Freshwater mussels are among the most interesting—and imperiled—critters on the planet.
For 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.
“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.” . . .
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