Citizen Mussels

North America's freshwater mussels are facing a mass extinction crisis, and ecologists are jumping into rivers to figure out why.


We’re knee deep in the Farmington River, the four of us, about two miles north of Otis, Massachusetts and somewhere south of Jacob’s Pillow. Ayla Skorupa, the one who called us here, is leaning on a protruding rock in a faded teal wetsuit, my mesh bag of freshwater mussels open at her side. A PhD student at the University of Massachusetts Amherst and researcher with the state’s Cooperative Fish and Wildlife Research Unit, Skorupa puzzles out the species of each mussel, one at a time, notching her fingers along its prominently curved umbo, then drops the most common species, the eastern elliptio, back into the water. The sun’s hot overhead, another 90-degree day in September. The water that pools in my orange sneakers—my lawn-mowing shoes—is startlingly cold.

Behind her, Tim Warren, a colleague with the US Fish and Wildlife Service, is doing the same with the other volunteer’s bag, only faster. He flicks the elliptio a bit further down the mesohabitat we’ve just spent the last thirty minutes crawling up, face down, in four methodical, meter-wide lanes, collecting every mussel we could find. Bag emptied, Skorupa turns and reports my count: “Forty nine elliptio, a triangle, and two creepers.” Then, in response to my hopeful query, she responds with an apologetic shake of the head: “Nope. Zero brook floaters.”

A wayward ellipitio glances off her shoulder and drops into the water. “Hey!” she calls out as Warren mumbles an apology amidst his count. Snorkel in hand, Skorupa eyes up the next 20m stretch while deadpanning a clickbait headline: “Mussel biologist gets knocked out by a mussel.”

There will be no such news story. Media coverage in this line of work is something of a rarity. But word is spreading. Freshwater mussels (Unionoida) are undergoing a mass extinction crisis that has accelerated in the past twenty years. One 2014 study found that “Freshwater mussels have the highest extinction and imperilment rate of any group of organisms on the planet,” with 65% of species currently extinct, endangered, threatened, or vulnerable.

The loss is no small matter. North America is home to the richest diversity of freshwater mussels, with over 300 kinds and counting. Wedged into riverbeds with shells agape and tiny cilia hairs quivering in the current, freshwater mussels can filter up to eight gallons of water per day, depending on the species. They draw out algae and bacteria, along with particulates, including pharmaceuticals and heavy metals, from the water column. Their calcified shells serve as substrate habitat for other fish and river life, and they function as a key food source within an interdependent riverine web.

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