Bering Sea | Mammals MASTER’S POSTER PRESENTATION Occurrence of microplastics in spotted seal stomachs from the Chukchi and Bering Seas, in 2012 and 2020 Presenter: Alexandria Sletten , alsletten@alaska.edu, University of Alaska Fairbanks Lara Horstmann , lahorstmann@alaska.edu, University of Alaska Fairbanks Katrin Iken , kbiken@alaska.edu, University of Alaska - Fairbanks Anna Bryan , anna.bryan@alaska.gov, Alaska Department of Fish and Game Microplastics pose a significant threat to marine ecosystems across multiple trophic levels. Spotted seals ( Phoca largha ) are piscivorous and occupy one of the higher trophic positions in the Chukchi and Bering seas. Arctic cod ( Boreogadus saida ) are a common prey for spotted seal and are known to contain microplastics. Spotted seals are, therefore, at risk to ingest and bioaccumulate microplastics. This project aims to determine if microplastics are present in the stomachs of spotted seals harvested for subsistence purposes at Shishmaref and Gambell, AK. Microplastics are predicted to increase over time due to increased climate warming and subsequent deposition of microplastics from melting sea ice. Therefore, we chose to examine stomachs from 2012 and 2020 to explore changes over time. As spotted seal pups (<1 yr. old) and non-pups are known to forage differently, we expect a difference in microplastic ingestion between age classes. To assess if spotted seals are ingesting microplastics, stomachs are processed using enzymatic digestion and vacuum filtration. Filters are examined with a stereomicroscope, and microplastic frequency of occurrence (FO) is calculated. To date, 15 (4 from 2012 and 11 from 2020) stomachs from Shishmaref and Gambell have been examined and a total of 90 microplastic particles were isolated from 13 stomachs (86.7% FO), containing 1 to 23 particles per stomach. Preliminary analysis shows no statistical difference in FO between 2012 (100% FO) and 2020 (81.8% FO). Additionally, no significant difference in FO was detected for spotted seal pups (n = 8) and non-pups (n = 7), with 87.5% FO and 85.7% FO, respectively. These preliminary data indicate microplastic ingestion has not changed in frequency between the two years and ingestion did not vary between age classes. We will retest our hypotheses with a greater sample size once we have processed 10 stomachs per age class and sample location for both years. Additionally, as Shishmaref and Gambell represent the Chukchi and Bering seas, respectively, a comparison of environmental variability in microplastic ingestion will be conducted. Identifying the presence of microplastics and monitoring their FO changes over time will serve as an indicator of ecosystem health in the Chukchi and Bering seas.
Alaska Marine Science Symposium 2023 268
Made with FlippingBook flipbook maker