Relationship between Water chemistry, the Gill Microenvironment, and TFM toxicity in Non-Target Fish

Session: 10. - Physiology and Conservation of Sturgeon in the Great Lakes

Laura Tessier, Wilfrid Laurier University, [email protected]
Scott Hepditch, Wilfrid Laurier University, [email protected]
Oana Birceanu, Wilfrid Laurier Univ., Dept. of Biology, [email protected]
Lisa O'Connor, Fisheries and Oceans Canada, [email protected]
Jonathan Wilson, Wilfrid Laurier University, [email protected]
Michael Wilkie, Wilfrid Laurier University, Dept. Biology, [email protected]

Abstract

Lake sturgeon, a potamodromous cartilaginous fish, are currently listed as extirpated, endangered, or a species of concern in the Great Lakes. As juveniles, sturgeon live in tributaries that sometimes overlap with larval invasive sea lamprey, and may be exposed to the piscidide TFM (3-trifluoro-4-nitrphenol) during lampricide applications. Juvenile lake sturgeon are sensitive to TFM, for reasons not completely understood. One possibility is that the unique sturgeon gill structure may affect TFM speciation in the microenvironment next to the gills, increasing TFM uptake and toxicity. Sturgeon gills have a dorsal-lateral opercular slit, allowing bi-directional ventilation when feeding. We hypothesize that this arrangement leads to greater gill CO₂ accumulation, increasing water acidity and TFM uptake. In preliminary studies using rainbow trout in a divided chamber, we demonstrated that water pH decreased by 0.2 units after crossing the gills. Because TFM is a weak acid, a greater proportion would have been in its un-ionized, bioavailable form at this lower pH. Experiments using radio-labeled ¹⁴C-TFM demonstrated that TFM uptake was much higher at low (pH 6.5) compared to moderate pH (pH 7.8). Further evidence will illustrate that TFM uptake is dependent upon the pH of the gill microenvironment water in trout and sturgeon.

1. Keyword
Great Lakes basin

2. Keyword
fish toxins

3. Keyword
fish

4. Additional Keyword
Physiology

5. Additional Keyword
Toxicology