A comparative study of Phoebetria albatrosses' interactions with mesoscale oceanographic features south of the African continent

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dc.contributor.advisorRouault, Mathieuen_ZA
dc.contributor.authorRasehlomi, Tshikana Phillipen_ZA
dc.date.accessioned2016-06-10T07:40:22Z
dc.date.available2016-06-10T07:40:22Z
dc.date.issued2015en_ZA
dc.description.abstractTwo sympatric Phoebetria albatrosses, P. fusca and palpebrata breeding at Marion Island in the South Indian Ocean were studied. Adult individuals were tracked between 2008 and 2011. The study examined the foraging distribution of the two species in relation to environmental parameters such as sea surface temperature. Interaction with mesoscale features expressed by sea surface temperatures, was tested with statistical models. Tracked P. fusca demonstrated positive association with sea surface temperatures in the Southern Indian Ocean, in particular during incubating and chick-provisioning periods, by travelling shorter distances to the interfaces of mesocale features created as a result of the Agulhas Return Current located << 500 km to the north of breeding islands. During nest construction, tracked P. fusca travelled greater distances in search of food possibly because they had no chick to return to at the colonies. Contrastingly, tracked P. palpebrata did not demonstrate any positive association with sea surface temperatures. During incubating and chick-provisioning periods, tracked P. palpebrata travelled shorter distances to foraging grounds located to the south of breeding islands possibly to maximise returns to chicks while minimising efforts. During nest construction, tracked P. palpebrata travelled to distant foraging grounds to the south of the Antarctic Polar Front in areas of low mesoscale variability suggesting that greater distances can be achieved when they have no chick to feed at the colonies. Individuals of both tracked species foraged within close proximity during energy-demanding periods indicating their ability to employ an efficient foraging strategy that ensures minimal effort whilst maximising returns. Generalised Linear Models with the response variable being species and explanatory variables comprised of sea surface temperatures, annual breeding stages, distance traversed and activity, were conducted to examine the effect of environmental factors on seabird foraging distribution. These models were subjected to robust fitness tests and those that represented ecological reality of the two tracked albatrosses were chosen. The study demonstrates that the most important foraging areas for these two tracked seabird species overlap with the Indian Ocean Tuna Commission Convention area making them vulnerable from incidental capture from high longline fisheries. These results have implications to the conservation of these albatrosses suggesting a need for a multi-faceted approach on fisheries management particularly on mitigation of seabird bycatch in the Indian Ocean Tuna Convention area.en_ZA
dc.identifier.apacitationRasehlomi, T. P. (2015). <i>A comparative study of Phoebetria albatrosses' interactions with mesoscale oceanographic features south of the African continent</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Oceanography. Retrieved from http://hdl.handle.net/11427/20005en_ZA
dc.identifier.chicagocitationRasehlomi, Tshikana Phillip. <i>"A comparative study of Phoebetria albatrosses' interactions with mesoscale oceanographic features south of the African continent."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Oceanography, 2015. http://hdl.handle.net/11427/20005en_ZA
dc.identifier.citationRasehlomi, T. 2015. A comparative study of Phoebetria albatrosses' interactions with mesoscale oceanographic features south of the African continent. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Rasehlomi, Tshikana Phillip AB - Two sympatric Phoebetria albatrosses, P. fusca and palpebrata breeding at Marion Island in the South Indian Ocean were studied. Adult individuals were tracked between 2008 and 2011. The study examined the foraging distribution of the two species in relation to environmental parameters such as sea surface temperature. Interaction with mesoscale features expressed by sea surface temperatures, was tested with statistical models. Tracked P. fusca demonstrated positive association with sea surface temperatures in the Southern Indian Ocean, in particular during incubating and chick-provisioning periods, by travelling shorter distances to the interfaces of mesocale features created as a result of the Agulhas Return Current located << 500 km to the north of breeding islands. During nest construction, tracked P. fusca travelled greater distances in search of food possibly because they had no chick to return to at the colonies. Contrastingly, tracked P. palpebrata did not demonstrate any positive association with sea surface temperatures. During incubating and chick-provisioning periods, tracked P. palpebrata travelled shorter distances to foraging grounds located to the south of breeding islands possibly to maximise returns to chicks while minimising efforts. During nest construction, tracked P. palpebrata travelled to distant foraging grounds to the south of the Antarctic Polar Front in areas of low mesoscale variability suggesting that greater distances can be achieved when they have no chick to feed at the colonies. Individuals of both tracked species foraged within close proximity during energy-demanding periods indicating their ability to employ an efficient foraging strategy that ensures minimal effort whilst maximising returns. Generalised Linear Models with the response variable being species and explanatory variables comprised of sea surface temperatures, annual breeding stages, distance traversed and activity, were conducted to examine the effect of environmental factors on seabird foraging distribution. These models were subjected to robust fitness tests and those that represented ecological reality of the two tracked albatrosses were chosen. The study demonstrates that the most important foraging areas for these two tracked seabird species overlap with the Indian Ocean Tuna Commission Convention area making them vulnerable from incidental capture from high longline fisheries. These results have implications to the conservation of these albatrosses suggesting a need for a multi-faceted approach on fisheries management particularly on mitigation of seabird bycatch in the Indian Ocean Tuna Convention area. DA - 2015 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2015 T1 - A comparative study of Phoebetria albatrosses' interactions with mesoscale oceanographic features south of the African continent TI - A comparative study of Phoebetria albatrosses' interactions with mesoscale oceanographic features south of the African continent UR - http://hdl.handle.net/11427/20005 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/20005
dc.identifier.vancouvercitationRasehlomi TP. A comparative study of Phoebetria albatrosses' interactions with mesoscale oceanographic features south of the African continent. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Oceanography, 2015 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/20005en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Oceanographyen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherOcean and Atmosphere Scienceen_ZA
dc.titleA comparative study of Phoebetria albatrosses' interactions with mesoscale oceanographic features south of the African continenten_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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