Bering Sea | Ecosystem Perspectives MASTER’S POSTER PRESENTATION Refined spatial analysis of tissue mercury concentration variation in the Aleutian marine food web provides insight into discrete pathways Presenter: Scott Chandler , sdchandler@alaska.edu, University of Alaska - Fairbanks
Lorrie Rea , ldrea@alaska.edu, University of Alaska - Fairbanks Greg Breed , gabreed@alaska.edu, University of Alaska - Fairbanks Todd O’Hara , tmohara@tamu.edu, Texas A&M University Todd Loomis , tloomis@oceanpeaceinc.com, Ocean Peace, Inc
Along the Aleutian Island archipelago, multiple wildlife species show marked spatial variation in tissue total mercury (Hg) concentrations ([THg]). The spatial scale and pattern of this variation may yield critical insights into Hg pathways through the food web to higher-level predators. Using archived and recent observations from muscle tissues of 10 fish species and 2 cephalopods (n = 1461), linear mixed effect models were fit to assess variation of [THg] across the western and central Aleutian Islands. [THg] were compared at multiple spatial resolutions to test the hypothesis that seven deep-water “oceanic passes” act as discrete barriers that define Hg pathways through the marine food web. Dividing the study area by passes explained significantly more variation in [THg] compared to broader ecosystem boundaries used in previous studies. [THg] were highest west of Amchitka Pass and east of the Near Islands with a gradual decrease in [THg] with distance from this area. We infer from this pattern that oceanic passes may limit the movement of fish and environmental exposure to Hg, creating localized patterns of [THg]. This spatial compartmentalization of Hg pathways in the Aleutian food web would strongly influence the degree to which higher trophic level predators are exposed to Hg in this dynamic marine ecosystem.
Alaska Marine Science Symposium 2023 169
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