Influence of Water Quality on the Outbreak of Proliferative Kidney Disease - Semi-Field and Field Studies

M El-Matbouli1, RW Hoffmann1, S Adam2, R Triebskorn3, J Schwaiger4

1 Institut of Zoology, Fish Biology and Fish Diseases, University of Munich, Kaulbachstreet 37, 80539 Munich, Germany

2 Animal Physiological Ecology, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany

3 Steinbeis-Transfer Center for Ecotoxicology and Ecophysiology, Kreuzlingerst. 1, 72108 Rottenburg, Germany

4 Bavaria Water Management Agency, Dept. Aquatic Ecology Research, Demollstr. 31, 82407 Wielenbach, Germany

Proliferative kidney disease (PKD) and whirling disease (WD) are economically and ecologically important parasitic diseases occurring in both cultured and wild populations of salmonids. Great progress has been made recently in understanding the nature and source of the long known, yet mysterious PKD. It is now apparent that the causative agent is the recently described Tetracapsula bryosalmonae Canning, Curry, Feist, Longshaw, Okamura, 1999.

The striking seasonality of PKD led us to consider water temperature as a major environmental factor affecting the initiation and progression of the disease. Water quality has been discussed also as another exogenous factor, important in the development of the disease. This paper presents data of field and semi-field studies and the possible association of limno- and physicochemical parameters in the outbreak of PKD in rainbow and brown trout.

The investigations were carried out at three brooks (Singold, Krähenbach, Körsch) in Southern Germany exhibiting different water qualities. Exposure experiments and sampling of wild fish were performed in the Singold river at least twice a year between 1992 and 1994 as well as between 1996 and 2000. The investigations in the Krähenbach and the Körsch stream were conducted between 1995 and 1999 and included 13 semi-field experiments and 6 field studies. Both wild fish collected from the specific sites and experimentally-exposed rainbow and brown trout were investigated histologically for the occurrence of PKD. At the time of sampling various water parameters at the respective river sites were measured. The results indicate strongly the existence of a correlation between organic pollution of the water and the occurrence of PKD.

PKD-Workshop, July 2 and 3, 2001, EAWAG Kastanienbaum, Switzerland

Project “fischnetz”, www.fischnetz.ch