Seasonal patterns of metal accumulation in Arctic char (Salvelinus alpinus) from an oligotrophic Alpine lake related to temperature

Cd and Pb concentrations in the liver, kidney, and stomach contents of Arctic char (Salvelinus alpinus) from an oligotrophic high mountain lake (Schwarzsee ob Solden Tyrol, Austria) with low pH (4.8 to 6.4) and alkalinity (-8 to +8 mu equiv.. L(-1)) were investigated over the course of 1 year. Peak concentrations of Cd and Pb in the water coincided with the drop of pH during snowmelt, whereas metal concentrations in liver and kidney were lowest at the end of winter and increased during summer. Furthermore, the Cd and Pb load of the food was considerably higher in winter than during summer. Thus, fluctuations in the metal levels in fish did not correlate with seasonal variations in the metal concentrations in lake water or in the diet. Rather, patterns of metal accumulation in the fish indicated that enhanced metal uptake was a consequence of increasing metabolic rates during summer. Thus, water temperature appeared to be the driving force of metal accumulation in fish from an oligotrophic lake. Concentrations of Cd and Pb in liver and kidney were positively correlated to age. A simple empirical model illustrates the ability of the fish to eliminate considerable amounts of accumulated metals.