Tag: crayfish

Small, rare crayfish thought extinct is rediscovered in cave in Huntsville city limits

Dr. Matthew L. Niemiller’s team found individuals of the Shelta Cave Crayfish in 2019 and 2020 excursions into Shelta Cave – its only home.

HUNTSVILLE, Ala. (June 1, 2022) – A small, rare crayfish thought to be extinct for 30 years has been rediscovered in a cave in the City of Huntsville in northern Alabama by a team led by an assistant professor at The University of Alabama in Huntsville (UAH).

Dr. Matthew L. Niemiller’s team found individuals of the Shelta Cave Crayfish, known scientifically as Orconectes sheltae, in 2019 and 2020 excursions into Shelta Cave – its only home.

The Shelta Cave Crayfish is known to exist only in Shelta Cave. Courtesy Dr. Matthew L. Niemiller

Dr. Niemiller, an assistant professor of biological sciences at UAH, a part of the University of Alabama System, is co-author of a paper on the findings in the journal Subterranean Biology. Besides Dr. Niemiller, authors are UAH’s Katherine E. Dooley and K. Denise Kendall Niemiller, and Nathaniel Sturm of the University of Alabama.

The crayfish’s home is a 2,500-foot cave system that’s owned and managed by the National Speleological Society (NSS) and is unobtrusively located beneath the organization’s national headquarters in northwest Huntsville and is surrounded by subdivisions and bustling roadways.

Map of Shelta Cave showing the distribution of aquatic habitat during high water levels and the location of Shelta Cave Crayfish observations (black crayfish symbol) during the study. Map modified with permission of the Alabama Cave Survey.

“The crayfish is only a couple of inches long with diminutive pincers that are called chelae,” Dr. Niemiller says. “Interestingly, the crayfish has been known to cave biologists since the early 1960s but was not formally described until 1997 by the late Dr. John Cooper and his wife Martha.”

But the aquatic ecosystem, including the Shelta Cave Crayfish, crashed sometime in the early 1970s. The crash may be related to a gate that was built to keep people out of the cave and yet still allow a grey bat maternity population to still move freely in and out.

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.”

The crayfish was rediscovered during an aquatic survey aimed toward documenting all life that encountered in 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.”

Dr. Matthew L. Niemiller snorkels in Shelta Cave, where a species of crayfish believed to be extinct was rediscovered. Photo by Amata Hinkle

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.”

“The second Shelta Cave Crayfish that we encountered was in August 2020 in the West Lake area,” he 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.

To aid identification, the team analyzed short fragments of mitochondrial DNA in the tissue samples collected.

“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.”

Outside of the dissertation work done by Dr. Cooper, little about the life history and ecology of the species is known.

 “Groundwater is critically important not just for the organisms that live in groundwater ecosystems, but for human society for drinking water, agriculture, etc.,” Dr. Niemiller says.

“The organisms that live in groundwater provide important benefits, such as water purification and biodegradation,” he says. “They also can act like ‘canaries in the coal mine,’ indicators of overall groundwater and ecosystem health.” 

Research article:

Dooley KE, Niemiller KDK, Sturm N, Niemiller ML (2022) Rediscovery and phylogenetic analysis of the Shelta Cave Crayfish (Orconectes sheltae Cooper & Cooper, 1997), a decapod (Decapoda, Cambaridae) endemic to Shelta Cave in northern Alabama, USA. Subterranean Biology 43: 11-31. https://doi.org/10.3897/subtbiol.43.79993

About The University of Alabama in Huntsville

Launched from America’s quest to conquer space, The University of Alabama in Huntsville is one of America’s premier doctoral-granting, research-intensive universities. Located in the second largest research park in the United States, UAH has robust capabilities in astrophysics, cybersecurity, data analytics, logistics and supply chain management, optical systems and engineering, reliability and failure analysis, rotorcraft and unmanned systems, severe weather, space propulsion and more. UAH prepares students for demanding positions in engineering, the sciences, business, nursing, education, the arts, humanities and social sciences.

Read the full press release by The University of Alabama in Huntsville.

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Invasive crayfish can cause high fisheries damage

In Zambia and Zimbabwe, a single crayfish may cause annual fishery losses of as much as $6.15

Guest blog post by Josie South

Invasive crayfish have the potential to cause high economic cost to artisanal fisheries in southern Africa through scavenging behaviour and destroying fish fry habitat.

A recent study by C∙I∙B Research Associate Josie South (University of Leeds, UK) with scientists from the South African Institute for Aquatic Biodiversity (SAIAB) quantified the damage caused by two invasive crayfish compared to native crab species, at two temperatures, on tilapia catch and macrophytes.

