Washed up: how an elusive amphipod made a powerful ally
Walter Sidney Abbott may not be a household name, but the early 20th-century entomologist is still known in the field today for devising “Abbott’s formula,” an equation for calculating the efficacy of a pesticide.
He may have another claim to fame.
In 1921, a “W.S. Abbott” collected a specimen of a mysterious amphipod from a well at the federal Bureau of Entomology’s Agricultural Experiment Station in Vienna, Virginia.
We know, because he submitted the specimen to the Smithsonian Institution. You can see the collection record here.
Walter Sidney Abbott worked at the station in Vienna from 1912 until his retirement in 1938. Odds are he is the W.S. Abbott who collected, and recognized the novelty of, the tiny, colorless, shrimp-like creature now known as the Northern Virginia well amphipod.
It’s a good thing he did. The amphipod wasn’t seen again until 1948, when a dozen were collected in a well in Alexandria, Virginia. After that, it eluded detection for nearly 50 years.
Watershed moment
In 1996, the amphipod had a watershed moment. Scientists collected 15 specimens from the leaf litter at the outlets of several groundwater springs in a ravine on U.S. Army Fort Belvoir in Virginia. It turned out to be a good place to wash up.
Thanks to habitat protections that were put in place by the U.S. Army, the U.S. Fish and Wildlife Service has announced that the Northern Virginia well amphipod does not warrant listing under the Endangered Species Act.
In 2005, the Army designated 70 acres encompassing the amphipods’ habitat a “Special Natural Area,” managed to support specific goals for conservation and biodiversity detailed in the Fort’s Integrated Natural Resources Management Plan (INRMP). Developed by the Army, the Commonwealth of Virginia, and the Service, the plan identifies key natural resources and the actions needed to manage them in a way that ensures the continuation of the installation’s military mission.
But the Army has taken additional steps not included in the INRMP, like installing a berm at the southern end of a nearby solid waste transfer station to discourage illicit dumping that could affect water quality in the sole aquifer where the amphipod is known to live today.
When I spoke with John Pilcicki, environmental protection specialist for the Fort’s Directorate of Public Works, he had just checked on the site where the amphipod washed up in 1996.
“We just had a heavy rain, so I wanted to make sure there weren’t any log jams or fallen trees that could back water up into the seeps,” he explained.
Of course, he looked for amphipods while he was there too, peeling back wet decomposing leaves stuck together “like the pages of a book,” hoping to find “a little white shrimp thing, wiggling around.”
No luck, but it was remarkably lucky anyone found them there in the first place.
“They are five millimeters long and live underground in habitat you can’t access,” Pilcicki said. “If Chris Hobson hadn’t been out there looking around, it never would have been detected.”
Right place, right time
Hobson, a natural heritage zoologist for the Virginia Department of Conservation and Recreation, spends most of his days looking for rare or novel species around the Commonwealth. When I called to talk with him about the discovery of the amphipod, he answered the phone from the middle of a prairie wetland on the western slopes of the Blue Ridge Mountains, where he was looking for butterflies.
“We were doing an inventory of rare species for the Fort when we stumbled upon the seepage,” he recalled. He collected specimens of the amphipod, and took them back to his lab to make the initial identification. Then he brought them to John Holsinger, a professor of biology at Old Dominion University and a pioneer of amphipod taxonomy. Holsinger, who died in 2018, had identified and described W.S. Abbott’s mysterious amphipod specimen in 1975. His name is in the Smithsonian collection record too.
Holsinger confirmed that Hobson’s specimen was the same species that had been pulled out of wells in Vienna and Alexandria decades earlier. “He was pretty excited about it, since it hadn’t been seen since the 1940s,” Hobson said. It made them wonder where else it might be hiding.
“We sampled all over for them — along the Potomac, in Prince William Forest Park, and other accessible public lands around the region,” Hobson said.
They even double checked the Fort. In 2003, he and Pilcicki suspended jars baited with shrimp into several wells dug throughout the installation to try and lure in amphipods. No bites.
The ravine remains the only known location for the species, and only because erosion and runoff forced a sort of emergency exit from the underground aquifer where the species lives most of its life.
“Their micro-environment is so mysterious,” Pilcicki said. “There could be billions of them down there, but we can’t get to them, we can’t communicate.”
Instead, they stand guard. “We continually monitor the conditions around the seeps for things that could affect recharge zones,” he explained.
Water quality and quantity are the key ingredients for an aquifer-dwelling species. Surface or groundwater contamination, excess water withdrawal, and climate change all pose a threat. More frequent intense rain events could flush amphipods from their habitat and erode the surrounding landscape, or progressive loss of water in the aquifer from drought could leave amphipods high and dry.
However, the best available information indicates that these are distant threats, and the species faces a low risk of extinction in the foreseeable future.
Splash forward
Pilcicki and Hobson hope there’s an easier way to keep tabs on the Northern Virginia well amphipod on the horizon: an environmental DNA sampling protocol for the species that could eliminate the need to try to collect specimens from groundwater seeps, wells, or wherever they turn up next, in order to confirm their presence.
Known as eDNA, this evolving forensic technique can find genetic traces of a target species in a water sample, a powerful tool for detecting organisms that are difficult to capture, in places that are hard to get to.
“One of the most important things we can do for this species is collect more so we can figure out their genetic code, and then continue looking for them other places by sampling the water,” Hobson said.
I asked him about the historic wells that gave the amphipod its name. Could they still be down there?
“There are a lot of houses in Old Town Alexandria that may still have wells,” he said. “But there’s no record of where that specific well was.”
As for the Agricultural Experiment Station in Vienna where Abbott discovered the amphipod, “It was a nice farm on the south side of what is Roland Road today,” recalled Anne Stuntz, president of Historic Vienna Inc. “Single family homes now.”
Stuntz mused that Vienna residents would probably welcome the unexpected connection to a creature they will likely never see. “This town would get a kick out of having special ties to an amphipod!”
For good reason. Whether or not the amphipod still lives in the aquifer below, its discovery in Vienna helped make conservation history.
