Fig. 1: Studied rivers and dams, water temperature and proliferative kidney disease (PKD) in brown trout.
From: Dams threaten salmonids by triggering temperature-dependent proliferative kidney disease
A The study area consisting 14 dams. B Distances of the study sites from the dam, boxplots showing the distributions for up-and downstream sites. C. Left: Distribution of dam heights in relation to Tb occurrence including two consecutive dams in two rivers. Right: Tb life-cycle and scheme of the effect of temperature on parasite prevalence, load and PKD. D Mean summer water temperature with lines connecting upstream and downstream locations. E Number of days over 15 °C upstream and downstream of the dam. F Left: Effect of reservoir area (log10 ha) on water temperature change. Right: Temperature change downstream of 35 small dams according to Zaidel et al. (2021). G Aerial photo of small dam and reservoir (10.6 ha) at R. Mustoja. H Photo of a large bryozoan colony covering most of the bottom downstream of the dam at R. Ahja with a close-up image of the bryozoan colony (Plumatella fungosa). I Dead wild YOY brown trout found from downstream section of R. Mustoja with extreme renal hyperplasia. Sagittal cross section of a trout with normal (left), swollen (middle) kidney and extreme renal hyperplasia (right, dead trout from the same subfigure). The yellow arrows mark the location of the kidney, K/B indicates kidney-to-body thickness ratio as a measure of renal hyperplasia.
