Effects of temperature acclimation on thermal performance for sea lamprey larvae

Abstract

Sea lamprey (Petromyzon marinus) invaded the Laurentian Great Lakes in the early 20th century and remain a threat to fisheries in the largest freshwater ecosystem of the world. Nowadays, population growth is restrained by a highly successful control program that mainly relies on the application of the lampricide 3-trifluoromethyl-4’-nitrophenol (TFM) to streams infested with larval sea lamprey. Recent work shows that the effectiveness of TFM is affected by temperature, with the toxicity to larval sea lamprey decreasing with increasing temperature. As such, we set out to unveil the thermal breadth of larval sea lamprey using intermittent-flow respirometry. To do so, we calculated thermal performance curves for this life stage using two approaches: First, we acclimated larvae to 7, 13, 18, 21, 25 and 28°C and tested their aerobic scope at the respective acclimation temperature. Second, we acclimated larvae to 6, 13 and 21°C and subsequently performed acute exposure tests (6, 10, 13, 15, 18, 21, 25, 28 and 31°C), with a temperature increase/decrease rate of approx. 0.1°C/min. Our results show a wide thermal tolerance, consistent with the plasticity required to become a successful invasive species. Further, sea lamprey larvae show a thermal optimum nearing 28°C, indicating that their tolerance to TFM will likely continue to increase as water temperatures in the Great Lakes continue to rise due to climate change.