Abundance of an economically important nematode parasite increased in Puget Sound between 1930 and 2016: evidence from museum specimens confirms historical data

1. Does disturbance increase or decrease parasite transmission among wildlife hosts? Ecologists cannot answer this controversial question, in part because few historical datasets rigorously document parasite abundance. Without such a baseline, it is difficult to determine whether contemporary ecosystems are experiencing elevated parasite burdens. 2. Here, we investigate change over time in the abundance of a parasite that affects the economic value of a fish species. Clavinema mariae is a nematode parasite of benthic fishes that is common in English sole (Parophrys vetulus) of Puget Sound, WA. We obtained historical records of its abundance from the literature and from unpublished government agency data, and resampled the same locations using the same methods in 2017. We also used a new approach by estimating the C. mariae burden for museum specimens of English sole collected between 1930 and 2016.3. Both the historical data and museum specimen data suggested increases over time in C. m...