scholarly journals The Fluctuating Abundance of Endangered Mammals on Bernier And Dorre Islands, Western Australia - Conservation Implications.

1998 ◽  
Vol 20 (1) ◽  
pp. 53
Author(s):  
J. Short ◽  
B. Turner ◽  
C. Majors
Keyword(s):  
Population Size ◽  
Western Australia ◽  
Severe Drought ◽  
Shark Bay ◽  
Conservation Implications ◽  
Captive Populations ◽  
Average Rainfall

Bernier and Dorre Islands in Shark Bay, Western Australia, provide refuge to populations of five species of threatened mammals that are extinct on the mainland other than as reintroduced or captive populations. This paper provides estimates of changes in population size of four species over three years from 1988-9 to 1991-2. The period from November 1986 to March 1989 was one of below average rainfall intensifying to severe drought on the islands; the period from mid 1989 to 1992 was one of average to above-average rainfall. Three of the four species (L. hirsutus, B. lesueur and P. bougainville) showed substantial and significant increases and one species (L. fasciatus) showed a small but non-significant increase in abundance. Combined estimates of minimum population size for both islands in 1991-2 vary from c. 4,000 P. bougainville to c. 10,000 L. fasciatus. If these densities are regarded as typical of average rainfall years then the drought in the late 1980s reduced populations of P. bougainville by up to 75%, B. lesueur by 65%, and L. hirsutus by up to 60%. Combined estimates for the four species give densities for the community of medium-sized mammals which vary between 160 km-2 in drought and 260 km-2 in years of average to above average rainfall.

Studies of Dugons at Shark Bay, Western Australia I. Analysis of Population Size, Composition, Dispersion and Nabitat USe on the Basis of Aerial Survey

1982 ◽  
Vol 9 (1) ◽  
pp. 69 ◽  
Author(s):  
PK Anderson
Keyword(s):  
Population Size ◽  
Western Australia ◽  
Cloud Cover ◽  
Size Composition ◽  
Aerial Survey ◽  
Vegetation Patterns ◽  
Depressing Effect ◽  
Shark Bay ◽  
Or Groups ◽  
Analysis Of Dispersion

In midwinter dugongs concentrate in western Shark Bay, adjacent to Dirk Hartog I., although scattered individuals or groups remain in other regions. Up to 496 dugongs were counted in intensively surveyed western areas in July 1979. At least 553 individuals are calculated to have been present in the region, and a minimum population of over 900 individuals estimated for the Bay as a whole. The population seems to be a well defined isolate, and is relatively undisturbed. Conditions are very favourable for more detailed study. A method for estimating the number of animals overlooked in the blind zone directly beneath the aircraft is described. Aerial counts of dugongs varied greatly with conditions. Cloud cover had a large depressing effect: surface turbulence and subsurface turbidity were less significant. Dugong activity is concentrated on the sublittoral platform. Sites of major aggregation may not be the same in successive years. Locally favoured habitats are at the seaward margins of the sublittoral platform, and on offshore shoals. Vegetation patterns at favoured sites may reflect dugong grazing. Persistent use of favoured localities, and local shifts in concentration were observed. Distribution of other large vertebrates, and of boats, relative to that of dugongs was examined and a significant correlation between sightings of large sharks and larger aggregations of dugongs was found. Analysis of dispersion revealed that most dugongs were in groups although most sightings were of single individuals. Cows with calves were less likely to be in the company of other dugongs than were adults without calves. From ll to 12% of individuals were calves.

Integration of Cretaceous Morro do Chaves rock properties (NE Brazil) with the Holocene Hamelin Coquina architecture (Shark Bay, Western Australia) to model effective permeability

2016 ◽  
Vol 22 (2) ◽  
pp. 105-122 ◽  
Author(s):  
Patrick W. M. Corbett ◽  
Rayana Estrella ◽  
Andrea Morales Rodriguez ◽  
Ahmed Shoeir ◽  
Leonardo Borghi ◽  
...  
Keyword(s):  
Western Australia ◽  
Effective Permeability ◽  
Rock Properties ◽  
The Holocene ◽  
Shark Bay

Evolution and Diagenesis of Quaternary Carbonate Sequences, Shark Bay, Western Australia

1974 ◽  
Author(s):  
Brian W. Logan ◽  
James F. Read ◽  
Gregory M. Hagan ◽  
Paul Hoffman ◽  
Raymond G. Brown ◽  
...  
Keyword(s):  
Western Australia ◽  
Shark Bay
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