ILOILO CITY, Iloilo, Philippines?The adverse effects of the massive oil spill that damaged the island-province of Guimaras still linger three years after the calamity, scientific studies showed.

Seven separate studies conducted mainly by scientists from the Institute of Environmental Science and Meteorology (IESM) of the University of the Philippines have bolstered conclusions that the Guimaras coastal environment has not completely healed, according to Dr. Lemuel Aragones, IESM associate professor and Guimaras consultant on environmental matters.

Aragones said the results of the studies on marine plants and animals in the affected areas showed abnormalities that were attributed mainly to the contamination from the oil spill.

The oil spill on August 11, 2006 was considered the country?s worst marine disaster and was triggered after the MT Solar 1, chartered by Petron Corp., sank in stormy seas southeast of Guimaras and spilled more than 2.1 million liters of bunker fuel oil it was transporting from Bataan to Zamboanga.

A study conducted since July last year by a team led by Dr. Rene Rollon showed that the populations of mangroves and seagrass have declined, especially in the southern part of the island, which was the worst affected by the oil spill.

Mollusks, including snails and slugs, have also declined in population and even disappeared in some areas, according to a study of Dr. Benjamin Vallejo Jr. conducted from 2007 to this year. This was also more evident in the southern part of Guimaras.

A main concern is the impact on the health of residents who have consumed oil-contaminated mollusks. A study conducted by a team headed by Dr. Flerida Cariño said there was an urgent need to test for harmful residues in the species consumed by the population in the affected areas.

Fishing has also declined in the five towns of Guimaras based on fish catch. While over-fishing could have caused this situation, the oil spill also contributed to the drop because the mangrove and sea grasses, which were important fish nursery and breeding grounds, were affected.

After three years, the economy of Guimaras has recovered, although it has not reached the pre-oil spill status.

A study headed by Rodelio Subade showed an increase in tourist arrivals in 2008 after registering drops from 2005 to 2007. But tourism revenues continued to decline, which can be attributed to the effects of the global financial crisis.

But most of the fishers surveyed in Subade?s study considered themselves worse off after the spill.

Many fishers have had alternative and supplementary livelihood as a coping strategy against the effects of the oil spill, with 13 percent engaging in farming, while another 13 percent turning to hog raising. Seven percent did carpentry and another 7 percent were into charcoal making.

Subade?s study said 14 percent of the fishermen sampled seemed to shift to another livelihood since they now spend more time on other sources of income, aside from fishing or fisheries-dependent livelihood.

This was confirmed by a separate three-year social and economic impact study conducted by Artchil Fernandez of the Central Philippine University Research Center.

Based on a sample of 309 households, Fernandez noted a drop in the mean monthly income of households from the pre-oil spill level of P9,661 pre-oil spill to P2,602 in September 2006 when a fishing ban was declared at the height of the calamity.

There was an increase in the mean monthly income to P6,727 in 2007 but it dropped again to P4,965 last year, which could also be explained by the impact of the rice crisis and global economic crisis.