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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its abundance from the literature and from unpublished government agency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. mariae abundance, with robust agreement between the two approaches. 4.
In addition to documenting a previously unrecognized ~eightfold increase
in the burden of an economically important parasite, our work demonstrates
– for the first time – that parasitological examination of
liquid-preserved museum specimens can produce reliable data on long-term
trends in parasite abundance, at a much greater temporal resolution than
is possible to obtain from historical records. 5. Synthesis and
applications. Defining a baseline state of infection is vital for natural
resource management and policy, which must respond to the threat of
disease; without such a baseline, managers attempting to maintain or
recover the health of ecosystems under their stewardship are shooting in
the dark. The method we present here – using museum specimens to
reconstruct detailed chronologies of parasite abundance change – offers a
solution. Our approach would allow managers to accurately characterize
past population disease states, informing the development of appropriate
disease management targets. Given the broad representation and
availability of liquid-preserved specimens across ecosystems, geographic
regions, and host taxa, this solution may be feasible for the management
of biological resources not only in marine ecosystems, but in freshwater
and terrestrial ecosystems as well.20-Aug-2018
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