Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/22355
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dc.contributor.advisorTurnbull, James F-
dc.contributor.advisorLeaver, Michael J-
dc.contributor.authorHarper, Kirsten Jennifer-
dc.date.accessioned2015-10-27T09:28:03Z-
dc.date.issued2015-08-31-
dc.identifier.urihttp://hdl.handle.net/1893/22355-
dc.description.abstractAquatic invasive species are a major threat to native freshwater biodiversity. The North American signal crayfish Pacifastacus leniusculus was introduced to Great Britain during the 1970s and is now widely distributed throughout England, Wales and Scotland. First recorded in Scotland in 1995, P. leniusculus is now established at more than twenty sites. The only other introduced crayfish species present in Scotland is the white-clawed crayfish Austropotamobius pallipes. A. pallipes is restricted to only two locations in Scotland, Loch Croispol and Whitemoss Reservoir. P. leniusculus negatively impacts macrophytes, invertebrates and fish though ecological and physical processes. Additionally, P. leniusculus has displaced A. pallipes throughout much of its native range within Great Britain due to competition and disease. Consequently, the two A. pallipes populations in Scotland have a high conservation value. This PhD study aimed to improve understanding of P. leniusculus invasion success by examining trophic dynamics and to develop methodologies that could improve the detection and control of P. leniusculus populations in Scotland. Stable isotope analysis was used to determine the diet composition, trophic position and whether an ontogenetic dietary shift occurs in the Loch Ken population of P. leniusculus. Bayesian mixing models indicated that P. leniusculus in Loch Ken do exhibit an ontogenetic dietary shift. Additionally, individuals of all sizes occupied the trophic position of a predator in Loch Ken suggesting that invertebrates and fish constitute an important component of P. leniusculus diet. Stable isotope analysis was used once again to compare the isotopic niche width and diet composition of P. leniusculus populations from Loch Ken and A. pallipes populations from Loch Croispol and Whitemoss Reservoir. At the species level, A. pallipes exhibited a larger niche width than that of P. leniusculus. At the population level, the isotopic signatures of the A. pallipes populations were considerably different from each other suggesting an overestimation of A. pallipes’ niche width at species level. Results showed no dietary overlap between species and Bayesian mixing models suggested P. leniusculus and A. pallipes were consuming different resources, indicating there would be no direct competition for food resources if they were to co-occur. A plus-maze study was used to determine if P. leniusculus exhibited a preference for one of four food attractants (Oncorhynchus mykiss, P. leniusculus, beef or vegetation), which could be used to improve trapping efficiency. In the maze system, P. leniusculus exhibited no preference for any food attractant presented. This would suggest that either the maze was not a good model or food attractants would not improve trapping efficiency of P. leniusculus. Additionally, a comparative investigation into the use of gill nets as a method to control P. leniusculus was conducted. Results showed that the net type and the presence of fish entangled in the net influenced the number of P. leniusculus caught. Finally, environmental DNA (eDNA) was used and evaluated for detection of P. leniusculus. A robust quantitative Polymerase Chain Reaction (qPCR) assay and DNA extraction protocol were developed. Using the developed qPCR assay, P. leniusculus eDNA was detected in controlled aquaria conditions but not in environmental water samples collected from the field. Furthermore, the quantities of P. leniusculus eDNA declined in aquaria conditions while individuals were still present suggesting the mechanisms for eDNA release by P. leniusculus are complex. Stable isotope analysis indicates that P. leniusculus exhibit an ontogenetic dietary shift, and in each life stage, P. leniusculus function as an omnivore but occupy the trophic position of a predator. Niche width analysis revealed that the diet of P. leniusculus was less general than that observed in A. pallipes and thus diet of P. leniusculus may not be responsible for invasive success. Food attractants will not enhance trapping efficiency but nets may present a potential new method to control P. leniusculus. Similarly, eDNA presents a promising new method for rapid detection of P. leniusculus. It will not be possible to eradicate P. leniusculus in Scotland but the findings of this PhD may help prevent establishment of new populations. These results should be incorporated into future management strategies for P. leniusculus populations in Scotland and may have broader applications in Great Britain and Europe.en_GB
dc.language.isoenen_GB
dc.publisherUniversity of Stirlingen_GB
dc.subjectCrayfishen_GB
dc.subjectPacifastacus leniusculusen_GB
dc.subjectInvasiveen_GB
dc.subjectTrophic nicheen_GB
dc.subjectDetectionen_GB
dc.subjectControlen_GB
dc.subjectEnvironmental DNAen_GB
dc.subjecteDNAen_GB
dc.subjectAustropotamobius pallipesen_GB
dc.subject.lcshPacifastacus leniusculusen_GB
dc.subject.lcshCrayfish culture Scotlanden_GB
dc.subject.lcshIntroduced animals Scotlanden_GB
dc.subject.lcshNonindigenous aquatic pests Scotlanden_GB
dc.subject.lcshConservation of natural resources Scotlanden_GB
dc.subject.lcshBiological invasions Scotlanden_GB
dc.titleTrophic niche and detection of the invasive signal crayfish (Pacifastacus leniusculus) in Scotlanden_GB
dc.typeThesis or Dissertationen_GB
dc.type.qualificationlevelDoctoralen_GB
dc.type.qualificationnameDoctor of Philosophyen_GB
dc.rights.embargodate2017-07-31-
dc.rights.embargoreasonAt the request of the author the thesis has been embargoed on the grounds of a Publication Exception to the RCUK required 12 month maximum. RCUK have agreed that, at the discretion of the University, authors can request a short extension up to a further year beyond this 12 months. Only in very exceptional rare circumstances can a thesis be placed under an embargo longer than a total of 24 months.en_GB
dc.contributor.funderNERCen_GB
dc.author.emailkirstenharperhiggins@gmail.comen_GB
dc.rights.embargoterms2017-08-01en_GB
dc.rights.embargoliftdate2017-08-01-
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