The tsunamis of Sunday 26 December 2004 caught many people unprepared and unaware in Indian Ocean countries. This unexpected event struck without apparent warning on a clear day; many local people and tourists were on the beach and some walked over coral reef flats as the water receded to investigate a hidden realm. Within minutes, a series of massive waves returned to carry them away and invade the land. The tsunamis resulted in more than 250,000 people killed or missing and caused massive destruction to coastal resources and infrastructure.
ReefBase is compiling reports from the affected areas on observed impacts to coral reefs and related environments, which are listed below. Currently there are 171 papers and reports available in ReefBase literature section regarding this phenomenon from various part of the world. If you have any field observations on the impacts thus phenomenon on coral reefs, fish populations, mangroves or otherwise, please contact
ReefBase
or you can upload the report using our use input page at
user input page.
Other information on tsunami impacts:
Field reports on tsunami impacts
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11 Jan 2006 |
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A multinational team of seven scientists and three support crew carried out the Aceh expedition from 17 to 30 October aboard the vessel, Mermaid of the Equator. Starting from Sibolga, the expedition covered the area affected by the earthquakes and tsunami -- over 660 kilometers to Pulau Rondo, the northern-western tip of the Indonesian archipelago. Unfortunately, high turbidity due to heavy rainfall limited the ability of the team to effectively survey many of the reefs adjacent to the mainland coast. Surveys were carried out using manta tows and the globally-standard Reef Check protocol. The surveys recorded food fish sizes and abundance, as well as mobile and attached invertebrates including corals. A special survey was carried out to detect newly settled corals as a measure of recovery.
The results of the underwater surveys indicated that relatively minor physical damage to coral reefs was caused by the tsunami as compared with the well-documented devastation experienced on land. Tsunami damage recorded included overturned corals and swathes of broken corals where large tree branches and tree trunks had been washed across the reef as the waves receded.
No tsunami damage was observed at more than half of the reefs surveyed. Even in areas where severe tsunami damage was recorded, there were still large areas of intact, living coral reef present nearby. These areas may act as an important source of larvae for recolonization of the damaged reefs. However, of the 5,280 quadrats surveyed for recruits, only 18 recruits were recorded, and 15 of these were in the Banyak Island group. This low density of coral recruits indicate that recovery is proceeding very slowly.
The earthquake damage to coral reefs was more severe than that caused by the tsunami. Damage included uplifted reefs, shattered beds of coral, and overturned coral colonies. Several islands such as Simeulue were tilted, with one end rising as much as 2 m while the other end descended a similar amount. This caused tens of hectares of living coral reef to be raised above the high tide level and killed, while other reefs descended into deeper water, altering the ecological zonation.
On land, the earthquakes and tsunami caused slope failures and removed vegetation facilitating increased erosion, sediment transport, and discharge during rainy periods. A longer-term and more insidious type of reef damage could occur if the observed turbidity and sedimentation continue. In addition to inhibiting coral settlement, sedimentation can directly injure and kill adult corals.
A low abundance and small mean size of the ten primary food fish families in Aceh was recorded suggesting that stocks of these fish are overfished. Evidence of destructive fishing practices was common. Overfishing can lead to an imbalanced ecosystem in which the lack of herbivorous fish allows fleshy algae to overgrow corals and dominate the coral reef.
The findings from this study suggest that sedimentation (exacerbated by the tsunami), overfishing, and the use of destructive fishing methods may represent a greater threat to Aceh’s reef ecosystems than the immediate impacts of the earthquakes and tsunami.
The earthquakes and tsunami have left the Acehenese more dependent than ever on their marine resources for survival. Coral reefs can recover relatively quickly following a reduction in fishing pressure. There is now an opportunity to invest in a long-term strategy to rehabilitate the marine resources of Aceh through education, coastal management, regular monitoring and the establishment and maintenance of marine protected areas.
To access this important and interesting document, click here.
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30 Dec 2005 |
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'Impacts of the Tsunami on Coral Reefs in the Northern Aceh Region' was released recently by Wildlife Conservation Society, Bogor, Indonesia providing detail observation on the effect of the event to coral reef ecosystem of Northern Aceh Region.
