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Effects of Water Alkalinity, pH, and Dosing Regimen on Lake Sturgeon Sensitivity to the Lampricide, 3-trifluoromethyl-4-nitrophenol (TFM).

The lampricide, 3-trifluoromethyl-4-nitrophenol (TFM), selectively targets larval sea lampreys (Petromyzon marinus), which have a lower capacity to detoxify and eliminate TFM through its conversion to TFM-glucuronide than non-target fishes. Although non-target fish mortality is relatively uncommon, juvenile lake sturgeon (Acipenser fulvescens) are vulnerable to TFM-induced mortality, particularly when smaller than 10 cm, and they appear to be more susceptible to TFM toxicity in waters of higher alkalinity. There is therefore a need to determine why lake sturgeon are more vulnerable to TFM in their early life stages, especially in waters with different alkalinities and pHs, and to better understand how they take-up and detoxify TFM. The objectives of this project are to: I) Determine how differences in water chemistry (pH and alkalinity) affect TFM uptake, tissue distribution and elimination in juvenile lake sturgeon; (II) Elucidate how gill-mediated acid-base exchange processes and the gill microenvironment affect TFM speciation, uptake and toxicity; (III) Determine if exposure to lower doses of TFM for longer periods in the lab and the field protects lake sturgeon from TFM toxicity, without reducing sea lamprey mortality. Accordingly, rates of TFM uptake and elimination will be measured using radiolabelled TFM (14C-TFM). Tissue TFM and TFM-glucuronide concentrations will also be measured using HPLC. As part of Objective II, the water chemistry of the gill microenvironment will be studied to determine if gill-mediated processes such as CO2 and metabolic acid excretion could be creating a more acidic microenvironment near the gill surface that results in higher rates of TFM uptake. Immunohistochemistry and immunoblotting will be used to characterize how these processes are mediated by different transport proteins in the gills. To address Objective III, larval sea lamprey and lake sturgeon will be exposed to doses of TFM that are lower than those typically applied to streams in the field, and the survival and pathophysiological effects of TFM monitored in each species. It is predicted that longer exposure times will still lead to a lethal accumulation of TFM in larval sea lamprey, which cannot detoxify TFM very effectively, but that sturgeon will be able to effectively detoxify TFM and prevent it from reaching toxic levels. This work will be accompanied by measurements of tissue TFM and TFM-metabolite levels, allowing us to determine how effectively each animal handles and detoxifies the TFM. This research will explain why the sensitivity of lake sturgeon to TFM is unexpectedly greater in high alkalinity waters, and also test the feasibility of using “long and low” TFM exposure regimens in waters known to contain lake sturgeon, without compromising treatment effectiveness. This work will also shed more light on the possible adverse effects of TFM on sensitive lake sturgeon populations, which are threatened throughout the Great Lakes.

Status
In progress
Type
Project
Start Date
End Date
Scope of Study
Laboratory Investigation
Scale of Phenomena
Organism
Physical/Chemical
Impact of Pollutants
Exotic Species
Toxic Organics
Processes
Natural Physical/Geological Processes
Land Use and Habitat
Shoreline
Wetlands
Resource Management
Fisheries
Lake Basin Connecting Channels
Lake Erie
Lake Huron
Lake Ontario
Lake St. Clair
Lake Superior
St.Lawrence River
State Province
Michigan
Ontario
Purpose of Project
Program Effectiveness / Regulatory
Region Being Monitored
Coastal Wetlands
Near and OpenShore Waters
Tributary Mouth
Resource Being Monitored
Bottom Sediment
Fisheries
Habitat
Biology And Life History
Physiology and Behavior
Control And Mitigation
Integrated Control Strategy
Ecosystem Effects
Habitat (physical / chemical)
Socio-economic Consideration and Analysis
Resource Management Issues
General
Monitoring
Aquatic Nuisance Species

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