Conservation, Biology, and Natural History of Crayfishes from the Southern US
2010 Southeastern Naturalist 9(Special Issue 3):1–10
Foreword
Zachary J. Loughman, Thomas P. Simon, and Stuart A. Welsh
During the last several decades, declines in crayfish diversity have generated
an increased interest in the conservation and management of freshwater
crayfishes. The crayfish fauna of North America is represented by two families:
Astacidae, with one genus on the Pacific slope, and Cambaridae, with
12 genera east of the Rocky Mountains. Cambaridae is a diverse family (over
500 species and subspecies), reaching its highest diversity within the southeastern
United States. This center of crayfish diversity has become a center
of conservation concern. Extirpation and declines of crayfish populations
have resulted in an imperiled southeastern crayfish fauna. Crayfish conservation
efforts are often constrained because the biology and natural history of
many species are poorly understood.
To encourage and synthesize crayfish research, a symposium was held at
the 2008 annual meeting of the Southern Division of the American Fisheries
Society in Wheeling, WV. Symposium presentations (n = 23) are represented
in this special issue as peer-reviewed research papers or as the original
symposium abstracts (Appendix 1). The research papers within this volume
represent the Symposium’s initial emphasis on conservation, biology, and natural
history of southeastern crayfishes. This symposium attracted the attention
of researchers from a wider geographic region than that of the southeastern US
(Fig. 1); hence, this proceedings reflects a broader geographic emphasis.
The conservation of crayfishes would benefit from additional studies of
geographic distributions and taxonomy. Species inventory studies can provide
valuable distribution information for conservation and management of
crayfishes. Further, studies of species inventory, morphology, and genetics
lead to the discovery and description of new taxa. This volume includes information
on crayfish distributions in Alabama, Arkansas, Georgia, Indiana,
Maryland, Missouri, North Carolina, and West Virginia.
Crayfishes are critical components of aquatic and terrestrial communities
and ecosystems. Crayfishes are important prey species (Stein 1977), omnivores
and predators (Nystrom 2002), shredder-collector facilitators (Heard
and Richardson 1995), bioturbators (Usio and Townsend 2004), bioprocessors
of vegetation and carrion (Taylor et al. 2007), geomorphic agents and
ecosystem engineers (Statzner et al. 2000), and keystone species (Holdich
2002). These roles reflect the importance of crayfishes at community and
ecosystem levels in various ecological systems, but these roles are often underemphasized
and poorly understood (Momot 1995). The losses of crayfish
diversity by population extirpation and geographic range reduction have altered
community and ecosystem function. Some contributions of crayfishes
to communities and ecosystems are noted in this volume.
2 Southeastern Naturalist Vol. 9, Special Issue 3
Figure 1. Participants of the crayfish symposium of the Southern Division American Fisheries Society Meeting, Wheeling, WV, 28 February–
2 March 2008. Front row (kneeling); Sully Stocker, Jay Kilian, Casey Swecker, Tom Jones, Jacob Westhoff, Tom Simon, Jeff Simmons,
Bob Distefano, Tyler Black. Back Row (standing); Whitney Stocker, Jim Fetzner, Matt Ashton, Casey Dillman, Brian Wagner, Roger Thoma,
Guenter Schuster, Shane Welch, Jake Burskey, Nicole Garrison, Chris Skelton, Chris Taylor, Zac Loughman, and Stuart Welsh.
2010 Foreword 3
Crayfish biodiversity reaches its highest levels globally in the
southeastern United States. Two regions in particular, the Appalachian
Mountains and coastal plain swamps, harbor the majority of this diversity.
In both of these regions, speciation events occurred frequently as crayfishes
colonized these regions and became isolated. Following speciation,
the majority of taxa did not radiate into additional watersheds, becoming
specialized to the environmental theaters unique to single watersheds. This
endemism lends itself to conservation issues. Given their limited natural
ranges, endemic species are vulnerable to environmental perturbations.
A major threat for all crayfishes is the introduction of non-native crayfishes (Lodge et al. 2000). Non-native crayfishes have often been labeled as
“invasive” and, in some cases, led to the extirpation of native species. In this
volume, effects of non-native species are noted in most papers on geographic
distributions, and are the main focus of two papers.