Excerpt from the report
"The effect of the tsunami on corals was highly dependent on habitat, although within
habitats the geomorphology of the coastal zone was also important. West facing coral
reefs with shallow slopes incurred greatest damage, however corals attached to solid
substrata in the shallows (0-2m depth), generally incurred little damage. We detected no
significant change in shallow coral assemblages between March 2003 and March 2005,
with the exception of one site smothered by sediment. Many sites remain in excellent
condition, particularly on Pulau Weh, where local management has proved effective.
An exception to this pattern was on the southern edge of the fringing reef of Lampuuk,
where a previously flourishing Acropora assemblage has been smothered by sediments,
most likely of terrestrial origin. The change in sediment regime and increased turbidity
following the tsunami, particularly on the west coast reefs of the Acehnese mainland,
continues to threaten corals, with some bleaching evident, possibly as a consequence of
low light."
To access this important and interesting document, clickclick here.
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30 Dec 2005 |
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'Impacts of the Tsunami on Coral Reefs in the Northern Aceh Region' was released recently by Wildlife Conservation Society, Bogor, Indonesia providing detail observation on the effect of the event to coral reef ecosystem of Northern Aceh Region.
Excerpt from the report
"The effect of the tsunami on corals was highly dependent on habitat, although within
habitats the geomorphology of the coastal zone was also important. West facing coral
reefs with shallow slopes incurred greatest damage, however corals attached to solid
substrata in the shallows (0-2m depth), generally incurred little damage. We detected no
significant change in shallow coral assemblages between March 2003 and March 2005,
with the exception of one site smothered by sediment. Many sites remain in excellent
condition, particularly on Pulau Weh, where local management has proved effective.
An exception to this pattern was on the southern edge of the fringing reef of Lampuuk,
where a previously flourishing Acropora assemblage has been smothered by sediments,
most likely of terrestrial origin. The change in sediment regime and increased turbidity
following the tsunami, particularly on the west coast reefs of the Acehnese mainland,
continues to threaten corals, with some bleaching evident, possibly as a consequence of
low light."
To access this important and interesting document, click here.
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16 Aug 2005 |
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New report on the effect of recent tsunami on coral reefs at Weh Island, North Sumatera, Indonesia by Dr. Gerald R. Allen was included into ReefBase literature section. The article was published in GOLDEN DOLPHIN Video CD Magazine Issue No 23: July/September 2005 and included into ReefBase literature section.
Excerpt from the article:
"The reef next to Iboih Village presented a rare opportunity to study the effect of the tsunami on reef fish populations. Although about 75 percent of the reef was destroyed, two mainly undamaged sections provided a baseline of sorts for comparisons. We laid a measuring tape on the bottom running perpendicular from shore and counted every fish within two metres of the tape and also estimated their total biomass using length-weight data. The experiment was repeated four times, two times each on heavily damaged and lightly impacted sections of reef. Slightly over twice as many species and almost five times as many individuals were found in the lightly impacted areas compared to the severely impacted ones. Moreover, the lightly impacted sections had a biomass value that was about four times greater than that of the severely impacted areas.
There is no doubt that the tsunami had a profound impact on local fish communities. Certainly the most dramatic impact we witnessed was at Gapang Lagoon and near Iboih Village. In both instances the entire reef was scoured clean leaving only the basement rocks that formed the foundation of the former living reef. Most of these areas now look like “ghost towns” with drastically reduced fish populations. The adjacent debris fields are oddly reminiscent of the tsunami refugee camps seen around the outskirts of Banda Aceh. They are essentially populated by refugee fishes that have been displaced from their normal living coral reef habitat.
Many species, particularly coral-associated damselfishes and butterflyfishes, were noticeably scarce. There has also been a profound effect on sand-dwelling fishes, particularly gobies, as nearly all the former sand bottom disappeared from depths less than 8 m. This was especially noticeable at Gapang Lagoon.
To access the full paper of the documents, click here.
GOLDEN DOLPHIN Video CD Magazine Issue No 23: July/September 2005
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12 Apr 2005 |
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Four out of the 10 Southeast Asian countries were affected by the December 26 2004 earthquake and tsunami - Indonesia, Thailand, Malaysia and Myanmar, all with coastlines lying within the Indian Ocean.
Numerous rapid environmental assessments were made within the first quarter of 2005, conducted in all cases with due regard to the sensitivity of the situation and the needs of the survivors. Preliminary coral reefs assessments were conducted in all four countries, either as independent and focused assessments, or part of wider environmental assessment efforts.
