The Hindu , 02 January 2006

Scientists divided over ecological impact

KOCHI, JAN. 1. The killer waves that hit the State on December 26 have left the scientific community clueless on its impact on marine environment and bio-resources.

While a section of the marine scientists argue that the tsunami has passed through the water mass without causing much damage to its bio-resources, some others are of the view that it would have done much damage to them. They say that issue is being addressed by the Indian scientific community 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.

Absence of debris

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, differs on the issue. 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 such as 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 had been absorbed by the mangrove vegetation in the Vypeen area without which the island would have been washed away, he says.