Guest guest Posted January 15, 2003 Report Share Posted January 15, 2003 ***************************Advertisement*************************** eCentral - Your Entertainment Guide http://www.star-ecentral.com ***************************************************************** This message was forwarded to you by yitzeling. Comment from sender: This article is from thestar.com.my URL: http://thestar.com.my/lifestyle/story.asp?file=/2003/1/14/features/lipangkor1 & se\ c=features ________________________ Tuesday, January 14, 2003 Marine ecosystem under siege By TAN CHENG LI SEA urchins & #8211; those thorny balls we see strewn over seabeds or wedged inside coral growths & #8211; are the bane of swimmers, divers and snorkellers. Touch or graze one of them and you will suffer excruciating pain for days. They are a nuisance not only to people but to coral reefs as well. In large numbers, the spine-covered balls can grind down a reef into sand and rubble. They can do this because they feed on algae growing on corals. While grazing on algae, they inevitably scrape up the coral substrate as well & #8211; a process scientists call bioerosion. This is no problem when sea urchin numbers are within the norm, says Universiti Malaya (UM) marine biologist Dr Rosman Abdullah. When their population escalates, however, sea urchins can destroy more reef than is rebuilt. “When they graze around bases of large coral colonies, they erode and destabilise coral heads. This makes it easier for storm waves to knock the corals over,” explains Dr Rosman. “And when sea urchins crunch on corals, they may also ingest coral spats (juveniles) attached to the substrate, thus preventing new coral growths.” In Pulau Pangkor, Perak, scientists believe there is a sea urchin population explosion. A marine research project undertaken by the Institute of Biological Sciences of Universiti Malaya on Dec 17 and 18 found huge numbers of Diadema setosum scattered over the seabed and burrowed deep into reefs. Their densities ranged from “medium” at Pulau Mentangor (16 urchins per 100sq. m), “high” at Pulau Giam (23 urchins per 100sq. m) and “phenomenally high” at Pulau Dua (222 urchins per 100sq. m). “At the level of density seen at Pulau Dua, the bioerosion of the reef would be tremendous,” says Dr Rosman. In the Caribbean reefs, the maximum density was 0.8 individuals per sq. m in a 2001 study. A 1996 Singapore study estimated the population at 0.004 to 0.379 per sq. m. To what extent sea urchins have destroyed or will destroy Pangkor reefs requires more scientific work, says Dr Rosman who has just embarked on a three-year study of the marine invertebrate. But there is enough foreign research to show that sea urchins are significant bioeroders capable of corroding 1cm of reef a year. In fact, the stomachs of sea urchins have been found to comprise 90% calcium carbonate, the substance which reefs are made of. Culling sea urchins to control their population in Pangkor is not an option, says Dr Rosman, since they are members of the marine ecosystem and have ecological functions. Their diet of algae keeps reef from being smothered by marine plants. Fingerlings of some fish species shelter from predators among the long spines of sea urchins, as do small shrimps and crabs. Removing sea urchins from the sea will deprive other species of a food source as sea urchins are preyed upon by wrasses, grunts, porcupine fishes, toad fishes and trigger fishes. “A moderate urchin population is critical to maintain the natural balance between algae and coral in a healthy reef ecosystem,” says Dr Rosman. What triggered the sea urchin explosion in Pangkor waters will be addressed in Dr Rosman & #8217;s study. However, it is a known fact that sea urchins thrive in polluted waters. It is a vicious cycle: pollution from sewage leads to extensive growth of algae which fuels growth of sea urchins. Because of this link, scientists regard sea urchins as a bioindicator of water pollution & #8211; if there are lots of sea urchins, it means a polluted environment. The green-tinted water instead of clear blue that visitors see in Pangkor is a sure sign of high sedimentation and plankton-enriched water that could only have been caused by eutrophication (excessive nutrients in the water, such as from sewage). “There has been lots of development on the island in recent years,” says UM marine geologist Dr Azhar Hussin. “This has sent silt into the sea. Development of tourism facilities which started in Pasir Bogak has over the years, spread northwards to other beaches such as at Teluk Nipah. Even if chalets have sewage treatment, the system cannot cope with an influx of visitors.” Pollution has wrought much damage to Pangkor & #8217;s coral reefs but sea urchins may just finish off whatever little there is left. Many may find it hard to believe, but there are coral beds lurking beneath the murky waters of Pangkor and its surrounding islands. During the two-day survey last month, the UM team found good coverage of hard corals off the islands of Mentangor and Dua. “The reefs are still there and are in relatively good condition,” says UM marine biologist Affendi Yang Amri. He and other divers observed