open access

https://hdl.handle.net/2115/87056

Relative importance of host-dependent versus physical environmental characteristics affecting the distribution of an ectoparasitic copepod infecting the mouth cavity of stream salmonid

英語

stream-drift paradox

2021-11

John Wiley & Sons

Ecological Research

36(6)

1015-1027

Understanding parasite distributional patterns is fundamental for elucidating host-parasite relationships. The genus Salmincola is an ectoparasitic copepod group specifically infecting freshwater salmonids. Considering their strong association with their hosts, we can predict that the distribution and prevalence (analogs to abundance) of Salmincola reflect host salmonids. An alternative hypothesis is that their distribution will be strongly affected by environmental factors like stream drift because they have a free-living stage with low swimming ability. If this is the case, we predict a longitudinal gradient with higher occurrence or infection levels in downstream areas. To estimate the relative strength among factors affecting infection levels, we investigated the distribution pattern of Salmincola sp. on wild white-spotted charr Salvelinus leucomaenis in a southern Hokkaido river system. Based on data from 19 sites across three seasons, we found that host density and flow velocity affected the prevalence of Salmincola. On the other hand, no longitudinal gradient was observed and the prevalence was extremely low in some fragmented habitats (i.e., above dams and waterfalls). This indicates some compensation mechanisms against unidirectional downstream dispersal. We found that parasite prevalence and intensity were much higher in large migratory (anadromous) fish and, therefore, hypothesize that long-distance upstream migration helps the redistribution and population persistence of parasites in upstream areas.

学術雑誌論文

Accepted Manuscript

This is the peer reviewed version of the following article: Hasegawa, R., Koizumi, I. Relative importance of host-dependent versus physical environmental characteristics affecting the distribution of an ectoparasitic copepod infecting the mouth cavity of stream salmonid. Ecological Research. 2021; 36(6): 1015-1027, which has been published in final form at https://doi.org/10.1111/1440-1703.12262. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.

0912-3814

1440-1703

AA10667816