Preliminary results so far have generated the following general observations:
a. Coral reefs in the region showed varying levels of impact from the earthquakes and tsunami, ranging from total destruction to no visible impacts;
b. Impact on coral reefs from the earthquake and the tsunami had different manifestations, with the earthquake causing direct physical change to reef systems, while the actual tsunami wave front did not cause as much damage compared to post-wave impacts such as backwash and debris deposition;
c. Severity of impact on coral reefs did not always correspond to severity of impact on adjacent land, as seen at several sites near Patong, Phuket, where damage to reefs were low while adjacent land areas suffered extensive damage;
d. Moderate to high impact on coral reefs from the tsunamis showed positive correlation to anthropogenic influences, as seen by damage to coral reefs in the vicinity Phi Phi island, which were mostly associated with deposition of debris like beach umbrellas, furniture, vehicles and uprooted vegetation;
e. Coral reef fish fauna was not adversely affected, with sites surveyed showing no change in pre- and post- tsunami coral reef fish diversity and abundance;
f. At some survey areas, high proportional tsunami related coral damage were found to correlate with areas that did not have substantial live hard coral cover prior to the tsunami; and
g. Intact and healthy coral reefs (together with associated ecosystems comprising mangroves and seagrass beds) have shown to correlate with shoreline protection and correspondingly less impact on land.
To access this summary report click here.
This summary report will be updated regularly once new information is available.
WorldFish Center, GCRMN and Japan Wildlife Research Center
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11 Apr 2005 |
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At the invitation of the Department of Marine & Coastal Resources, the Department of
National Park, Wildlife & Plant Conservation, and the Ministry of Natural Resources of the
Royal Thai Government; the UK based NGO, Coral Cay Conservation (CCC), undertook a
study of the coral reefs of the Surin Islands Marine National Park to assess the level of
damage that had occurred as a result of the tsunami of December 26th 2004. A team of CCC
marine scientists carried a programme of underwater surveys around the islands; the first
week spent identifying and quantifying specific indictors of tsunami-induced damage, the
second undertaking a preliminary assessment of the current state of the extant marine
resources of the islands.
Live hard coral cover was found to be exceptionally high on the north-east coast of the island
of North Surin, with an average value of 75% and a maximum value of 90%. Interesting
patterns developed in the data set where areas of high proportional tsunami related coral
damage were found in areas that previous to the tsunami did not have substantial live hard
coral cover. Whilst at the localised scale, the tsunami would have far-reaching ecological
consequences on these areas, overall, in the Surin National Park, it was calculated that only
8% of the pre-tsunami coral quantity or coverage may potentially have been lost to the
tsunami if all of this damaged coral subsequently now dies. Encouragingly however, signs of
coral regrowth were discovered and documented. It would appear that healthy coral reef
systems such as those of Surin can begin to regenerate rapidly even in the aftermath of a
natural event as momentous as a tsunami.
To access this report click here.
To access previous reports of the area before tsunami event, click here.
Coral Cay Conservation
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16 Mar 2005 |
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An assessment of the geomorphology of reef flats, shorelines and islands of 19 inhabited and uninhabited islands of Laamu and Thaa Atoll was undertaken. The tsunami approached islands from the outside of the atoll, including on the western side. Despite significant damage to buildings, the tsunami had less impact on the reef flats, islands and beaches than was expected:
* Reef flats on the outside of atolls were minimally impacted.
* Beaches exposed to the tsunami experienced limited erosion, and some toppling of vegetation that may increase the likelihood of further seasonal erosion.
* The ends of islands suffered more extensive erosion.
* The island surface and soil structures of the islands remained relatively intact, and there were no major accumulations of reef sand or shingle.
* On the beaches on the lagoon side of the atolls, scour pit formation caused significant erosion and deposition of sediment on the adjacent reef flats, except on islands where the water did flow right across the island.
* One case of an island breaching was documented. The importance of shoreline vegetation for erosion prevention was significant in all environments.
Much of the building damage was caused by scour under and around structures, and by physical damage by debris. On coral walls without rendering, water entering cracks led to rapid collapse of walls. Increased groundwater pressures probably caused some lifting of solid floors. Huraa on North Malé Atoll was visited where one area of collapse of the ground was probably assisted by the tsunami, but a cavity or area of loose sand beneath a cemented layer, which led to the collapse, is not unusual.
To access this report click here.
