Jeff Collins, Westminster College
Biology
The Great Salt Lake (GSL) has some of the highest mercury concentrations ever measured in surface waters. The accumulation of high levels of mercury, particularly its more toxic and readily biomagnified form, methylmercury, has been recorded in many species that inhabit or feed directly in the GSL, including waterfowl. However, no studies at the GSL, and very few studies elsewhere, have investigated the transfer of mercury from aquatic ecosystems to terrestrial ecosystems. We hypothesized that brine flies are able to accumulate mercury during their larval stages in the lake, then transfer this mercury to adjacent terrestrial ecosystems when they become flying adults. Concentrations of total mercury (HgT) and methylmercury (MeHg) were measured in samples of surface water and brine flies (larvae, pupae, and adults) collected once each month between February and July at Antelope Island, in the GSL. Samples were collected from two distinct sites: one along Gilbert Bay on the west side of the Island, and the other along Farmington Bay on the east. On average, HgT concentrations are greater in water samples from Farmington Bay (19.3 ± 9.0 ng/L unfiltered; 13.5 ± 10.1 ng/L filtered) compared to Gilbert Bay (8.5 ± 7.5 ng/L unfiltered; 9.2 ± 9.6 ng/L filtered). MeHg and HgT levels in brine flies displayed the opposite trend, with higher levels at Gilbert Bay (567 ± 123 ppb HgT; 425 ± 12 ppb MeHg) than at Farmington Bay (270 ± 60 ppb HgT; 208 ± 35 ppb MeHg). Potential explanations for the trends observed will be discussed.