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.

评估野生动物疾病负荷的时间动态模式需要长期数据集，但关于寄生虫丰度的历史数据却极为匮乏。一个多世纪以来，自然历史标本馆藏持续积累液浸保存标本，此类标本理应留存宿主在被保存时感染的寄生虫。然而，在利用这一独特数据源前，我们需明确保存过程所引入的人为干扰效应。本研究通过实验探究：采用视觉寄生虫检测技术时，液浸保存鱼类标本内后生寄生虫（metazoan parasites）的可检测水平是否会因保存过程发生改变。
我们将3个物种的鱼类样本（*Gadus chalcogrammus*、*Thaleichthys pacificus*、*Parophrys vetulus*）随机分为两组处理。第一组处理中，鱼类按照鱼类学标本馆藏的标准流程完成保存。液浸保存流程结束后，我们立即对这些标本开展寄生虫学解剖。第二组为对照组，鱼类未经过液浸保存流程，直接进行解剖。我们对两组处理间的寄生虫丰度进行了对比分析。
本次实验共涉及298尾个体、59组宿主-寄生虫配对组合，结果显示两组处理间差异极小：27组配对组合中有24组的寄生虫丰度在两组间无显著差异。其中，1组配对组合在保存处理组中的寄生虫丰度显著高于对照组，另有2组配对组合在保存处理组中的寄生虫丰度显著低于对照组。
本研究数据表明，液浸保存过程对后生寄生虫的可检测水平无显著实质性影响。本研究仅探讨了固定与保存过程的影响；若要明确保存后数月、数年乃至数十年的存储期间，寄生虫可检测水平是否保持稳定，仍需开展长期实验。若该结论成立，生态学家便可借助自然历史标本馆藏的液浸保存标本，重建过去一个世纪乃至更久时间跨度内的寄生虫多样性与丰度长期数据集。