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The functionality of Eurasian otters (Lutra lutra) as top-down predators in marine ecosystems / JASMINE KNIGHT

Swansea University Author: JASMINE KNIGHT

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Abstract

Ecological niche (Elton, 1927) has been adapted over the years to fit the various definitions within the broad spectrum of an ecological niche. The term ‘trophic niche’ is referred to most commonly now and can be measured by width/ breadth using various diversity indices to determine whether a speci...

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Published: Swansea, Wales, UK 2023
Institution: Swansea University
Degree level: Master of Research
Degree name: MRes
Supervisor: Forman, Dan. W.
URI: https://cronfa.swan.ac.uk/Record/cronfa64022
first_indexed 2023-08-03T10:05:41Z
last_indexed 2024-11-25T14:13:17Z
id cronfa64022
recordtype RisThesis
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spelling 2023-08-03T11:11:09.7898796 v2 64022 2023-08-03 The functionality of Eurasian otters (Lutra lutra) as top-down predators in marine ecosystems eb686488b112ef8789c64eefed08585c JASMINE KNIGHT JASMINE KNIGHT true false 2023-08-03 Ecological niche (Elton, 1927) has been adapted over the years to fit the various definitions within the broad spectrum of an ecological niche. The term ‘trophic niche’ is referred to most commonly now and can be measured by width/ breadth using various diversity indices to determine whether a species is a generalist or a specialist (Hutchinson, 1957). This study explores the methodology utilised by existing literature for Lutra lutra spraint analysis and subsequent dietary studies. The data from seven studies in the UK and Europe in the last 40 years has been extracted and processed to create a meta-dataset of the relative frequency of occurrence (R.F.O %) of prey within spraints, and four selected prey characteristics or traits; body form, ecosystem type, habitat classification and prey type. Trophic niche analysis using Shannon- Weiner diversity index and Levins measure of niche breadth index indicates the hypothesis that the diet of Lutra lutra is more likely to be generalist than specialist is correct (Mean J’ = 0.75 (± 0.08), mean Levins = 0.35 (± 0.05)). Prey trait analysis demonstrates that the most prevalent body form is fusiform (39.6%), ecosystem type with prey presence at two interfaces was most frequent, (36.4%) demersal is the most common habitat classification (48.7%) and type of food (prey) consumed by the prey species/group is small invertebrates, small crustaceans, fish fry (type 3, 43.5%). Furthermore, Welch’s two sample t-test indicates that there is no significant difference between the mean R.F.O (%) of marine prey and non-marine prey at family level (t= 1.97, p= 0.06). The clear need for the standardisation of current approaches towards spraint analysis to improve our understanding of Lutra lutra’s diet and by extension ecological niche, to ultimately protect this semi-aquatic mammal from potential threats in rapidly changing dynamic coastal and marine environments (Gutiérrez, et al., 2019). E-Thesis Swansea, Wales, UK Eurasian otter, Lutra lutra, marine ecosystems, marine prey, top-down predator, trophic niche, spraint analysis 22 6 2023 2023-06-22 COLLEGE NANME COLLEGE CODE Swansea University Forman, Dan. W. Master of Research MRes 2023-08-03T11:11:09.7898796 2023-08-03T11:02:43.7313446 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Biosciences JASMINE KNIGHT 1 64022__28237__0d5f870065254b50910e26c204e4d10e.pdf 2023_Knight_J.final.64022.pdf 2023-08-03T11:07:51.4147260 Output 1830305 application/pdf E-Thesis – open access true Copyright: The Author, Jasmine Knight, 2023. true eng
title The functionality of Eurasian otters (Lutra lutra) as top-down predators in marine ecosystems
spellingShingle The functionality of Eurasian otters (Lutra lutra) as top-down predators in marine ecosystems
JASMINE KNIGHT
title_short The functionality of Eurasian otters (Lutra lutra) as top-down predators in marine ecosystems
title_full The functionality of Eurasian otters (Lutra lutra) as top-down predators in marine ecosystems
title_fullStr The functionality of Eurasian otters (Lutra lutra) as top-down predators in marine ecosystems
title_full_unstemmed The functionality of Eurasian otters (Lutra lutra) as top-down predators in marine ecosystems
title_sort The functionality of Eurasian otters (Lutra lutra) as top-down predators in marine ecosystems
author_id_str_mv eb686488b112ef8789c64eefed08585c
author_id_fullname_str_mv eb686488b112ef8789c64eefed08585c_***_JASMINE KNIGHT
author JASMINE KNIGHT
author2 JASMINE KNIGHT
format E-Thesis
publishDate 2023
institution Swansea University
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Biosciences{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Biosciences
document_store_str 1
active_str 0
description Ecological niche (Elton, 1927) has been adapted over the years to fit the various definitions within the broad spectrum of an ecological niche. The term ‘trophic niche’ is referred to most commonly now and can be measured by width/ breadth using various diversity indices to determine whether a species is a generalist or a specialist (Hutchinson, 1957). This study explores the methodology utilised by existing literature for Lutra lutra spraint analysis and subsequent dietary studies. The data from seven studies in the UK and Europe in the last 40 years has been extracted and processed to create a meta-dataset of the relative frequency of occurrence (R.F.O %) of prey within spraints, and four selected prey characteristics or traits; body form, ecosystem type, habitat classification and prey type. Trophic niche analysis using Shannon- Weiner diversity index and Levins measure of niche breadth index indicates the hypothesis that the diet of Lutra lutra is more likely to be generalist than specialist is correct (Mean J’ = 0.75 (± 0.08), mean Levins = 0.35 (± 0.05)). Prey trait analysis demonstrates that the most prevalent body form is fusiform (39.6%), ecosystem type with prey presence at two interfaces was most frequent, (36.4%) demersal is the most common habitat classification (48.7%) and type of food (prey) consumed by the prey species/group is small invertebrates, small crustaceans, fish fry (type 3, 43.5%). Furthermore, Welch’s two sample t-test indicates that there is no significant difference between the mean R.F.O (%) of marine prey and non-marine prey at family level (t= 1.97, p= 0.06). The clear need for the standardisation of current approaches towards spraint analysis to improve our understanding of Lutra lutra’s diet and by extension ecological niche, to ultimately protect this semi-aquatic mammal from potential threats in rapidly changing dynamic coastal and marine environments (Gutiérrez, et al., 2019).
published_date 2023-06-22T14:26:32Z
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