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Dr Arthur White, President of the NSW Frog and Tadpole Study Group (FATS) is enthusiastic about a new project that could assist the iconic Green and Golden Bell frog. |
| The decline in populations of the iconic Green and Golden Bell frog across New South Wales is well known. One region of note of the lower Hunter region which hosting massive populations only 30 to 40 years ago. One of the largest populations lived in the Hexham Swamp area but, sadly, they are no longer found there. There was also a population on Kooragang Island in the middle of the Hunter River. This low lying island was first used as a dumping ground for steel mill waste but was later developed into industrial land by filling and raising the island’s level.
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Above: Green and Golden Bell Frog bred at Newcastle University
More recently still, parts of the island have been developed into a coal storage and coal loader facility. With the recent expansion of coal mining in the Hunter Valley, another two coal loading port facilities have been built, with yet another being planned. To create these coal facilities low lying wetlands are filled in, thereby removing habitat Green and Golden Bell frogs and wading birds.
The good news is that the coal companies have begun restitution work to offset the habitat that has been lost on Kooragang Island. The aim is to consolidate the Bell frog population still existing on the island by expanding the available habitat for the frogs in areas away from the coal loading bays. This project is being done in collaboration with the University of Newcastle, with Dr Michael Mahony heading their efforts.
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| Forming the ponds on Ash Island
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The first part of the project, which is being funded by the coal consortium NCIG, will see trial ponds established on the western part of Kooragang Island, known locally as Ash Island. The Chytrid fungus is a problem for Green and Golden Bell frogs, so the ponds will be manipulated to see if pond conditions can be created that allow the frogs to survive the presence of the fungus.
The chytrid pathogen does not tolerate the presence of heavy metals so the industrial wastes on the island have, ironically, helped this species. The pathogen is also intolerant of salt and any concentrations higher than 3% above seawater causes it grief. The frogs, on the other hand, can withstand salt concentrations as high as 5% so the ponds have been designed to reflect different salt concentrations. There are 16 ponds in place at the moment; the ponds vary in depths and water pH. The acidity of the water is being tested as the soils on Kooragang Island are fairly acidic and the response of the Bell frogs and the chytrid fungus to acidic water is being assessed.
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| Green and Golden Bell Frog breeding tanks, Newcastle University
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The ponds have been stocked with captive-bred Bell frogs; these frogs have been bred at Shortland from parent frogs originally taken from Kooragang Island. These hundreds and hundreds of Bell frog tadpoles will be monitored by Dr Michael Mahony and his students. Juvenile frogs have already been detected with the chytrid pathogen but these young frogs are surviving despite the disease.
This suggests that the slightly salty water in the ponds is helping to restrict chytrid and limit infections. The initial results look promising since some frogs can exist with sub-lethal doses of chytrid and , it is hoped, that they will in time breed a generation of chytrid-resistant Bell frogs. The project then will try to extend habitats across Ash Island, recreating the features of the successful ponds, creating sustainable habitats on Kooragang Island.
If this project is a success, the same method may later be used to restore Bell frogs back into Hexham swamp. It seems that pondering the ponds may well lead to better security for the iconic Green and Golden Bell Frog.
Dr Arthur White was interviewed for A Question of Balance by Ruby Vincent. Images provided by Dr White. Summary text by Victor Barry, August 2013.
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