Multifaceted implications of the competition between native and invasive crayfish: a glimmer of hope for the native's long-term survival-Manuscript Draft-Manuscript Number: BINV-D-18-00491R1 Full Title: Multifaceted implications of the competition between native and invasive crayfish: a glimmer of hope for the native's long-term survival Article Type: Research paper
The crayfish plague agent Aphanomyces astaci is one of the world's most threatening invasive species. Originally from North America, the pathogen is being imported alongside American crayfish species, which are used for various purposes. In this study, we investigated the marginal, currently known distribution area of the pathogen in Eastern Europe by sampling narrow-clawed crayfish (Astacus leptodactylus) and spiny-cheek crayfish (Orconectes limosus) populations. In addition, using specific real-time PCR, we tested several marine decapod species, which also occur in brackish waters of the Danube at the West coast of the Black Sea and the Dniester River basin. By sequencing the nuclear chitinase gene, mitochondrial rnnS/rnnL DNA and by genotyping using microsatellite markers, we identified the A. astaci haplogroups of highly infected specimens. The A. astaci DNA was detected in 9% of the investigated A. leptodactylus samples, both in invaded and non-invaded sectors, and in 8% of the studied O. limosus samples. None of the marine decapods tested positive for A. astaci. The results revealed that narrow-clawed crayfish from the Dniester River carried the A. astaci B-haplogroup, while A. astaci from the Danube Delta belonged to the A- and B-haplogroups. In the invaded sector of the Danube, we also identified the A-haplogroup. Microsatellite analysis revealed a genotype identical to the genotype Up. It might be that some of the detected A. astaci haplogroups are relics from older outbreaks in the late 19th century, which may have persisted as a chronic infection for several decades in crayfish populations.
This survey analyzed the eco-physiological requirements of caddisflies assemblages in Jiu River (south-west Romania). The output revealed that the communities are driven by a synergic combination of natural factors and pollutants. Their ecological profiles are diverse and the degree of tolerance is related to a decrease of water quality over a longitudinal gradient, overlapped with natural variation of physic-chemical factors. The assemblage is dominated by hydropsychids, very tolerant to anthropogenic disturbances, and two other communities separated by large distances (characteristic of headwaters and of lowland areas, respectively) that do rather reveal stronger affinities to the microhabitat requirements then to water pollution. Polyhedral diagrams were employed in order to reveal caddisflies larvae tolerances/intolerances to environmental parameters, in order to test their usefulness for local areas and less numerous samples, as frequently encountered in routine surveys. RÉSUMÉ Les exigences écologiques des larves de trichoptères (Insecta : Trichoptères) et leur utilité dans l'évaluation de la qualité de l'eau dans le sud-ouest de la Roumanie
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