The Indian Ocean tsunami on 26 December 2004 brought catastrophic human suffering to coastal communities in South and Southeast Asia. It also affected many marine ecosystems in the region, through broken coral reefs, sedimentation, and piling of debris, among other impacts. Efforts are underway region-wide to assess the undersea damage from the disaster, including effects on MPAs.
Such efforts have not been easy. Tsunami damage to research vessels has delayed surveys in some areas, while scientists elsewhere have had to develop assessment methods on the fly, unprepared for a rare tsunami event in the region. This month, MPA News examines some of the assessment efforts so far and what lessons they may hold for MPA practitioners.
Thailand: Measuring coral damage, repairing reefs
Following the tsunami, the government of Thailand moved swiftly to initiate assessments of the disaster’s impact on its marine ecosystems. With diving and other marine tourism accounting for a significant portion of national revenue, government officials were eager to measure how the tsunami had affected its marine national parks, which were closed to visitation following the disaster.
By 30 December, government and university researchers were dispatched to collect preliminary data on impacts to sandy areas, rocky shores, mangroves, and coral reefs. A week later, the Thai Department of Marine Natural Resources and senior scientists used these preliminary data to develop an underwater survey protocol for more intensive assessments. The protocol has since been distributed to eight universities and dozens of volunteer divers nationwide, who have used it to collect data on the extent of damage, types of coral affected, and other indicators.
Biologist Suchana Chavanich of Chulalongkorn University (Thailand) was part of the preliminary survey group and also participated in follow-up research trips. Her work focused on the coral-laden Ko Similan Marine National Park, a popular destination for dive tourists and a site she had surveyed previously as part of normal research. In her surveys since the tsunami, Chavanich observed a range of impacts. Some coral reefs had been heavily damaged – even as deep as 90 feet – while others appeared unaffected. Similarly, some beaches and seafloor areas had lost sand, while others had gained it: she observed that a significant amount of sand was missing from one seafloor site 100 feet below sea level.
The assessment effort has been essential to grasping the damage to Thailand’s marine resources. However, Chavanich warns that the protocol is imperfect and may result in inaccurate damage estimates. She points out, for example, that it offers no rigorous method for measuring the percentage of coral damage, aside from relying on divers’ best estimates. Furthermore, she says, the protocol requires no prior familiarity with a survey site, thus making it difficult in some circumstances for surveyors to tell whether a coral died before the tsunami, such as from prior bleaching.
“I think these are big problems,” she says. The committee that created the survey protocol has said that an error factor of up to 25% between damage estimates and real damage would be acceptable, although Chavanich says the estimates may be off by more. She says one survey team estimated 80% tsunami damage in an area with which her own survey group was familiar; her group, surveying afterward, estimated only 30% tsunami damage.
Although the lower figure still is cause for concern, Chavanich says that at least the impacts to coral in Thailand do not appear to be as severe as first feared. She says the effects have been greater on the tourism industry, where offices and tourist lodgings in most of the marine national parks were destroyed. “This is the peak tourist season, which ends in April,” she says. “It may take two to three months to build even temporary buildings.”
While repairs to the tourist infrastructure are underway, so are efforts to repair broken and smothered corals. From 19-24 January, 140 volunteer divers worked in Ko Similan to uncover smothered sea fans, table corals, and other reef structures and re-set them in the seafloor. Henry Aruffo, director of the Coral Reef Institute, a research and education organization in nearby Phuket, was a participant. “A significant percentage of the larger coral species still had a majority of corals alive,” he says. He expects survival rates for corals that were completely buried in sand to be 20-50%, whereas broken but not buried corals could have 80% survival rates.
The sites for repair work were selected in part based on results of the intensive assessments: the sites with greatest damage were repaired first. “At whatever rate the corals survive – and we will monitor survival in the future – repopulation of the reefs will occur much faster than if the corals had been left unrepaired,” says Aruffo.
Standardizing the long-term monitoring of tsunami effects region-wide
What Thailand did in facilitating a national damage-assessment campaign, an international project is aiming to do for the entire Indian Ocean. Led by regional and global coral-research institutions, the project has produced a draft set of guidelines for rapid assessment and monitoring, to be finalized within the next several weeks. The guidelines were assembled from a range of sources, including a technical manual for post-disaster environmental assessment in the Caribbean (see box, “Importance of conducting surveys prior to disasters”, at the end of this article). The project is led by the Global Coral Reef Monitoring Network (GCRMN), the International Coral Reef Initiative (ICRI), the International Society for Reef Studies (ISRS), and CORDIO, an international research program created to respond to coral reef degradation in the Indian Ocean.
