An ecological study was undertaken on four populations of Krefft�s River Turtle
Emydura krefftii inhabiting the Townsville Area of Tropical North Queensland. Two sites
were located in the Ross River, which runs through the urban areas of Townsville, and two
sites were in rural areas at Alligator Creek and Stuart Creek (known as the Townsville
Creeks). Earlier studies of the populations in Ross River had determined that the turtles
existed at an exceptionally high density, that is, they were superabundant, and so the
Townsville Creek sites were chosen as low abundance sites for comparison.
The first aim of this study was to determine if there had been any demographic
consequences caused by the abundance of turtle populations of the Ross River. Secondly, the
project aimed to determine if the impoundments in the Ross River had affected the freshwater
turtle fauna. Specifically this study aimed to determine if there were any difference between
the growth, size at maturity, sexual dimorphism, size distribution, and diet of Emydura krefftii
inhabiting two very different populations.
A mark-recapture program estimated the turtle population sizes at between 490 and
5350 turtles per hectare. Most populations exhibited a predominant female sex-bias over the
sampling period. Growth rates were rapid in juveniles but slowed once sexual maturity was
attained; in males, growth basically stopped at maturity, but in females, growth continued
post-maturity, although at a slower rate. Sexual maturity was at 6-7 years of age for males,
which corresponded to a carapace length of 150-160 mm, and 8-10 years of age for females,
which corresponded to a carapace length of 185-240 mm. The turtles were omnivorous,
although in the Ross River they ate more submerged vegetation (by percent amount and
occurrence) than those of the Townsville Creeks. Turtles in Townsville Creeks ingested more
windfall fruit and terrestrial insects.
| Identifer | oai:union.ndltd.org:ADTP/218948 |
| Date | January 2005 |
| Creators | Trembath, Dane F., n/a |
| Publisher | University of Canberra. Resource, Environmental & Heritage Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | ), Copyright Dane F. Trembath |
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