Year-round presence of dugongs in Pumicestone Passage, south-east Queensland, examined in relation to water temperature and seagrass distribution

Lanyon, J. M., Johns, T. and Sneath, H. L. (2005) Year-round presence of dugongs in Pumicestone Passage, south-east Queensland, examined in relation to water temperature and seagrass distribution. Wildlife Research, 32 4: 361-368.


Author Lanyon, J. M.
Johns, T.
Sneath, H. L.
Title Year-round presence of dugongs in Pumicestone Passage, south-east Queensland, examined in relation to water temperature and seagrass distribution
Journal name Wildlife Research   Check publisher's open access policy
ISSN 1035-3712
Publication date 2005
Sub-type Article (original research)
DOI 10.1071/WR04063
Volume 32
Issue 4
Start page 361
End page 368
Total pages 8
Editor C. Myers
Place of publication Collingwood
Publisher C S I R O Publishing
Collection year 2005
Language eng
Subject C1
270500 Zoology
780105 Biological sciences
Abstract Pumicestone Passage is a narrow waterway that lies to the north of and adjacent to Moreton Bay, and between mainland Queensland and Bribie Island, Australia. Anecdotal reports have suggested that the Passage is home to dugongs year-round despite winter water temperatures that are known to cause dugongs to migrate elsewhere. To examine the pattern of distribution and abundance of dugongs within the passage on a year-round basis, eight years of sightings data collected by a charter boat operator were examined. Dedicated aerial surveys of the passage were also conducted at two-monthly intervals over two years, and more intensively over a single winter. Dugong sightings were examined in relation to water temperatures and seagrass prevalence. The number of dugongs sighted in the area on any one survey varied from 0 to 13. Dugongs were seen in all months of the year and in each of the eight winters, indicating that Pumicestone Passage is used year-round despite winter water temperatures dropping to below 18 degrees C from June to August inclusive and below 16 degrees C in June. All dugong sightings occurred in the southern part of the passage, south of Tripcony Bight. Dugongs were associated with shallows that support Halophila and Halodule species of seagrass, food species that are favoured elsewhere in their range. The northern part of the passage also supports seagrasses that are eaten by dugongs and has water temperature ranges that are not appreciably different to those of the southern passage. However, the narrow channels and very shallow nature of the northern passage provides little to no deep-water refugia for dugongs and the seagrass beds are less extensive. This study suggests that southern Pumicestone Passage requires protection concomitant with it being a year-round refuge of the vulnerable dugong.
Keyword Ecology
Zoology
Shark Bay
Western-australia
Abundance
Q-Index Code C1

 
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