HUNTSVILLE, Ala. (WHNT) — A team led by an assistant professor at The University of Alabama in Huntsville (UAH) made a recently rediscovered crayfish thought to be extinct for the past 30 years deep inside one of Huntsville’s cave systems.
Dr. Matthew L. Niemiller’s team found the crayfish, called, “Shelta Cave Crayfish” (scientifically known as “Orconectes sheltae) in a “Shelta Cave” – the species’ only home.
The crayfish was rediscovered during an aquatic survey aimed at documenting all life that was encountered in the cave system.
Niemiller says the crayfish’s home is a 2,500-foot cave system that’s owned and managed by the National Speleological Society (NSS) in Huntsville, and is unobtrusively located beneath the organization’s national headquarters in the northwest portion of the city, and is surrounded by subdivisions and bustling roadways.
“No other cave system to date in the U.S. has more documented cave crayfishes co-occurring with each other,” Dr. Niemiller says.
But the aquatic ecosystem, including the Shelta Cave Crayfish, says Niemiller, crashed sometime in the early 1970s. The crash may be related to a gate that was built to keep people out of the cave, while still allowing a grey bat maternity population to move freely in and out.
“The initial design of the gate was not bat-friendly, and the bats ultimately vacated the cave system,” Dr. Niemiller says. “Coupled with groundwater pollution and perhaps other stressors, that all may have led to a perfect storm resulting in the collapse of the aquatic cave ecosystem.”
Even before the decline in the aquatic cave community, the Shelta Cave Crayfish was never common compared to the other two species, Southern Cave Crayfish (Orconectes australis) and Alabama Cave Crayfish (Cambarus jonesi).
“To the best of our knowledge, only 115 individuals had been confirmed from 1963 through 1975. Since then, only three have been confirmed – one in 1988 and the two individuals we report in 2019 and 2020,” Dr. Niemiller says.
“After a couple of decades of no confirmed sightings and the documented dramatic decline of other aquatic cave life at Shelta Cave, it was feared by some, including myself, that the crayfish might now be extinct.”
While it’s encouraging that the Shelta Cave Crayfish still persists, he says scientists still haven’t rediscovered other aquatic species that once lived in the cave system, such as the Alabama Cave Shrimp and Tennessee Cave Salamander.
“The groundwater level in Shelta Cave is the result of water that works its way naturally through the rock layers above the cave – called epikarst – from the surface,” says Dr. Niemiller. “However, urbanization in the area above the cave system may have altered rates at which water infiltrates into the cave and also increased rates of pollutants, such as pesticides and heavy metals entering the cave system.”
“I really wasn’t expecting to find the Shelta Cave Crayfish. My students, colleagues and I had visited the cave on several occasions already leading up to the May 2019 trip,” Dr. Niemiller says. “We would be fortunate to see just a couple of Southern Cavefish and Southern Cave Crayfish during a survey.”
While snorkeling in about 15 feet of water in North Lake located in the Jones Hall section of the cave, Dr. Niemiller spotted a smaller-sized cave crayfish below him.
“As I dove and got closer, I noticed that the chelae, or pincers, were quite thin and elongated compared to other crayfish we had seen in the cave,” he says. “I was fortunate to swoop up the crayfish with my net and returned to the bank.”
It was a female, measuring under an inch in carapace length, and had developing ova internally, so it was a mature adult.
“We noted some other morphological characters, took photographs, acquired a tissue sample and released the crayfish,” Dr. Niemiller says.
The team had searched much of the area and didn’t see much aquatic life. As they started to make their way out the lake passage to return to the surface, Nate Sturm, a master’s student in biology at the University of Alabama who had accompanied the lab for the trip, noticed a small white crayfish in an area that the team had previously walked through.
“It was a male with thin and elongated chelae,” Dr. Niemiller says. “I had already walked ahead of the area and did not see the crayfish. Thank goodness for young eyes!”
“We compared the newly generated DNA sequences with sequences already available for other crayfish species in the region,” Dr Niemiller says. “A challenge we faced was that no DNA sequences existed prior to our study for the Shelta Cave Crayfish, so it was a bit of a process of elimination, so to speak.”
Although this research occurred prior to the grant, Dr. Niemiller is currently conducting the first-ever comprehensive assessment of groundwater biodiversity in the central and eastern United States, a pioneering search for new species and new understanding of the complex web of life that exists right under our feet.
The research is funded by a five-year, $1.029 million National Science Foundation (NSF) CAREER award.