engleski

Freshwater crayfish pathogens as potential invasive species - A review of existing studies

Invasive non-indigenous crayfish species (NICS) impact native crayfish populations through competition and hybridization, but more importantly, through transmission of pathogens which can spread rapidly and have a detrimental effect on existing native species/populations. The impact of pathogens on freshwater crayfish has been studied extensively, especially in species important for aquaculture. However, for many alleged pathogens, the pathogenicity has never been experimentally confirmed since the infection trials have never been conducted. Detection of a potential pathogen in moribund or dead crayfish has often led to the assumption that the organism is able to cause disease. Therefore, the aim of this study was to analyze the available literature to determine which microbes (bacteria, viruses and fungi) can be classified as ‘proven’ pathogens for freshwater crayfish, and which of them are classified inadvertently or incorrectly. We analyzed over 70 scientific publications and classified the alleged crayfish pathogens into the following categories: a) pathogen – pathogenicity confirmed by infection trials, b) potential pathogen – although classified as pathogen in literature, no infection trials have been recorded, c) non-pathogen – infection trials failed to prove pathogenicity for crayfish and d) indirect pathogen/opportunist – infection trials indicate possible crayfish mortality under stress conditions. We recorded 39 microbial species belonging to these categories, with the majority of them (41 %) classified as pathogens, including bacterial, viral and fungal representatives. We discuss our results in the context of microbial potential effects on both invasive non-indigenous and native crayfish populations during the range expansion of the invasive NICS to the novel environment.

pathogenicity ; infection trials ; freshwater invasion ; literature review

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