engleski

Effect of infection by crayfish plague pathogen on growth of juvenile marbled crayfish Procambarus virginalis (Lyko, 2017)

Crayfish plague is one of the most lethal diseases for native freshwater crayfish, while invasive crayfish are tolerant but may be chronically infected. In chronically infected populations the disease can cause direct (mortaility) but also indirect effects such as reduced growth due to increased energy investment in immune response.The aim of this study was to examine the direct (mortality) and indirect (reduction of growth) effects of chronic infection by crayfish plague pathogen (Aphanomyces astaci strain Psl) on individually kept juvenile marbled crayfish (Procambarus virginalis) under laboratory conditions. We conducted an infection trial using two concentrations of A.astaci spores (7500 and 15000 spores/ml) to test if repeated infection by A. astaci (at least two infections) leads to change in growth of infected compared to non- infected individuals (control group). We recorded mortality and measured length and weight of control group and infected groups before each succeeding infection. At the end of the trial the presence of the pathogen was analysed using previously developed A. astaci specific PCR assay. Direct effects of infection by A. astaci were observed at a concentration of 15000 spores/ml. Mortality was recorded in 20 % of infected individuals and additional 15 % of infected individuals had reduced viability and visible signs of infection. Indirect effects in terms of significantly lower length and weight increments of repeatedly infected individuals compared to control group were observed.

invasive species ; immunity cost

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