Observations of dugongs at Aldabra Atoll,western Indian Ocean: lagoon habitat mapping and spatial analysis of sighting records |
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| Authors: | Sarah M Hamylton Annelise B Hagan Naomi Doak |
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| Institution: | 1. Cambridge Coastal Research Unit, University of Cambridge , Cambridge , UK shamylto@uow.edu.au;3. Cambridge Coastal Research Unit, University of Cambridge , Cambridge , UK;4. Seychelles Islands Foundation , Victoria , Seychelles |
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| Abstract: | Until recently, it was thought that dugongs (Dugong dugon) were extinct in the Seychelles. However, a collection of sightings at Aldabra Atoll, a World Heritage Site in the Seychelles, has renewed interest in dugong distribution in the western Indian Ocean. This article consolidates the records of dugong sightings held in the Aldabra Research Station library and explores their spatial patterning. The locations of sightings (2001–2009) are plotted onto a high-resolution benthic habitat map of the Aldabra lagoon created by classifying a QuickBird satellite remote-sensing image in January 2009. A spatial cluster detection procedure is applied to point records of sightings to reveal a statistically significant cluster of sightings in the north-west of the lagoon, at Bras Monsieur Clairemont, suggesting a mutual co-existence of dugongs and seagrass beds. A habitat suitability model combines the point data set of dugong sightings within the continuous benthic habitat map and identifies the central western area as containing the most suitable habitat for dugong inside the Aldabra lagoon. |
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| Keywords: | Seychelles benthic habitat map remote sensing cluster analysis dugong habitat suitability |
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