Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Biology

Program Name/Specialization

Integrative Biology

Faculty/School

Faculty of Science

First Advisor

Dr. Michael Wilkie

Advisor Role

Supervisor

Second Advisor

Dr. Jonathan Wilson

Advisor Role

Committee Member

Third Advisor

Dr. Allison McDonald

Advisor Role

Committee Member

Abstract

Sea lampreys (Petromyzon marinus) have a complex life cycle that involves a parasitic phase in which they feed on the blood and bodily fluids of large piscivorous fishes. Following the invasion of the Great Lakes by sea lampreys in the early 20th century, sea lamprey parasitism contributed to major declines in the populations of commercial and sports fisheries in that basin. The lampricide 3-trifluoromethyl-4-nitrophenol (TFM), developed in the late 1950s,is now routinely applied to tributaries of the Great Lakes to control sea lamprey populations. This lampricide is selectively toxic to larval sea lampreys, which typically reside as burrow-dwelling filter-feeders in streams. Although the TFM concentrations commonly applied to streams and rivers is 1.2 - 1.5 times the 9 h LC99.9 (minimum lethal concentration; MLC)of the larvae, surviving residual sea lamprey may be observed after treatments. The underlying causes for “residuals” are poorly understood, however. The main goal of my M.Sc. thesis was to determine how body size and life stage influenced TFM uptake, excretion andsurvival of larval sea lampreys following TFM exposure. Because rates of oxygen consumption (ṀO2) are inversely proportional to body size in animals, I predicted that correspondingly lower rates of ventilation would result in lower rates of TFM uptake and greater TFM tolerance in larger compared to smaller larval sea lampreys. As predicted, smaller lampreys had exponentially higher rates of ṀO2 and TFM uptake compared to larger animals. I alsopredicted that due to higher metabolic demands, more activepost-metamorphic sea lampreys would have higher TFM uptake rates compared to larval sea lampreys. Surprisingly, both ṀO2 and TFM uptake rates were similar in size matched larval and post-metamorphic sea lampreys. Body mass wasalso correlated with TFM elimination, following intraperitoneal injection of TFM, but there were no differences in the TFM clearance rates between larval and post-metamorphic sea lampreys. Finally, toxicity tests indicated that larval sea lamprey with greater mass and condition factor (CF) were able to survive exposure to TFM longer than smaller sea lampreys. Collectively, these results suggest that large larval sea lampreys may be more tolerant to TFM, suggesting that streams containing high densities of large larvae may be at risk for increased residual sea lamprey following TFM treatment. Thus, it would be advisable to take precautions to reduce the chances of residuals when TFM is applied tosteams with high densities of large larvae.

Convocation Year

2016

Convocation Season

Fall

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