Australian Government Mission and the Maldives Marine Research Centre
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20 Feb 2005 |
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Thus these preliminary assessments suggest that extensive damage was done by the tsunami
to all coral reefs in northern and eastern island groups that have carbonate frameworks. It
might be that this is also the case for outer atolls and islands, and surveys should be
prioritized to the eastern islands closest to the tsunami origin, and not protected by the
shallow waters of the Seychelles bank. Little direct damage from the tsunami is expected for
all coral reef habitats in the central, south and western parts of the granitic islands, and all
outer islands sheltered by the Mascarene plateau and Seychelles bank (e.g. the Amirantes,
Aldabra and others). In these areas, some damage is possible for shallow corals on carbonate
substrates, but little damage is expected for all deeper habitats and all sites with granitic
substrate.
Comparing these two patterns numerically, these surveys documented > 50% of substrate
damage and >25% of direct damage to corals in northern and eastern-facing carbonate
framework sites), <10% damage in shallow carbonate substrate sites in central, western and
southern locations, and < 1% damage on all granitic substrate sites. Given the importance of
coral reefs to the economy, society and infrastructure of the Seychelles (all the damaged
northern sites are prime tourist locations for the country, the most highly damaged terrestrial
locations are adjacent to degraded reef areas) this provides a strong threat to the country and
requires action for mitigation.
To access this report click here.
IUCN/UNEP
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18 Feb 2005 |
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The Universiti Malaya Maritime Research Centre (UMMReC) together with WWF-Malaysia, Malaysian Society of Marine Sciences (MSMS), Universiti Kebangsaan Malaysia (UKM) and The World Fish Centre has conducted a post tsunami environmental assessment survey on the islands of the Langkawi archipelago and Pulau Perak (Lat: 5.689, Long: 98.933) which is situated in the middle of the straits of Malacca. This survey was conducted from 28th of January to the 2nd of February 2005.
The status of the biological resources were assessed using survey methods such as a modified Reef Check method and a rapid assessment and monitoring survey technique for tsunami damage in development by GCRMN/CORDIO/Reefbase/ReefCheck for ICRI/ISRS.
Resources such as reef fish, invertebrates and hard corals were documented. Damage assessment and comparisons with previous data for the sites were done.
The Rapid Assessments and Line Intercept Transect (LIT) data collected during survey found that the tsunami did not cause any structural damage to the coral reefs. However, there has been recent signs of resuspension and sedimentation of fine sediment (silt) on corals and there may have longer-term impacts on corals.
The tsunami wave which arrived at Langkawi about 12.20 pm , 26 December 2004 caused more damaged in the western part of the island. Due to the arrival at the lower diurnal high tide, damaged was caused by the interaction of the waves with the upper shore slope and tidal flats, and caused almost no damaged to the deeper seafloor where the coral reefs are located. Destruction of several coastal areas were a combined result of natural embayment and enhanced by man-made structures. Pulau Perak which rises almost vertically from a depth of 80 meters suffered no damage as there is no shallow shelf to allow the tsunami runup.
Further surveys and monitoring of damaged areas must be initiated to further understand the effects of big waves or tsunami to our coastal resources. Further funding, assistance from other institutions and expertise are being sought.
The Universiti Malaya Maritime Research Centre (UMMReC), WWF-Malaysia, Malaysian Society of Marine Sciences (MSMS), Universiti Kebangsaan Malaysia (UKM) and The World Fish Centre report to ReefBase.
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20 Jan 2005 |
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Coral reefs at five sites in south and southwest and one site in the east of Sri Lanka were
surveyed. Impact of the tsunami was highly varied, and the areas range from almost
unaffected to extremely damaged. Almost total destruction of a reef was seen at Dutch
Bay off Trincomalee town in eastern Sri Lanka. Most damage observed was mechanical,
with breakage of fragile corals, notably Acropora and Montipora spp., and larger massive
colonies toppling over. Impact on fish population seems correlated with reef damage,
most likely due to loss of fish habitat. The impact on larger reef fish species such as
groupers (Serranidae), snappers (Lujanidae), sweetlips (Haemulidae), emperors
(Lethrinidae) seemed low whilst smaller reef dwelling species such as damselfish
(Pomacentridae), butterflyfish (Chaetodontidae), gobies (Gobiidae) and wrasses
(Labridae) seemed high in damaged areas. A negative impact on the marine aquarium
fishery can be expected as a result of a reduction in the populations of smaller reef
dwelling species and loss of habitats. Some smothering has been observed, but it appears
primarily from resuspended marine sediments rather than terrigenous matter. Litter and
debris were abundant, although it is expected a lot of the debris from land has actually
been washed further out than the near-shore shallow reefs visited. Much of the rubble
formed after the coral mass mortality in 1998 has shifted and in some locations had
damaged live corals. Damage to seagrass beds was minor and where present mostly due
to shifting rubble. Hardly any uprooting was observed. Severe beach erosion was
observed both in the east and southwest, but impact was patchy. Severe damage on the
coast was observed where coral mining in the sea has been rampant. While there are signs
of absorbed impact and less damage in healthier vegetation and less disturbed
ecosystems, more information on how the tsunami has been shaped, deflected, weakened
or focused by bathymetry and shore profile is essential to draw more detailed
conclusions.