Redclaw crayfish entangled in a gill net in the Kafue River. Photo by Bruce Ellender

Economic costs of invasive species are vital to prioritise and incentivise management spending to reduce and restrict invasive species. No economic costs have been published for the global invader – the redclaw crayfish (Cherax quadricarinatus), and none for the entire continent of Africa. Another prolifically invasive crayfish, the red swamp crayfish (Procambarus clarkii) is also invasive in various countries of southern Africa. Anecdotal reports of crayfish scavenging from artisanal gillnet fisheries are abundant across the invasive ranges but lacked quantification. Similarly anecdotal information about macrophyte stands being destroyed by crayfish has been reported.

For their study, Josie and colleagues compared the feeding rates per gram of crayfish to that of the native Potamonautid crabs at 19°C and 28°C on simulated fisheries catch and macrophytes to identify how much damage may be caused.

Gill net fish catch damaged by crayfish scavenging. Photo by Josie South

The red swamp crayfish consumed the most macrophytes regardless of temperature, at a higher rate than the redclaw crayfish or crabs. In contrast, redclaw crayfish consumed the most tilapia regardless of temperature, and targeted the tail, abdomen, and fins whereas the crab only consumed the head of the fish. The damage rates of redclaw crayfish were then combined with average mass of crayfish in three invasion cores in Zambia and Zimbabwe. It was found that the damage one crayfish may cause annual fishery losses from $6.15 (Kafue River); $5.42 (Lake Kariba); and $3.62 (Barotse floodplain).

Inland fisheries contribute substantially to the livelihoods and quality of life in Africa. The two invasive crayfish have different capacities for ecological and socio-economic impact depending on the resource and the temperature which means that impact assessments should not be generalised across species.

Redclaw crayfish capacity to damage fish catch was substantial but this should be caveated with two over/under estimation issues: 1) the potential for fisher behavioural change which may reduce crayfish damage and 2) small damage to the fish may render the catch unsaleable and therefore the cost of the whole fish is lost.

Dr Josie South states that while these data are a crucial first step in filling knowledge gaps in crayfish impacts in Africa, it also stresses the need to derive observed costs from fisheries dependent data to avoid misleading estimates.

Also of concern, is the capacity for ecological and socio-economic damage from the red swamp crayfish, which was recently removed from the NEM:BA regulations of prohibited species due to lack of impact evidence.

Read the paper published in NeoBiota

Madzivanzira TC, Weyl OLF, South J (2022) Ecological and potential socioeconomic impacts of two globally-invasive crayfish. NeoBiota 72: 25–43. https://doi.org/10.3897/neobiota.72.71868

This blog post was first published by DSI-NRF Centre for Invasion Biology, Stellenbosch University.

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New Indonesian crayfish species escapes the decor market to become a freedom fighter

With its orange to greenishly orange motley tip, the new crayfish species has been long-confused with its relatives by the tradesmen who have been collecting them for ornamental purposes. Being exported to countries in Europe, East Asia and America C. snowden specimens inevitably landed in the hands of the scientists from Lukhaup’s team who eventually recognised and proved them as a new crayfish species. Their research is available in the open-access journal ZooKeys.

Although the new crayfish species has probably been sold along with its motley relatives under another name for decades, the scientists figured that it is in fact easily distinguishable by its shape of body and colouration. In order to prove it as a separate species, the team used sequence divergence as well.

Having travelled across the world from its so far only known locality, West Papua, New Guinea, the new freshwater crustacean was given the name of the controversial former CIA employee and government contractor Edward Snowden. Its ‘godfather’ is famous for leaking secretive information from the U.S. National Security Agency, which later led him to a continuous search for political asylum. The authors speak of him as an “American freedom fighter” with “achievements in defence of justice, and freedom.”

In their conclusion the authors note that there could be potential threats to the new species. The freshwater crayfish is being collected in large numbers for both the ornamental fish global market and for food for the locals. Asked about the crustacean’s populations, the collectors spoke about a decline in the last few years.

“Clearly, the continued collection of these crayfish for the trade is not a sustainable practice, and if the popularity of the species continues, a conservation management plan will have to be developed, potentially including a captive breeding program,” the researchers comment.

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Original source:

Lukhaup C, Panteleit J, Schrimpf A (2015) Cherax snowden, a new species of crayfish (Crustacea, Decapoda, Parastacidae) from the Kepala Burung (Vogelkop) Peninsula in Irian Jaya (West Papua), Indonesia. ZooKeys 518: 1-14. doi: 10.3897/zookeys.518.6127