Mason Klafka and Sam Pruhns, “PolyFluoroAlkyl Substances (PFAS) and Microplastics in the Lake Michigan Lower Foodweb”
Mentor: John Berges, Biological Sciences, Letters & Science (College of)
Poster #173
Polyfluoroalkyl substances (PFAS), so-called “forever chemicals” are an emerging contaminant in aquatic ecosystems that have been prioritized by Wisconsin Sea Grant. PFAS are found in Milwaukee Harbor and co-occur with microplastics, another priority contaminant. Recently, we have examined the uptake of microplastics by the opossum shrimp, Hemimysis anomala, a species that invaded the Great Lakes in the mid 2000’s and is now resident in Lake Michigan Harbors. We have also measured significant levels of PFAS in Hemimysis collected from Milwaukee Harbor, which raises important questions about the transfer of PFAS in the foodweb and connections between PFAS and microplastics. The overall goals of this project is to explore these associations. We examined: whether PFAS bound to microplastics is efficiently transferred to Hemimysis when Hemimysis ingests plastic particles. Hemimysis were collected from Lake Michigan using previously-constructed lighted funnel traps. Some animals were directly sampled, measured and staged and PFAS contents determined. Others were maintained in laboratory aquaria and used in short-terms laboratory feeding experiments with microplastic beads. For micro plastics feeding experiments, fluorescent polyethylene microplastic beads (30 µm diameter) were exposed to polyfluorooctanoic acid (PFOA) for 24 h and efficient of binding determined. Triplicate sets of three Hemimysis were allowed to graze plastic beads in small-volume beakers, or held without beads as controls. Beads ingested was determined by measuring disappearance from water from the start to end of the grazing period, using flow cytometry. After 3 h grazing, animals were transferred to clean water and 3 h were allowed for animals to clear their guts of beads. Hemimysis were then collected and analyzed for PFAS, following US-EPA 1633, extracting tissues in KOH/methanol, followed by anion exchange, liquid chromatograph and mass spectrometry. We anticipate that PFOS from plastic beads will be transferred to Hemimysis at high efficiency.