engleski

First record of idiopathic necrotizing hepatopancreatitis in the signal crayfish Pacifastacus leniusculus (Dana, 1852) in Croatia

As the most successful crayfish invader and possible reservoir of new pathogens, signal crayfish Pacifastacus leniusculus (Dana, 1852) is among the major drivers of native crayfish species decline in Europe. We present data on lesions and frequency of idiopathic necrotizing hepatopancreatitis along the invasion range of signal crayfish in the Korana River in Croatia. We sampled and histologically analysed 73 signal crayfish individuals collected during three consecutive years (2018-2020). Our results show a very high prevalence of the lesions in hepatopancreas of signal crayfish (>91%), with 14% of individuals displaying heavy and 51% moderate changes within tubular and interstitial structures of the organ. Recorded lesions were more frequent in females and within the invasion core where population density is higher. Heavy histopathological changes in hepatopancreas were correlated with lower hepatosomatic index which indicates that this disease affects the individual condition and may affect invasion success. Our preliminary screening of co-occurring native narrow-clawed crayfish Pontastacus leptodactylus (N=3) showed similar hepatopancreatic lesions and highlighted the susceptibility of native crayfish populations to this newly detected disease. Aetiology of necrotizing hepatopancreatitis and potential new pathogen in Korana River are still unknown, and need to be further investigated.

signal crayfish, narrow-clawed crayfish, invasive species, hepatopancreas, Korana River

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