Recovering Turkish narrow clawed crayfish (Astacus leptodactylus) populations carryAphanomyces astaci

Abstract

Crayfish stocks collapsed in Turkey in mid 1980's due to crayfish plague epidemics, with up to 25% survival in some cases. The collapsed stocks have then recovered slowly and commercial crayfish fishery was reinitiated gradually within a decade. We examined the prevalence of Aphanomyces astaci DNA in the narrow clawed crayfish (Astacus leptodactylus) collected from two Turkish lakes, Lake İznik and Hirfanlı Dam (N = 40 from both sites). The qPCR results, verified by conventional PCR and sequencing, indicated that nearly all sampled crayfish were A. astaci carries with some of them showing gross symptoms of infection, such as tissue erosion and melanisation, while some did not show any visible symptoms. The prevalence of A. astaci DNA was high in both stocks, being on the average 95% in both Lake İznik and Hirfanlı Dam. Our results show that these stocks are carries of A. astaci, but capable of forming productive stocks which indicates past and contemporary partial resistance adaptation in the host or virulence evolution in the A. astaci. RÉSUMÉ Des populations turques d'écrevisses à pattes grêles (Astacus leptodactylus) productives porteuses d'Aphanomyces astaci

Aphanomyces astaciPsI-genotype isolates from different Finnish signal crayfish stocks show variation in their virulence but still kill fast

“…Chitinase production has been claimed to be adaptation to parasitic life style and one of the virulence factors (Unestam, 1966;Hochwimmer et al, 2009). The reports of A. astaci adaptation to the European crayfish hosts (Jussila et al, 2011;Viljamaa-Dirks et al, 2011;Kokko et al, 2012;Svoboda et al, 2012;Kušar et al, 2013) are most probably all concerning As-genotype adaptation. The 150 year history in Europe, with high selection pressure, has caused a rather rapid co-evolution of both the host and the pathogen.…”

“…In general, this disease has a bad reputation, but some A. astaci strains seem to show signs of avirulence (Jussila et al, 2011a;Makkonen, 2013). Certain strains of this parasite have likely adapted to their fairly recent European hosts, as the As-genotype is currently causing highly variable mortalities among native European crayfish both in laboratory experiments and among wild populations (Jussila et al, 2011Kokko et al, 2012;Svoboda et al, 2012;Caprioli et al, 2013;Kušar et al, 2013). So far, however, the evidence of virulence differences and potential evolution among PsI-genotype, or other more recently introduced A. astaci genotypes, has been lacking.…”

Variation in Resistance to the Invasive Crayfish Plague and Immune Defence in the Native Noble Crayfish

“…As a consequence of the epidemics, the native European noble crayfish Astacus astacus is facing a high risk of extinction in the wild (Red List Category & Criteria: Vulnerable A2; IUCN Red List of threatened species) and therefore A. astaci is being listed among the 100 worldwide worst invasive species (Lowe et al 2004). The remaining European native crayfish populations, including noble crayfish, differ in their experience of crayfish plague infections, varying from acute disease epidemics to pristine populations without a known history of outbreaks (Jussila et al 2011b, Kokko et al 2012, Makkonen et al 2012b. Understanding of the dynamics of crayfish plague epidemiology is still ambiguous (Fürst 1995, Edgerton et al 2004 (Jussila et al 2011b, Viljamaa-Dirks et al 2011.…”

“…This indicates that individual-and population-specific differences in disease resistance potentially play a role in the crayfish plague dynamics (Makkonen et al 2012b) and have prolonged the existence of the disease in certain waters. Furthermore, there are recent reports on population recoveries after crayfish plague epidemics among the Turkish narrow clawed crayfish populations (Harlioğlu 2008, Kokko et al 2012, Svoboda et al 2012. These crayfish carry the infection and are commercially exploited despite the lack of a long co-evolutionary history with A. astaci.…”

Present distribution and future spread of louisiana red swamp crayfishProcambarus clarkii(Crustacea, Decapoda, Astacida, Cambaridae) in Britain : Implications for conservation of native species and habitats

“…This individual was found in a section of canal outside of the known range of P. clarkii and P. leniusculus and therefore may have been in an area unaffected by crayfish plague. Additionally, recent research has shown that A. leptodactylus may be able to develop a partial resistance to crayfish plague (Hokko et al, 2012). Of the 26 sites surveyed over 41 km; 15 were found to have P. clarkii present, indicating an approximate linear range of 11 km ( Figure 1).…”