Meeting Abstract
Methylmercury is a widespread environmental stressor known to disrupt endocrine and neural function of organisms even with exposure at sublethal levels. Previous studies of its effects on physiology and behavior have focused mainly on aquatic organisms. However, more recent studies have shown that mercury also bioaccumulates in terrestrial food webs. This study sought to discern the effects of sublethal levels of mercury on spatial learning and memory in songbirds, an understudied group exposed to the neurotoxicant. We conducted 5-phase spatial memory trials where captive zebra finches (Taeniopygia guttata) learned to find and remember the correct location of food in covered, baited blocks across several days. Zebra finches were either exposed to environmentally relevant levels of methylmercury (1.2 parts per million) or control diet throughout their lifespans. Birds exposed to methylmercury required more trials to learn and return to the location of food than did control counterparts. At the same time, dietary mercury did not affect recall of food location once they had been learned. This difference in learning food location could be due to effects of mercury on neural processes in the hippocampus, a region of the brain related to learning and memory. These results suggest heavy metal contamination could have severe implications for songbird conservation, particularly migratory and/or food-caching species.
