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Warming causes bleaching
Alit Kertaharja , The Jakarta Post , Buleleng | Mon, 06/22/2009 12:46 PM | Bali
A recent survey conducted by the Reef Check Indonesia Foundation (YRCI) revealed around 30 percent of reefs in northern Balinese waters have suffered mass bleaching.
Similar phenomena, found at several prominent dive sites in South Bali, experts believe were triggered by global warming.
The foundation's expert Jensi Sartin disclosed that, according to the resilient force theory, the mass bleaching was due to increasing sea temperatures. Coral reefs, which have a low level of ambient water movement, are more vulnerable to the impact of the changing temperature, which includes bleaching.
"Such conditions may *trap' the heat in the water which lead to the reefs' mass bleaching," said Sartin while carrying out the survey over the weekend at Pemuteran Bay in Gerokgak subdistrict, Buleleng regency.
The YRCI recorded that during April the weather around Pemuteran Bay was quite hot and bright, with little or no cloud cover. The hot sun shining on the surface of the sea had heated it up and released microscopic algae from the reefs, triggering the bleaching.
In theory, he stressed, the reefs could adapt quite well to such conditions. However, the reefs in the waters off northern Bali have already struggled against other threats, such as damaging sedimentation, waste and garbage disposal and powerful tidal waves. It is feared the presence of yet another threat, in this case global warming, will inflict massive damage on the reefs.
"It could damage several square kilometers of reefs," Sartin warned.
He said through direct observation of 11 reef locations in the island's western, northern and eastern waters, the YRCI found the level of reef bleaching in Pemuteran Bay, Lovina, Sembiran, Bondalem, Tejakula, Penuktukan, Tulamben, Amed, Padang Bay and Sanur was less than 10 percent of the total reef area. However, the surveying divers established that at the Bio Rock reef colony in Pemuteran Bay, the bleaching had affected more than 50 percent of the colony.
The survey showed at Spice beach, Sembiran beach, Bondalem, Tejakula and Penuktukan in Buleleng, the reefs' mass bleaching had reached up to 30 percent. Similar damage was observed on Karangasem's Liberty shipwreck, one of the island's most popular diving sites, and in Lipah beach, it was 40 percent.
"We have not yet received any reports of mass bleaching in Padang Bay and Sanur. Nevertheless, we are still on alert," he added.
Despite the global warming factor, the survey revealed the mass bleaching might also be caused by Drupella predator snails. The Drupella population has allegedly bloomed in Balinese waters since November. The Bio Rock Center said its diving team had pulled out 26,374 sea snails from one single dive site during a survey from early November 2008 until June 2009.
The YRCI conducts regular surveys to monitor the status of the country's coral reefs. In Bali, the survey is conducted with assistance from diving operators and volunteer divers.
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Naneng Setiasih (not verified) — Thu, 06/25/2009 - 10:44am
Reef Check Foundation Indonesia had received a lot of report since three weeks ago from fisherman, dive operators, and colleagues about the “white” coral around Bali. This had triggered us to do a rapid survey that the result was posted in this article (the survey was done in early June 2009).
Our survey focus to measure the extent of the bleaching, so we did not measure the white/predatory scar from Drupella or other predator as part of our data. For a train eye, this is not something difficult to distinguish. I agree, predatory scar is a dead coral, not bleaching.
The last bleaching recorded in Bali was in 2003 in Ngurah Rai reef airport. At that time, other rapid survey at other places in Bali, and our network did not find any other bleaching in other places. So it was likely a localized bleaching.
The extent we found from our survey this year, however, covered a quite large area: from Pemuteran (not on Biorock, but the reef adjacent to it, and the data we had revealed 10% bleaching) up to Amed. Prior to this, we had report also from Raja Ampat of a slight bleaching in April. Lately, we received a report from Bali Barat National Park, Padang Bay, and even Karimun Jawa and Aceh. So we don't think this is a localized bleaching.