An improved understanding of the natural history of crayfish species
is a critical need. Life-history parameters and behaviors are poorly understood.
For most species, basic life-history parameters are unknown for size
at sexual maturity, egg diameter, clutch size, embryonic and instar growth,
post-instar growth, seasonality of breeding, and rates of fecundity and mortality.
Conservation efficiency is hindered drastically for these animals if
this information remains unknown. A major emphasis of this special issue is
natural history, with 6 papers focusing on elucidating the natural history and
behavioral ecology of a diverse array of species.
Further research at population, community, and ecosystem levels will
provide important and useful information for the management and conservation
of crayfishes. An understanding of the biology and natural history of
crayfishes is critical for crayfish conservation, but information needs are too
complex to cover in a single symposium. As editors and astacologists, we
hope that this special issue will act as a springboard for future symposia on
crayfishes, since conservation concerns and the complexity of crayfish issues
will benefit from research and collaboration.
Literature Cited
Heard, S.B., and J.S. Richardson. 1995. Shredder-collector facilitation in stream
detrital food webs: Is there enough evidence? Oikos 72:359–366.
Holdich, D.M. 2002. Chapter 1. Background and functional morphology. Pp. 3–29,
In D.M. Holdich (Ed.). Biology of Freshwater Crayfish, Blackwell Science, Oxford,
UK. 702 pp.
Lodge, D.M., C.A. Taylor, D.M. Holdich, and J. Skurdal. 2000. Nonindigenous crayfishes threaten North American freshwater biodiversity: Lessons from Europe.
Fisheries 25(8):7–20.
Momot, W.T. 1995. Redefining the role of crayfish in aquatic ecosystems. Reviews
in Fisheries Science 3:33–63.
Nystrom, P. 2002. Ecology. Pp. 192–235, In D.M. Holdich (Ed.). Biology of Freshwater
Crayfish, Blackwell Science, Oxford, UK. 702 pp.
4 Southeastern Naturalist Vol. 9, Special Issue 3
Statzner, B., E. Fievet, J.Y. Champagne, R. Morel, and E. Herouin. 2000. Crayfish
as geomorphic agents and ecosystem engineers: Biological behavior affects
sand and gravel erosion in experimental streams. Limnology and Oceanography
45:1030–1040.
Stein, R.A. 1977. Selective predation, optimal foraging, and the predator-prey interaction
between fish and crayfish. Ecology 58:1237–1253.
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 awareness. Fisheries 32:372–389.
Usio, N., and C.R. Townsend. 2004. Roles of crayfish: Consequences of predation
and bioturbation for stream invertebrates. Ecology 85:807–822.
2010 Foreword 5
Appendix 1. Abstracts that were not submitted as manuscripts, but were presented at
the 2008 crayfish symposium, Southern Division American Fisheries Society meeting,
Wheeling, WV.
Crayfishes of Alabama—What We Do and Don't Know?
Schuster*, G.A., Eastern Kentucky University, Richmond, KY; C.A. Taylor, Illinois
Natural History Survey, Champaign, IL; and J.W. Johansen, Tulane University, New
Orleans, LA; *Corresponding author - guenter.schuster@eku.edu.
As a first step toward elucidating the current status of Alabama’s crayfish
fauna, museums known to have significant crayfish collections were queried for
their holdings from that state. A total of 4649 records of Alabama crayfishes were
obtained from seven museums, of which 330 did not have enough information to be
geo-referenced. The largest holdings were found in the National Museum of Natural
History (2544 records). Specimen identifications were verified, and once verified,
all records were geo-referenced. Geographic distribution strongly favored upland
drainages in the northern and central portions of the state. The Tennessee River
drainage was the single most- collected (1018 records, 23.6% of records) drainage.
A total of 85 species of crayfishes are reported for the state of Alabama; only Orconectes
virilis is deemed to be non-native. Even with the total number of crayfish
records in museums, there is a need for crayfish inventory work in Alabama. Of all
the records, a total of 3107 (76.3%) were collected prior to 1987, and 1379 (33.8%)
were collected prior to 1970. In addition, there is a paucity of records from the
coastal drainages of SE Alabama. There is also an under-representation of burrowing
crayfishes, primarily those classified as either primary or secondary burrowers.
