Sensitivity of early life stages of vendace, Coregonus albula, to acid pH in postmining lakes: An experimental approach

Since 1990, many highly acidic lakes with very hard water have formed in Lu satia, eastern Germany, following the decommissioning of most open-cast lig nite mines. Even after neutralization of the water, the lakes may reacidify due to the high acidification potential of soil and groundwater. Hence, in vestigation of critical pH-levels for the respective fish species is requir ed when planning to use the lakes for fisheries. Sensitivity of early life stages of vendace, Coregonus albula, to low pH was determined in reconstitu ted water with the hydrochemical characteristics of the postmining lakes. E ggs were transferred to test solutions with pH-values ranging from 3.50 to 7.40 either 10 min after artificial insemination (series A) or 7 h later (s eries B) and incubated using a static-renewal procedure. Water hardening of the eggs at exposure pH (series A) led to a severe reduction in egg diamet er at pH less than or equal to 5.00 and to an earlier and stronger increase in egg mortality, but by the time of hatching, differences between both se ries were small. Hatching percentages at pH less than or equal to 5.00 were very low and the eleutheroembryos died shortly after hatching. In both ser ies, hatching percentages at pH 5.50 did not differ from those at pH 7.40. Feeding activity of vendace exposed to pH 5.50 was, however, reduced and th e fish did not survive. Hence, early life stages of vendace can be regarded as very sensitive to low pH and associated elevated concentrations of Al, and maintenance of neutral pH is essential when postmining lakes are stocke d with vendace. (C) 2000 by John Wiley & Sons, Inc.