Great leap in frog science
2009-10-19 08:59
Brunei - If you ever thought that finding a needle in a haystack was difficult, try looking for a microchipped frog in a rainforest.
This is what German biologist Ulmar Grafe is attempting in one of the world's few remaining untouched rainforests in the oil-rich sultanate of Brunei.
Situated on the north-eastern coast of the island of Borneo, more than half of Brunei's 5 700 square kilometres are covered in rainforests, with one third of the territory under protection.
Setting out at dusk from a research station on the Belalong river in the middle of mangrove forests and jungle, undeterred by pouring rain, waist-deep water, biting insects, snakes and other creeping forest dwellers, Grafe and a colleague start their search for some of the region's 66 known species of frog.
The scientists are looking for one particular frog. Grafe had previously implanted several of the tiny creatures with microchips, hoping the telemetric data received can help broaden knowledge about their range of movement.
World's most dangerous snakes
The researchers unfold a huge antenna among the towering trees. A signal shows that one of them, a Borneo River Frog, must be close by. However, the signal does not necessarily mean the animal is still alive.
"The chip keeps sending signals, even when it is inside a snake," Grafe says.
The frog expert is not unduly worried by the fact that Borneo is home to some of the world's most dangerous snakes. "You just have to keep your distance," he said.
Stumbling through the pitch-dark night, the researchers close in on the chipped frog, the antennae read-outs leading them to a steep slope. Hidden under fallen leaves they find the animal, which has fortunately evaded becoming a snake's dinner.
Grafe marks the site with a satellite navigation unit, the information to be entered later into his computer program mapping the amphibians' movements.
'A complex ecosystem'
The variations among Borneo's frogs seem endless. A tiny specimen sitting on a leaf next to a stream turns out to be a Foot-Flagging Frog.
The male has developed a special way to attract females over the noise of running water - it waves its legs, which sport bright white webbing.
The forest is a complex ecosystem, which can become unbalanced even by the smallest changes - like a road cutting through it.
One such swathe, near Temburong for example, led to the introduction of the Rough-Sided Frog, a species distinguished by its bark-like croak. It prefers open spaces and small ponds.
"Is their arrival good or bad? Do other species vanish or does the number of them increase. We just don't know," Grafe says. "Do we have to look into that? Well, the answer simply is: You never know what it's good for."
Changes to the ecosystem could, for example, lead to the disappearance of frogs, whose skin secretions may help cure cancer. The rainforests have to stay intact in order to keep those possibilities alive.
"The rainforests provide all those free gifts - clean water and clean air," Grafe says. If the primary forests are cut down, the animals vanish.
Plantations suck the nutrients from the soil and in the end the ground karstifies. Rainforests also help keep down natural pests like mosquitoes, which are responsible for transmitting diseases such as dengue fever.
- SAPA