Soil pollution threatens Bali's precious coral reefs

By I Wayan Juniarta

DENPASAR, Bali (JP): Bali's world famous coral reefs, increasingly important in attracting tourists to the paradise island, are being threatened by soil pollution, according to preliminary research by the World Wide Fund for Nature's (WWF) Wallacea Program.

A WWF team of international scientists, who conducted the research, presumed that some of the pollution was caused by the excessive use of phosphorous and potassium fertilizers by Balinese rice farmers.

"It is still too soon to draw definitive conclusions from this research. However, the initial findings strongly suggest that the coral reefs are in a serious condition due to the impact of soil pollution, including agricultural runoff," deputy director of WWF Indonesia's Wallacea Program Ketut Sarjana Putra said last week.

He said the team was still continuing the study.

Soil-based pollution is one of the major threats to coral reefs, besides the crown-of-thorn sea star (Acanthaster plancii), which in 1997 destroyed most of Bali's northern coastal coral reefs. Government officials, environmental activists, tourism operators and local fishermen killed at least 800,000 crown-of- thorn during a battle to protect the coral reefs.

The WWF team comprises Ketut Sarjana Putra, Ghislaine Llewllyn from the University of Connecticut in the United States and Jim Kremer and Richard Murphy of Ocean Future Society.

Earlier this month, the team conducted a significant comparative study on the condition of coral reefs in waters located close to major rice-growing areas with those located far from the areas.

After diving and observing at least 13 different sites around Nusa Penida island, Candidasa, Sanur and Amed, the team concluded that many of Bali's coral reefs are now in a dilapidated condition.

Some coral reefs are being destroyed by "bomb fishing", coral bleaching and crown-of-thorn outbreaks. The rapid growth of algae also destructs numerous coral reefs in the island's waters.

"We took 50 algae tissue samples from reefs and rivers to determine if the growth of algae was linked to fertilizer runoff," Sarjana Putra commented, adding that those samples would be sent to a a laboratory in the United States for further scientific investigation.

He explained that fertilizer runoff resulted in excessive nutrient levels which had harmful effects on both the freshwater and marine ecosystems.

"Coral reefs, adapted to low nutrient conditions, are particularly sensitive and vulnerable," he explained.

The vulnerable coral reefs trigger other marine species such as algae to grow faster, occupying the living space of the reefs. Excessive nutrients can also cause toxic algal blooms, which can kill fish and make shellfish poisonous to eat. And it also triggered the outbreak of the crown-of-thorns, which eat the coral.

"Actually, the algae and reefs have a mutually beneficial relationship. But, if excessive nutrient level takes place this harmonious relationship will be destroyed. An excessive phosphorous level, for instance, make reefs unable to absorb calcium from the water," Murphy added.

Previously, in different research conducted from 1997 to 1998, an American anthropologist, Stephen Lansing, in collaboration with I Wayan Alit Artha Wiguna of Bali's Research Institute on Agricultural Technology (IP2PT), discovered that much of the phosphorous and potassium Balinese farmers apply to their rice paddies was not really required.

"We found that the ground water emanating from the volcanic soil of Bali is naturally rich in nutrients essential for rice growth, so there is no actual need for the application of manmade fertilizers," Lansing said.

Lansing, who is well-known for his in-depth work on Balinese traditional rice-growing culture and institutions, added that the findings of his research had been confirmed by several traditional irrigation organizations, subak, in Tegalalang, Gianyar.

"Those organizations have stopped using certain fertilizers that contain nitrogen. That action did not affect the well-being of their rice or paddy fields. Presently, most Balinese subak enjoy a good harvest twice a year.

Both Lansing and the WWF team urged the central and provincial government to critically review the current agricultural policy that requires the application of fertilizers with a high level of phosphorous and potassium.

The application of the fertilizers should be reduced to better suit local conditions, otherwise Balinese farmers will suffer a tremendous loss and the island's coral reefs will be in great danger.