Bering Sea | Mammals MASTER’S POSTER PRESENTATION Total mercury concentrations among unique bone elements varies within individual adult Steller sea lions Presenter: Mary Keenan , mpkeenan@alaska.edu, University of Alaska Fairbanks Nicole Misarti , nmisarti@alaska.edu, University of Alaska Fairbanks Lara Horstmann , lara.horstmann@alaska.edu, University of Alaska Fairbanks Bone is a biologically resilient material that is well preserved over millennial time scales. Therefore, it can be used to study past concentrations of various chemicals, such as mercury (Hg), incorporated into bone over time. As an environmental contaminant, Hg may have adverse effects that impact population dynamics. Some modern-day Alaska marine mammals, including Steller sea lions (SSL; Eumetopias jubatus ), are known to have high total Hg concentrations ([THg]) in fur and organ tissues; however, little is known about the differences in [THg] among bone elements (e.g., femur, mandible, rib) within individuals. SSL are an ideal species for this study due to their central role in the Alaska marine ecosystem as long-lived top predators that bioaccumulate and biomagnify Hg. Differences in bone composition, growth, development, and turnover rate likely affect [THg] among bone elements. We hypothesized that bone elements with potentially greater mechanical stress and turnover rates, such as long bones and phalanges in SSL, may represent the most recent Hg concentrations within an individual and will have greater [THg]. Bioaccumulation and biomagnification may lead to differences in [THg] in age classes of SSL. Six bone elements (cranium, mandible, nasal turbinate, rib, long bone, phalange) were collected from individual SSL skeletons (n=3 fetuses, 5 pups, 3 juveniles, 4 adults). The bones were obtained from NOAA-MML and ADFG field collections and the University of Alaska Museum of the North mammal archives. The bones were macerated in nanopure water to remove soft tissue as needed, and freeze- dried for 48 hours. Each bone was sub-sampled for ~0.2g of compact and spongy bone. [THg] was quantified in three technical replicates with a Nippon MA-3000. Using repeated measures ANOVA, no significant difference was found in [THg] among bone elements for fetuses, pups, and juveniles. Fetuses and pups likely show no difference in [THg] among bone elements due to limited time for bioaccumulation and bone remodeling. However, adult nasal turbinate compact bone had greater [THg] compared with mandible (p=0.035, 49.06 + 26.5ppb and 10.79 + 8.82ppb, respectively). Nasal turbinates are a thin sheet of bone with a high turnover rate potentially representing most recent intake of Hg. This work will contribute to a better understanding of [THg] within marine mammals and determine what bone elements in an archival collection will equally represent the [THg] for an individual. Caroline Funk , cfunk@buffalo.edu, University of Buffalo Todd O’Hara , tmohara@tamu.edu, Texas A&M University Lorrie Rea , ldrea@alaska.edu, University of Alaska - Fairbanks Julie Avery , jpavery@alaska.edu, University of Alaska Fairbanks
Alaska Marine Science Symposium 2023 261
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