Abstract:

The lampricide, 3-trifluormomethyl-4-nitrophenol (TFM) is used to control invasive sea lamprey (Petromyzon marinus) populations in the Great Lakes. TFM uncouples mitochondria oxidative phosphorylation, leading to a mismatch between energy supply and demand, which eventually kills the animal. Recent studies have raised concern about risks of TFM resistance developing in the sea lampreys due to longstanding use, but studying multigenerational effects of TFM in fishes is time consuming and resource draining. The brown flatworms (Dugesia dorotocephala) could be used as a model for testing resistance, due to its ability to multiply by fission, with a short regeneration time. However, before modelling resistance, we need to have a better understanding of the effects of TFM on brown flatworm physiology. The current study is the first to determine how TFM affects behaviour, metabolites and energy reserves in brown flatworms. To this end, we exposed worms to increasing concentrations of TFM in soft water (alkalinity 100mg/L CaCO3, pH 7.59, temperature 20.2°C) and determined the 2h LC50 to be 2.79 mg/L. Locomotion was reduced within 5 min of exposure to TFM, in a dose-dependent manner, suggesting that the lampricide impacts motility. Next, animals were exposed to the 2h LC50 and samples were collected to measure whole-body lactate, glucose and glycogen at 0.5, 1.0, 1.5, 2.0 h of exposure. Our work to date has shown that flatworms are highly sensitive to TFM at environmentally relevant concentrations, leading to decreased locomotion and mortality that could be due to impaired ATP production.