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Helping bleached coral recover
Colors fading: Bleached corals can be seen in Lypah Bay, Amed, Karangasem regency, Bali
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span class="inline inline-left">Colors fading: Bleached corals can be seen in Lypah Bay, Amed, Karangasem regency, Bali. A team of marine scientists recently conducted a survey to examine the condition of the coral after mass bleaching was reported in 2009 and 2010.Marine scientists have warned Indonesia’s coral reefs may experience another cycle of bleaching this year.
Studies have shown 2010 was not a good year for South East Asian reefs, as unusually high or prolonged summer sea temperatures caused mass bleaching.
So what exactly is bleaching?
Corals have a single-cell algae called zooxanthellae that lives within their tissue. Through photosynthesis, zooxanthellae produces sugars to feed the corals. Sugars make up 98 percent of the corals’ food.
Zooxanthellae with their brilliant reds, oranges and browns give corals their color.
Bleaching occurs when corals lose their zooxanthellae. The corals’ tissue becomes transparent, a white skeleton can be seen, making the corals look bleached white.
Without zooxanthellae, corals will not only lose their color, but also slowly starve to death.
Zooxanthellae are expelled from the tissue when water temperature increases. It could take days to weeks for corals to turn from a “healthy” state to a “bleached” one.
Mass bleaching has been recorded in 20 locations across the archipelago, including Aceh and Padang in Sumatra, the Thousand Island National Park and Karimun Jawa National Park in Java, Gili Indah Islands in Lombok, Wakatobi and Tomini Bay in Sulawesi, Maluku, and Raja Ampat, West Papua.
Roughly 50 different organizations and individuals, ranging from surfers, anglers, divers, dive operators and scientists, have reported bleaching from mid-March to mid-July 2010.
Severe bleaching was reported in Sumatra and Sulawesi (more than 75 percent of corals were said to be bleached), while reports of coral bleaching in Java, Bali Lombok, Maluku and West Papua ranged from mild to medium.
Up to 90 percent of bleaching was reported in Sabang and East Aceh and up to 40 percent of corals in Lypah Bay in Amed, Karangasem regency were reported as bleached.
Other mass bleaching was also reported in Bali’s Menjangan Island and Labuhan Lalang, Lovina, Tejakula and Tulamben.
Although temperatures are already decreasing in many areas in Indonesia, many experts fear that recovery will be a struggle.
A resilience survey in Gili Indah by Reef Check Foundation Indonesia showed that some corals found bleached a month ago was already dead and covered by algae, while other coral had been affected by diseases.
More worrying is a recent report from the Wildlife Conservation Society, James Cook University and Syiah Kuala University in Sabang, Aceh, which found that most of the corals reported as bleached in May and June, died only one month later.
Their assessment showed that 80 percent of hard corals were bleached, including Acropora, Montipora, Pocillopora, Seriatohora, Favia and Favites. Some more resistant species were still bleached, with most of them expected to die within the next few weeks.
Scientists reported bleaching in some marine areas of Bali in January, explaining mass bleaching had probably been exacerbated by La Nina, an ocean phenomenon, which is predicted to last until April.
Every year, the temperature of the sea rises, between April and June, and between October and January.
“We’re anticipating some bleaching around May this year due to the El Nino phenomenon,” said Jensi Sartin, Reef Check Foundation Indonesia program manager.
In response to the series mass bleaching in 2009 and 2010, The Nature Conservancy’s (TNC) Indonesia Marine Program builds an ongoing rapid bleaching assessment funded and implemented by the Wildlife Conservation Society (WCS) and Reef Check Indonesia Foundation in Aceh, Bali and Lombok.
The studies aim to assess the severity of bleaching, the different susceptibility of coral to the bleaching, and mortality rates by measuring the impact on coral cover in the marine protected areas (MPA).
“The results will feed into our overall analysis of bleaching resistance hypothesis and resilience principles, and will be used to improve the MPA network design,” said Joanne Wilson, deputy director of science from TNC Indonesia Marine Program.
The scientists are working together to identify areas that may be more resilient to bleaching.
“Including these resilient areas in marine protected areas is one of the most important strategies to address climate change,” Naneng Setiasih, Reef Check Foundation Indonesia chairwoman, added.
The team has also initiated a bleaching network in Indonesia to compile reports and studies about bleaching and reef resilience in the face of climate change since 2007.
After recently conducting a post-bleaching survey in Amed, in the eastern part of Bali, Reef Check has been monitoring a total of 31 locations in Tulamben, Tejakula, Lovina and Gili Islands to see how corals responded to mass bleaching.
“We also analyzed the composition between the resistant, intermediate and susceptible corals,” said Jensi.
“From our findings, we saw that susceptible species have started to adapt and transition toward an ‘intermediate’ condition, thus becoming more resilient,” he said.
They also found the recruitment process was good, as indicated by the existence of newly grown baby corals, most of which are from the genus of Porites and Favites.
Scientists calling for urgent action to reduce all existing manmade threats to ensure the reefs recover from bleaching.
“Coral reefs in Indonesia are already under threat from overfishing, anchoring, coral mining, pollution, sedimentation and reclamation of reefs associated with coastal development,” said Naneng.
“Reefs affected by these stresses have less chance of recovering from coral bleaching, the most obvious sign of climate change,” she said.
Joanne added that many studies showed healthy reefs were better able to recover from the effects of climate change.
“It is important to reduce ‘everyday’ threats to ensure their survival in the face of climate change,” Joanne said.
According to Jensi, bleaching is not only difficult to control, but also has a tremendous impact on the marine ecosystem, occurring more and more frequently.
“It’s like we’re racing against time to save the corals, while we have yet to find the pattern of the bleaching, we’re working to map out and assess the impacts.”
He said fishermen in Indian Ocean had started to feel the impact of bleaching, since it affected the fish population.
“They have to sail further, and it takes them longer to catch fish.”
— Photos by Stanny Angga
