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Habitat Characteristics and Conservation Status of Three Pennides Crayfish in Marion County, Georgia
JoAnn Chadwick and George E. Stanton

Southeastern Naturalist, Volume 10, Issue 3 (2011): 533–546

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2011 SOUTHEASTERN NATURALIST 10(3):533–546 Habitat Characteristics and Conservation Status of Three Pennides Crayfish in Marion County, Georgia JoAnn Chadwick1 and George E. Stanton2,* Abstract - Habitats of three crayfish species, Procambarus (Pennides) gibbus (Muckalee Crayfish), Procambarus (Pennides) versutus (Sly Crayfish), and Procambarus (Pennides) spiculifer (White Tubercled Crayfish) were studied at nine localities in Marion County, GA. Major objectives of this year-long study were to compare habitats of these sister species and assess the current conservation status of the Muckalee Crayfish and the Sly Crayfish in Georgia. Sites were characterized by a one-time physical assessment of the substrate followed by bimonthly assessment of physicochemical conditions. Results indicated that Sly Crayfish habitats had lower pH and turbidity than habitats used by the other two species. Muckalee Crayfish habitat had higher gravel and coarse sand content and higher conductivity than those of the other two species. Captures indicated year-round activity of populations of each species across study locations; however, both the Muckalee Crayfish and the Sly Crayfish merit conservation status due to their limited ranges. Introduction The southeastern United States contains some of the most evolutionary significant aquatic systems in North America. Georgia is ranked second in the number of species of amphibians, third in freshwater fishes and crayfishes, and seventh in the number of reptiles and vascular plants (Isophording and Fitzpatrick 1992). An awareness of the diversity of the Southeast has led to an understanding of the importance of preserving the distinct biotic communities that house these many unique species (GADNR 2004). Little is known about many of the 68 crayfish species found in Georgia, several of which are endemic (Fetzner 2002). Because of their various roles within ecosystems, crayfish are often characterized as a keystone species and often constitute the most abundant faunal group, as well as the one with the highest biomass, within aquatic invertebrate communities (Creed and Reed 2004). In addition to their importance in food webs, crayfish significantly alter the surrounding environment by shredding macrophytes, building burrows (Nystrum 2002), and carrying out additional behaviors that may alter bedform roughness, physical particle distribution, and/or growth of filamentous algae (Statzer et al. 2003). Georgia crayfishes belong to the family Cambaridae, of which there are two sub-families: Cambarellinae and Cambarinae. Within the Cambarinae 1Environmental Science Program, Columbus State University, 4225 University Avenue, Columbus, GA 31907. 2Department of Biology, Columbus State University, 4225 University Avenue, Columbus, GA 31907. *Corresponding author - stanton_george@ 534 Southeastern Naturalist Vol. 10, No. 3 is the genus Procambarus, and sub-genus Pennides. All Pennides are stream inhabitants. Of 18 species of Pennides, five occur in Georgia, appearing to occupy similar niches within streams, and are thus seldom sympatric (Hobbs 1981). Three Pennides species are found in Marion County, within the drainage basins of the Chattahoochee and Flint Rivers. We focus our study on Procambarus (Pennides) gibbus Hobbs (Muckalee Crayfish), endemic to Georgia, Procambarus (Pennides) versutus Hagen (Sly Crayfish), which, although found in Alabama and Florida, has a limited range in Georgia, and Procambarus (Pennides) spiculifer LeConte (White Tubercled Crayfish), the most widespread Pennides species in the state. The Muckalee Crayfish was first described in 1968, having been previously identified as a variant of the White Tubercled Crayfish. Hobbs (1981) documented 210 specimens of this species from 13 sites from 1932 through 1972 (Fig.1). Eleven of these historical sites are in Muckalee Creek. One record is from Baker County and one from Crawford County; both sites are in tributaries of the Flint River, but the information in Hobbs (1981) is insufficient