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Adair, J. (1999). Resource partitioning among the freshwater turtles of the daly river, northern territory. 
Added by: Admin (17 Aug 2008 18:17:29 UTC)   Last edited by: Sarina Wunderlich (22 Sep 2008 10:19:36 UTC)
Resource type: Thesis/Dissertation
BibTeX citation key: Adair1999
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Categories: General
Keywords: Australien = Australia, Carettochelyidae, Carettochelys, Carettochelys insculpta, Chelidae, Chelodina, Chelodina rugosa, Elseya, Elseya dentata, Emydura, Emydura subglobosa, Emydura tanybaraga, Emydura victoriae, Ernährung = nutrition, Habitat = habitat, Schildkröten = turtles + tortoises
Creators: Adair
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Abstract     
The Daly River, in the Top End of the Northern Territory supports a greater diversity of freshwater turtles than any river system in Australia, making it the ideal place to study a freshwater turtle community. The aims of this study were to describe the diet and microhabitat use of Carettochelys insculpta, Elseya dentata, Chelodina rugosa, Emydura victoriae, Emydura subglobosa and Emydura tanybaraga from the Daly and Douglas Rivers, and to examine both intraspecific and interspecific resource partitioning. Carettochelys insculpta is an opportunistic omnivore, and consumed mostly ribbonweed (Vallisneria spiralis) and snails (Notopala sp.). Elseya dentata is primarily herbivorous, and consumed aquatic algae (Oedogonium and Spirogyra sp.), and occasionally carrion and freshwater sponge (Corvospongilla sp.). Overlap between the diet of Carettochelys insculpta and Elseya dentata was high, but overall niche overlap between the two species was low because they occupied different microhabitats. Chelodina rugosa is a carnivore that usually feeds on fast moving prey, but in the Daly River primarily consumed slow moving prey such as snails (Thiara sp.). Chelodina rugosa consumed very little food relative to other species and to previous studies. Chelodina rugosa appear to use the Daly River as a dry season refuge, the majority of their dry season feeding is known to occur in ephemeral billabongs. Emydura victoriae is an opportunistic omnivore that consumes relatively more molluscs (of the genera Thiara and Notopala) as it grows. The dietary shift appears to be associated with the growth of head musculature and crushing plates. This specialisation allows Emydura victoriae to exploit mollusc resources to a greater degree than other turtle species, and resulted in their diet overlapping little with other species. Emydura subglobosa and Emydura tanybaraga are both omnivorous, and are relatively uncommon in the Daly River. Emydura subglobosa consumed primarily freshwater sponge (Corvospongilla), a food resource which was consumed little by the more common turtle species. Emydura tanybaraga has trophic adaptations that resemble that of Emydura victoriae, and appeared to have a similar diet. The rarity of Emydura subglobosa and Emydura tanybaraga may be due to competition with other species, or they may be at the limit of their geographic distribution. The high species richness of turtles in the Daly River may reflect the geographic distribution of species and the favourable climate of the tropics. On a local scale, species richness may be sustained by the influence of resource partitioning, predation, spatial variation in the distribution of species, and temporal variation in food availability associated with a wet-dry tropical ecosystem. The opportunistic feeding ecology of the turtles of the Top End may be an adaptation to a dynamic environment that allows them to exploit unpredictable food resources.
Added by: Admin  Last edited by: Sarina Wunderlich
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