If it hasn't been studied it can't be conserved- Fellows visit crayfish expert and natural history collection at TVA

Jeff Simmons invited the River Fellows to his lab and natural history collection where we learned some surprising and fascinating things about crayfish. Most of us thought there were just a couple of different species of crayfish and we were astounded to learn about the species diversity of this animal. The Tennessee Wildlife Resources Agency reports that of the 550 species of crayfish that occur worldwide, more than 78 of these live in Tennessee which may rank us as having more crayfish species than any other US state. 

We learned that not all crayfish live in streams and rivers. There are some beautiful, brightly colored burrowing crayfish that dig elaborate underground tunnels and take advantage of locations where groundwater is close to the surface. These crayfish build mud chimneys and are difficult to catch, because they can have five or more exits from their burrows. In addition, some crayfish are secondary burrowers and have an entrance from a stream while their networks expand to the riverbank. Crayfish have an important place in an ecosystem as they are a source of food for otters and fish. In turn, they have an omnivore diet and consume small fish and breakdown leaf litter.

Cambarus (Jugicambarus) dubius: Upland Burrowing Crayfish (photo credit: nps.gov)

Invasive species are a constant threat to countless species and crayfish and fish are no exception. Jeff told us about a current political debate related to this issue that is occurring in Kentucky. It is reminiscent of the first court battle to test the endangered species act: the snail darter vs. Tellico dam (you can read more about that case here: http://www.mhhe.com/Enviro-Sci/CaseStudyLibrary/Topic-Based/CaseStudy_TheSnailDarterVersus.pdf) In Kentucky, the dam on the Cumberland River had been broken for seven years during which time many species colonized the now more riverine environment. One of these species was a rare fish discovered during a mussel survey of the area. As was the precedent with the snail darter, this dam was repaired and the habitat for this fish re-flooded. In a survey one year after the habitat returned to slow moving water, the invasive rusty crayfish was found to be the dominant species in the area.

This invasive rusty crayfish is a problem in many aquatic ecosystems in our area. Another example is in the Big South Fork where it outcompetes a native fish that lays eggs under slabs of rock by infringing on this space. It is also outcompeting the native crayfish in that river. Anglers using it as bait mostly spread the rusty crayfish from water body to water body. If limits were to be put on this bait, it could be seen as infringing on angler’s rights.

Two species of Bottlebrush crayfish, Barben simmonsi on the left

In order to help protect species from extinction, surveys and studies of rivers and streams are needed. Without this historical data, species in danger of becoming extinct cannot be listed as an endangered species and protected under the endangered species act. Jeff gave us an example of a stream that had rich historical data and when it was recently surveyed, chicken farming had destroyed almost all species with the exception of one and this fish will now likely be listed as an endangered species. Jeff then introduced us to the amazing natural history collection of 2500 jars of crayfish. In order to find a particular jar, the collection is set up like the old card catalog at a library. We got to see the species that was named after Jeff in 2009-2010, the Barben simmonsi, commonly called a bottle brush crayfish. We had never seen a large, pale crayfish like this and Jeff explained that they live under huge boulders in certain streams and rivers. Overall, the message we left the lab with was that study and historical collections are essential for conservation.