A Study of Orconectes shoupi, Mill Creek Basin, Tennessee, 1985.
MISSISSIPPI MUSEUM OF NATURAL SCIENCE JACKSON, MS
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Fourteen sites on Mill, Sevenmile, and Indian creeks in Davidson and Williamson Counties, Tenn., were surveyed for crayfish in July 1985. Orconectes shoupi, considered for listing as Endangered by the US Fish and Wildlife Service, numerically dominated at 8 of the 14 locations and comprised 78 percent of the crayfish community. The remaining 22 percent of the crayfish community consisted of two species, O. minus and O. palacidus. At sites where quantitative collections were made, O. shoupi densities ranged for 0.6sq m to 11.9 sq m. Orconectes shoupi was numerically dominant at the majority of sites in Mill Creek, whereas the other two species of orconectes were most common in Sevenmile Creek, a major tributary of Mill Creek. When O. shoupi dominates the community, it had a greater proportion of larger sized individuals than when it was subdominant to the other two species of Orconectes. Length-frequency analysis for this species indicated an early cohort 17 to 25 mm, a late chohort maximum size 15 mm, and a group larger than 25 mm, which probably had overwintered from the previous year Orconectes shoupi is a nocturnal, aggressive crayfish that is densest at sites with sufficient cover consisting of slab rock for large individuals or cobble or gravel for juveniles. Results of this survey indicated that, although this species has been reported only from well-oxygenated, sediment-free water, it is tolerant of suspended and settled sediment and eutrophic conditions.
- Biological Oceanography