Only 212 (4.9%) of all records are of burrowing species. Lastly, a limited amount
of field work in Alabama has documented the presence of a species previously unreported
for the state.
The Crayfishes of the Ohio River
Jones*, T.G., C. Swecker, and K. Donahue; Marshall University, Department of Integrated
Science and Technology Huntington, WV; *Corresponding author - jonest@
marshall.edu.
Very little is known about crayfishes in large rivers. Biological impacts and
habitat alterations have resulted from pollution and maintenance of navigation
channels. Since the Clean Water Act, improvements in water chemistry and possibly
habitat have opened large rivers for re-colonization or expansion of refugia
populations of aquatic species. In particular, segments of the Ohio River have seen
significant improvements in water chemistry, habitats, and biological condition.
Most crayfish biologists have ignored large rivers due to their perceived impacts,
including lack of suitable habitat, high predator rates, and the difficulties in
sampling. A series of projects from recent years has led to the sampling of the Ohio
River from Pittsburg, PA to Cario, IL. We have sampled using a series of techniques
including bank searches and SCUBA transects. From the mouth of the Muskingum
River upstream, two native species occur in the mainstem. Orconectes obscurus accounts
for 99% of the specimens in our collections. The invasive O. rusticus is the
only crayfish we have found downstream from the Muskingum to Smithland Pool.
In the Smithland pool, O. palicidus and O. rusticus occur. Further downstream, in
6 Southeastern Naturalist Vol. 9, Special Issue 3
pools 52 and 53, O. palicidus, O. pardalotus, and Cambarus rusticiformis were all
collected. The dominance of O. rusticus in almost 700 miles of the Ohio River mainstem
may mean the recently identified O. pardalotus could face extirpation. Invasion
from downstream O. rusticus may jeopardize other Orconectid natives including the
federally listed O. jeffersoni.
The Conservation Status of Three Rare Crayfish Species in Southwest Virginia
Thoma, R.F., Ohio University, Voinovich Center for Leadership and Public Affairs,
Athens, OH; bartonii@roadrunner.com.
Southwestern Virginia houses parts of the headwaters of three major North
American river systems, the Tennessee, Ohio, and New. In these basins are found
many rare and endemic species of aquatic organisms. Fishes, bivalves, snails, and
crayfishes all have rare and endemic faunal components in the area. This paper presents
the current results of a multi-year study of three crayfish species, Cambarus veteranus,
Cambarus jezerinaci, and an undescribed species of Cambarus. Ranges for
the species are well known within the state. Life histories, food preferences, habitat
quality, and abundances are being determined. Of the three taxa, Cambarus veteranus
is currently the most imperiled. At least one additional taxon with a highly restricted
range has been discovered. This new species illustrates a significant problem for
crayfish conservation in that many undescribed taxa in the Appalachian region are
yet to be named and given conservation status. Currently, though insufficient and
declining, moneys are available for studying known species, but funds are not available
to resolve the many imperiled undescribed species. In addition, the purposeful
underfunding of the USFWS's endangered species efforts forms a near insurmountable
impediment to crayfish conservation efforts.
Status and Distribution of the Rusty Gravedigger, Cambarus miltus: A Case of
Recovery or Neglect?
Taylor*, C.A., Illinois Natural History Survey Champaign, IL; and G.A. Schuster,
Department of Biological Sciences Eastern Kentucky University Richmond, KY;
*Corresponding author - ctaylor@mail.inhs.uiuc.edu.
The primary burrowing Rusty Gravedigger, Cambarus miltus , is a narrowly
endemic species formerly known only from Baldwin County, AL. In an effort to
determine if listing under the Endangered Species Act is warranted, field surveys
were conducted across portions of southern Alabama and western Florida. Our efforts
have revealed the presence of new populations of the species and added to our
knowledge of it’s habitat preferences. Historical field efforts and resulting literature
are also discussed.
Status of Crayfish in Indiana
Simon, T.P., Bloomington, IN; Thomas_Simon@juno.com.
