The Natural Heritage Program of the Division of Parks and Recreation requests a grant to conduct inventories of uncommon crayfish in North Carolina over a 3-year period. In particular, surveys will be conducted for 21 species that may be in need of conservation. About half of these species occur in the mountains, while the other half occur in the coastal plains.
Crayfish play important
roles in aquatic and terrestrial ecosystems, both as food sources for many
animals and as consumers of plant and animal material. Crayfish are linked directly and indirectly
to the ecosystems in which they live. Because they are omnivorous (i.e., consume
both plant and animal food, living or dead), and because they are consumed by
animals from various trophic levels, crayfish form multiple links in aquatic
and terrestrial food webs (Lodge et al. 1994, Charlebois
and Lamberti 1996, Nystrom et al. 1996).
Thus, crayfish are involved in the transfer of large amounts of energy
in these systems. Crayfish process nutrients and make them available to
other animals by (1) breaking down large material via shredding into smaller
sizes, and (2) converting nutrients into biomass. Crayfish feed on aquatic vegetation (e.g., macrophytes, algae,
and periphyton), macroinvertebrates (e.g., aquatic insects, mollusks, small
crustaceans), and small vertebrates (e.g., amphibians, small/juvenile
fish). Crayfish also consume nonliving
organic matter such as leaf litter or terrestrial animal carcasses from the
riparian zone or shore and decaying aquatic plant and animal matter (Lodge and
Hill 1994). Crayfish in turn are
consumed by invertebrates (including other crayfish),
fish, amphibians, reptiles, birds, and mammals (Lodge and Hill 1994).
Crayfish perform an important role as a member of symbiosis with many
invertebrates and as host to various aquatic parasites (Lodge
and Hill 1994). Crayfish also
experience competition, both between species and among different sizes of
individuals within a population (Lodge and Hill 1994).
Despite the magnitude of their ecological roles, we have much to learn about crayfish distributions, life histories, and taxonomy. In the United States and Canada, approximately 350 taxa of crayfish are recognized (Taylor et al. 1996, J.E. Cooper, pers. comm.). However, many species still await description (J.E. Cooper, pers. comm.). For example, several current species are now recognized to be species complexes consisting of more than a single taxon. The greatest diversity of crayfishes occurs in the Southeast (Hobbs III 1991, Taylor et al. 1996), and North Carolina harbors at least 37 (possibly up to 46) native and 3 introduced species of Cambarus, Procambarus, Orconectes, and Fallicambarus (Cooper and Braswell 1995, J.E. Cooper, pers. comm.). Many of these species have naturally small native ranges and are therefore vulnerable to environmental change. About half of the described crayfishes in North Carolina are of undetermined conservation status due to a deficiency of data on the distribution and abundance of these animals. Additionally, there are perhaps as many as a dozen native species yet to be described (J.E. Cooper, pers. comm.). Of those species for which we have at least some information, the Scientific Council on Freshwater and Terrestrial Crustaceans suggests that 8 species be listed as significantly rare (suggested state special concern), and that 13 species be put on a watch list (Clamp 1999). These species and 3 newly described species (1 proposed special concern and 2 proposed watch list) are listed accordingly by the North Carolina Natural Heritage Program (LeGrand et al. 2001). Thus, at least 67% of the crayfishes occurring in North Carolina may need some form of protection. Other species have either recently been described or are currently under investigation, and it is too early to say whether these species should also be awarded protective status. New information about current distributions has recently been reported (Cooper and Braswell 1995, Cooper et al. 1998). Yet there are still many geographical gaps across the state where surveys have either not been conducted at all, or not thoroughly or recently. The proposed listing of certain crayfishes by the Scientific Council on Freshwater and Terrestrial Crustaceans (Clamp 1999) is a first step; the authors admit that these decisions have been made based on limited data and that more extensive surveys may provide new information that could alter the conservation of any of these species.
Because we have limited historical
data with which to compare current distributions, it is hard to determine
whether land-use practices and other effects of human actions (e.g.,
introductions of nonindigenous crayfishes) have negatively affected the
crayfish in North Carolina. However,
crayfish can be affected by both water and habitat quality. Changes in water quality that interfere with
respiration (e.g., drastic temperature changes, acidification, pollution) can
be detrimental to crayfish populations.
