Seasonal changes in whole brain amine levels of white sucker exposed to elevated levels of copper and zinc

Levels of dopamine, serotonin, and noradrenalin were measured in whole brains collected from white sucker (Catostomus commersoni) exposed to increased waterborne levels of copper and zinc associated with mining wastes. Few differences were detected between sites, and these findings are consistent with previous studies that failed to indicate chronic, direct effects of the metals on the white sucker populations. Levels of dopamine and serotonin were higher during postspawning periods than during prespawning or spawning. Noradrenalin levels showed parallel trends, although the differences were not significant owing to higher variability. Serotonin levels showed significant circadian variation at both sites, especially during the spawning season. Dopamine levels also showed circadian fluctuations, but only in females at one site. The results are discussed in relation to the potential use of whole brain amine levels as indicators of contaminant impact.