Immune deficiency causes annual late summer brown trout (Salmo trutta) mortality in Austrian prealpine river systems

Lahnsteiner, Franz; Haunschmid, Reinhard; Mansour, Nabil

doi:10.1007/s00027-009-0110-6

Cited by 7 publications

(5 citation statements)

References 20 publications

(20 reference statements)

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“…The total number of blood cells was counted using a Bürker Türk counting chamber as described previously (Lahnsteiner et al., 2009) from ten different fields of the counting chamber. Thereafter the samples were stained in Giemsa stain for 30 min and the number of erythrocytes with normal appearance, aged or damaged erythrocytes having an irregular shape, an eccentric nucleus, or two nuclei, erythroblasts, fusiform and rounded thromboyctes, lymphocytes, and granulocytes were counted (Lahnsteiner et al., 2009).…”

Section: Methodsmentioning

confidence: 99%

“…This phenomenon is therefore called the ‘Schwarze Bachforelle Phänomen’ or ‘proliferative darkening syndrome’ (Born and Schwaiger, 2003). A recently published study (Lahnsteiner et al., 2009) showed that the affected fish suffered from severe immune deficiency because the number of peripheral blood granulocytes and lymphocytes, plasma lysozyme activity and plasma immunoglobulin levels were drastically reduced. Changes in the hematopoietic tissue of spleen and kidney were also observed (Lahnsteiner et al., 2009).…”

Section: Introductionmentioning

confidence: 99%

“…A recently published study (Lahnsteiner et al., 2009) showed that the affected fish suffered from severe immune deficiency because the number of peripheral blood granulocytes and lymphocytes, plasma lysozyme activity and plasma immunoglobulin levels were drastically reduced. Changes in the hematopoietic tissue of spleen and kidney were also observed (Lahnsteiner et al., 2009). It is speculated that the observed immune deficiency could lead to secondary infections, with various pathogens causing death of the fish (Lahnsteiner et al., 2009).…”

Section: Introductionmentioning

confidence: 99%

“…Changes in the hematopoietic tissue of spleen and kidney were also observed (Lahnsteiner et al., 2009). It is speculated that the observed immune deficiency could lead to secondary infections, with various pathogens causing death of the fish (Lahnsteiner et al., 2009).…”

Section: Introductionmentioning

confidence: 99%

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Possible reasons for late summer brown trout (Salmo trutta Linnaeus 1758) mortality in Austrian prealpine river systems

Lahnsteiner

Haunschmid

Mansour

2010

Journal of Applied Ichthyology

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For years, severe mortality of brown trout (Salmo trutta) in late summer has been reported in the prealpine river systems of Austria. For an initial understanding of the potential reasons for this mortality, brown trout were exposed to water under differing conditions from an affected river system. Blood parameters, histology of various organs, hepatic ethoxyresorufin-O-deethylase (EROD) activity, and occurrence of ectoparasites and fish diseases were investigated. In brown trout exposed to water from the affected river, concentrations of peripheral blood lymphocytes, granulocytes, plasma immunoglobulin and plasma lyszoyme activity decreased significantly, indicating a reduction in unspecific, innate and specific, adaptive immune response. Erythropoietic and thrombopoietic functions were also disturbed, with fish mortalities up to 100%. From the results of the present study it seems unlikely that ectoparasites, diseases, or effluent water from sewage plants were causative for the observed phenomenon. However, brown trout maintained in river water and in the dark survived longer than those under natural light conditions, and their immune systems were less drastically affected. As periods of high solar UV-radiation occurred during the experiment and the Traun River water temperature was quite variable, these factors might have had an effect on immune systems. Laboratory studies were therefore conducted to ascertain whether water temperature variations and ⁄ or UV could indeed affect the immune system. The tested temperature variations (10°C ⁄ d) suppressed the brown trout immune system, whereas UV radiation (0.045 mW ⁄ m 2 for 6.5 h per day) had no effect. However, UV-radiation did enhance the immune-suppression effect of variable temperatures.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Possible reasons for late summer brown trout (Salmo trutta Linnaeus 1758) mortality in Austrian prealpine river systems

Lahnsteiner

Haunschmid

Mansour

2010

Journal of Applied Ichthyology

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“…For decades, PDS has caused a massive decline of brown trout populations in the grayling zone of several pre-alpine rivers in Southern Germany [6,7]. These mass mortalities affect a major part of the brown trout population every late summer until autumn, whereas rainbow trout (Oncorhynchus mykiss) populations are not affected.…”

Section: Introductionmentioning

confidence: 99%

Proliferative Kidney Disease and Proliferative Darkening Syndrome are Linked with Brown Trout (Salmo trutta fario) Mortalities in the Pre-Alpine Isar River

Arndt¹,

Fux

Blutke

et al. 2019

Pathogens

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For many years, brown trout (Salmo trutta fario) mortalities within the pre-alpine Isar River in Germany were reported by the Bavarian Fisheries Association (Landesfischereiverband Bayern e.V.) and local recreational anglers during August and September. Moribund fish seemed to be affected by proliferative darkening syndrome (PDS). In addition, proliferative kidney disease (PKD) caused by Tetracapsuloides bryosalmonae was discussed. To investigate this phenomenon, the present field study monitored brown trout mortalities by daily river inspection in 2017 and 2018. Moribund brown trout (n = 31) were collected and examined using histology, immunohistochemistry, qPCR, and quantitative stereology. Our investigations identified 29 (93.5%) brown trout affected by PKD. Four brown trout (12.9%) displayed combined hepatic and splenic lesions fitting the pathology of PDS. The piscine orthoreovirus 3, suspected as causative agent of PDS, was not detectable in any of the samples. Quantitative stereological analysis of the kidneys revealed a significant increase of the renal tissue volumes with interstitial inflammation and hematopoietic hyperplasia in PKD-affected fish as compared to healthy brown trout. The identified T. bryosalmonae strain was classified as part of the North American clade by phylogenetical analysis. This study highlights PKD and PDS as contributing factors to recurrent autumnal brown trout mortalities.

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Pathophysiology of Ichthyophthirius multifiliis Infection in Rainbow Trout (Oncorhynchus mykiss) and Chub (Leuciscus cephalus)

Abdel-Hafez

Lahnsteiner

Mansour

et al. 2014

Journal of Comparative Pathology

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Immune deficiency causes annual late summer brown trout (Salmo trutta) mortality in Austrian prealpine river systems

Abstract: For several years, severe brown trout (Salmo trutta) mortality has been observed in different prealpine river systems

Cited by 7 publications

References 20 publications

Possible reasons for late summer brown trout (Salmo trutta Linnaeus 1758) mortality in Austrian prealpine river systems

Possible reasons for late summer brown trout (Salmo trutta Linnaeus 1758) mortality in Austrian prealpine river systems

Proliferative Kidney Disease and Proliferative Darkening Syndrome are Linked with Brown Trout (Salmo trutta fario) Mortalities in the Pre-Alpine Isar River

Pathophysiology of Ichthyophthirius multifiliis Infection in Rainbow Trout (Oncorhynchus mykiss) and Chub (Leuciscus cephalus)

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