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|Presentation Title||Spatial trends of mercury and feeding ecology of select groundfish from the Bering Sea and Aleutian Islands|
|Presenting Author Name||Andrew Cyr|
|Presenting Author Affiliation||University of Alaska Fairbanks|
|Unit Meeting||Alaska Chapter|
|General Topic||Contaminants and feeding ecology|
|Type of Presentation||Oral|
Mercury (Hg) concentrations in fish are influenced by a myriad of behavioral, physiological, and environmental factors. One factor that has been shown to be a potential driver of Hg concentrations in fish is feeding location. Hg sources, short and long-range transport of Hg, and conditions for the methylation of Hg to the more toxic and bioavailable form, methylmercury, all interact to form a heterogenous landscape of Hg bioavailability and resulting concentrations in wildlife. A leading example of this variability in Alaska is along the Aleutian Islands, where numerous species, including Steller sea lions (Eumetopias jubatus) and Pacific halibut (Hippoglossus stenolepis), have demonstrated a consistent regional trend of Hg concentrations. Halibut and seal lions from the western portion of the Aleutian Islands consistently have elevated Hg concentrations as compared to those individuals from more central or easterly portions of the Aleutians. Here, we sought to investigate this trend in more detail by performing a thorough examination of the fish food web along the Aleutian Islands. We measured total Hg concentrations, and carbon and nitrogen stable isotope ratios in muscle samples from 1,100 fish, representing 22 species, from the Western Aleutian Islands (WAI) and the Central Aleutian Islands (CAI). We identified a consistent regional trend of elevated Hg concentrations in fish species from the WAI. Additionally, we identified a consistent shift of ~1‰ in the baseline δ13C values between the WAI and CAI. This indicates a consistent regional difference in the chemistry of the food webs between the WAI and the CAI, and that feeding location is one consistent driver of the observed differences in Hg concentrations. Finally, we note that all species in the study are within safe consumption recommendations according to the State of Alaska consumption guidelines. Restricted consumption is suggested only for Yellow Irish lord (Hemilepidotus jordani).