Many crayfish are oxygen regulators and can survive changes in oxygen
levels (Reiber 1995), but some are oxygen conformers and are less likely to
successfully contend with these changes (Hobbs III 1991). Water pollution, caused by sources such as
sewage, agricultural and urban runoff, acidification, and auto exhaust, can
result in bioaccumulation of pesticides and trace heavy metals (e.g., lead,
copper, and cadmium). This can harm
animals that consume crayfish in addition to directly causing negative effects
on crayfish (e.g., mutation, reproductive failure, death) (Taylor et al. 1995,
Daveikis and Alikham 1996, Anderson et al. 1997, Zaranko et al. 1997). Habitat destruction also can negatively
affect crayfish populations. Land use
practices (e.g., agriculture, logging, and development) can alter habitat
resulting in fewer areas available as shelter to crayfish (Smith et al. 1996,
Richter et al. 1997). For example,
siltation and runoff can decrease macrophyte (a source of food and shelter)
availability, and channelization can alter streambed sculpture. The introduction of non-indigenous
crayfishes to areas currently occupied by native crayfish can result in
competition or even extirpation of natives and can have impacts on other
components of the ecosystem (e.g., fishes, amphibians, macroinvertebrates,
macrophytes, and algae) (Charlebois and Lamberti 1996, Perry
1998, Lodge et al. 2000a).
Nonindigenous crayfishes can affect natives via competition, predation,
genetic dilution, and by serving as disease vectors. Further, introductions of nonindigenous crayfishes can enhance
the negative effects of environmental change on native species because
non-natives are often more tolerant to environmental degradation. Lodge et al. (2000a) consider nonindigenous
crayfish introductions to be the single greatest threat to native crayfish
biodiversity worldwide. In Europe,
nonindigenous crayfishes have contributed to serious declines and even local
extinctions of its 5 native species. In
several areas of North America, combinations of environmental degradation and
introductions of non-native crayfishes have led to declines in native species,
and to the extinction of at least one native crayfish in northern California
(Lodge et al. 2000a). During recent decades, at least 3 exotic crayfish species
have been introduced into North Carolina; therefore, we are concerned about
potential impacts to our ecosystems and native crayfish species. Based on species-specific hydrologic basin
distributions and what is known about habitat preferences of native crayfishes,
it may be possible to correlate crayfish distributions with anthropogenic
activities affecting water and stream quality.
Much of our information about the current status of crayfishes in North Carolina comes from previous surveys. Many of these surveys for crayfish were conducted as parts of larger inventories for multiple types of animals (e.g., State Parks, Game Lands, and county inventories conducted by NC Wildlife Resources Commission personnel; surveys for amphibians conducted by NC State Museum of Natural Sciences personnel; basin-wide water quality surveys conducted by Division of Water Quality personnel). Since the proposed project will be taxa specific, we should increase the quality of knowledge relative to (1) quantification, (2) substantial life history and ecology information, (3) seasonality, and (4) sufficient data on burrowing crayfish. Given that undescribed species exist and that we have much to learn about the distributions of crayfishes in North Carolina, it is imperative that we continue to improve our knowledge of crayfish by filling in the distributional gaps with further inventories.
We propose to carry out an extensive inventory for crayfish species occurring on the proposed special concern and watch lists in North Carolina. We will also collect information for all other crayfish taxa that we encounter during this statewide inventory. Because this inventory will be conducted solely for crayfish, methods specific to crayfish collection will be employed, and 100% of effort will be directed toward crayfish, thus increasing the quality of the data collected. This information will build upon data collected during previous surveys, and should give us a better understanding of crayfish in North Carolina.
Species occurring on the proposed special concern and watch lists, the species for which we will survey, are listed below. We will focus efforts on those species occurring on the special concern list. Each of these species either has an extremely limited range (see individual distribution maps) or is rare where it occurs. Several of these species are endemic to North Carolina. Certain species have been recently surveyed to some extent (e.g., Greensboro burrowing crayfish in 1993, Hiwassee headwaters crayfish and Hiwassee crayfish in 1994-5), but we could benefit from more extensive and more recent information. However, most effort will be spent surveying crayfishes about which we know the least.