to locate the Baker County locality. Its current conservation status is one of special concern (Fetzner 2002). The Sly Crayfish was first described in 1870. Its range was predicted by Hobbs (1981) as being “from the Mobile River drainage in Alabama eastward to the Chattahoochee-Apalachicola drainage in Alabama, Florida, and Georgia.” Five specimens were listed in The Crayfishes of Georgia (Hobbs 1981). Until 1980, it was documented from only two locations in Georgia; one in Marion County, 11.4 miles (18.4 km) NNW of Buena Vista, GA on State Route 355; and the other in Muscogee County on Fort Benning Military Reservation (Fig. 1). Later sampling by Stanton and Lopez (1982) suggested that the Muscogee County location was actually in Chattahoochee County. Stanton (2006) reported that collections from Auburn University and Columbus State University added 28 additional localities in Chattahoochee and Marion counties for this species. In Georgia, the most widespread Pennides species is the White Tubercled Crayfish (Fig. 1). Its range surrounds those of the Muckalee Crayfish and the Sly Crayfish, including streams adjacent to locations where either the Muckalee Crayfish or the Sly Crayfish is found (Fetzner 2002, Hobbs 1981). Occasionally, it has been documented to co-occur with other Pennides species. Stanton (2006) has suggested that locations where two Pennides species occur sympatrically represent habitats in transition. Our objectives in this study were to compare habitats of these three sister species, looking for environmental differences that might account for their isolated distributions within Marion County and throughout the Southeast, as well as assess the conservation status of the Muckalee Crayfish and the Sly Crayfish. Since the White Tubercled Crayfish seems to be a “default” species occurring where neither the Muckalee Crayfish nor the Sly Crayfish is present, its habitat was compared to theirs. 2011 J. Chadwick and G.E. Stanton 535 Methods Prospective study sites were first identified using a United States Geological Survey 7.5-minute topographic map of Marion County and locating bridge crossings and historical sites documented by Stanton and Lopez (1982) and Hobbs (1981). At each accessible site identified in the county, we hand-netted (30-cm D-frame net) approximately 100 m of stream, upstream of any bridges, in order to determine species presence. Based on this preliminary survey Figure 1. Ranges of Procambarus (Pennides) species in Georgia and location of study area in Marion County, circled in west-central part of the state. Species in this study are indicated by the triangles in the legend (Δ). Illustration derived from Hobbs (1981). 536 Southeastern Naturalist Vol. 10, No. 3 Table 1. Locations of the nine study localities in Marion County, GA. Species sites Geographic locations GPS coordinates Site 1 (Procambarus gibbus) Muckalee Creek at Mt. Zion Road 32.26161N, 84.44858W Site 2 (P. gibbus) Muckalee Creek at Powell Road 32.24090N, 84.47646W Site 3 (P. gibbus) Muckalee Creek at Mt. Carmel Road 32.22680N, 84.45165W Site 4 (P. spiculifer) Lanahassee Creek at Bill Merritt Road 32.15560N, 84.47756W Site 5 (P. spiculifer) Lanahassee Creek at Mill Creek Road 32.23470N, 84.56007W Site 6 (P. spiculifer) Kinchafoonee Creek at Pineview Road 32.25640N, 84.57708W Site 7 (P. versutus) Pine Knot Creek at HWY 355 32.43921N, 84.64869W Site 8 (P. versutus) Juniper Creek at Anthony Road 32.51552N, 84.52466W Site 9 (P. versutus) Black Creek at HWY 240 32.54962N, 84.53298W Figure 2. Detail of the nine study sites in Marion County, GA (derived from information from the Georgia GIS Clearinghouse 2005). 2011 J. Chadwick and G.E. Stanton 537 of 40–50 sites, nine were selected for this study, consisting of three sites occupied by each species of crayfish (Table 1, Fig. 2). All study sites were established in 2nd or 3rd order streams at bridge crossings, where minimal visible human impact or impeded water flow was evident. All three Muckalee Crayfish sites were either on Muckalee Creek or its tributaries. Sly Crayfish sites were located in Pine Knot, Juniper, and Black creeks, while White Tubercled Crayfish sites were on the main branch of Kinchafoonee Creek and two Lanahassee Creek tributaries. Pine Knot, Juniper, and Black creeks are tributaries of the Chattahoochee