water mites are a cosmopolitan, understudied organism,” Nelson said. “I hope
to explore using mites as indicators for environmental health in the future.”
PHOTOS:
(Torrenticola.jpg)
Torrenticola water mite
(WM_stream collecting.jpg)
Graduate students Ray Fisher, Whitney Nelson and Joe O’Neill collect water mites from
a stream in Montana during a 2012 excursion. They set two nets in the stream and dig
just upstream of the nets so the water current carries sediment and organisms into the
nets.
The University of Arkansas is an equal opportunity/affirmative action institution.