The number of crayfish inhabiting Indiana includes 23 species. Primary burrowers
are represented by four species, secondary burrowers by eight species, and
tertiary burrowers by eleven species. Six checklists have been historically compiled
for crayfish within Indiana; however, little is known about species distributions.
2010 Foreword 7
From the period between 1891 and 1955, only ten crayfish species were documented
and significant confusion existed in our understanding of species distribution,
identity, and biology. Most early studies (less than 1950) were focused on the “blind” cave
crayfish of the Orconectes inermis complex. Descriptions of O. inermis inermis, O.
pellucidus, and O. inermis testii have caused confusion over the status of O. inermis
testii. Orconectes indianensis was studied and found to be stable, while conservation
efforts are needed for two species. Significant efforts on species distribution have
been accomplished. Prior to 1980, less than 150 sites were studied, with most done
in caves and a few watersheds in northern Indiana. During 1980–1995, nearly 3000
collections were made statewide. Since 1995, intensive watershed surveys resulted
in over 2000 sites. Another study included 675 sites that focused on the distribution
and ecology of burrowing crayfish species, while additional intensive investigations
collected 1080 sites in southern Indiana. Two new species have been described
including Cambarus (Tubericambarus) polychromatus and Orconectes (Procericambarus)
theaphionensis. Life-history studies have been initiated for all crayfish
species, which will provide new information on preferred habitat, reproductive biology,
age, growth, and diet. Additional species are pending formal description once
distributions are known. A minimum of an additional eleven species will be added to
the list of crayfish occurring in Indiana. Another two species are hypothetical in occurrence,
while hypothetical species considered in the most recent checklist have all
been confirmed statewide. It is possible that the actual number of crayfish occurring
in Indiana may reach or exceed 36 species.
Invasive Crayfishes of the New/Kanawha River System in West Virginia and a
Comparison of Large River Collection Techniques
Casey*, C.D., and T.J. Jones, Marshall University, Department of Integrated Science
and Technology Huntington, WV; *Corresponding author - Swecker4@marshall.edu.
There are six species of orconectid crayfishes historically recorded from West
Virginia. Orconectes rusticus and Orconectes virilis are both non-native invasives.
In 1978, researchers found a small population of O. rusticus in Fourpole creek in
Huntington, WV and a second population on the Kanawha River. Orconectes virilis
is historically known from the far eastern panhandle, and limited sites in the
New/Kanawha River valley. Recent collections are locating a broader distribution
of both species. This study focuses on New/Kanawha River from Bluestone Lake
to the Ohio River. Currently there is no consensus on the best means for collecting
crayfishes from large rivers. During this project SCUBA provided the easiest
means of collecting crayfish from the Kanawha River and deep sections of the New
River. Seining proved the best means of collecting in backwater areas and shallow
portions of the New River. Underwater transects, pivot searches, meter surber
samples, and other techniques were utilized to find the most efficient method for
collecting crayfish in a large river environment. The resulting efforts suggest that
O. rusticus is the dominant crayfish in the Kanawha River mainstem with O. virilis
being the dominate orconectid species in the New River mainstem. Significant expansion
of these two invasives in the New/Kanawha system, Ohio River, and other
streams in West Virginia warrant greater attention by regulatory agencies, educators,
and researchers.
8 Southeastern Naturalist Vol. 9, Special Issue 3
Preliminary Results of a Multi-year Survey to Monitor Orconectes rusticus, a
Recent Invader of Maryland
Ashton*, M.J., J. Gerber, J.V. Kilian, and A.J. Becker; Maryland Department of Natural
Resources, Monitoring and Non-titdal Assessment, Annapolis, MD; *Corresponding
author - mashton@dnr.state.md.us.
In June 2007, Orconectes rusticus (Rusty Crayfish) was discovered in a tributary
to the Monocacy River, Maryland. Following this discovery, the Maryland
Department of Natural Resources joined with local government and academic
institutions to begin a multi-year survey of O. rusticus throughout the Monocacy
River watershed. Our goals were to: 1) determine the distribution of O. rusticus
and other crayfish species and 2) establish baseline data to examine the effects of
O. rusticus on native crayfishes in the Monocacy River. We surveyed at all bridge
crossings (n = 21) on the Monocacy mainstem and tributaries. We collected O.
rusticus (n = 464) from the six furthest upstream sites. They were the most abundant
species (mean relative abundance ± SE = 0.86 ± 0.07) at five of those sites.
