Chronic Aphanomyces astaci infection in wild white-clawed crayfish: risks and implications for breeding programs

Area of Science:

• Aquatic Ecology
• Pathogen Biology
• Conservation Genetics

Background:

• Aphanomyces astaci causes crayfish plague, a severe disease impacting European crayfish.
• Low virulence strains of A. astaci are increasingly found with native European crayfish.
• Understanding pathogen-host dynamics is vital for conserving susceptible crayfish species.

Purpose of the Study:

• To investigate the prevalence and impact of Aphanomyces astaci in white-clawed crayfish populations.
• To identify the source and cause of a crayfish plague outbreak in a conservation breeding facility.
• To assess the effectiveness of broodstock health monitoring for preventing disease introduction.

Main Methods:

• Molecular assays (RAPD-PCR, mtDNA, nuclear markers) were used to detect and characterize A. astaci.
• Longitudinal monitoring of 19 wild Austropotamobius pallipes populations over nine years.
• Epidemiological investigation of a crayfish plague outbreak in a captive breeding facility.

Main Results:

• Chronic A. astaci infections were detected in 8 out of 19 monitored populations.
• Two populations exhibited persistent A. astaci infection without significant mortality.
• Introduction of chronically infected broodstock led to a severe crayfish plague outbreak and high mortality in the breeding facility.

Conclusions:

• Undetected chronic A. astaci infections in broodstock pose a significant risk to conservation programs.
• Rigorous health screening of broodstock is essential to prevent disease outbreaks in ex situ conservation facilities.
• Management strategies must consider pathogen presence and potential stressors for effective crayfish conservation.