Javier Diéguez-Uribeondo

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Knowledge and Management of Aquatic Ecosystems (2009) 394-395, 02 http://www.kmae-journal.orgc  ONEMA, 2010DOI: 10.1051/kmae/2010004Opinion paperCurrent techniques, approaches and knowledgein diagnosis of crayﬁsh plague and other crayﬁsh diseasesRound table 3 (chairman: Javier Diéguez-Uribeondo)Javier Diéguez-Uribeondo(1)Received November 11, 2009 / Reçu le 11 novembre 2009Accepted January 7, 2010 / Accepté le 7 janvier 2010Crayﬁsh diseases are one of the main causes of crayﬁsh decline in Europe and speciﬁcally,crayﬁshplague (Edgertonet al., 2004).Knowledge of its causativeagent,Aphanomyces astaci(Oomycetes), is still one of the crucial key aspects in crayﬁsh management, and design-ing and implementing action plans for restoring the European indigenous crayﬁsh species(ICS). In the Regional European Crayﬁsh Workshop dealing with the Future of Native Crayﬁshin Europe held in Pisek, Czech Republic, a number of researchers joined a round table fo-cused on crayﬁsh diseases, and discussed the main problems and needs in crayﬁsh diseasestudies. The data discussed only refer to the countries represented in this group discussion(Czech Republic, Estonia, Finland, France, Italy, Spain and Sweden) and the main topics arediscussed next.CRAYFISH PLAGUE: CURRENT SITUATION AND ACTIONS IN EUROPEThe situation and actions among European countries regarding the impact, monitoring, con-trol and diagnosis of this disease are diverse. This is mainly due to: (1) the distinct presence,distribution and spread of non-indigenous crayﬁsh species (NICS), and (2) the existence ornot of crayﬁsh plague specialists and ongoing research on this matter.In each country, the number of detected and diagnosed mortalities due to crayﬁsh plaguevaries from a couple of cases to a dozen cases per year. Thus, in Finland, Spain, Swedenand Estonia the number of crayﬁsh plague cases diagnosed is around 10 per year, in theCzech Republic from 5 to 8 per year, in France around 2 per year, and a recently reportedcase in Italy. The number of cases does not appear to be related to actual status but ratherto the intensity of research carried out.In general, crayﬁsh mass mortalities are detected by chance and the correct diagnosis de-pends on whether they are reported, and whether there is an available laboratory with skillsin A. astaci identiﬁcation. In some countries, there are laboratories with specialists wheresamples can be routinely sent and where established protocols for collecting and submittingsamples exist, i.e., Czech Republic, Finland, Sweden and Spain.In this round table, researchers pointed out the active presence of crayﬁsh plague and itscontinuous threat to indigenous populations of European freshwater crayﬁsh. Researchers,inaddition, emphasized the need to have in each country: a center of reference for diagnosingthe disease, and a protocol for collecting and submitting samples. These aspects are crucialin order to efﬁciently detect, monitor and prevent the presence and effect of crayﬁsh plagueand distinguish it from other mass mortality events in freshwater crayﬁsh.(1) Department of Mycology, Real Jardín Botánico CSIC, Plaza Murillo 2, 28014 Madrid, Spain,dieguez@rjb.csic.esArticle published by EDP SciencesJ. Diéguez-Uribeondo:Knowl. Managt. Aquatic Ecosyst. (2009) 394-395, 02APPLICATION OF MOLECULAR TECHNIQUESAphanomyces astaci is a difﬁcult organism to study and problems are associated with sub-mission of crayﬁsh samples, availability of expertise in laboratories, difﬁculty in isolating andmaintaining strains of A. astaci, and interpreting the results of samples. The advent of molec-ular techniques, however, has allowed the development of new methods for rapid and reliableidentiﬁcation of A. astaci (Oidtmann et al., 2006; Ballesteros et al., 2007; Hochwimmer et al.,2009; Kozubíková et al., 2009;V r å l s t a det al., 2009). More research, however, is needed onAphanomyces biodiversity and molecular markers, since in recent years, a number of newAphanomyces species have been described, and it has been found that some species arepresent in crayﬁsh and provide false positives (Ballesteros et al., 2006, 2007;O i d t m a n net al.,2006; Diéguez-Uribeondo et al., 2009). Improvement of the currently developed moleculartechniques for diagnosing crayﬁsh plague is also allowing us to improve the speciﬁcity ofmolecular tests. The combined knowledge of disease history, culture-based or histologicalstudies and molecular studies are key aspects for providing accurate diagnosis.CRAYFISH PLAGUE SPREAD AND EPIDEMIOLOGYCrayﬁsh plague is the most studied invertebrate disease, and its causative agent A. astaciis one of the best-known pathogens (see reviews by Söderhäll and Cerenius, 1999;Diéguez-Uribeondo et al., 2006; Cerenius et al., 2009). The biology and phylogeny of A. astacihas been extensively studied and this knowledge has allowed us to achieve important goals incrayﬁsh management. However, there are still some gaps in the knowledge that need furtherstudies such as the existence of low-virulence strains.This aspecthas been noticed in Finlandand Sweden (Viljamaa-Dirks and Heinikainen, 2006; Diéguez-Uribeondo and