Orconectes virilis composed nearly the entire crayfish community (0.98 ± 0.02) at
nine sites within the middle portion of the river. The native O. obscurus was the
predominant species (0.68 ± 0.06) at the lower seven sites. At 27 of 29 tributary
sites sampled, O. virilis was the only species present. Non-native species were encountered
throughout most of the watershed. A distinct pattern of species replacement
by non-natives was evident in the Monocacy River. Only a few sites existed
where species coexisted in similar relative abundance. Orconectes rusticus has become
established throughout the upper 18 km of the Monocacy River in Maryland.
If dispersal becomes evident, we hope to document changes in species distribution
and community composition.
Differential Production of Procambarus troglodytes Across a Large River Floodplain
in South Carolina
Welch*, S.M., and A.G. Eversole; Clemson University, Clemson, SC; *Corrsponding
author - shanemwelch@gmail.com.
The distribution of the freshwater crayfish Procambarus troglodytes is limited
to parts of South Carolina and Georgia, where it inhabits floodplains. The species
reproduces in association with flood pulses that seasonally inundate the habitat. We
repeatedly sampled P. troglodytes at three sites within each of five landscape patch
types. Crayfish were sexed, measured, and released. Frequency histograms of crayfish
class intervals were visually inspected and used to identify cohorts. Seasonal
shifts in cohorts, field observations of water depths at sampled sites, and historical
flood patterns were used to infer the life cycle of P. troglodytes at the Congaree
National Park in South Carolina. Changes in biomass within sampled locations
were used to estimate production, which was then compared across the 5 landscape
patch types. Procambarus troglodytes had an annual recruitment that coincided
with the flood pulse. Production varied across the landscape, with shallower, more
ephemeral habitats exhibiting highest production. The study highlights the importance
of maintaining the spatial and temporal heterogeneity associated with river
flood pulses.
2010 Foreword 9
Microhabitat Characterization of the Nashville Crayfish (Orconectes shoupi) in
Mill Creek Watershed, Tennessee
Walton*, C.F., and S.B. Cook; Tennessee Technological University, Department of
Biology, Cookeville, TN; *Corresponding author - cfwalton21@gmail.com.
The Nashville crayfish (Orconectes shoupi) is one of four federally listed endangered
crayfish in the United States and the only one occurring in Tennessee. Orconectes
shoupi is endemic to the Mill Creek watershed, which is located in the southwest portion
of Nashville, TN in Williamson and Davidson counties. This watershed drains
approximately 280 km2 within the Nashville Basin. The objectives for this study were
to: (1) identify seasonal micro-habitat variables influencing habitat utilization, and
(2) develop a predictive habitat model. Fifteen 200-m long sites were sampled throughout
the Mill Creek watershed during the spring, summer, fall, and winter of 2007.
Within each 200-m site, 11 transects perpendicular to flow were established at 20-m
intervals. Random points along each transect were sampled with a 0.25-m2 quadrate
sampler and 10 microhabitat variables were measured at each point. Logistic regression
was used to model Nashville crayfish presence/absence as a function of one or
more of these habitat variables. Currently, the Nashville Crayfish population appears
stable, but because the species is endemic to Mill Creek watershed, which is increasingly
undergoing urbanization, this status could change. Hopefully, models generated
from this study will be helpful in maintaining and protecting this species.