River; whereas Muckalee, Kinchafoonee, and Lanahassee are tributaries of the Flint River (Fig. 2). Scouting and site selection were carried out in the spring of 2005, and voucher samples were collected and identified from each of the study sites, preserved in ethanol, and retained at Columbus State University. During June 2005 at the study’s onset, a one-time physical assessment was completed, including data on stream width, maximum depth, and flow rate along with information regarding adjacent land use and vegetation using EPA’s Rapid Bioassessment Protocols for Streams and Wadeable Rivers (Barber et al. 1999). To analyze streambed composition, a sample was collected randomly from the main channel at each site in June 2005, dried, weighed, and sieved, separating the gravel, course sand, and fine sand. Individual soil types were weighed, and a percentage of the total weight was calculated for each sample (Inman 1952). To measure total suspended solids, EPA 160.2 methodology was employed and water samples were poured through a glass fiber filter disc in a Gooch crucible with vacuum applied (USEPA 1999). Filters were dried in an oven at 103–105 °C for one hour, sediments were weighed, and percentages of dissolved material calculated from the total weight of each water sample (Inman 1952, NCASI 1977). Depth was measured at the deepest location in the channel at each sample location. Rate of flow was measured in June 2005 using a Swoffer 2100 current velocity meter. Measurements of water temperature, conductivity, alkalinity, pH, dissolved oxygen, and turbidity were collected every other month from June 2005 through April 2006 using a Hydrolab Surveyor 3 datasonde, taking a single sample from the approximate center of the stream at each site (9 sites x 6 readings = 54 readings for each parameter). To better understand the seasonal activity and life-history characteristics of these three species, we trapped at all nine sites from June 2005 through April 2006 using Trapper crayfish traps (Trapper Arne, Payson, AZ). This cylindrical trap measures 45.7 x 24.1 cm and is covered by vinyl hardware cloth with a 1.3- cm mesh. There are 5-cm funnel openings at each end, each fitted with a “crayfish escape stopper”. The middle of the trap has a crossbar, and the trap has a hinged side door for putting bait into and removing crayfish from the trap. At each site, three traps were baited with a small can of cat food with three holes punched in the top, and were tethered by parachute rope to roots, snags, branches, or other available structures on the stream bottom. Traps were left out continuously between June 2005 through April 2006, and were checked, and rebaited every 5 to 538 Southeastern Naturalist Vol. 10, No. 3 12 days. Each time they were cleared, traps were removed and reset near structure thought to provide crayfish shelter. Trapped crayfish were removed and returned to the stream; species, gender, and carapace lengths were recorded for each specimen. Over the trapping period (380 days), we checked the traps 49 times at one site and 48 times at the other eight. Physical and chemical data from the three sets of species’ associated sites were compared using ANOVAs in SPSS 15.0. Multivariate cluster analysis was used to determine relational similarities among the nine creek sites using pH, conductivity, temperature, dissolved oxygen, turbidity, and alkalinity in order to create a graphical tree diagram, where sites were linked according to aggregate similarity. Since trapping periods varied, we calculated daily catch rates (# of crayfish per 24 hrs), and aggregated these to obtain a weekly catch per unit effort (CPUE). We then averaged across sites and weekly sampling periods to report CPUEs on a month basis for each species (Fig. 3). A two-way ANOVA analyzed the log-transformed weekly mean values (ln [x +1]) across species and sample months. Means were compared with LSD pairwise comparisons. Figure 3. Catch per unit effort of Procambarus gibbus, P. spiculifer, and P. versutus calculated as weekly mean catch per trap averaged across sites and sampling weeks for each month of the study, May 2005 through May 2006. 