The draft guidelines are available for viewing at http://www.unep-wcmc.org/latenews/emergency/tsunami_2004. The document is intended to serve two purposes: to assist field teams and monitoring programs to collect relevant tsunami data, and to promote comparisons of data from local to national and regional levels. By standardizing such surveys, says David Obura of Kenya-based CORDIO, the resulting datasets and reports will be comparable in the next months and years – the timescale he believes will be necessary for accurate analysis.
“Direct biological impacts of the tsunami, I think, can be estimated reasonably accurately within three to four months’ time, and probably quite well after a year – not so much by having more accurate surveys but by having the chance to visit more sites,” says Obura. “However, there may be longer term repercussions that will need several years of monitoring, such as the loss of structures used as cues for fish-spawning aggregations. It’s hard to know. Also, the extreme damage on land may have very strong impacts on the recovery of reefs: changed river mouths and underground streams, mobile debris persistent over multiple years, or trapping of waste sludge or other materials into depressions on reefs.”
The draft guidelines, he says, are not so much a list but a set of recommendations on key variables and indicators to measure, and how to conduct sampling at different levels of expertise. “Because people have used a variety of monitoring techniques in the past, and to maximize compatibility with past surveys, users will be urged to use a strategy similar to their past ones, while also trying to cover broad areas and make their results compatible with others’,” says Obura.
The guidelines are fairly comprehensive, with tips on site selection, data units, damage indicators, data management, and even how best to use photo/video equipment, among other information. The authors state two “critical rules” to follow when sampling within a given area:
- Always use the same methodology, so that data can be compared; and
- Do not pre-select areas to sample (such as selecting only areas with maximum damage), as this biases the damage assessment.
Karenne Tun, Southeast Asia regional coordinator for GCRMN, says the guidelines when finalized will be distributed to practitioners throughout the Indian Ocean. “GCRMN and ICRI will publish regular updates on the impacts, and will produce a more detailed report in the second half of 2005 for global release,” says Tun. “There are also plans to publish several papers on the socioeconomic and ecological effects of the tsunami on coastal communities.”
Sri Lanka: Assessing coral reefs and the protective role of MPAs
The draft guidelines mentioned above have already been tested in Sri Lanka as part of post-tsunami reef assessments there. Jerker Tamelander, South Asia regional coordinator for CORDIO, GCRMN, and the IUCN Regional Marine Programme, applied the methodology in rapid assessments of six sites, including a no-take MPA – Hikkaduwa National Park. The sites were selected due to their inclusion in an existing reef-monitoring program under Sri Lanka’s National Aquatic Resources Research and Development Agency (NARA).
“These sites are the only locations where we have good baseline information, so they were natural ‘first stops’,” says Tamelander. “While they consist of similar reef types, they have slightly different characteristics in terms of their exposure and whether inner lagoons or outer slopes, or both, are sampled. Given the patchiness of the damage from the tsunami, it is important to sample broadly, covering many different sites and a lot of area at each site.” Seagrass beds and beaches in association with the reefs are also being sampled, he says, as well as mangroves where they occur. Other assessment teams are examining terrestrial systems like broader mangrove, coastal dune, and wetland areas.
The results of the rapid assessment suggest the protected status of 0.45-km2 Hikkaduwa National Park may have fostered resilience to the tsunami. Whereas non-protected sites on the same coast of Sri Lanka experienced moderate to high losses in fish abundance following the disaster, Hikkaduwa exhibited little change in such abundance, which had been high prior to the tsunami. The limited impact on fish was despite the tsunami-caused deposit of large quantities of debris on the Hikkaduwa reef: textiles, tree branches, parts of boats, and other materials. (Volunteer divers cleaned the Hikkaduwa reef lagoon in late January, and will return to clean fringing reef areas.) The assessment is available online in PDF format at http://www.nara.ac.lk/RAP%201st%20report%20FINAL1.pdf.
Although Tamelander is cautious about attributing Hikkaduwa’s apparent resilience to its status as an MPA, he says it is generally acknowledged that healthier ecosystems are better able to dissipate wave energy, withstand stress, and recover from damage than degraded ones. “Marine and coastal protected areas will serve as a good comparison with surrounding unprotected areas on tsunami impacts,” he says. The other sites in the Sri Lanka reef survey have all experienced fishing pressure in recent years, including from blast-fishing and other destructive techniques. (Most of the sites, including Hikkaduwa, had also suffered heavily from a 1998 bleaching event and were at various stages of recovery prior to the tsunami, in terms of coral and fish diversity.)