A Recreational Fishery for Longpincered Crayfish (Orconectes longidigitus) in
Table Rock Reservoir, Missouri: Effects of Season and Environmental Factors
on Trapping
DiStefano*, R.J., M.E. Litvan, and K.J. Walker; Missouri Department of Conservation,
Columbia, MO; *Corresponding author - Bob.DiStefano@mdc.mo.gov
Longpincered Crayfish (Orconectes longidigitus), native to the White River
drainage of Missouri and Arkansas, are among the largest crayfishes in North
America, and a recreational fishery for them is becoming increasingly popular at
Table Rock Reservoir in southwest Missouri. Possession of a Missouri fishing license
allows harvest of 150 crayfish/day with an unlimited number of baited traps. This
unusual North American fishery represents a unique opportunity for recreationalists
and resource managers. However, no information exists concerning this crayfish's
life history, ability to sustain exploitation, or how it may be effectively sampled by
biologists. Our objectives were to determine if baited trap catch rates and sex ratios
of captured Longpincered Crayfish vary among seasons and depth, and if they are
affected by selected environmental variables. From September 2006 through September
2007, we sampled monthly at two sites representing two habitat types. At
each site, 20 traps were deployed along transects at each of three depths (0–2 m, 6–8
m, 11–13 m). Temperature loggers were deployed with each trap line, and vertical
temperature and dissolved oxygen profiles were obtained at each site. SCUBA was
used to obtain substrate composition estimates. Crayfish catch rates were highest in
autumn and late spring, low in winter, and generally higher at the gently sloping cove
habitat site than the steeply sloping ledge site. Dissolved oxygen, temperature, and
reservoir stratification/mixing appeared to influence catch rates at various depths.
Results will be used to design future studies to determine effects of crayfish exploitation
and ultimately address the potential need for modified regulations.
10 Southeastern Naturalist Vol. 9, Special Issue 3
Implementation of a Spatial-Temporal Focus to Predict Habitat Locations and
Distribution of Cambarus veteranus
Jones*, T.G., and K.B. Channell; Marshall University, Department of Integrated Science
and Technology Huntington, WV; *Corresponding author - jonest@marshall.
edu
Statewide surveys in 1988 and 1989 found forty-nine Cambarus veteranus from
only eight locations in the Upper Guyandotte watershed, WV. A pristine stream is
speculated as the ideal habitat, yet, the upper Guyandotte is known for its extensive
habitat alteration due to extractive industry. Current highway construction now intrudes
on C. veteranus territory. Already, thirty-eight percent of all streams in the
Upper Guyandotte River drainage are classified as impaired including C. veteranus’
type locality, Indian Creek, Wyoming County, WV. This impairment plays a role in
the creation of habitat patches. Finding suitable habitat is advanced with the use of
a geographic information system (GIS). Historical and current biological data provide
the baseline validation values for suitable habitat and prediction models. The
final suitability map shows optimum habitat locations for C. veteranus in the Upper
Guyandotte by means of ArcMap® 8.1 thematic maps and spatial and geostatistical
analysis. Final analysis reduced the potential search area, yet ground verification
produced no updates for C. veteranus.
Comparative Ecology of Orconectes (C.) obscurus and Cambarus (C.) b. bartonii
in the Cacapon River Basin, West Virginia
Garrison, N.L., West Liberty University, West Liberty, WV; ngarrison@westliberty.
edu.
Hobbs described three discrete crayfish behavioral groups based upon a species’
propensity to burrow. Two of these groups, secondary and tertiary burrowers, were
examined in this study which elucidated differences in abiotic variable use between
two sympatric, behaviorally distinct crayfish. Orconectes (C.) obscurus, a tertiary
burrower, and Cambarus (C.) bartonii, a secondary burrower were used as models for
their respective behavioral groups. A randomized group of forty 150-m stream reaches
were selected by GIS for each sub-basin of the Cacapon River basin within West
Virginia. Of the potential sites, 55 were chosen and surveyed in order to calculate
catch-per-unit-effort values for each species at each site. Abiotic variables were also
recorded at each site and included dissolved oxygen, pH, water temperature, stream
order, hydroperiod, and stream gradient. Correlations were determined between
CPUE and each abiotic variable to determine variable importance for each species.
Results indicated that Orconectes (C.) obscurus prefers high-ordered streams and
rivers and Cambarus (C.) b. bartonii is better suited for smaller order streams and
headwater systems. High gradient, low stream order, and complete drawdown limit
the distribution of Orconectes (C.) obscurus within the basin. Cambarus (C.) b.
bartonii is limited by the presence of O. (C.) obscurus and large stream orders. Physiochemical
variables such as dissolved oxygen, pH, and temperature did not have an
impact on either species’ distribution.