2011 J. Chadwick and G.E. Stanton 539 Results Creek morphology One-time creek morphology metrics did not vary significantly among the habitats of the three crayfish species. Mean maximum depth ranged from 0.24 m at White Tubercled Crayfish streams to 0.39 m at Sly Crayfish streams and 0.48 m at Muckalee Crayfish sites. Mean stream width ranged from 5.72 m at Sly Crayfish sites to 6.83 m at White Tubercled Crayfish habitat and 7.54 m at Muckalee Crayfish sites. Similarly, mean floodplain width ranged from 7.97 m at Sly Crayfish sites to 14.5 m at White Tubercled Crayfish habitat to 15.2 m at Muckalee Crayfish sites. Mean water flow velocity ranged from 0.18 m/s at Muckalee Crayfi sh sites to 0.28 m/s at White Tubercled Crayfish habitat to 0.31 m/s at Sly Crayfish sites, but these were not significantly different. Benthic substrate analysis comparing the relative composition of gravel, coarse sand, fine sand, and clay-silt indicated significant differences among streams used by the three species (Table 2). Muckalee Crayfish substrates consisted of significantly greater proportions of gravel and coarse sand and a lower proportion of fine sand than did the other two habitats. Sly Crayfish streams had significantly lower proportions of clay and silt than did those of the other two species. Mean water flow velocity ranged from 0.18 m/s at Muckalee Crayfish sites to 0.28 m/s at White Tubercled Crayfish habitat to 0.31 m/s at Sly Crayfish sites, but were not significantly different. Water conditions Water temperature, dissolved oxygen, pH, conductivity, and turbidity were measured six times between June 2005 and April 2006 (Table 3). Water temperature and dissolved oxygen varied seasonally, but there were no significant differences among the three streams types (Fig. 4). Over the year, mean water temperature was 16.47 ºC for Muckalee Crayfish sites, 16.22 ºC for White Tubercled Crayfish sites, and 15.90 ºC for Sly Crayfish sites. Mean dissolved oxygen was 9.47 mg/L for Muckalee Crayfish habitats, 10.19 mg/L for White Tubercled Crayfish habitats, and 10.11 mg/L for Sly Crayfish habitats. Mean pH tended to be highest in winter months and lowest in either spring or summer, and was significantly lower at Sly Crayfish sites (4.97) than at Muckalee Crayfish sites Table 2. Mean percentages (± SE) of substrate constituents from stream habitats of three Procambarus (Pennides) species in Marion County, GA. Samples for P. gibbus were collected from Muckalee Creek at Mt. Zion Road, Powell Road, and Mt. Carmel Road. Those for P. spiculifer were taken from Lanahassee Creek at Bill Merritt Road and at Mill Creek Road and from Kinchafoonee Creek at Pineview Road. The samples for P. versutus came from Pine Knot Creek at WY 355, Juniper Creek at Anthony Road, and Black Creek at HWY 240. Mean values (within columns) with the superscript A are significantly greater (at P = 0.05) than values indicated by the superscript B. Crayfish species Gravel (%) Coarse sand (%) Fine sand (%) Clay/silt (%) P. gibbus 6.24 (± 1.92)A 15.28 (± 1.64)A 78.21 (± 3.39)B 0.27 (± 0.20)A P. spiculifer 0.70 (± 0.06)B 3.01 (± 1.80)B 95.88 (± 1.56)A 0.41 (± 0.30)A P. versutus 0.07 (± 0.06)B 1.92 (± 1.24)B 97.98 (± 1.30)A 0.03 (± 0.01)B 540 Southeastern Naturalist Vol. 10, No. 3 Figure 4. Mean water temperatures (a) and dissolved oxygen (b) levels from the one year survey averaged across sites (three sites per species) for the three crayfish species in Marion County, GA. 2011 J. Chadwick and G.E. Stanton 541 (6.54) or White Tubercled Crayfish sites (6.42) (Table 3). Specific conductivity measurements in Muckalee Crayfish habitats were significantly higher, at 0.06 uS/cm, relative to 0.03 uS/cm for White Tubercled Crayfish habitats and 0.02 uS/ cm for Sly Crayfish habitats (Table 3). Mean turbidity was significantly lower at Sly Crayfish sites (6.15 NTU) than at either Muckalee Crayfish sites (21.08 NTU) or White Tubercled Crayfish sites (22.70 NTU) (Table 3). To further assess relatedness of the study sites, a cluster analysis (Fig. 5) was constructed based upon the similarity of water attributes from the bimonthly measurements (Table 3). Sites inhabited by Sly Crayfish clustered together and were distinct from the other six sites. Sites inhabited by Muckalee Crayfish and White Tubercled Crayfish did not clearly segregate, sorting instead into three distinct groupings. Two of the Muckalee Crayfish sites (in the same tributary) were very similar. One White Tubercled Crayfish site was similar