Bythotrephes longimanus, a predatory exotic cladoceran, has spread rapidly to numerous lakes through the Laurentian Great Lakes region of Ontario and North America. Post-invaded lakes are known to have reduced zooplankton species richness, biomass and altered community structure. Bythotrephes may also affect the diet and trophic position of macroinvertebrate predators and prey species for fish (e.g., Mysis relicta). However, the effects of this species in altering higher trophic levels remain largely unexamined. Using a combined approach of stable isotope (d13C and d15N) and THg analysis, the trophic position of Bythotrephes in two invaded lakes was investigated. Based on d15N values, Bythotrephes shared a similar trophic position to native macroinvertebrate predators (9 and 7‰ for Peninsula and Harp lakes, respectively). Using a mixing model and stomach content analysis we show that, despite low and patchy lake abundance, Bythotrephes may be a key prey item to fish and has approximate dietary contributions similar to native prey items, such as zooplankton, Chaoborus and Mysis. In both lakes, Hg conformed to predicted biomagnification trends as indicated by 15N. When Bythotrephes invades lakes with native macroinvertebrate predators, it inserts itself into the same trophic position and does not have major effects on food web length. / Thesis (Master, Biology) -- Queen's University, 2008-01-10 22:00:22.188
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/984 |
| Date | 15 January 2008 |
| Creators | Hatton, Elizabeth Courtney |
| Contributors | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | 493234 bytes, application/pdf |
| Rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
| Relation | Canadian theses |
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