Toxicity in Fish Tissue: Redefining our Understandings by Quantifying Mixture Toxicity

This is a past event.

Monday, November 29, 2021 3 pm

This is a past event.

A Joint EPSSI/Environmental Engineering Graduate Seminar

Emily Shaw, PhD Candidate, Environmental Engineering, Michigan Tech


Emily Shaw is settler scholar living and working within the Anishinaabe Ojibwe homelands of Northern Michigan. Currently, Emily is a PhD candidate in environmental engineering doing research that bridges knowledge systems to understand mixture toxicity. As an indiginist researcher, her work rebuilds systems of accountability and responsibility between humans and the environment that are aligned to Anishinaabe philosophies. Prior to graduate school at Michigan Tech, Emily earned a bachelor’s degree in public policy from Indiana University in Bloomington, IN. For four years, she was the Education and Volunteer Coordinator at Inland Seas Education Association, a non-profit in Suttons Bay, MI with a mission to inspire a lifetime of Great Lakes curiosity, stewardship, and passion in people of all ages. In the two years leading up to graduate school she spent most of her time in Antarctica, washing dishes at the South Pole research station and hiking and sailing throughout New Zealand. Now she enjoys exploring her new home, Houghton, playing roller derby, and gardening.


In response to generations of inequitable research to/for Indigenous communities, many have and are developing research practices that center Indigenous priorities. This presentation shares the Seasons of Research framework developed, in partnership with the Keweenaw Bay Indian Community. The guidance aims for balance between and among four seasons of research: relationship building, planning and prioritization, knowledge exchange, and synthesis and application. Research partnerships with/by/as the Community demonstrate respect for each other's differences, honor reciprocity in actions, exemplify responsibility for differing commitments, and express reverence for shared lands, waters, and living beings. The framework uses the medicine wheel to illustrate an interconnected system of partnership teachings and is the framework that guides my quantitative research. 

To better protect human health from mercury and PCBs accumulated in fish, the objective of this research is to elucidate patterns in mixture toxicity. Specifically, this research asks, Are fish in productive lakes, defined by chlorophyll-a and nutrient concentrations, more toxic than fish in less productive lakes? In the early 2000s, the US EPA conducted a fish tissue survey and quantified contaminant concentrations in fish tissue from ~500 lakes (NLFTS lakes). Using these data, we calculated hazard quotients (HQs) for mercury, dioxins, furans, and polychlorinated biphenyls which can be summed to represent mixture toxicity. Preliminary results show bottom-dwellers are significantly more toxic than predator fish (p<0.001) and the toxic contribution of the compounds vary between composite types. Predator samples have more mercury toxicity and bottom-dwellers are dominated by the hydrophobic compounds. Geographic weighted regression helped predict nutrient (TP and TN), chlorophyll-a, and DOC concentrations based on land uses within the watershed. While the model performs better for DOC and TN, we plan to do a correlation analysis to identify patterns related to mixture toxicity and water quality. Understanding these patterns will facilitate the prediction of mixture toxicity in unmonitored waterbodies and better protect human health.

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