to a Muckalee Figure 5. Cluster analysis illustrating percent similarity across crayfish habitats based upon bimonthly water quality parameters. Brackets connect related streams. Table 3. Mean (± SE) water quality parameters across stream habitats used by the three Procambarus (Pennides) species in Marion County, GA measured bimonthly between June 2005 and April 2006. Samples for P. gibbus were collected from Muckalee Creek at Mt. Zion Road, Powell Road, and Mt. Carmel Road. Those for P. spiculifer were taken from Lanahassee Creek at Bill Merritt Road and at Mill Creek Road and from Kinchafoonee Creek at Pineview Road. The samples for P. versutus came from Pine Knot Creek at WY 355, Juniper Creek at Anthony Road, and Black Creek at HWY 240. Mean values (within columns) with the superscript A are significantly greater (at P = 0.05) than values indicated by the superscript B. Crayfish Water Dissolved Conductivity Turbidity species temperature (oC) oxygen (mg/l) pH (μS/cm) (NTO) P. gibbus 16.47 (± 2.50)A 9.47 (± 0.66)A 6.54 (± 0.17)A 0.06 (± 0.01)A 21.08 (± 4.39)A P. spiculifer 16.22 (± 2.50)A 10.19 (± 0.66)A 6.42 (± 0.17)A 0.03 (± 0.01)B 22.07 (± 4.39)A P. versutus 15.90 (± 2.50)A 10.11 (± 0.66)A 4.97 (± 0.17)B 0.02 (± 0.01)B 6.15 (± 4.39)B 542 Southeastern Naturalist Vol. 10, No. 3 Crayfish site, a second White Tubercled Crayfish site clustered with the other two Muckalee Crayfish sites, while the third White Tubercled site did not cluster with any other sites. Crayfish collections During the year of sampling, 124 Muckalee Crayfish specimens (96 males/28 females), 81 White Tubercled Crayfish specimens (57 males/24 females), and 83 Sly Crayfish specimens (62 males/21 females) were collected. Capture of females was uncommon during summer months. Muckalee Crayfish captures were most common during June and December, while White Tubercled Crayfish were most common from June through September (Fig. 3). Sly Crayfish were collected during every month of the year, except March, with little variation from month to month. The only nontarget crayfish species collected was Cambarus latimanus (LeConte); 11 were collected along with Sly Crayfish in December and January in Juniper and Black creeks. There was no significant difference between the mean catches of White Tubercled Crayfish and Sly Crayfish across sampling months. Mean catches of Muckalee Crayfish were significantly greater than for the other two species in May, June, and December of 2005, as well as in January of 2006. There was a significant spike in June 2005, and catches of males accounted for all four of these increases in catch. Mean carapace length of collected males was significantly larger than for females among Muckalee Crayfish and White Tubercled Crayfish. There was no significant difference among the mean carapace lengths of females of the three species. Male Sly Crayfish had a mean carapace length significantly smaller than did males of the other two species and female White Tubercled Crayfish (Table 4). Discussion We found both substrate and water chemistry differences among streams occupied by the three Procambarus spp. in Marion County, GA. Benthic substrates were distinct in Muckalee Crayfish streams, consisting of more gravel and coarse sand. White Tubercled Crayfish habitats displayed no unique characteristics. Since it is widely distributed throughout the state, it likely occupies a much broader variety of substrates. Based upon our survey in Marion County, White Tubercled Crayfish benthic habitat substrate was similar to that of Muckalee Table 4. Mean carapace length of female and male Procambarus spiculifer, P. gibbus, and P. versutus trapped from May 2005 through June 2006. Mean values with different superscripted letters are significantly different (at P = 0.05) from each other. Gender P. spiculifer P. gibbus P. versutus Female 3.87 (± 0.153)B 3.71 (± 0.160)BC 3.31 (± 0.181)BC Male 4.62 (± 0.153)A 4.49 (± 0.096)A 3.21 (± 0.096)C 2011 J. Chadwick and G.E. Stanton 543 Crayfish. Both habitat substrates were dominated by fine sands. Our sampling of this stream attribute was minimal, and we do not know if these substrate characteristics have a selective influence on these lotic crayfish species, but this environmental variable may merit further investigation. Radcliffe and DeVries (2004) did not find