This study aimed to describe the key consequences of three invasive species within freshwater systems, namely Lagarosiphon major, Squalius cephalus and Hemimysis anomala. I utilised a combination of tried and tested traditional methods such as age, growth and diet analyses alongside modern methods such as stable isotope analysis (SIA) and assessment of functional responses. Research questions or hypotheses were examined to assess the impacts (if any) an invader was having on ecosystem function within freshwater systems. The research methods applied and developed in this study will help ecologists quantify the direction of ecological change after an invasion has taken place. It may also help ecologists to forecast the effects an invader is likely to have in an ecosystem. In Lough Corrib the potential impacts of a L. major invasion were assessed. The findings showed that macroinvertebrate assemblage structure differed between L. major dominated habitats and native macrophyte habitats. Fish captured in invaded and native habitats differed in key, characteristics. SIA revealed that L. major made little contribution to the food-web. In the River Inny, the non native fish Squalius cephalus was discovered in 2005. This study assesses the potential for this species to have an ecological impact. 1 concluded that the population size was low. SIA revealed that the diet of this species overlapped that of several species of conservation concern. This study contributed to the probable eradication of this species from Ireland. 1 also describe the most recent distribution of the Ponto-Caspian invader Hemimysis anomala in Ireland including its spread to the River Erne catchment. In addition, functional response experiments showed the potential for this species to be a voracious predator when compared to its closest native ecological equivalent.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:726348 |
| Date | January 2017 |
| Creators | Gallagher, Kevin |
| Publisher | Queen's University Belfast |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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