SURVIVAL OF CRUCIAN CARP, CARASSIUS-CARASSIUS, EXPOSED TO A HIGH LOW-MOLECULAR-WEIGHT INORGANIC ALUMINUM CHALLENGE

Crucian carp were exposed to three combinations of pH and inorganic al uminium concentrations for 25 days. Mortality, plasma chloride and hae matocrit, and gill aluminium content were investigated. No mortality w as observed in any of the three exposures. Crucian carp survived acidi c Al-rich water (pH 5.17) with a high concentration of low-molecular w eight inorganic Al species (242 mu gl(-1)) for 25 days. These fish had lowered plasma chloride levels and high amounts of aluminium on their gills compared to fish exposed to acidic Al-poor water (pH 5.16 and 1 2 mu gl(-1) Al,) and control water (pH 6.29 and 4 mu gl(-1) Al-i). Hae matocrit was the same in all three exposures. Because aluminium was no t acutely toxic to the anoxia tolerant crucian carp, the present resul ts give support to the hypothesis that Al polymerization with subseque nt hypoxia is of high importance for the mechanism of acute Al toxicit y to fish.