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Macroparasites of the Eurasian otter: distributions, life-cycles and population dynamics

Sherrard-Smith, Eleanor 2013. Macroparasites of the Eurasian otter: distributions, life-cycles and population dynamics. PhD Thesis, Cardiff University.
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Potential alterations of host and parasite ranges are likely with climate change so an understanding of the host traits and ecological factors that can influence host-parasite interactions is vital for the effective protection of ecosystems. Accidental introductions of non-native species can place elevated stress on native ecosystems so that the examination of key species can act as early warning systems. The Eurasian otter, Lutra lutra¸ is a top predator and sentinel species for the health of European freshwater ecosystems and is therefore a suitable model for exploring parasite fauna introductions. In this PhD, the patterns and processes that define macro-parasitic infections were explored using evidence from post-mortems of 587 otters. Specifically, the invasive status of two helminths (Pseudamphistomum truncatum and Metorchis albidus: Trematoda; Opisthorchiidae) was investigated, both species having been identified in the UK otter populations for the first time within the last 10 years. Genetic variation, however, was similar across Europe indicating neither helminth is likely to have been a recent introduction to the UK., The distribution of both helminths as well as the only ectoparasite, Ixodes hexagonus (Arthropoda; Ixodidae), recovered from UK otters, were associated with abiotic factors, particularly temperature. The complexity of the parasite life cycles was investigated; otters act as a definitive host for both helminth species considered in this thesis and early stage intermediate hosts were identified for P. truncatum as the snail Radix balthica and the roach Rutilus rutilus. Metacercariae of M. ablidus were detected on chub (Leuciscus cephalus), rudd (Scardinius erythrophthalmus) and roach. Parasite aggregation and parasite fecundity of the P. truncatum populations were influenced by abiotic factors, region and season, whilst P. truncatum abundance was defined better by the biotic factors host age-class and condition demonstrating how multiple factors combine to produce parasite population dynamics in wild fauna. Ultimately, the data collated throughout this PhD was used to parameterise a susceptible-infected Susceptible-Infected (SI) model describing the host population dynamics of opisthorchiid trematodes. This model is applied to the P. truncatum system to examine which factors might determine the proportion of hosts that become infected.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Biosciences
Subjects: Q Science > QL Zoology
Uncontrolled Keywords: Eurasian otter, Trematode, Tick, Ixodes hexagonus, Opisthorchiida,
Funders: NERC, Somerset Otter Group
Date of First Compliant Deposit: 30 March 2016
Last Modified: 19 Mar 2016 23:21

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