Blue Ridge Country - September/October 2018 - 10

C R E AT U R E F E AT U R E
By NANCY HENDERSON

KEEPERS OF THE WATER WATCH

Mussel Mania

Freshwater mussels are among the most interesting-and imperiled-critters on the planet.

or an animal with no eyes and no head, says Bernard Kuhajda, an aquatic conservation biologist
and science program manager at the Tennessee
Aquarium Conservation Institute in Chattanooga, freshwater mussels are very clever. "They're
fascinating creatures," he insists. "They have personalities. They really do."
Most of them, for example, instinctively package their
larvae to mimic fish food-crayfish, aquatic insects
or even small fish-in order to hitch them
a ride on a much-needed host fish.
"Some mussels actually have a fishing line of snot, and on the end
of it they have a packet of larvae
that looks like a minnow and it
'swims' in the current," Kuhajda says. "A bass comes to eat
that minnow and it gets a face
full of little larval mussels."
Despite their ingenuity, freshwater
mussels are the most at-risk animals in the
U.S., which harbors 300 species. The Southeast, considered the hotspot for mussel diversity in North America, is
home to 240 of them.
Massive shell mounds found in former Native American encampments show that at one time these mollusks
were plentiful. Today, 75 percent of freshwater mussels in
the Blue Ridge states are facing some level of imperilment
and many are already extinct.
The main culprit: Humans have altered their waterways with dams and reservoirs, disrupting natural ecosystems, especially for critters that live in big rivers. Decades
ago, deep pools and shallow shoals punctuated free-flowing rivers that receded and warmed in the summer, then
rose and got colder in winter.

"Everything we do to our water,
ends up inside a mussel."
- Bernard Kuhajda

BLUERIDGECOUNTRY.COM

"Well, now we've got these huge artificial lakes behind
dams and it's all deep water and flow," Kahajda notes.
"Then below the dams, for many, many years before they
improved the dams, it cut off populations that live in the
tailwaters. They just started getting relatives spawning
with each other and eventually they blinked out."
Unfortunately, the manmade problems don't stop
there. Runoff from Georgia factories and chicken farms,
for instance, has washed into nearby streams,
infusing them with hormones and disrupting the reproductive capabilities of
male mussels. Pharmaceutical compounds, which aren't removed by
waste treatment plants, end up in
the water too. And chemicals that
are commonly mixed with herbicides to make them spray evenly
have, according to Kuhajda, caused
"huge mussel kills" in the Clinch River in
Virginia and Tennessee. If that isn't enough, some
of the host fish the mussel larvae require to live on as
they grow in a caterpillar-to-butterfly transformation are
also on the decline due to habitat loss.
"Altering the habitats has not only affected the mussels, but the fishes that the mussels depend on to reproduce," says Kuhajda. "So it's a double whammy."
The fact that mussels, which filter organic substances
and purify the water, are ultra-sensitive makes them exceptional indicators of the health of rivers and streams.
It also makes them more susceptible to harm. Some live
more than 100 years, absorbing contaminants the whole
time. "Everything we do to our water," Kuhajda says,
"ends up inside a mussel."
To combat the decline, experts across the Southeast
are working to raise them in specialized hatcheries and
reintroduce them into the wild, with the ultimate goal of
saving the mussels from extinction. The general public
can help too, by scaling back on fertilizers and insecticides and being careful not to apply them just before a
hard rain.
In addition to containing compounds that may fight
cancer and heal wounds, mussels are key to keeping our
water clean, Kuhajda points out. "Healthy rivers make
healthy people and healthy communities. Fresh water is
the one item that we cannot do without."

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Blue Ridge Country - September/October 2018

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