Latest Articles from NeoBiota Latest 3 Articles from NeoBiota https://neobiota.pensoft.net/ Thu, 28 Mar 2024 13:52:58 +0200 Pensoft FeedCreator https://neobiota.pensoft.net/i/logo.jpg Latest Articles from NeoBiota https://neobiota.pensoft.net/ Headwater refuges: Flow protects Austropotamobius crayfish from Faxonius limosus invasion https://neobiota.pensoft.net/article/110085/ NeoBiota 89: 71-94

DOI: 10.3897/neobiota.89.110085

Authors: Alina Satmari, Kristian Miok, Mihaela C. Ion, Claudia Zaharia, Anne Schrimpf, Lucian Pârvulescu

Abstract: This study explores the geospatial relationship between the invasive crayfish species Faxonius limosus and the native Austropotamobius bihariensis and A. torrentium crayfish populations in Eastern Europe, identifying the environmental factors which influence the invasion. We used species distribution modelling based on several climatic, geophysical and water quality variables and crayfish distributional data to predict sectors suitable for each species within the river network. Thus, we identified the sectors potentially connecting invasive and native population clusters and quantified the degree of proximity between competing species. These sectors were then extensively surveyed with trapping and hand searching, doubled by eDNA methods, in order to assess whether any crayfish or the crayfish plague pathogen Aphanomyces astaci are present. The predictive models exhibited excellent performance and successfully distinguished between the analysed crayfish species. The expansion of F. limosus in streams was found to be limited by flash-flood potential, resulting in a range that is constrained to lowland rivers. Field surveys found neither crayfish nor pathogen presence in the connective sectors. Another interesting finding derived from the screening efforts, which are among the most extensive carried out across native, apparently healthy crayfish populations, was the existence of a latent infection with an A. astaci strain identified as A-haplogroup. Our results provide realistic insights for the long-term conservation of native Austropotamobius species, which appear to be naturally protected from F. limosus expansion. Conservation efforts can thus focus on other relevant aspects, such as ark-sites establishment for preventing the spread of more dangerous invasive crayfish species and of virulent crayfish plague pathogen strains, even in locations without direct contact between crayfish hosts.

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Research Article Wed, 8 Nov 2023 16:47:31 +0200
Long-term changes in the prevalence of the crayfish plague pathogen and its genotyping in invasive crayfish species in Czechia https://neobiota.pensoft.net/article/79087/ NeoBiota 74: 105-127

DOI: 10.3897/neobiota.74.79087

Authors: Michaela Mojžišová, Jitka Svobodová, Eva Kozubíková-Balcarová, Eva Štruncová, Robin Stift, Michal Bílý, Antonín Kouba, Adam Petrusek

Abstract: The widespread presence of North American alien crayfish in Europe is a major driver of native crayfish population declines, mainly because they are chronic carriers of the oomycete Aphanomyces astaci responsible for crayfish plague. Screening for the crayfish plague pathogen in host populations has become a common practice across Europe, but sampling usually covers spatial but not temporal variation. Our study focuses on the current situation in Czechia, where screening for A. astaci was first conducted in the mid-2000s. We provide data about the distribution and prevalence of this pathogen at almost 50 sites with three host crayfish: the spiny-cheek crayfish Faxonius limosus, signal crayfish Pacifastacus leniusculus, and marbled crayfish Procambarus virginalis. Among these sites were 20 localities that were resampled several years (usually more than a decade) after the original screening for A. astaci. We did not detect any A. astaci infection in two studied P. virginalis populations but documented several new hotspots of highly infected P. leniusculus in Czechia, and the first site with the coexistence of the latter with F. limosus. Our data suggest that despite some fluctuations, A. astaci prevalence in North American host populations generally does not tend to change significantly over time; we only observed two cases of a significant increase and one of a significant decrease. We no longer detected A. astaci in several originally weakly infected populations, but our data suggest it likely still persists in these areas and threatens native crayfish populations. At the single known site in the country where P. leniusculus and F. limosus coexist, we documented the presence of the same A. astaci genotype group in both crayfish species, likely due to interspecific transmission of the pathogen from the former host to the latter. However, genotyping of A. astaci in infected host individuals still supported the link between specific pathogen genotypes and crayfish hosts, suggesting that assessment of sources of mass mortalities from the pathogen genotyping is feasible in European regions where the mutual contact of different American crayfish species is uncommon.

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Research Article Fri, 15 Jul 2022 16:47:41 +0300
Simultaneous detection of native and invasive crayfish and Aphanomyces astaci from environmental DNA samples in a wide range of habitats in Central Europe https://neobiota.pensoft.net/article/49358/ NeoBiota 58: 1-32

DOI: 10.3897/neobiota.58.49358

Authors: Johannes C. Rusch, Michaela Mojžišová, David A. Strand, Jitka Svobodová, Trude Vrålstad, Adam Petrusek

Abstract: Crayfish of North American origin are amongst the most prominent high-impact invasive invertebrates in European freshwaters. They contribute to the decline of European native crayfish species by spreading the pathogen causing crayfish plague, the oomycete Aphanomyces astaci. In this study we validated the specificity of four quantitative PCR (qPCR) assays, either published or newly developed, usable for environmental DNA (eDNA) screening for widely distributed native and non-native crayfish present in Central Europe: Astacus astacus, Pacifastacus leniusculus, Faxonius limosus and Procambarus virginalis. We then conducted an eDNA monitoring survey of these crayfish as well as the crayfish plague pathogen in a wide variety of habitat types representative for Central and Western Europe. The specificity of qPCR assays was validated against an extensive collection of crayfish DNA isolates, containing most crayfish species documented from European waters. The three assays developed in this study were sufficiently species-specific, but the published assay for F. limosus displayed a weak cross-reaction with multiple other crayfish species of the family Cambaridae. In the field study, we infrequently detected eDNA of A. astaci together with the three non-native crayfish species under examination. We never detected eDNA from A. astaci together with native crayfish, but in a few locations eDNA from both native and non-native crayfish was captured, due either to passive transport of eDNA from upstream populations or co-existence in the absence of infected crayfish carriers of A. astaci. In the study, we evaluated a robust, easy-to-use and low-cost version of the eDNA sampling equipment, based mostly on items readily available in garden stores and hobby markets, for filtering relatively large (~5 l) water samples. It performed just as well as the far more expensive equipment industrially designed for eDNA water sampling, thus opening the possibility of collecting suitable eDNA samples to a wide range of stakeholders. Overall, our study confirms that eDNA-based screening for crayfish and their associated pathogen is a feasible alternative to traditional monitoring.

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Research Article Fri, 19 Jun 2020 08:28:40 +0300