PCR ‐based prevalence of a fatal reovirus of the blue crab, C allinectes sapidus ( R athbun) along the northern A tlantic coast of the USA

There is a need for more information on the relationship between diseases and fluctuations of wild populations of marine animals. In the case of C allinectes sapidus reovirus 1 ( C s RV 1, also known as RLV ), there is a lack of baseline information on range, prevalence and outbreaks, from which to develop an understanding of population‐level impacts. An RT ‐ qPCR assay was developed that is capable of detecting 10 copies of the C s RV 1 genome. In collaboration with state, federal and academic partners, blue crabs were collected from sites throughout the north‐eastern U nited S tates to assess the northern range of this pathogen. In addition, archived crab samples from the C hesapeake B ay were assessed for C s RV 1 by RT ‐ qPCR and histology. PCR ‐based assessments indicate that C s RV 1 was present at all but one site. Prevalence of C s RV 1 as assessed by RT ‐ qPCR was highly variable between locations, and C s RV 1 prevalence varied between years at a given location. Mean C s RV 1 prevalence as assessed by RT ‐ qPCR was >15% each year, and peak prevalence was 79%. The wide geographic range and highly variable prevalence of C s RV 1 indicate that more study is needed to understand C s RV 1 dynamics and the role the virus plays in blue crab natural mortality.