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Cambarus cymatilisConasauga Blue Burrower
Federal Protection: No US federal protection
State Protection: Endangered
Global Rank: G1
State Rank: S1
SWAP High Priority Species (SGCN): Yes
Element Occurrences (EOs) in Georgia: 6
Habitat Summary for element in Georgia: Complex burrows adjacent to streams or in low areas where the water table is near the surface of the ground
The overall color of the Conasauga Blue Burrower is typically deep blue and the tips of the claws are orange. Specimens from the Hiwassee River system in Tennessee have more orange on the claws and may have an orangish wash on the cephalothorax. There are two rows of tubercles along the mesial margin of the palm. The areola is obliterated and the abdomen appears narrower and shorter than the cephalothorax. This species reaches a maximum total body length of about 75 mm (3 in).
This is the only predominantly blue crayfish that occurs within its range.
Complex burrows adjacent to streams or in low areas where the water table is near the surface of the ground.
No studies of the Conasauga Blue Burrower are known and the diet of burrowing crayfishes in general is poorly understood. Crayfishes are considered opportunistic omnivores and likely feed on a variety of items, both plant and animal, living or dead. Burrowing crayfishes may forage around the mouths of their burrows, eat organisms that crawl or fall into the burrow, or eat worms that inadvertently tunnel through a burrow wall.
Burrowing crayfishes inhabit a system of tunnels that may be very complex with several openings to the surface. Openings to the tunnels are often marked by piles of dirt or mud pellets (chimneys). Depending on the soil type and moisture content, these chimneys can reach heights of 15 cm (6 inches) or more. These crayfishes are typically confined to their burrows, but a male must leave its burrow to search for females during the reproductive season. As mentioned above, they may also forage near the opening of their burrow. Active burrows with fresh soil are seen from late spring to late fall, particularly after rain events. During the dry part of the summer, burrow openings may be plugged to help conserve moisture in the burrow. Reproduction probably occurs during the spring and fall, but males in reproductive condition may be found at any time during the year. It is rare to find more than one adult crayfish in the same burrow. When a female crayfish releases her eggs, she attaches them to her swimmerets and is said to be “in berry.” Upon hatching, the juvenile crayfish are attached to the mother by a thread. After the juveniles molt for the second time, they are free of the mother, but stay close and will hold on to her for some time. Multiple juveniles are occasionally found in a single burrow. Eventually they move off on their own. Crayfishes molt 6 or 7 times during their first year of life and most are probably able to reproduce by the end of that year. They molt once or twice a year for the remainder of their lives. Although it is difficult to study burrowing crayfishes, some researchers believe they may live as long as 10 years. Males of Conasauga Blue Burrower in reproductive condition have been collected in April and a single female with 7 eggs, 1.9–2.0 mm (slightly less than ⅛ inch) diameter, was collected the same month.
Burrowing crayfishes may be collected by direct excavation of their burrows, by trapping, and during night surveys. Excavating burrows is time consuming and can be very difficult. It also results in destruction of the animals’ burrow. Traps made with PVC pipes or mist nets can be effective. Burrowing crayfishes are sometimes captured around the openings of their burrows on damp nights. The species is most easily collected from burrows showing recent activity (fresh soil; usually from about mid-March to mid-November) when the water table is within about two feet of the surface of the ground.
The Conasauga Blue Burrower is known from the Conasauga and Hiwassee river systems in the Ridge and Valley physiographic province in northwestern Georgia and southeastern Tennessee. In Georgia, it has recently been found in only about five locations including areas around Chatsworth in Murray County (Hobbs 1981), and in wetlands around the Conasauga River in Murray and Whitfield counties (Skelton 2016).
The small range of this species makes it vulnerable to land disturbing activities around streams and wetlands that could destroy burrows and alter hydrology. In addition, urban growth around Chatsworth, GA threatens the species.
This species is in danger of declining in Georgia based simply on the fact that it is known to occur in so few places. One-half of the historic populations in Georgia occurred within the Chatsworth city limits, including a location (type locality) in the yard of a Chatsworth citizen; this population is still extant. However, the historic site from downtown has now been paved; this population was probably never viable and may now be extirpated. A third historic site, in a field near Holly Creek, appears to have been extirpated since the introduction of cattle (Hobbs 1981, Skelton 2016). Fortunately, there is a population on the Conasauga River Natural Area which is owned and managed by the State of Georgia, and a population on a mitigation property developed and managed by Dalton Utilities in Whitfield County. Both of these receive protection from development activities.
If possible, areas with burrows should be protected from land disturbing activities. Additional surveys and life history studies are needed to better define the range of the Conasauga Blue Burrower and help predict its response to environmental change. Environmental education programs should include information about burrowing crayfishes and encourage protection of burrows.
Hobbs, H.H., Jr. 1970. New crayfishes of the genus Cambarus from Tennessee and Georgia (Decapoda: Astacidae). Proceedings of the Biological Society of Washington 83:241–259.
Hobbs, H.H., Jr. 1981. The crayfishes of Georgia. Smithsonian Contributions to Zoology 318:1–549.
Skelton, C.E. 2016. Status Assessment for 14 Crayfish Petitioned for Listing. Final Report. United States Fish and Wildlife Service, Athens, GA. 71 pp.
Taylor, C.A., G.A. Schuster, J.E. Cooper, R.J. DiStefano, A.G. Eversole, P. Hamr, H.H. Hobbs III, H.W. Robison, C.E. Skelton, and R.F. Thoma. 2007. A reassessment of the conservation status of crayfishes of the United States and Canada after 10+ years of increased awareness. Fisheries 32:372–389.
Christopher E. Skelton
C. Skelton, 2008: original account.
C. Skelton, December 2018: general update of account.