Data from: Fluid preservation causes minimal reduction of parasite detectability in fish specimens: a new approach for reconstructing parasite communities of the past?

Long-term datasets are needed to evaluate temporal patterns in wildlife
disease burdens, but historical data on parasite abundance are extremely
rare. For more than a century, natural history collections have been
accumulating fluid-preserved specimens, which should contain the parasites
infecting the host at the time of its preservation. However, before this
unique data source can be exploited, we must identify the artefacts that
are introduced by the preservation process. Here, we experimentally
address whether the preservation process alters the degree to which
metazoan parasites are detectable in fluid-preserved fish specimens when
using visual parasite detection techniques. We randomly assigned fish of
three species (Gadus chalcogrammus, Thaleichthys pacificus, Parophrys
vetulus) to two treatments. In the first treatment, fish were preserved
according to the standard procedures used in ichthyological collections.
Immediately after the fluid-preservation process was complete, we
performed parasitological dissection on those specimens. The second
treatment was a control, in which fish were dissected without being
subjected to the fluid-preservation process. We compared parasite
abundance between the two treatments. Across 298 fish individuals and 59
host–parasite pairs, we found few differences between treatments, with 24
of 27 host–parasite pairs equally abundant between the two treatments. Of
these, one pair was significantly more abundant in the preservation
treatment than in the control group, and two pairs were significantly less
abundant in the preservation treatment than in the control group. Our data
suggest that the fluid-preservation process does not have a substantial
effect on the detectability of metazoan parasites. This study addresses
only the effects of the fixation and preservation process; long-term
experiments are needed to address whether parasite detectability remains
unchanged in the months, years, and decades of storage following
preservation. If so, ecologists will be able to reconstruct novel,
long-term datasets on parasite diversity and abundance over the past
century or more using fluid-preserved specimens from natural history
collections.