Effects of gill water chemistry on lampricide speciation and toxicity to non-target fishes

Session: Imperiled Species in the Great Lakes Basin: Identifying Threats and Restoring Populations (1)

Laura Tessier, Wilfrid Laurier University, [email protected]
Oana Birceanu, Wilfrid Laurier Univ., Dept. of Biology, [email protected]
Michael Wilkie, Wilfrid Laurier University, Dept. Biology, [email protected]

Abstract

Invasive sea lamprey populations (Petromyzon marinus) in the Great Lakes are suppressed using TFM (3-trifluoromethyl-4-nitrophenol) applied to streams containing larval sea lampreys, which have a lower capacity to detoxify and eliminate TFM compared to most non-target fishes. However, juvenile lake sturgeon (Acipenser fulvescens) live in habitat that may overlap with that of larval lamprey, and may experience adverse affects arising from TFM exposure. Due to differences in the gill structure of lamprey compared to bony fishes, we hypothesized that acidification of water as it was expired (exhaled) across the gills altered TFM speciation, and explained differences in the rates of TFM uptake and toxicity. To test this, divided chambers were designed to monitor water pH at the surface of the gill in the presence and absence of TFM. In rainbow trout, exposed to inspired (inhalant) water at neutral or basic pH, expired water was more acidic than the surrounding water, altering TFM speciation, and increasing its bioavailability. We conclude that for many compounds an understanding of how water chemistry at the gill surface differs from that of the bulk water is needed to more accurately understand the toxic properties of lampricides, pesticides and other xenobiotics.