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Recent advances in crayfish biology, ecology, and conservationAuthor(s): Brian Helms, Zachary J. Loughman, Bryan L. Brown and James StoeckelSource: Freshwater Science, 32(4):1273-1275. 2013.Published By: The Society for Freshwater ScienceDOI: http://dx.doi.org/10.1899/13-204.1URL: http://www.bioone.org/doi/full/10.1899/13-204.1

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Recent advances in crayfish biology, ecology, and conservation

Brian Helms1,5, Zachary J. Loughman2,6, Bryan L. Brown3,7,AND James Stoeckel4,8

1 Department of Biological Sciences, Auburn University, Auburn, Alabama 36849 USA2 Department of Natural Sciences and Mathematics, West Liberty University, West Liberty,

West Virginia 26074 USA3 Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg,

Virginia 24061 USA4 School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, Alabama 36849 USA

Crayfishes are familiar organisms that play integralroles in many freshwater ecosystems as a result of theirbiodiversity, abundance, or function (Momot 1995,Taylor et al. 2007). Considerable work has been focusedon the roles and ecological effects of introducedcrayfish, and increasing attention is being directed atunderstanding the distributions, life histories, phylog-enies, ecological roles, and conservation issues ofnative crayfish species. Progress also is being madetoward using crayfishes as model organisms. Thisspecial series of papers is an extension of nearly 30presentations given at a special session featuringstudies on crayfish biology, ecology, and conservationat the 2012 annual meeting of the Society forFreshwater Science in Louisville, Kentucky, USA. Thatsession highlighted many recent advances in astacol-ogy and brought together scientists at various careerstages and with differing perspectives to shareresearch, interact, and develop strategies for futureresearch and conservation endeavors.

A theme that became increasingly obvious duringthe session was the lack of basic natural-history andecological information for most native crayfishes,particularly in light of conservation and managementneeds. This predicament was reviewed by Moore etal. (2013). Their review is followed by several studieshighlighting various aspects of crayfish naturalhistory and ecology. Loughman et al. (2013) showedthat radio telemetry is a useful tool for shedding lighton the fine-scale movements of stream-dwellingcrayfish. Less-familiar predatory behaviors of crayfishare described in papers by Dorn (2013), who

investigated the nonconsumptive effects of crayfishon planorbid and physid snail populations in theFlorida Everglades, and Thomas and Taylor (2013),who studied crayfish predation on benthic fish (Etheos-toma spp.) in Illinois streams. The potential interplaybetween in-stream physical conditions and crayfishnatural history is described in 2 papers. Headwaterimpoundments and differing life-history strategiesinteract to influence seasonal crayfish assemblagestructure in low-gradient and typically incised streamsof northern Mississippi (Adams 2013), and in-streamconditions and stream connectivity to the floodplainaffect the distribution of crayfish burrows in Alabamafloodplains (Helms et al. 2013). Collectively, thesestudies provide insight into the nuances of crayfishnatural history and local assemblage structure and(perhaps more important) suggest the need for furtherinvestigation on understudied species.

Crayfish are hosts for multiple ectosymbionts, themost notable of which are clitellate annelid worms ofthe order Branchiobdellida. Historically, these wormswere considered commensal or sometimes parasitic,but recent work has shown that crayfish can benefitfrom this relationship, at least under certain environ-mental conditions. Skelton et al. (2013) reviewed whatwe know and, to a large extent, do not know about therelationship between branchiobdellids and their cray-fish hosts and discuss the potential use of this systemas a model for investigating symbioses in general.Their review is followed by a study of the influence ofenvironmental fouling and initial worm density onpartner regulation (i.e., crayfish grooming) by thecrayfish host and, ultimately, on worm reproductionand abundance on the host (Thomas et al. 2013).

The current distributions of crayfish are the result ofmultiple events from the near-past (e.g., nonnative

5 E-mail addresses: helmsbs@auburn.edu6 zloughman@westliberty.edu7 stonefly@vt.edu8 jas0018@auburn.edu

Freshwater Science, 2013, 32(4):1273–1275’ 2013 by The Society for Freshwater ScienceDOI: 10.1899/13-204.1Published Online: 22 October 2013