a link between substrate composition and distribution of crayfi sh species and reported that their method, similar to ours, may not have been sufficiently sensitive. Stewart et al. (2010) examined habitat selection by crayfish in streams of Southeastern Alabama, and reported that Sly Crayfish were found on sand in 96% of the samples taken from that habitat, while they were only collected from about 10% of the gravel substrate samples. Jordan et al. (1996) found that P. alleni (Faxon) collected from a wetland habitat in Florida did not show a preference for sandy substrate. Water chemistry in Sly Crayfish streams distinguished its habitat from those occupied by the other two species. The pH values in these streams are consistently lower than those measured in streams supporting the other two species, and would perhaps be considered stressful for many crayfish species. Unpublished data on survivorship in low pH indicated that at least White Tubercled Crayfish does not survive long in pH values encountered in Sly Crayfish habitats (G.E. Stanton, 2009 pers. observ.). Their habitats were also characterized by very low turbidity levels and low conductivity. Temperatures in the Sly Crayfish streams varied less than in the other two habitats throughout the year, being generally lower in the summer and higher in the winter. Dissolved oxygen, negatively correlated with water temperature, mirrored the annual temperature pattern, and was, consequently, also less variable throughout the year in Sly Crayfish habitat. Ratcliffe and DeVries (2004) found this species in sites with the lowest alkalinity and a relatively low pH (4.51) in the Tallapoosa River drainage. Their results correspond with ours for this species. The cluster analysis supports our conclusion that the habitat for Sly Crayfish is distinct from the other two species. We hypothesize that water conditions such as pH and conductivity are selective conditions for this species. Trapping data supported our expectation that these species of subgenus Pennides are present and active in streams throughout the year. The difference between CPUE in May 2005 and May 2006 suggests that either conditions were different between the two years or crayfish were developing trap avoidance. We are aware of no literature suggesting the latter. Carapace length data suggest that recruitment occurs in the spring, but too few small individuals were trapped to carry out meaningful analysis. Although the Muckalee Crayfish was most abundant in our study, its conservation status remains one of special concern, since it seems to be largely restricted to one stream system. Furthermore, in a survey of historic sites, it was not present in a number of these localities. Stanton’s (2006) sampling found populations in Muckalee headwaters north of Americus, GA and in Muckaloochee Creek and its tributaries, south of Americus. He did not find Muckalee Crayfish in eastern Muckalee tributaries south of Americus. It also appears that it has been extirpated from 544 Southeastern Naturalist Vol. 10, No. 3 the type locality on HWY 19 just north of Americus. The common element in sites where it was not found appears to be anthropogenic changes that resulted in decreased water velocity and increased siltation. Two historical sites have been reported from other streams, one in Baker County and the other in Crawford County, but these were not sampled during this study. Additional sampling of these sites, where individual populations of Muckalee Crayfish were recorded in the 1970s (Hobbs 1981), may reveal additional information concerning its conservation, habitat, and life history. However, Stanton (2006) has concluded that efforts to protect this species should focus on the Muckalee Creek watershed. A new concern is the introduction of Orconectes palmeri (Faxon) (Gray-speckled Crayfish) into the Flint River, where it appears to be replacing White Tubercled Crayfish between Albany, GA, and Lake Blackshear. Since Muckalee Creek enters the Flint in that reach of the river, the invasion of this species might be a serious threat (C.E. Skelton, Georgia College and State University, Milledgeville, GA, 2011 pers. comm.). In April 2009, the Georgia Department of Natural Resources (GADNR 2010) declared the conservation status of the Muckalee Crayfish to be “threatened”. Habitat