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Title: Distribution and habitat use of bottlenose dolphins (Tursiops truncatus) at varying temporal and spatial scales
Author: Bailey, Helen
ISNI:       0000 0001 3436 0328
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2006
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The primary aim of this thesis was to investigate the distribution of a marine top predator, the bottlenose dolphin, within the Moray Firth (Scotland) both temporally and spatially, and to determine which environmental factors drive these patterns. At a small-scale (4 km2), habitat use was investigated within a narrow, deep channel known to be regularly frequented by bottlenose dolphins. A modified technique was developed to increase the precision of locations derived from a theodolite.  The locations of the localised feeding areas were significantly related to the gradient of the seabed, most frequently occurring in the regions with the steepest seabed slopes. Three topographically controlled fronts were identified in the study area.  Dolphins spent a significantly greater proportion of their time within 4000m of these features.  Temporal variation in dolphin sightings in this area was examined using a generalised estimating equations approach. There was significant interannual variation and sightings peaked in May – July, during the early morning and flooding tide.  On a larger scale, only about 10% of the 1513 km2 Special Area of Conservation (SAC) for bottlenose dolphins within the Moray Firth has been regularly surveyed.  Little was therefore known of their distribution further offshore or of other marine mammal species. Combined visual and passive acoustic surveys were conducted and the relationship between distributions and environmental variables analysed.  Bottlenose dolphins had a primarily coastal distribution whereas harbour porpoises occurred throughout the SAC. This study provides an insight into the habitat use of bottlenose dolphins and the importance of the oceanographic environment in determining these patterns. This has been used to advise local conservation management groups.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available