an interesting array of hard corals, soft corals, sponges and anemones. However, the diversity of corals was low. Much of the reef was covered by large patches of dominant hard coral species. “The low diversity is due to the corals having to cope with high stress from human activities and high bioerosion. It also signals that the coral reef ecosystem is weak and prone to collapse,” says Affendi. Another unhealthy sign is corals with white band disease which is triggered by sewage pollution. Fleshy seaweed was absent at all study sites and the scientists suspect over-grazing by sea urchins to be the cause. Results of the UM survey point to a marine ecosystem under seige and inadequately managed. Marine invertebrates which indicate healthy reefs are absent in Pangkor waters. Fish life is also poor. Most of the fish species which imply a healthy habitat are either not abundant or not seen. “This is worrying. The non-existence of the indicator species usually means overfishing,” says Affendi. The extent of damaged reef off Pulau Giam (Coral Island) which is a favourite snorkelling site worries him. Trampled by tourists and smashed by boat anchors, a quarter of the reef has been reduced to rubble. Picnickers also leave indelible marks. Foam clamshells, disposable plastic spoons, aluminium cans, tetrapaks and snack packaging litter the beach and reef. Corals are also collected as souvenirs. In the Sea View Resort where the research team stayed, a photograph on the reception wall shows tourists posing with pieces of staghorn coral which had obviously been plucked from the sea. Pangkor reefs may not rival the East Coast & #8217;s in terms of richness and diversity, but they are no less important. “Because of the turbid water, you get different coral species, especially hardy ones which have adapted to extreme conditions and those which can withstand high sedimentation and low light,” says Affendi. One example is the green-coloured Tubastrea coral which is rarely seen in East Coast reefs. Affendi says coral reefs in the West Coast are less known compared to those in the East Coast. “Pangkor reefs deserve more attention from the scientific community, the public and the relevant government bodies. We hope that by studying and highlighting them, we will help protect them.” And since much of coral reefs in the West Coast has been destroyed, it is vital to preserve whatever remains. “In Pangkor, we see a lot of dead corals but there are also live ones. But if development on the island continues unchecked, these live corals will eventually die,” warns Dr Azhar. To protect the reef, he urges for controls over visits to coral reefs. One way is by closing damaged areas to visitors for parts of the year to allow the reef to regenerate. Providing mooring buoys will also prevent tourist boats from dropping anchor onto reefs, he adds. Ultimately, the best protection for Pangkor is to turn it into a marine protected area, and that is what the scientists have recommended. In the long run, a healthy marine ecosystem will safeguard the island & #8217;s thriving ikan bilis industry, says Yusri Yusuf, a research assistant at the Penang-based World Fish Centre, who surveyed fishlife during the project. “The ikan bilis industry in Langkawi and Kedah grew after Pulau Payar was gazetted as a marine park.” Presently, with the limited data available, Yusri concludes the coral fish population in Pangkor seems to be coping well. However, their well-being is dependent on the health of the whole ecosystem. “Without the corals there will not be a healthy population of coral fish,” adds Yusri. Thus public awareness is essential. Pangkor residents must understand that the cleaner the sea, the smaller the sea urchin infestation on coral reefs, says Lim Chen Leong Alsagoff, executive director of A & L Adventure & Leisure (the local distributor of Suunto diving computers) which sponsored the project. “Since Pangkor & #8217;s economic activities and the people & #8217;s livelihood are directly linked to tourism there, they should make an earnest effort to check the escalation of sea pollution.” Preliminary survey by the university has revealed that the sea surrounding Pangkor is no wasteland. There are coral reefs which are worth preserving because they are marine habitats with eco-tourism potential. Even in the murky water, one can see faint outlines of beautiful coral formations & #8211; a reminder of what once were and what could be if pollution from the land is curbed and if damaging human activities are curtailed.<p> ________________________ Your one-stop information portal: The Star Online http://thestar.com.my http://biz.thestar.com.my http://classifieds.thestar.com.my http://cards.thestar.com.my http://search.thestar.com.my http://star-motoring.com http://star-space.com http://star-jobs.com http://star-ecentral.com http://star-techcentral.com 1995-2002 Star Publications (Malaysia) Bhd. All rights reserved. Reproduction in whole or in part in any form or medium without express written permission of Star Publications is prohibited. Quote Link to comment Share on other sites More sharing options...
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