Schmidt-Posthaus Heike, Schneider Ernst, Schölzel Nils, Hirschi Regula, Stelzer Moritz, Peter Armin
Centre for Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
Thalwil, Switzerland.
PLoS One. 2021 Mar 17;16(3):e0247482. doi: 10.1371/journal.pone.0247482. eCollection 2021.
Natural and uninterrupted water courses are important for biodiversity and fish population stability. Nowadays, many streams and rivers are obstructed by artificial migration barriers, often preventing the migration of fish. On the other hand, distribution of pathogens by migrating fishes is still a point of concern. Pathogen transport and transmission is a driving force in the dynamics of many infectious diseases. The aim of the study was to investigate the possible consequences of the removal of an artificial migration barrier for the upstream transport of Tetracapsuloides bryosalmonae, the causative agent of Proliferative Kidney Disease (PKD) in brown trout, by migrating fish. To test this question, a river system was selected with a migration barrier separating a PKD positive river from a PKD negative tributary. After removal of the barrier, PKD prevalence and pathology was examined during five years after elimination of the barrier. In the tributary, no PKD was recorded at any time of the survey. By means of unidirectional PIT (passive integrated transponder)-tagging, we confirmed upstream migration of adult brown trout into the tributary during the cold season, presumably for spawning. By eDNA, we confirmed presence of T. bryoalmonae and Fredericella sp., the definitive host, DNA in water from the PKD positive river stretch, but not in the PKD negative tributary. Our study illustrates the importance of the connectivity of streams for habitat maintenance. Although migration of brown trout from a PKD-positive river into a PKD-negative tributary, mainly for spawning, was confirmed, upstream spreading of PKD was not observed.
自然且不间断的水道对于生物多样性和鱼类种群稳定性至关重要。如今，许多溪流和河流被人工迁移障碍所阻断，常常阻碍了鱼类的洄游。另一方面，鱼类洄游传播病原体仍是一个令人担忧的问题。病原体的传播和扩散是许多传染病动态变化的一个驱动因素。本研究的目的是调查拆除人工迁移障碍对褐鳟增殖性肾病（PKD）病原体——脑粘体虫（Tetracapsuloides bryosalmonae）通过洄游鱼类向上游传播的可能影响。为了验证这一问题，选择了一个河流系统，其中一个迁移障碍将一条PKD阳性河流与一条PKD阴性支流隔开。拆除障碍后，在障碍消除后的五年内对PKD的患病率和病理情况进行了检查。在支流中，调查期间任何时候都未记录到PKD。通过单向被动集成应答器（PIT）标记，我们证实成年褐鳟在寒冷季节向上游洄游进入支流，推测是为了产卵。通过环境DNA（eDNA），我们证实了PKD阳性河段水中存在脑粘体虫和终末宿主弗雷德里克苔藓虫（Fredericella sp.）的DNA，但在PKD阴性支流中未检测到。我们的研究说明了溪流连通性对于栖息地维持的重要性。虽然证实了褐鳟主要为产卵从PKD阳性河流洄游到PKD阴性支流，但未观察到PKD向上游扩散。