Söderhäll, un-published, respectively). The presence of low-virulence strains could mean that some strainscan stay in native crayﬁsh for long periods similar to chronic interaction of A. astaci in theirnatural carriers, i.e., North American crayﬁsh, and eventually manifest as acute plague. This isan important issue in management since it emphasizes the need for carrying out health con-trols in native crayﬁsh for restocking. On the other hand, the presence of such strains wouldalso mean that it could be native crayﬁsh with an enhanced resistance. Further studies needto be done in this exciting area of research.OTHER CRAYFISH DISEASESOther important crayﬁsh diseases are: virosis, porcelain disease caused by Thelohania spp.,psorospermiasiscausedby Psorospermium spp., and others are relatedto high density of ec-toparasites or ectocommensals such as branchiobdelidan species (Diéguez-Uribeondo et al.,2006). These diseases are only of particular importance on scarce occasions and economicimpact is more relevant in crayﬁsh farming than in natural populations.FINAL REMARKSThe European ICS are endangered species and in some regions are at risk of extinction. Thehabitats where ICS can be restored are restricted by the distribution of NICS: in many coun-tries, the ICS have been forced to live in limited habitats continuously threatened by crayﬁshplague and also other diseases. Thus, the future situation is linked to crayﬁsh plague andNICS distribution and therefore, studies on biodiversity, biology, diagnosis and epidemiologyof crayﬁsh plague as well as spread of NICS are crucial for development of action plans andstrategies for ICS conservation. Moreover, research on other crayﬁsh diseases should alsonot be neglected.02p2J. Diéguez-Uribeondo:Knowl. Managt. Aquatic Ecosyst. (2009) 394-395, 02ACKNOWLEDGEMENTSSpecial thanks to all participants of the round table: Ambrosius Dörr, Lennart Edsman,Frederic Grandjean, Tiit Paaver, Satu Viljamaa-Dirks, Jenny Makkonen, Eva Kozubíková andJiˇ rí Skoboda.REFERENCESBallesteros I., Martín M.P. and Diéguez-Uribeondo J., 2006. First isolation of Aphanomyces frigidophilus(Saprolegniales) in Europe. Mycotaxon, 95, 335–340.Ballesteros I., Martín M.P., Cerenius L., Söderhäll K., Tellería M.T. and Diéguez-Uribeondo J., 2007. Lackof speciﬁcity of the molecular diagnostic method for identiﬁcationof Aphanomyces. Bull. Fr. PêchePiscic., 385, 17–24.Cerenius L., Andersson G. and Söderhäll K., 2009. Aphanomyces astaci and crustaceans. In:L a m o u rK .and Kamoun S. (eds.), Oomycete Genetics and Genomics – Diversity, Interactions, and ResearchTools, John Wiley & Sons, Inc., Hoboken, New Jersey.Diéguez-Uribeondo J., Cerenius L., Dyková I., Gelder S., Henntonen P., Jiravanichpaisal P., Lom J. andSöderhäll K., 2006. Pathogens, parasites and ectocommensals. In: Souty-Grosset C., HoldichD.M., Noël P.Y., Reynolds J.D. and Haffner P. (eds.), Atlas of Crayﬁsh in European,Muséum nationald’Histoire naturelle, Paris, Collection Patrimoines Naturels.Diéguez-Uribeondo J., García M.A., Cerenius L., Kozubíková E., Ballesteros I., Windels C., Weiland J.,Kator H., Söderhäll K. and Martín M.P., 2009. Phylogenetic relationships among plant and animalparasites, and saprobionts in Aphanomyces (Oomycetes). Fungal Genet. Biol., 46, 365–376.Edgerton B.F., Henttonen P., Jussila J., Mannonen A., Paasonen P., Taugbøl T., Edsman L. and Souty-Grosset C., 2004. Understanding the causes of disease in European freshwater crayﬁsh. Conserv.Biol., 18, 1466–1474.Hochwimmer G., Tober R., Bibars-Reiter R., Licek E. and Steinborn R., 2009. Identiﬁcation of two GH18chitinase family genes and their use as targets for detection of the crayﬁsh-plague oomyceteAphanomyces astaci. BMC Microbiology, 9, 184.Kozubíková E., Petrusek A., Filipová L., Kozák P., ˇ Duriš Z., Martín M.P., Diéguez-Uribeondo J. andOidtmann B., 2009. Crayﬁsh plague reservoirs: prevalence of the crayﬁsh plague pathogenAphanomyces astaci in populations of invasive American crayﬁshes in the Czech Republic.Conserv. Biol., 23, 1204–1213.Oidtmann B., Geiger S., Steinbauer P., Culas A. and Hoffmann R.W., 2006. Detection of Aphanomycesastaci in North American crayﬁsh by polymerase chain reaction. Dis. Aquat. Org., 72, 53–64.Söderhäll K. and Cerenius L., 1999. The crayﬁsh plague fungus: Hystory and recent advances.Freshwater Crayﬁsh, 12, 11–35.Viljamaa-DirksS. and HeinikainenS., 2006.Clinicalevidence of a chroniccrayﬁsh plague (Aphanomycesastaci) infection in noble crayﬁsh (Astacus astacus) populations, 16th Symposium of theInternational Association of Astacology, The Gold Coast, Queensland.Vrålstad T., Knutsen A.K., Tengs T. and Holst-Jensen A., 2009. A quantitative TaqMan MGB real-timepolymerase chain reaction based assay for detection of the causative agent of crayﬁsh plagueAphanomyces astaci. Vet. Microbiol., 137, 146–155.02p3

Knowledge and Management of Aquatic Ecosystems

Current techniques, approaches and knowledge in diagnosis of crayfish plague and other crayfish diseases Round table 3 (chairman: Javier Diéguez-Uribeondo)

Current techniques, approaches and knowledge in diagnosis of crayfish plague and other crayfish diseases Round table 3 (chairman: Javier Diéguez-Uribeondo)

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