engleski

Predicting the effects of climate change on the interplay between invasive oomycete Aphanomyces astaci and indigenous European crayfish

Transmission of crayfish plague by invasive crayfish is one of the main drivers of native European crayfish populations declines. The causative agent of crayfish plague Aphanomyces astaci (Schikora, 1906) is listed among the 100 worst invasive species in the world, and it has been spreading throughout Europe since its introduction in the late 19th century. The future of the interplay between this pathogen and its hosts is hard to predict, but it has been shown for other pathogen-host pairs that elevated water temperature caused by climate change favours spreading of pathogens. Therefore, the aim of this study was to investigate whether a 4 °C increase in water temperature will also increase the virulence of A. astaci (strain B, PsI genotype) towards two indigenous crayfish species: the stone crayfish Austropotamobius torrentium (Schrank, 1803) and the narrow-clawed crayfish Astacus leptodactylus Eschscholtz, 1823. Before the experiment, we have tested all animals for A. astaci presence and only A. astaci-free animals were included into the experiment. After acclimatization, we have infected the crayfish with 500 zoospores per mL at water temperature of 18⁰C (control conditions) and 22⁰C (increased water temperature - simulation of climate change). After four weeks the results have shown that the mortality of both crayfish species was significantly lower at increased water temperature (22⁰C). This suggests that the increase of water temperatures caused by climate change will probably not result in the increased spread of A. astaci strain B in stone crayfish and narrow-clawed crayfish populations. Results will be discussed in adaptation and evolutionary perspective as well as in the context of A. astaci strains that have different water temperature preference. In conclusion, this study presents the first experimental data on the balance between A. astaci and indigenous crayfish in the context of climate change.

Aphanomyces astaci, climate change, native crayfish

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