A Preliminary Assessment of Mercury Concentrations in a Terrestrial Songbird on Antelope Island

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Heather Reynolds, Westminster College

Biology

The presence of mercury in a food chain can have harmful effects, including altering behavior, on organisms. Mercury is typically found in aquatic ecosystems, however recently is also recognized as a potential problem in terrestrial ecosystems. High levels of mercury have been found in the Great Salt Lake in a form able to bioaccumulate up the food chain. If the aquatic ecosystem is linked to the terrestrial ecosystem, then some of the highest predators included in this food chain may be songbirds that eat spiders. We quantified mercury in the blood of the Loggerhead Shrike, Lanius ludoviciaus, on Antelope Island. Upon being caught, the birds were measured, color banded, and a blood and feather sample taken from each of the 15 shrikes to be tested for mercury. Mercury concentrations ranged from 0.96 to 4.00 ppm, with a mean 1.14+/0.31 ppm. Sub-lethal effects in songbirds from another study were seen with concentrations ranging from 2.0-3.5 ppm. Two shrikes we tested exceeded that range. There was high variability in concentrations of mercury, which might be related to distance from shore. These preliminary data demonstrate that some mercury from the aquatic ecosystem is bioaccumulating in the terrestrial ecosystem on Antelope Island, and there may be harmful levels in the birds which could lead to change in behavior, and eventually decline in population. Future studies will investigate the costs of mercury contamination.