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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Vet. Sci. | doi: 10.3389/fvets.2019.00281

Keeping a wild eye on brown trout (Salmo trutta) populations: Correlation between temperature, environmental parameters and proliferative kidney disease

  • 1Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Switzerland
  • 2Other, Switzerland
  • 3High School of Landscape Engineering and Architecture, University of Applied Sciences Western Switzerland, Switzerland
  • 4Département d'écologie et évolution, Faculté de biologie et médecine, Université de Lausanne, Switzerland
  • 5Center for Animal Health Research, National Institute of Agricultural and Food Research and Technology, Spain

Proliferative kidney disease (PKD) is an emerging disease of salmonids caused by the myxozoan parasite Tetracapsuloides bryosalmonae, which plays a major role in the decrease of wild brown trout (Salmo trutta) populations in Switzerland. Strong evidence demonstrated that water temperature modulates parasite infection. However, less knowledge exists on how seasonal water temperature fluctuations influence PKD manifestation under field conditions, how further environmental factors such as water quality may modulate the disease, and whether these factors coalesce with temperature role possibly giving rise to cumulative effects on PKD. The aims of this study were to (1) determine the correlation between seasonal course of water temperature and PKD prevalence and intensity in wild brown trout populations, (2) assess if other factors such as water quality or ecomorphology correlate with the infection, and (3) quantitatively predict the implication of these factors on PKD prevalence with a statistical model. Young-of-the-year brown trout were sampled in 45 sites through the Canton of Vaud (Switzerland). For each site, longitudinal time series of water temperature, water quality (macroinvertebrate community index, presence of wastewater treatment plant effluent) and ecomorphological data were collected and correlated with PKD prevalence and intensity. 251 T. bryosalmonae infected trout of 1118 were found (overall prevalence 22.5 %) at 19 of 45 study sites (42.2 %). Relation between PKD infection and seasonal water temperature underlined that the mean water temperature for June and the number of days with mean temperature ≥15°C were the most significantly correlated parameters with parasite prevalence and intensity. The presence of a wastewater treatment plant effluent was significantly correlated with the prevalence and infection intensity. In contrast, macroinvertebrate diversity and river ecomorphology were shown to have little impact on disease parameters. Linear and logistic regressions highlighted quantitatively the prediction of PKD prevalence depending on environmental parameters at a given site and its possible increase due to rising temperatures. The model developed within this study could serve as a useful tool for identifying and predicting disease hot spots. These results support the importance of temperature for PKD in salmonids and provides evidence for a modulating influence of additional environmental stress factors.

Keywords: Proliferative kidney disease, Salmo trutta (L.), Tetracapsuloides bryosalmonae, water temperature, Water Quality, ecomorphology, wild fish population, aquatic fieldwork

Received: 03 May 2019; Accepted: 07 Aug 2019.

Edited by:

Robert J. Ossiboff, Aquatic, Amphibian, and Reptile Pathology, College of Veterinary Medicine, University of Florida, United States

Reviewed by:

Franz Lahnsteiner, Bundesamt für Wasserwirtschaft, Austria
Bartolomeo Gorgoglione, Michigan State University, United States  

Copyright: © 2019 Rubin, De Coulon, Bailey, Segner, Wahli and Rubin. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: PhD. Aurélie Rubin, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Bern, 3012 Berne, Bern, Switzerland, aurelie.rubin@students.unibe.ch