Out mussel-ed: Mollusk native to Ohio River watershed officially declared extinct
The U.S. Fish and Wildlife Service this week officially took 21 species off the endangered list — but not in a good way. The agency, which announced its intention to do so in 2021, delisted animals ranging from birds and fish to eight kinds of mussels because they're now officially declared extinct.
Two Ohio natives are among those lost, including the Scioto madtom — a small, catfish-looking fish once found in the Big Darby Creek near Columbus — and the tubercled-blossom pearly mussel. While the news was made final this week, neither species have been spotted in decades.
The tubercled-blossom pearly mussel hasn't been seen since the 1960s, with the last confirmed spotting in 1969. Its native habitat extended throughout the Ohio River Basin in states including Ohio, Kentucky, Indiana, Illinois, Alabama, Tennessee and West Virginia. It was added to the Endangered Species Act list in 1976.
"Their extinction had been set into motion up to 100 years earlier, or more," says Wendell Haag, Ph.D., research fisheries biologist with the USDA Forest Service. "In the case of the tubercled-blossom pearly mussel, the major factor that caused its extinction is all those large rivers (in the Ohio River Basin) were dammed. For example, the Ohio River was dammed up completely by about 1929. And when that happened, it eliminated that free flowing river habitat that the mussels needed to survive."
Freshwater mussels are important because they're filter-feeders. That means they constantly filter large volumes of water, removing pollutants like algae and bacteria. They're bioindicators, meaning they function like a "canary in a coal mine" to warn us of problems in our environment.
The tubercled-blossom pearly mussel was found in large rivers along shallow sand and gravel shoals with rapid currents. The building of dams and reservoirs, coupled with agricultural and other pollutants, spurred their demise.
A dam shame
"This is something, unfortunately, that freshwater mussels in North America have been dealing with for a long time," says Melinda Voss, education programs manager for the Ohio River foundation, which does educational outreach about, among many things, the importance of mussels. "In a lot of these cases, we're going back 50, 75, even 100 years, where these populations were decimated for all kinds of reasons."
Voss notes freshwater mussels are among the most endangered organisms in all of North America. She points out this region is particularly vital for mussels. Of the 297 types found in North America, 127 have historically called this region home. The addition of eight types of mussels to the list of those that are extinct, she says, drives home the importance of protecting, and improving the habitat for, those that are still around.
"Hopefully this information helps spread the word about how critical some of these species are, but also allows expertise and resources to really be targeted towards those species that we know do still exist, but really need the attention to ensure we don't lose any more."
That work includes removing barriers — low-head dams, for example — that are harmful to mussels, their reproductive cycles and their habitat. It also includes cleaning up waterways and removing pollution.
Haag says it's tragic anytime Earth loses a component of its natural diversity.
"But it's also worrisome because anytime that you lose a species in an ecosystem, the overall function of that ecosystem is compromised. And we don't understand most ecosystems well enough to know what the effect of loss of different components of those ecosystems are, but it has an effect.
"It's like if you lose a part out of your car," he says, "it's going to affect its performance."