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In Queensland the spread of population declines in frogs was well monitored
for the upland frogs in "pristine" environments. Declines commenced in 1979 in
the D'Aguilar Ranges in southeast Queensland with the disappearance of the
southern day frog, Taudactylus diurnus. In the adjacent
Conondale Ranges the loss of the same species and the southern gastric
brooding frog, Rheobatrachus silus, followed very rapidly. At the
same time the numbers of
other species of frogs in the same areas declined, but did not disappear.
Litoria pearsoniana is one of these latter species.
The epidemic of declines in upland frogs in Queensland spread progressively north until in 1993 at Big Tableland near Cooktown in north Queensland, we discovered B. dendrobatidis as the only significant pathogen in dying frogs. Thus establishing that the amphibian chytrid was present at the northern end of the epidemic. Our aim now is to prove that B. dendrobatidis was there in the beginning. We are using specimens from the Queensland Museum to do this. To date we have pushed positive associations between the chytrid and frog declines back 4 years and south 300 km to Kirima Range in 1989. A Litoria genimaculata at this site was positive just before the population crashed. So at the moment the first statement to the left is our working hypothesis. It lacks the final proof, but the circumstantial evidence is good. |