To access this report click here.
NARA Sri Lanka
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13 Jan 2005 |
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A Thai environmentalist says up to 200 volunteer divers are needed to help save coral reefs damaged by the December 26 tsunami. Thai oceanographer Sakanan Plathong says a preliminary survey shows 20 per cent of the reefs examined around the Similan Islands, an archipelago with world-class dive sites, have been destroyed.
But more than half of the reefs were knocked over during the tsunami, which churned up sand on the ocean floor, removing reef foundations and causing them to fall.
Mr Plathong says if divers manage to move fallen reefs back into an upright position within a month, the coral should survive and keep growing.
"Based on the initial survey, we estimate that up to 20 per cent of reefs [in the Similan Islands] were destroyed, but some 60 per cent of reefs fell over and need to be turned upright," he said.
On Tuesday, the United Nations Development Program (UNDP) said a disaster assessment mission found that on average just 5 per cent of the coral reefs along the coast and around the main tsunami affected islands had been damaged.
UNDP said the reefs were littered with potentially deadly debris and needed to be cleaned.
It also determined that future development of sustainable eco-tourism and the recovery of fishing communities will rely heavily on the restoration and protection of coral reefs.
Mr Plathong says he wants to recruit a group of 40 volunteer divers to lift fallen reefs into healthy positions this week. He hopes to eventually find another 150 volunteers.
Mr Plathong says if the fallen reefs are not moved, up to 40 per cent of the reefs could be destroyed. The survey, conducted last week, was sponsored by the Tourism Authority of Thailand, the National Park Department and dive associations in Phuket and Bangkok.
News article posted by AFP
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12 Jan 2005 |
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We (CORDIO/NARA) just came back from the field in the southwestern parts of SL where we covered five rather different sites. With no possibilities for manta tow (not many boats around and too shallow anyway) we tried to swim as much as possible. In summary:
- Damage to reefs was less than we all expected
- Damage was mostly mechanical, from rubble movement and breakage to boats or pieces of debris scouring the reef
- Damage was very patchy, with scars ranging from 1 to several meters across, but many times far apart. Where damage was observed it was frequently quite severe, e.g. Blocks of over 1 cubic meter turned over (mostly large colonies killed in 98)
- Damage to reefs was not very well correlated with damage on land – e.g. where the beach has visibly shifted, with plenty of erosion and the only thing left standing 500 inland is palms, there are large stands of undamaged Montipora less than half a meter under the water surface!
- Some large areas of Acropora have been overrun by rubble or suffered a lot of breakage, however with low mortality so far.
- Many live branching and massive colonies (up to 50 cm) have been turned over
- There was virtually no smothering from sediment, and turbidity was within normal limits
- Seagrasses (limited extent in the areas visited) seemed almost undamaged
- Rubble formed since 98 has shifted, sometimes in very large heaps
- There was plenty of debris in some places, including parts of boats, TVs and motorbikes, but again less than expected considering entire homes have been washed into the sea. It is possible the amount of water leaving land after the tsunami has been enough to carry most things over and beyond the shallow reefs near to the shore. we need to take a look at some deeper sites too.
- Fish seemed fine, some groups at some sites inexplicably absent (e.g. Wrasses on one or two reefs) but mostly no notable difference
- Some initial observations indicate worse damage on land where reefs have been mined and dynamited severely, and there are clear signs of absorbed impact and less damage in healthier vegetation. However, bathymetry and shore profile seem to have played a major role in impact on coast and land, which means very good data will be needed to make broad statements of the increased protection from healthier coastal ecosystems
Jerkar Tamelander
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