Integrated field, laboratory, and theoretical study of PKD spread in a Swiss prealpine river

Carraro, Luca; Bertuzzo, Enrico; Mari, Lorenzo; Fontes, InÃas; Hartikainen, Hanna; Strepparava, Nicole; Schmidt‐Posthaus, Heike; Wahli, Thomas; Jokela, Jukka; Gatto, Marino; Rinaldo, Andrea

doi:10.1073/pnas.1713691114

Cited by 66 publications

(69 citation statements)

References 41 publications

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“…The fact that similar results were obtained testing higher temperature thresholds can be taken as a hint that infection is in fact related to extended periods of water temperatures higher than 15°C. Several other studies could not prove a correlation between temperature and site‐specific prevalence of T. bryosalmonae (Carraro et al., ; Schmidt‐Posthaus, Steiner, Müller, & Casanova‐Nakayama, ; Wahli, Bernet, Segner, & Schmidt‐Posthaus, ). Temperature data were not available from all rivers, especially data from some upstream locations are missing, which were free of the parasite and most likely exhibit low water temperatures.…”

Section: Discussionmentioning

confidence: 93%

Distribution and prevalence of T. bryosalmonae in Austria: A first survey of trout from rivers with a shrinking population

Lewisch

Unfer

Pinter

et al. 2018

Journal of Fish Diseases

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The first evidence of proliferative kidney disease (PKD) in an Austrian river (the River Kamp) was documented in 2016, and no information on the PKD infection status of trout in other rivers was available. Since then, brown trout (Salmo trutta fario) and rainbow trout (Oncorhynchus mykiss) have been collected from rivers in Upper and Lower Austria for different diagnostic purposes. In this study, we summarize the recent findings of a first survey concerning the distribution of Tetracapsuloides bryosalmonae, the causative agent of proliferative kidney disease (PKD), from these samples. Between September 2015 and October 2017, a total of 280 brown trout and 39 rainbow trout were collected from 21 rivers in the provinces of Upper and Lower Austria. T. bryosalmonae was detected by PCR of kidney tissue in 17 of 21 sampled rivers and in 138 of 280 brown trout as well as in 11 of 39 rainbow trout. Pathological signs of PKD (e.g., hypertrophy of the kidney) were observed in 33 analysed brown trout and six rainbow trout samples. No correlations between fish infected by T. bryosalmonae and the parameters size and age class, condition factor, geological origin of the streams and distribution within the river course were found, while positively tested fish are significantly increased at sampling sites exceeding water temperatures of 15°C for median periods of 115 days. The prevalence within the affected streams or stream sections is highly variable, and in single rivers, infection rates of up to 90% are confirmed.

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Section: Discussionmentioning

confidence: 93%

Distribution and prevalence of T. bryosalmonae in Austria: A first survey of trout from rivers with a shrinking population

Lewisch

Unfer

Pinter

et al. 2018

Journal of Fish Diseases

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“…The morphology of the watershed (derived as in Carraro et al ()) was obtained from a 25‐m resolution digital terrain model, whereas the river network was extracted by means of the Taudem method (Tarboton, Bras, & Rodriguez‐Iturbe, ). Flow directions were determined by following steepest descent paths.…”

Section: Case Studymentioning

confidence: 99%

“…Temperature variations related to climate change can have devastating repercussions on salmonid populations (Hari, Livingstone, Siber, Burkhardt-Holm, & Güttinger, 2006;McCullough et al, 2009). For instance, water temperature is a major driver of the highly lethal proliferative kidney disease in salmonids (Okamura, Hartikainen, Schmidt-Posthaus, & Wahli, 2011;Carraro et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

SESTET: A spatially explicit stream temperature model based on equilibrium temperature

Carraro

Toffolon

Rinaldo

et al. 2019

Hydrological Processes

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Stream‐water temperature is a key variable controlling chemical, biological, and ecological processes in freshwater environments. Most models focus on a single river cross‐section; however, temperature gradients along stretches and tributaries of a river network are crucial to assess ecohydrological features such as aquatic species suitability, growth and feeding rates, or disease transmission. We propose SESTET, a deterministic, spatially explicit stream temperature model for a whole river network, based on water and energy budgets at a reach scale and requiring only commonly available spatially distributed datasets, such as morphology and air temperature, as input. Heat exchange processes at the air–water interface are modelled via the widely used equilibrium temperature concept, whereas the effects of network structure are accounted for through advective heat fluxes. A case study was conducted on the prealpine Wigger river (Switzerland), where water temperatures have been measured in the period 2014–2018 at 11 spatially distributed locations. The results show the advantages of accounting for water and energy budgets at the reach scale for the entire river network, compared with simpler, lumped formulations. Because our approach fundamentally relies on spatially distributed air temperature fields, adequate spatial interpolation techniques that account for the effects of both elevation and thermal inversion in air temperature are key to a successful application of the model. SESTET allows the assessment of the magnitude of the various components of the heat budget at the reach scale and the derivation of reliable estimates of spatial gradients of mean daily stream temperatures for the whole catchment based on a limited number of conveniently located (viz., spanning the largest possible elevation range) measuring stations. Moreover, accounting for mixing processes and advective fluxes through the river network allows one to trust regionalized values of the parameters controlling the relationship between equilibrium and air temperature, a key feature to generalize the model to data‐scarce catchments.

