Tsunami: the impacts on wildlife

Conor Jameson arrived in Seychelles ten days after the tsunami struck. He reports here on some of the environmental impacts felt in Seychelles and beyond, and on the reaction of wildlife, both before and after the waves came.

The Indian Ocean tsunami of 26 December 2004 was first and foremost a natural disaster resulting in human catastrophe. Almost 300,000 people were killed, and an estimated 5 million people were directly affected. The tsunami death toll was still mounting in the days leading up to my departure from the UK for Seychelles, and in the days after I arrived.

The destruction of the road bridge at Cascade, Mahe, was one of the most visible signs of the widespread infrastructural damage done to Seychelles by the December 26th tsunami © Conor Jameson

The infrastructure and environmental damage have been significant here. The United Nations Environment Programme estimates that the rehabilitation of areas that suffered high beach erosion could cost between US$ 500,000 and US$1.4 million. Having said that, you have only to recall the dreadful images from Sri Lanka and Aceh province in Indonesia to know that it could have been a whole lot worse. Of course I realise it will not feel that way to relatives and friends of those who died in Seychelles. In a sense we had a warning from the wild here; a ‘wake-up’ call, a reminder of the raw power of nature, and the fragility of our existence. The issue now is how we heed that warning.

Nature’s early warnings

 

 

One of the first things I saw here was the missing road-bridge at Roche Caiman, near the airport, completely destroyed by the tidal surges. Even now, six months on, this lingers as a vivid reminder of what a tsunami can do. However, the devastation is generally less apparent here than in other countries, as, mercifully, the waves did not reach these shores with the same height and ferocity as elsewhere.

I have been told many and varied stories of what happened on that fateful day. The waves reached here some seven hours after the first rupturing of the seabed off Indonesia that triggered an earthquake measuring an unprecedented 9.0 on the Richter Scale, and set in motion the deadly wave. It had therefore been possible for warnings of the wave’s approach to be broadcast to residents. However, the great majority of people I have spoken to were blissfully unaware of the impending tide, and others still did not know what had happened until told later in the day.

So, warnings were possible here, and were issued. But were there other warning signs that could have been picked up on? I have been intrigued by some of the reports I have heard of how animals and birds – wild and domestic – were behaving in the earlier part of that day.

Catherina Onezia works for Nature Seychelles as a Warden and Visitor Guide on Cousin Island Special Reserve. On December 26 she was enjoying a day off, and relaxing on the island. She received a call from her family in Mahe to alert her to the possibility of approaching danger. It was perhaps fortunate that she had little time to panic as, within minutes, the first wave had arrived. It was also extremely fortunate that the beach at Cousin rises quite steeply, and absorbed most of the impact.

‘On the morning of the tsunami, the wardens patrolling the beach did not see any of the island’s 28 Giant Tortoises,’ says Nature Seychelles CEO Nirmal Shah. ‘The larger Giant Tortoises on Cousin are usually found on the beach in the early morning, but on this day they were nowhere to be seen.

‘Cousin is considered to be the most important nesting ground in the Western Indian Ocean for Hawksbill Turtles’, he adds. ‘That day, at the peak of the nesting season, we would have expected to spot some turtles, but none came ashore. The seabirds were behaving strangely as well. Some hours before the tsunami hit Cousin, many of the ground-nesting seabirds took flight.’

Looking ahead


Scientists reported in March that the earthquake that triggered the tsunami has increased the chances another earthquake, citing previous examples of so-called ‘coupled’ earthquakes striking within a year of each other.
‘Many of us are brought up to understand hazard as whenever you've had your bit of bad luck it doesn't happen again,’ said John McCloskey of the University of Ulster, UK. ‘But one great indicator that you're going to have an earthquake is that you've just had one.’ (Source: The Guardian)

In March, an earthquake registering 6.0 on the Richter Scale occurred beneath the seabed off Aceh province in Indonesia, but did not cause a tsunami. One region at increased risk of a more powerful event is a 31-mile stretch of the undersea Sunda trench, next to the 745-mile long zone that ruptured on Boxing Day. Earthquakes in the Sunda trench triggered fatal tsunamis in 1833 and 1861. (Source: The Guardian)

So what if there is a next time? Maybe we will be alerted to any future tsunami danger by a combination of seismological expertise and satellite technology. Maybe there will be time to act. But will we all have somewhere to go, somewhere wave-proof to shelter? Will our environment be in optimal condition to stand up to it?

‘Buildings and other infrastructure need to be built in less vulnerable areas and to standards that will protect them and their inhabitants in the event of future tsunamis,’ said Klaus Toepfer, Executive Director of the UN Environment Programme, in the wake of the event. ‘This makes sense not only in respect to tsunamis but also with respect to storm surges, floods, hurricanes and other extreme weather events.’

We need to make sure we integrate ourselves with the environment, not work against it. Realistically, the most intact coastal environment in the world is not going to stop a 100-foot wave or save the people who have to live on and want to holiday at the coast. But what will save lives is advance warning, giving people time to get out of the way. Tsunami-resistant towers or similar might also help in situations where escape is not possible.

I have heard a saying in Seychelles: you should not saw the branch you are sitting on. The simple truth of this applies here, I think, in terms of treating well the ground that supports you. In the RSPB, the UK’s sister organisation of Nature Seychelles, we often use the ‘canary in the coalmine’ analogy. A canary is a little songbird very much like the Seychelles Toktok. In the past, canaries were lowered in cages into coal mines as a test for noxious gases. When the canary stops singing, you know you are in trouble too. Perhaps if we heed the warnings from nature more closely, we might read and respond to the signs from the canary before the singing stops.

Ghost Crabs were reported to evacuate beaches on Mahe in advance of the tsunami © Martin Harvey

Environmental impacts


It is believed that the areas of reclaimed land on the eastern coast of Mahe acted as a buffer zone to dissipate the worst impacts of the waves. A similar effect was recorded elsewhere in the affected areas of the Indian Ocean where intact and preserved mangrove forests absorbed the worst of the impacts.

Many coastal wetlands were inundated with seawater and wreckage, changes to coastlines and damage to sea defences. Full impacts have to be assessed using satellite imagery and field visits. Forests are likely to die off as a result of saltwater intrusion. Debris and silt can also damage mangroves, which are important as ‘nursery’ grounds for many marine fish species. Surveys by the World Conservation Union have revealed substantial damage to coral reefs in Seychelles as a result of the tsunami. The worst damage to carbonate coral reefs occurred in the northern and eastern islands, where in excess of 50% were badly affected. Southern and western islands suffered generally below 10% damage due to their sheltered location and granite substrate.

Coral reefs are particularly sensitive and vulnerable to siltation as a result of tidal surges and erosion from the land. Already badly affected by sea warming events in recent years, coral re-growth takes a long time, and setbacks like these can be locally disastrous.

BirdLife International reports

 

 

BirdLife reported that 27 Globally Threatened Bird species regularly occur in the regions and habitats of Asia affected by the tsunami. It is thought that few threatened species are likely to have been seriously affected by the direct effects, and no extinctions are predicted. More survey work is required to confirm this.

What did you see?


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