- Title
- Improving understanding of the ecology of Indo-pacific bottlenose dolphins (tursiops aduncus) in Algoa Bay, South Africa
- Creator
- Shaanika, Titus Mwiitantandje
- Subject
- Bottlenose dolphin -- South Africa -- Port Elizabeth
- Subject
- Bottlenose dolphin -- Ecology -- South Africa -- Port Elizabeth Dolphins -- Ecology -- South Africa -- Port Elizabeth
- Date Issued
- 2018
- Date
- 2018
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- http://hdl.handle.net/10948/34788
- Identifier
- vital:33451
- Description
- Site fidelity and spatial distribution of Indo-Pacific bottlenose dolphins (Tursiops aduncus) were assesed using mark-recapture from opportunistic photographs collected between June 2008-May 2011 in Algoa Bay, South Africa. Over 10 000 photographs were collected, and assessed, resulting in 2472 photographs being catalogued and analysed. In total, 2002 individual dolphins were photographically identified. The discovery curve does not reach a plateau, indicating a large, open population, as a result, the re-sighting rate over the study period was low. 178 (8.9%) animals were re-sighted, and 32 animals these were seen three times or more. The individual which was re-sighted most often was sighted five times. The residency index averaged 0.05 and reached a maximum at 0.25. 41% of the data were collected in 2009, which skewed the identifications per unit effort (IDsPUE) across years (Kruskal-Wallis Anova, KW= 11.59 n=60, p= 0.009) and seasons (KW= 17.47, n= 60, p=0.007). Due to the relatively higher data collection in 2009, identifications across years (KW=13.29, n=60, P= 0.004) and across seasons (KW=17.81 n=60, P=0.007) also differed significantly. In contrast, there was no significant difference is re-sighting across years (KW = 6.9, n=56, p= 0.8) and seasons (KW=12.26, n=56, p=0.6). The association between the 32 individuals seen three times or more was measured using the Half Weight Index, the index ranged from 0 to 1. A dendrogram revealed two social clusters consisting of 23 and 8 animals each, with one individual having no associations. Xenobalanus was recorded on all but five surveys over the study period. Xenobalanus occurrence did not significantly differ across years (KW=1.49, n=42, p=0.68) and seasons (KW= 6.59, n=43, p=0.36). Dolphins were mostly sighted in depths of <15 metres all around the bay. Travelling (36%) behaviour was the most recorded, followed by feeding (29 %), socialising (15%), milling (11 %), Slow travel (6%), resting (2%) and fast travelling (1%). Other than milling the spatial distribution of all behaviours were similar to the general spatial distribution of sightings. The project provides information that can be used for further research and conservation management of T. aduncus. Photographs used in this project were opportunistically collected, which has resulted in the underestimation of photo-identified individuals and consequently results of this project.
- Format
- xii, 83 leaves
- Format
- Publisher
- Nelson Mandela University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela University
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