THE USE OF FISH AVOIDANCE RESPONSE IN IDENTIFYING SUBLETHAL TOXICITY OF HEAVY METALS AND THEIR MIXTURES

Abstract

Analysis of the experimental data obtained by the author over the last decade is presented. Laboratory tests were conducted on fishes of different ecological groups. It was found that fishes are able to detect and spontaneously avoid low sublethal concentrations of heavy metals and their mixtures. The intensity of avoidance response depended on fish species sensitivity, ecological, physiological and behavioural characteristics. Rainbow trout was found to be the most sensitive species among other fishes tested: three-spined stickleback, goldfish, roach, dace, vimba and perch. Rainbow trout intensively avoided heavy metal model mixtures of different combinations consisting of 5 to 8 representative heavy metals (Cu, Zn, Ni, Cr, Fe, Pb, Cd, Mn). The concentrations of heavy metals corresponding to threshold avoidance concentrations were very low. Such heavy metal concentrations can be found only in clean unpolluted waters. Moreover, the vast majority of them were considerably (on average 29-fold) lower than their Maximum Permitted Concentrations (MPC) accepted as Lithuanian water quality guidelines for the protection of aquatic biota. The possibility of appliance of fish avoidance response to heavy metals for the needs of bioassay testing is discussed.

Keywords:

• fish
• heavy metal mixtures
• toxicity assessment
• avoidance response