PREFERENCE-AVOIDANCE RESPONSES OF LAKE WHITEFISH (COREGONUS-CLUPEAFORMIS) TO COMPETING GRADIENTS OF LIGHT AND COPPER, LEAD, AND ZINC

The preference-avoidance responses of lake whitefish (Coregonus clupea formis) to copper, zinc, and Pb ions were tested in a countercurrent t rough that was either uniform in regard to illumination, or shaded in one half. Under uniform illumination, Cu was avoided at concentrations of 1 mu g/L and higher, Zn and Pb at and above 10 mu g/L. Fish prefer red the shade when presented with a choice between shaded and illumina ted. When metals were injected into the shaded, previously preferred a rea, avoidance of these ions was strongly suppressed, except for the h ighest concentrations, especially in the case of Pb. (C) 1998 Elsevier Science Ltd. All rights reserved.