Proposed Special Concern
Cambarus (Cambarus)
lenati (Broad River stream crayfish)
Cambarus (Depressicambarus) catagius (Greensboro
burrowing crayfish)*†
Cambarus
(Puncticambarus) chaugaensis (Oconee stream crayfish)
Cambarus
(Puncticambarus) georgiae (Little Tennessee River crayfish)
Cambarus
(Puncticambarus) parrishi (Hiwassee headwaters crayfish)
Cambarus
(Puncticambarus) spicatus (Broad River spiny crayfish)
Orconectes
(Crockerinus) virginiensis (Chowanoke crayfish)
Orconectes
(Procericambarus) carolinensis (North Carolina spiny crayfish)†
Procambarus
(Ortmannicus) braswelli (Waccamaw crayfish)†
Proposed Watch List
Cambarus
(Cambarus) davidi (Carolinda ladle crayfish)
Cambarus
(Cambarus) sp.
A (howardi?) (Chattahoochee crayfish)
Cambarus
(Hiaticambarus) chasmodactylus (New River crayfish)
Cambarus
(Jugicambarus) carolinus (red burrowing crayfish)*
Cambarus
(Jugicambarus) nodosus (Knotty burrowing crayfish)*
Cambarus
(Puncticambarus) hiwaseensis (Hiwassee crayfish)
Cambarus
(Puncticambarus) reburrus (French Broad River crayfish)†
Cambarus
(Tubericambarus) acanthura (spinytail crayfish)*
Orconectes
(Procericambarus) cristavarius (no common name)
Orconectes
(Procericambarus) spinosus (Tennessee River spiny crayfish)
Procambarus
(Ortmannicus ancylus (Edisto crayfish)
Procambarus
(Ortmannicus blandingii (Santee crayfish)
Procambarus
(Ortmannicus) medialis (Tar River crayfish)†
Procambarus
(Ortmannicus) pearsei (Sandhills crayfish)
Procambarus
(Ortmannicus) plumimanus (Croatan crayfish)†
*denotes primary burrower
†denotes endemic species
Those listed in red were added to the significantly rare
animal list by the NHP (LeGrand et al. 2001) after this project began.
For each of the target species, this project aims to (1) fill in gaps in the known distribution, (2) quantify abundance and size of each life history form collected per unit search time, (3) note specific habitats from which animals were collected (may differ temporally with life history form), (4) record species associates present and relative abundances, and (5) quantify seasonal and diel (night vs. day) differences. This information should provide a basis for decisions about protection status of each species inventoried.
In addition, we will record as much information as possible during these surveys for common species and species that were recently described or are currently under investigation. Further, we will record information about the 3 exotic species currently known to occur in North Carolina if/as we encounter each: Procambarus (Scapulicambarus) clarkii (red swamp crayfish), Orconectes (Gremicambarus) virilis (virile crayfish), and Orconectes (Procericambarus) rusticus (rusty crayfish). Any information gained will be useful for nonindigenous crayfish management (see Lodge et al. 2000b).
Inventories will be
conducted in areas where target species are suspected to occur (major arteries
and their tributaries, lakes/reservoirs, and floodplains). In addition, we will extend the search area
to define distribution perimeters.
Selected sites will be re-sampled seasonally. Methods will include (from most to least often used): (1)
walking, snorkel, or SCUBA (hand or net collection); (2) trapping (pitfall
traps and minnow traps, checked nightly); (3) digging from burrows; (4)
searches in streams and floodplains at night (with flashlights) and/or on rainy
days; (5) electrofishing. We will note relative efficiencies of
collection methods for each species. To maximize productivity, inventories
will be conducted statewide according to weather, stream, and lake conditions,
and scheduling of other projects. GPS
units will be used to precisely map all inventory areas, and the habitat conditions
at each site will be described. A
limited number of specimens of crayfish collected during this project will be
stored in 70% ethanol and maintained as part of reference collections owned by
the Nongame & Endangered Species Program or donated to the NC Museum of
Natural Sciences. If future taxonomy
studies need good samples for genetic testing, these specimens should be of
high enough quality to be used.
Further, many crayfish parasites (mostly ostracods) are proposed to be
listed as endangered, threatened, special concern, or put on a watch list
(Clamp 1999). Specimens of crayfish
collected during this inventory will be made available to persons interested in
examining them for commensals.
These data will be stored in an aquatic database maintained by the Nongame & Endangered Wildlife Program, and made available to other agencies (e.g., the Natural Heritage Program, NC Museum of Natural Sciences, and U.S. Fish and Wildlife Service). Reports containing analyses, GIS maps, and any survey limitations will be printed and made available to interested parties. Annual and final reports will be provided to the Natural Heritage Program. Personnel from the Wildlife Resources Commission’s Nongame Program will supervise the inventories and prepare the annual and final reports, and prepare data for incorporation into the Natural Heritage Program’s database.
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