Using stable isotopes as a tool to understand the trophic relationships and movement of seabirds off Southern Africa

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dc.contributor.advisorRyan, Peter Gen_ZA
dc.contributor.advisorWanless, Ross Men_ZA
dc.contributor.authorBarquete, Vivianeen_ZA
dc.date.accessioned2014-08-13T14:14:13Z
dc.date.available2014-08-13T14:14:13Z
dc.date.issued2012en_ZA
dc.descriptionIncludes abstract.en_ZA
dc.descriptionIncludes bibliographical references.en_ZA
dc.description.abstractStable isotopes (SI) have been widely applied in ecology to investigate the trophic relationships of animals. Stable isotope analyses were used to augment our understanding of the foraging ecology and movements of three globally threatened seabirds: African Penguins (Spheniscus demersus), Cape Gannets (Morus capensis) and White-chinned Petrels (Procellaria aequinoctiallis). The diets of captive penguins were varied to estimate the 15N turnover rates and discrimination factors of toenails and blood fractions. Plasma δ15N showed a faster turnover rate (7.6 ± 0.7 days) than erythrocytes (14.3 ± 1.6 days). Discrimination factors varied among tissues. No shift in nail δ15N signature was detected after 5 months, suggesting that toenails are insensitive to short to medium-term diet shifts. Among wild penguins and gannets sampled across the Benguela region, tow different responses to the effects of fisheries were observed,due to different feeding strategies, Age, sex year and colony location accounted for isotopic variation. Age-based differences may be linked to limited foraging skills of juvenile birds and their wider dispersion. Female gannets apparently feed on more live natural prey whereas males take more fishery discards, although the sex-based difference was confounded by colony effect. Marked inter-colony variation probably results from regional differences in oceanic conditions between, prey availability and among gannets, variation in dependence on fishery discards. Inter-annual variation in SI signatures might be linked to variation in primary production (African Penguins), or variation in prey availability (Cape Gannets)...en_ZA
dc.identifier.apacitationBarquete, V. (2012). <i>Using stable isotopes as a tool to understand the trophic relationships and movement of seabirds off Southern Africa</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/6229en_ZA
dc.identifier.chicagocitationBarquete, Viviane. <i>"Using stable isotopes as a tool to understand the trophic relationships and movement of seabirds off Southern Africa."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2012. http://hdl.handle.net/11427/6229en_ZA
dc.identifier.citationBarquete, V. 2012. Using stable isotopes as a tool to understand the trophic relationships and movement of seabirds off Southern Africa. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Barquete, Viviane AB - Stable isotopes (SI) have been widely applied in ecology to investigate the trophic relationships of animals. Stable isotope analyses were used to augment our understanding of the foraging ecology and movements of three globally threatened seabirds: African Penguins (Spheniscus demersus), Cape Gannets (Morus capensis) and White-chinned Petrels (Procellaria aequinoctiallis). The diets of captive penguins were varied to estimate the 15N turnover rates and discrimination factors of toenails and blood fractions. Plasma δ15N showed a faster turnover rate (7.6 ± 0.7 days) than erythrocytes (14.3 ± 1.6 days). Discrimination factors varied among tissues. No shift in nail δ15N signature was detected after 5 months, suggesting that toenails are insensitive to short to medium-term diet shifts. Among wild penguins and gannets sampled across the Benguela region, tow different responses to the effects of fisheries were observed,due to different feeding strategies, Age, sex year and colony location accounted for isotopic variation. Age-based differences may be linked to limited foraging skills of juvenile birds and their wider dispersion. Female gannets apparently feed on more live natural prey whereas males take more fishery discards, although the sex-based difference was confounded by colony effect. Marked inter-colony variation probably results from regional differences in oceanic conditions between, prey availability and among gannets, variation in dependence on fishery discards. Inter-annual variation in SI signatures might be linked to variation in primary production (African Penguins), or variation in prey availability (Cape Gannets)... DA - 2012 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2012 T1 - Using stable isotopes as a tool to understand the trophic relationships and movement of seabirds off Southern Africa TI - Using stable isotopes as a tool to understand the trophic relationships and movement of seabirds off Southern Africa UR - http://hdl.handle.net/11427/6229 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/6229
dc.identifier.vancouvercitationBarquete V. Using stable isotopes as a tool to understand the trophic relationships and movement of seabirds off Southern Africa. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2012 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/6229en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Biological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherZoologyen_ZA
dc.titleUsing stable isotopes as a tool to understand the trophic relationships and movement of seabirds off Southern Africaen_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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