Damselflies in distress: Effects of methylmercury-cysteine on foraging behaviour and escape response; aquatic invertebrates predators (Order Odonata)
LE3 .A278 2011
Bachelor of Science
Transfer of mercury from aquatic to terrestrial ecosystems occurs primarily via consumption of invertebrates by birds and fish. As intermediate predators, dragonfly and damselfly nymphs (Order Odonata) are important invertebrates in littoral zones and wetlands. Changes in foraging behaviour, responses to a predatory stimulus, and neuroanatomy of damselfly naiads as a result of mercury bioaccumulation were tested. Damselfly naiads were acquired from Big Dam East and Big Dam West Lakes of Kejimkujik National Park, Nova Scotia. Injections of methylmercury cysteine were administered into the abdominal thoracic articulations of naiads. Foraging and predatory response tests were completed at 24 hours and one-week intervals. Trials were performed on naiads that had been injected with one of five dilutions of methylmercury (100 ng of MeHg, 500 ng of MeHg, 1000 ng of MeHg, 2500 ng of MeHg, 5000 ng of MeHg) or a saline cysteine solution. Results suggest that MeHg has no biologically significant effect on foraging behaviour. Reduction of MeHg in damselfly bodies at 24-hr and one-week was not significant. However, a decrease in concentrations of MeHg was observed. MeHg injections lead to a significant increase in velocity. MeHg injections did not have a significant effect on angular movement in this experiment. The role of invertebrates in the food chain, and how they respond to environmental contaminations are the major gaps in research that this thesis will address.
The author grants permission to the University Librarian at Acadia University to reproduce, loan or distribute copies of my thesis in microform, paper or electronic formats on a non-profit basis. The author retains the copyright of the thesis.