Tamelander says more research is needed before concluding that the protected status of Hikkaduwa kept it safer in the disaster. “The problem is that the energy with which the tsunami struck different areas varies, influenced by such factors as bathymetry and shore profile,” he says. “So comparisons between different locations need to be made carefully.” Studies already underway by NARA are analyzing such oceanographic factors, and may yield findings by mid-2005. Tamelander says the studies could provide important information for policy development, as well as for the general population. “It should be noted that promoting healthy coastal ecosystems will provide physical protection from a range of other calamities as well, including cyclones and climate change effects,” he says.
As elsewhere throughout the Indian Ocean, fishing communities of coastal Sri Lanka were devastated by the tsunami. The Sri Lankan government is building replacement fishing vessels and trying to resurrect the industry, which could take years, say officials. Tamelander says that in rebuilding livelihoods, it will be important to ensure sustainability as well, avoiding a return to the past situation of overcapacity and rampant destructive fishing practices. “This will take a concerted effort from government, the conservation community, and other stakeholders,” he says. “It will also emphasize the need for development of sound and realistic alternative livelihood options.”
For more information:
Suchana Chavanich, Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand. Tel: +66 2 218 5395; E-mail: email@example.com
Henry Aruffo, Coral Reef Initiative, Phuket, Thailand. E-mail: firstname.lastname@example.org
David Obura, CORDIO East Africa, 8 Kibaki Flats, Kenyatta Beach,Bamburi Beach, P.O. Box 10135, Mombasa, Kenya. Tel: +254 41 548 6473; E-mail: email@example.com
Clive Wilkinson, Global Coordinator, GCRMN, Australian Institute of Marine Science, PMB #3, Townsville 4810 QLD, Australia. Tel: +61 7 47724314; E-mail: firstname.lastname@example.org
Jerker Tamelander, IUCN Regional Marine Programme, 53 Horton Place, Colombo 7, Sri Lanka. Tel: +94 11 2694094; E-mail: email@example.com
Arjan Rajasuriya, NARA, Colombo 15, Sri Lanka. Tel: +94 11 2521000; E-mail: firstname.lastname@example.org
BOX: Impacts of tsunami on marine ecosystems
A tsunami can damage marine ecosystems via (A) its initial surge and (B) the ensuing backwash, the latter of which may carry sediments and debris from land. The sediments and debris can smother and scrape seafloor habitats, such as coral, while introducing toxins and disease agents to the ecosystem.
The physical forces of a tsunami are powerful enough to alter river mouths or cause meter-wide coral boulders to tumble across the seafloor. In the Seychelles, the repeated draining and refilling of shallow bays over the course of 26 December exposed reefs there to direct sun and rain – elements they may not have experienced in more than a century, say experts.
BOX: Importance of conducting surveys prior to disasters
Although not prone to tsunamis, the Caribbean Sea annually experiences several hurricanes that cause destruction to terrestrial and marine ecosystems. In 2003, the Environment and Sustainable Development Unit of the Organization of Eastern Caribbean Countries (OECS) published a technical manual for member states to use in post-disaster rapid environmental assessment. The two-volume manual – adapted recently as part of draft guidelines for post-tsunami assessments in the Indian Ocean (see article above) – was applied on a trial basis in Grenada following Hurricane Ivan in 2004.
George Sammy of Ecoengineering Caribbean Limited authored the manual for OECS and says its basic principles are applicable to most small-island developing states worldwide. Among the most important principles is disaster preparedness, he says, including the mapping of natural assets like coral reefs, seagrass beds, and mangrove forests. Such mapping not only serves as a control for post-disaster assessments of damage, but also may be useful in litigation following various human-caused disasters, such as oil spills.
“The basic finding of the Grenada trial last year was that the assembly of pre-disaster information on environmental assets is important if values are to be placed on the damage,” says Sammy. “Although mitigation-related aspects of the manual can be applied without pre-disaster information, the usefulness of the manual in valuing damage is compromised if there is no reliable pre-disaster information.” The Manual for Post-Disaster Rapid Environmental Assessment is online at http://www.oecs.org/esdu.
For more information:
George Sammy, Ecoengineering Caribbean Limited, 62 Eastern Main Road, St. Augustine, Trinidad, West Indies. Tel: +1 868 645 4420; E-mail: email@example.com
BOX: More resources on tsunami
IUCN Information Paper: “Recovery from the Indian Ocean Tsunami – Guidance for Ecosystem Rehabilitation Incorporating Livelihoods Concerns”
IUCN Tsunami Response
UNEP Tsunami Response
ReefBase Tsunami Impacts