Application of a quantitative PCR TaqMan™ assay for the detection of Ergasilus labracis in mixed plankton samples from a Newfoundland bay

Ergasilids are an important group of parasitic copepods that occur globally in some coastal, estuarine, and freshwater habitats, including the south coast of the island of Newfoundland, Canada. Generally, males and developing females are not parasitic and remain in plankton. Adult females, however, become parasitic and seek a host following mating. Few studies have focused on detection and/or quantification of planktonic stages, and of those, all have utilized microscopic techniques. This method is time consuming and dependent on a specific parasitological skill set. In recent years, quantitative PCR (qPCR) techniques have become common in the detection and relative quantification of various invertebrate larval stages within plankton, including many metazoan parasites. In the present study, a qPCR assay using TaqMan™ minor groove binder probe technology, based on the Ergasilus labracis mitochondrial cytochrome c oxidase subunit I sequence, was developed for the first time to detect this parasite in mixed plankton samples taken near active salmonid aquaculture sites in a Northwest Atlantic coastal estuary. Ultimately, the technique can be used for tracking seasonal variability and abundance of planktonic stages of this parasite and thus illustrate patterns of seasonal infestation for both wild and cultured species in this region.