The Hindu : Kerala News : Scientists divided over ecological impact

Online edition of India's National Newspaper
Thursday, Dec 30, 2004

Kerala

Kerala

Scientists divided over ecological impact

By K.S. Sudhi

KOCHI, DEC. 29. The killer waves have left the scientific community, leave alone the hapless victims, clueless on its impact on marine environment and bioresources.

While a section of the marine scientists argue that the tsunami have passed through the water mass without causing much damage to its bioresources, some others are of the view that it would have done much damage to them. However, all of them agree that the issue is being addressed by the scientific community of the country for the first time and that no background information is available to verify their respective theories.

As there is no evidence of the sea bottom being churned up by the tsunami, there is nothing to suggest that the recent earthquake and the tsunami have caused damage to the marine environment, says Mohan Joseph Modayil, director of the Central Marine Fisheries Research Institute (CMFRI) here.

If the sea bottom was churned by the earthquake, there would have been turbidity in the seawater and dead organisms would have surfaced by now. The absence of any debris in the wave-hit areas suggests that no serious damage has been done to the marine environment, he says.

But, E.G. Silas, former director of the CMFRI and renowned fisheries scientist, refuses to fully subscribe to the views of Mr. Modayil. According to him, scientists should look into the issue. He fears that the benthic or sea-bottom community could have been affected by the churning following the earthquake, which in turn would affect marine organisms like prawns.

It has been reported that in many places the ocean receded to even one kilometre on the eventful days, exposing the ocean bed. In Nicobar, the whole sea receded and came back with violent energy. The impact of the killer waves would be more on the inshore benthic community, he says.

Algae bloom possible

Oceanographers of the National Institute of Oceanography (NIO), Kochi, are of the view that barring the physical damage caused, tsunamis have not affected the marine ecosystem of the region.

They allay fears that the productivity of the sea and fishing activities would be hit by the tsunami. However, there is the possibility of an algae bloom as large quantities of minerals and nutrients might have reached the sea by way of leeching from the land, says K.K.C. Nair, scientist-in-charge of the Kochi centre of the NIO.

A causality of the tsunami onslaught would be the saline water intrusion into freshwater ponds and wells in areas like Vypeen and destruction of freshwater aqua farms, he says.

He calls for putting up reinforced seawalls in areas of possible tidal attack and creation of greenbelts behind the seawalls by growing mangroves. The impact of huge waves has been absorbed by the mangrove vegetation in the Vypeen area without which the island would have been washed away, he says.

Oxygen depletion

B. Madhusoodana Kurup of the School of Industrial Fisheries of the Cochin University of Science and Technology is of the view that the seabed might have been stirred up by the earthquake, resulting in the depletion of dissolved oxygen in the water. Fish mortality will not be there as they would swim to areas that are less turbid. However, there is the possibility of a total ecosystem change in the sea following the earthquake and the tsunami, he says.

The putrification of dead bodies in the sea will also lead to depletion of dissolved oxygen. There is also the possibility of a red tide-like incident taking place in the sea, he says.

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