A recent survey showed that the condition of coral reefs in Bali was improving, as indicated by an increased level of healthy coral coverage, but experts warned better management was needed to prevent damage from human activity.
The marine survey, conducted from April 29 to May 11 in 33 sites around Bali, indicated that coral reefs in Bali waters had greatly recovered from the 1997 El Niño ocean phenomenon that caused major destruction, and predatory crown-of-thorn starfish — which feed on coral polyps — in several sites.
The coverage level of healthy coral varied from 10 to 70 percent, with an average of 36 percent. The highest coverage was found in Gili Selang and Gili Mimpang in Candidasa, Karangasem regency.
“The ratio between live and dead coral was seven to one. This is remarkable,” Conservation International Indonesia marine program director Ketut Sarjana Putra said.
“What is interesting is that the coverage of reef-building coral was 36 percent, higher than in other areas, such as Raja Ampat and Halmahera [29 percent], and in Fakfak and Kaimana [25 percent],” he said.
A high level of reef-building coral means high potential of flourishing coral growth.
The study was undertaken by top international marine scientists, including reef fish experts Gerard Robert Allen and Mark Van Nydeck Erdmann and coral experts Lyndon Devantier and Emre Turak.
Scientists from Conservation International Indonesia, Warmadewa University and the Oceanic Research and Observation Agency in Perancak also participated in the project supported by USAID’s Coral Triangle Support Partnership.
“The coral has recovered strongly thanks to the ocean’s good upwelling system that brings lower temperature currents to the surface. This means Bali’s coral has good resilience to climate change,” Sarjana said.
The coral’s ability to recover was evident in several sites, with coverage of healthy coral increasing by more than double since 1997’s El Niño , Ketut Sudiarta, a coral expert from Warmadewa University said.
“In Menjangan, the coverage was only around 15 percent in 1998, but now it has reached more than 50 percent. Ten to 15 years ago, coral in Amed was damaged, with only 10 percent coverage, but now this has increased to 50 percent,” he said.
The survey indicates several key sites that will be seen as priorities in building a network of marine protected areas in Bali due to their high conservation value. The sites include Nusa Dua, Uluwatu, Candidasa, Padangbai, Gili Mimpang, Gili Selang and Seraya.
Experts identified 952 species of reef fish in 28 sites, with an average of 153 species per site. Eight of the 952 species are new discoveries endemic to their areas. The richest sites for reef fish were Batu Kelibit, Tulamben, Menjangan, Jemeluk and Bunutan.
The scientists also recorded a total of 393 species of coral, two of which were new. The new species, Euphyllia sp. and Isopora sp. were found in Padangbai and Amed.
However, the study also found much plastic garbage underwater, hampering the coral’s ability to conduct photosynthesis.
“We found in many sites litter and mud fouling the reef as well as abandoned nets tangling the corals,” Sarjana said, citing Sanur, Melaya and Candidasa as problem areas.
He added that there was also a decrease in the shark, humphead wrasse and coral trout populations due to overfishing.