Are Worms Eating Our Mussels? The Presence of Infectious Proctoeces maculatus Detected in Mytilus edulis

The distribution of Proctoeces maculatus, parasitic trematode of Mytilus edulis (blue mussels) has increased in abundance recently. These parasites cause blue mussels to be less reproductive and viable to sell. Currently, the only way to be certain that trematodes are infecting our mussels is to sacrifice the mussels, thus the goal of this research was to find easier and less destructive methods for infection detection and to track trematode infection rates across different seasons. We isolated DNA from both water and mussel samples collected at Spectacle Island, MA between early spring to mid-summer. To specifically identify the trematodes infecting mussels in Boston Harbor, samples were PCR amplified. We tested two primers, 18S, which is specific for the trematode Proctoeces maculatus, and Cytochrome Oxidase 1 (COX1), a universal primer for the COX1 gene fragment. Samples with the highest concentrations of PCR products were sent for sequencing. The sequencing of 18S forward and reverse primers on a positive trematode sample, confirmed the presence of P. maculatus trematodes. We also quantified the infection rates and infection intensity of trematodes in collected mussel samples using quantitative PCR (qPCR). We detected the presence of trematodes throughout the duration of study, but March had the highest infection intensity and highest infection rate of 19%.