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dc.contributor.advisorPoulin, Robert
dc.contributor.authorMcPherson, Te Aroha Olivia Grace Taituha
dc.date.available2018-03-26T19:49:30Z
dc.date.copyright2018
dc.identifier.citationMcPherson, T. A. O. G. T. (2018). Direct and indirect effects of trematode exposure on the amphipod Paracalliope fluviatilis in terms of parasite acquisition, survival and behaviour (Thesis, Master of Science). University of Otago. Retrieved from http://hdl.handle.net/10523/7965en
dc.identifier.urihttp://hdl.handle.net/10523/7965
dc.description.abstractParasites are a debilitating threat to animal populations as they often increase host mortality. Since defences against parasites are costly, selection should favour individuals that only exhibit defences during times of high risk. As a danger must be interpreted before it can be counteracted, the specific cues used by hosts for parasite detection must first be determined. Knowing the importance of various cues would allow us to better understand the variability of host susceptibility to parasites. This is imperative as parasites affect not only their hosts but also the wider community and ecosystems. Reductions of host density by parasites can have wide repercussions, including indirect effects on interspecific interactions and ecosystem function. The present research investigates the effect of priming by chemical cues from the trematode Coitocaecum parvum on the ability of the freshwater amphipod Paracalliope fluviatilis to subsequently defend itself against C. parvum infective stages, i.e. cercariae, in laboratory tests. Paracalliope fluviatilis are the most abundant endemic amphipod in New Zealand waters and are a key species of prey and an intermediate host for many parasites. In an experimental infection, amphipods were first exposed to the odour of a source of cercariae (infected snail first intermediate hosts) or to control water (no odour), and then to actual cercariae. Subsequently, Coitocaecum parvum abundance (numbers of ‘new’ C. parvum parasites per amphipod) and survival were compared between primed and unprimed amphipods to assess the effects this type of chemical priming had on amphipod defence success against trematodes. A further study using EthoVision XT assessed aspects of P. fluviatilis behaviour (distance moved, and time spent in motion) in response to priming and the presence or absence of a live C. parvum cercaria. Overall, exposure to the odour of C. parvum-infected snails had no effect on the average parasite acquisition of primed amphipods compared to unprimed amphipods. However, amphipods already harbouring parasites from earlier natural infections were 20% more susceptible to acquiring further parasites than uninfected amphipods. Survival was unaffected by exposure to the chemical cue. Swimming behaviour of amphipods was also not affected by either priming or the presence or absence of a cercaria. These results suggest that other cues may be more significant than the chemical factors tested here for amphipod recognition and avoidance of trematode parasites. Further research will be necessary to determine which cues are the most important for parasite detection in amphipods to better understand the complexity of such host-parasite interactions.
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherUniversity of Otago
dc.rightsAll items in OUR Archive are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectParasites
dc.subjecttrematodes
dc.subjectinfection
dc.subjectsnails
dc.subjectamphipods
dc.subjectchemical
dc.subjectcues
dc.subjectParacalliope fluviatilis
dc.subjectCoitocaecum parvum
dc.subjectPotamopyrgus antipodarum
dc.subjectGobiomorphus cotidianus
dc.subjectNew Zealand
dc.subjectExperimental infections
dc.subjectEthovision
dc.subjectLake Waihola
dc.subjectOtago
dc.subjectDunedin
dc.subjectodour
dc.subjectsmell
dc.subjectchemical sensing
dc.subjectsusceptibility
dc.subjectabundance
dc.subjectsurvival
dc.subjectfirst intermediate host
dc.titleDirect and indirect effects of trematode exposure on the amphipod Paracalliope fluviatilis in terms of parasite acquisition, survival and behaviour
dc.typeThesis
dc.date.updated2018-03-26T07:59:54Z
dc.language.rfc3066en
thesis.degree.disciplineEcology
thesis.degree.nameMaster of Science
thesis.degree.grantorUniversity of Otago
thesis.degree.levelMasters
otago.openaccessOpen
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