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introductions) and the far-past (biogeographic history).Crayfishes have become one of the most widelyintroduced freshwater taxa, and the ecological effectsof nonnative crayfishes are well documented (Lodge etal. 2012). Twardochleb et al. (2013) used meta-analysis tosynthesize quantitatively the results of studies of theeffects of nonnative crayfish conducted over a period of30 y. They concluded that existing ecosystem conditionsmay be more important than species identity indetermining the effects of introduced crayfish. Authorsof 2 case histories highlighted the need to understandthe poorly known natural histories of crayfishes if weare to explain and predict the effects of nonnativecrayfishes. Westhoff and Rabeni (2013) used passiveintegrated transponder (PIT) telemetry to investigatehabitat use, selection, and movements of the invaderOrconectes hylas and the native Orconectes quadruncus at afine spatial scale. They found little difference in habitatuse between the species and, thus, high potential forinterspecific competition. Perry et al. (2013) usedgeometric morphometrics to detect phenotypic plastic-ity in Orconectes rusticus in lakes and streams andsuggested that chelae shape may be an important traitfor deflecting flow and might influence the invasibilityof this species. Thus, studies of morphological plasticityin this species and others could be used to help predictinvasion rates or success. Parvulescu et al. (2013)analyzed the distributions of the oldest crayfish speciesin Europe (Austropotamobius torrentium) and proposedthat underground karstic water bodies afforded ecolog-ical refuge during at least one Pleistocene glaciation,from which this species then expanded.

Much remains to be learned, but significantprogress is being made toward a better understandingof crayfishes. The large gaps in our knowledge of thelife-history traits and ecological effects of the vastmajority of the world’s nearly 600 crayfish species arebeing filled. The use of crayfish as a model in studiesof symbiosis is still in its infancy but is growing.Nonnative crayfish continue to expand their ranges(and to be introduced), often with negative effects onnative systems, but our understanding of crayfishbiology and ecology in light of conservation isincreasing. We hope that the papers in this specialissue will be the stimulus for further investigations ofthe multiple roles of crayfish, the complexity of theirecological interactions, and their basic biology.

Acknowledgements

We thank Jim Fetzner and the InternationalAssociation of Astacology for financial support ofthe special session and a student award at the 2012annual meeting. We thank Editor Pamela Silver for

her help and encouragement and all of the anony-mous referees of the individual papers that made thisseries possible. This is contribution 691 to the AuburnUniversity Museum of Natural History.

Literature Cited

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HELMS, B., W. BUDNICK, P. PECORA, J. SKIPPER, E. KOSNICKI,J. FEMINELLA, AND J. STOECKEL. 2013. The influence of soiltype, congeneric cues, and floodplain connectivity onthe local distribution of the devil crayfish (Cambarusdiogenes Girard). Freshwater Science 32:1333–1344.

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MOMOT, W. T. 1995. Redefining the role of crayfish in aquaticecosystems. Reviews in Fisheries Science 3:33–63.

MOORE, M. J., R. J. DISTEFANO, AND E. R. LARSON. 2013. Anassessment of life-history studies for USA and Canadiancrayfishes: identifying biases and knowledge gaps toimprove conservation and management. FreshwaterScience 32:1276–1287.

PARVULESCU, L., C. ZAHARIA, A. SATMARI, AND L. DRAGUT. 2013.Is the distribution pattern of the stone crayfish in theCarpathians related to karstic refugia from Pleistoceneglaciations? Freshwater Science 32:1410–1419.

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R. KUHNKE. 2013. Effects of water velocity on the sizeand shape of rusty crayfish, Orconectes rusticus. Fresh-water Science 32:1398–1409.

SKELTON, J., K. J. FARRELL, R. P. CREED, B. W. WILLIAMS,C. AMES, B. S. HELMS, J. STOECKEL, AND B. L. BROWN. 2013.Servants, scoundrels, and hitchhikers: our currentunderstanding of the complex interactions betweencrayfish and their ectosymbiotic worms (Branchiobdel-lida). Freshwater Science 32:1345–1357.

TAYLOR, C. A., G. A. SCHUSTER, J. E. COOPER, R. J. DISTEFANO,A. G. EVERSOLE, P. HAMR, H. H. HOBBS, H. W. ROBISON,C. E. SKELTON, AND R. F. THOMA. 2007. A reassessment ofthe conservation status of crayfishes of the United Statesand Canada after 10+ years of increased awareness.Fisheries 32:372–389.

THOMAS, C. L., AND C. A. TAYLOR. 2013. Scavenger or predator?Examining a potential predator–prey relationship

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between crayfish and benthic fish in stream food webs.Freshwater Science 32:1309–1317.

THOMAS, M. J., R. P. CREED, AND B. L. BROWN. 2013. The effectsof environmental context and initial density on symbi-ont populations in a freshwater cleaning symbiosis.Freshwater Science 32:1358–1366.

TWARDOCHLEB, L. A., J. D. OLDEN, AND E. R. LARSON. 2013.A global meta-analysis of the ecological impactsof nonnative crayfish. Freshwater Science 32:1367–1382.

WESTHOFF, J. T., AND C. F. RABENI. 2013. Resource selection andspace use of a native and an invasive crayfish: evidence forcompetitive exclusion? Freshwater Science 32:1383–1397.

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