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“…It is widespread in Europe and also occurs in Asia, Australia, and New Zealand but is rare in North America (Wood & Okamura, 2005). F. sultana clonally reproduces via fragmentation, when branches of the tubular colonies detach (Fontes, Hartikainen, Taylor, & Okamura, 2017), and the production of nonbuoyant statoblasts Carraro et al, 2017). Clearly, the widespread distribution of F. sultana reflects occasional dispersal that is likely to be mediated by zoochory (animal-mediated movement) and hydrochory but such dispersal has not been demonstrated.…”

Section: Study Systemsmentioning

confidence: 99%

“…Research on F. sultana has primarily focused on its role as a fish disease reservoir because it acts as host of the causative agent of salmonid proliferative kidney disease (Okamura, Hartikainen, Schmidt‐Posthaus, & Wahli, ). There have been no studies explicitly focusing on dispersal and gene flow of F. sultana although a recent study incorporated measures of F. sultana eDNA distributions to test a spatially explicit fish disease model within a river network setting (catchment; Carraro et al, ). Clearly, the widespread distribution of F. sultana reflects occasional dispersal that is likely to be mediated by zoochory (animal‐mediated movement) and hydrochory but such dispersal has not been demonstrated.…”

Section: Introductionmentioning

confidence: 99%

To remain or leave: Dispersal variation and its genetic consequences in benthic freshwater invertebrates

Ruggeri

Pasternak

Okamura

2019

Ecology and Evolution

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Variation in dispersal capacity may influence population genetic variation and relatedness of freshwater animals thus demonstrating how life‐history traits influence patterns and processes that in turn influence biodiversity. The majority of studies have focused on the consequences of dispersal variation in taxa inhabiting riverine systems whose dendritic nature and upstream/downstream gradients facilitate characterizing populations along networks. We undertook extensive, large‐scale investigations of the impacts of hydrological connectivity on population genetic variation in two freshwater bryozoan species whose dispersive propagules (statoblasts) are either attached to surfaces (Fredericella sultana) or are released as buoyant stages (Cristatella mucedo) and that live primarily in either lotic (F. sultana) or lentic environments (C. mucedo). Describing population genetic structure in multiple sites characterized by varying degrees of hydrological connectivity within each of three (or four) UK regions enabled us to test the following hypotheses: (1) genetic diversity and gene flow will be more influenced by hydrological connectivity in populations of C. mucedo (because F. sultana dispersal stages are retained); (2) populations of F. sultana will be characterized by greater genetic divergence than those of C. mucedo (reflecting their relative dispersal capacities); and (3) genetic variation will be greatest in F. sultana (reflecting a propensity for genetic divergence as a result of its low dispersal potential). We found that hydrological connectivity enhanced genetic diversity and gene flow among C. mucedo populations but not in F. sultana while higher overall measures of clonal diversity and greater genetic divergence characterized populations of F. sultana. We suggest that genetic divergence over time within F. sultana populations reflects a general constraint of releasing propagules that might eventually be swept to sea when taxa inhabit running waters. In contrast, taxa that primarily inhabit lakes and ponds may colonize across hydrologically connected regions, establishing genetically related populations. Our study contributes more nuanced views about drivers of population genetic structures in passively dispersing freshwater invertebrates as outlined by the Monopolization Hypothesis (Acta Oecologica, 23, 2002, 121) by highlighting how a range of demographic and evolutionary processes reflect life‐history attributes of benthic colonial invertebrates (bryozoans) and cyclically parthenogenetic zooplankton. In addition, growing evidence that genetic divergence may commonly characterize populations of diverse groups of riverine taxa suggests that organisms inhabiting lotic systems may be particularly challenged by environmental change. Such change may predispose riverine populations to extinction as a result of genetic divergence combined with limited dispersal and gene flow.Open Research Badges This article has earned an Open Data Badge for making publicly available the digitally‐shareable data necessa...

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Integrated field, laboratory, and theoretical study of PKD spread in a Swiss prealpine river

Cited by 66 publications

References 41 publications

Distribution and prevalence of T. bryosalmonae in Austria: A first survey of trout from rivers with a shrinking population

Distribution and prevalence of T. bryosalmonae in Austria: A first survey of trout from rivers with a shrinking population

SESTET: A spatially explicit stream temperature model based on equilibrium temperature

To remain or leave: Dispersal variation and its genetic consequences in benthic freshwater invertebrates

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