Lots of institutions will go hand in hand to measure the extent-severity and also the recovery of this event. Most of us will be using one of the method that Jamie Oliver, Paul Marshall, and Lara Hansen wrote with me (the global bleaching monitoring protocol) for the rapid assessment (extent and severity) and using the IUCN resilience method to measure the recovery ( we have a team called IUCN bleaching group in which I am actively involve).
The NOAA hotspot that available online for public is set on 50 X 50 km resolution. That is why some of bleaching event can not be detected, just like the 2003 and this year bleaching. However, the timing of the bleaching do happen on the “right time”. In the NOAA chart of the annual temperature, May and June are in fact belong to the warmest time in year. Another time is in November and December, but the rainy season help to “mild” the temperature.
I suggest a lot of skillful and knowledgeable people can join our effort to raise people understanding and awareness as well as to check for the bleaching and its recovery. By doing this, hopefully we can understand better on how to manage the reef under the changing climate.
Thank you
Naneng Setiasih
Director
Reef Check Foundation Indonesia
Dr. Thomas J. Goreau (not verified) — Wed, 06/24/2009 - 8:39am
"Warming causes bleaching" (Jakarta Post, June 22 2009) makes many completely incorrect statements. The fact that warming causes coral bleaching has been well established since I developed the HotSpot method for predicting coral bleaching in advance from satellite sea surface temperature data with Dr. Raymond Hayes 20 years ago. For mass coral bleaching ocean surface temperatures around 1 degree C above the average temperature for the warmest month are needed for a one month period. Those conditions took place over much of southern Indonesia in 1998, including Sumatra, Java, Bali, and Lombok, staying well above the threshold temperature for months, and very severe coral mortality took place that year in many places. In sharp contrast, this year the temperature only barely approached the threshold temperatures for about a week or two, not long enough to cause mass bleaching. Only mild and very localized bleaching took place in some places in Lombok and Bali in April where poor water circulation caused locally warmer temperatures, but only a small proportion of corals were affected in a few locations, and these quickly recovered when water temperatures cooled. There was no mass bleaching and little or no mortality this year because it simply did not get hot enough for long enough.
Similarly the claim in the article that high bleaching was seen on the world's largest coral reef restoration project, the Biorock Karang Lestari Reef Restoration Project at Pemuteran, Bali, is completely untrue. Almost no bleaching took place there in April. The report in the Jakarta Post in fact refers to a single Biorock Reef structure (out of around 60) with light colored corals. However the corals on that structure were not in fact bleached at all. On that particular structure we are propagating very rapidly growing corals of a single very unusually pale coral that looks almost white. However that is the normal color of this particular variety, it has looked as if it were "bleached" year round for years, and is in fact not bleached at all. Whoever told this to your reporter did not know how to properly identify bleached corals, and did not bother to check with those running the project. The report also confuses snails that eat coral with bleaching, but this is not bleaching at all, the coral that appears white is because the snail has eaten all the tissue exposing the white skeleton, whereas in bleaching the coral tissue is alive but turns transparent, allowing the skeleton to be seen through the tissue.
In actual fact Biorock reefs, while not preventing bleaching under severe high temperatures, do prevent death of the corals under these conditions. In the 2000 International Coral Reef Symposium in Bali we reported that Biorock reefs in the Maldives had 16 to 50 times higher survival of corals than surrounding reefs. So when severe bleaching does strike Indonesia again, which is inevitable given the current rate of global warming, but which did not happen this year, Biorock corals wll be the major survivors. It is therefore essential to grow Biorock Coral Arks in preparation for the events that will come, sooner or later. For that reason the Karang Lestari Project, and other Biorock reef restoration projects in Gili Trawangan (Lombok), Pulau Gangga, Pulau Badi, Palu, and the Gulf of Tomini (Sulawesi), Pulau Seribu (Java), Pulau Moyo (Sumbawa) and other locations in Indonesia are currently growing at least 80% of the coral genera in the world, and probably most of the coral species. That way when severe bleaching strikes, we will have surviving corals to propagate.
Dr. Thomas J. Goreau
Scientific Advisor
Yayasan Karang Lestari, Pemuteran, Bali
Gili Eco Trust, Gili Trawangan, Lombok
&
President
Global Coral Reef Alliance