protection will be critical for the future well being of this species. Hobbs (1981) stated that the White Tubercled Crayfish was the Muckalee Crayfish’s closest relative. He originally placed it in the “Spiculifer Group” of the genus, and later assigned it to subgenus Pennides. Our study indicated that the two species not only look similar, but their habitat attributes are also somewhat similar. They are currently listed as two separate species, but identification between the two can only be made by comparison of secondary sex characteristics of first-form males (Hobbs 1981). Genetic analyses are needed to clarify the degree of relatedness between these two species. Sly Crayfish have long been known to be unique to sandy, low-pH tributaries from the Mobile River drainage in Alabama eastward to the Chattahoochee- Apalachicola drainage in Alabama, Florida, and Georgia (Hobbs 1981). Our habitat assessments agree with this notion that this species is a habitat specialist. In Georgia, this consists of four streams: Pine Knot Creek, Juniper Creek, Ochillee Creek, and Oswichee Creek (Stanton 2006). Results from this study indicate that populations remain in Pine Knot, Ochillee, and Juniper creeks, but Stanton (2006) reported no specimens from Oswichee Creek in recent years, suggesting extirpation, perhaps a result of drought conditions in recent years. Bridge and highway construction have also impacted streams that have historically been home to Sly Crayfish, while extensive development of training areas for desert warfare have taken place in the Pine Knot catchment. Although this species is distributed across southern Alabama and the Florida panhandle, its distribution in Georgia is restricted to Chattahoochee and northern Marion counties (Stanton 2006), and its future in Georgia may be at risk. As of April 2009, the Sly Crayfi sh’s status is listed as “rare” (GADNR 2010), indicating that its habitat is in need of protection because of its scarcity. Much of the its habitat is located on the Fort Benning Military Reservation, which may result in greater protection, but also exposes those sites to unique threats. 2011 J. Chadwick and G.E. Stanton 545 Results of this study have extended our knowledge of the ecology of these three species and supports the addition of Muckalee Crayfish and Sly Crayfish to Georgia’s protected species list. Future studies are needed to improve our understanding of the biology and ecology of these two species and of the streams they inhabit. Acknowledgment Funding was provided through Columbus State University by the Georgia Department of Natural Resources and the US fish and Wildlife Service. Mr. Jon Haney assisted with figures. Literature Cited Barber, M.T., J. Gerritsen, B.D. Snyder, and J.B. Stribling. 1999. Rapid bioassessment protocols for use in streams and wadeable rivers: Periphyton, benthic macroinvertebrates and fish, second edition. EPA 841-B-99-002. US Environmental Protection Agency, Office of Water, Washington, DC. Creed, R.P., and J.M. Reed. 2004. Ecosystem engineering by crayfish in a head-water stream community. Journal of North American Bethological Society 23(2):224–236. 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Evaluation of conservation status of six west Georgia, Chattahoochee- Flint River crayfish species. Report to Georgia Department of Natural Resources, Georgia Natural Heritage Program, Atlanta, GA. 60 pp. Stanton, G.E., and P.T. Lopez. 1982. Descriptive demography of lotic crayfish (Cambaridae) inhabiting West-Central Georgia tributaries of the Chattahoochee River. Fifty-ninth annual meeting of the Georgia Academy of Science. Georgia Journal of Science 40:9. Statzer, B., O. Peltret, and S. Tomanova. 2003. Crayfish as geomorphic agents and ecosystem engineers: Effect of a biomass gradient on base flow and flood-induced transport of gravel and sand in experimental streams. Freshwater Biology 48:147–163. Stewart, P.M., J.M. Miller, W.H. Heath, and T.P. Simon. 2010. Macrohabitat partitioning of crayfish assemblages in wadable streams in the coastal plains of Southeastern Alabama. Southeastern Naturalist 9(Special Issue 3):245–256. US Environmental Protection Agency (USEPA). 1999. Method 160.2: Total Suspended Solids (TS) (Gravimetric, Dried at 103–105 °C). US Environmenal Protection Agency, Washington, DC.