The study was carried out by 21 organisations including the International Union for Conservation of Nature, Pakistan's environmental agencies and a United Nations Environment Program (UNEP) expert.

The MV Tasman Spirit, managed by Greek company Polembros shipping, left Pakistan with its worst oil spill after splitting in two near its Arabian Sea port of Karachi on August 13, two weeks after it ran aground in shallow water.

The spill occurred in a rich tropical marine ecosystem area, home to extensive mangrove forests, Green and Olive Ridley sea turtles, dolphins, porpoises, beaked whales and several species of lizards and sea snakes.

The study warned that a seasonal change in wind direction could push the slick towards an arid mangrove ground.

"To the east of the grounding site are mangrove forests, the largest arid climate mangroves in the world ... Cessation of the monsoon season and changes in the wind direction may reach the areas that are not contaminated so far."

A study showed that the slick of 28,000-tonnes of oil had cut off vital sunlight to microbial phytoplankton -- organisms that provide a source of nourishment for many marine creatures.

"Observations showed that the phytoplankton groups usually inhabiting this area during the July-September or monsoon period were either absent or were rarely present," it said.

The study called for in-depth ecological studies to assess environmental damage and a socio-economic study to determine the damages that may be claimed.

Pakistani port authorities have already claimed one billion dollars in damages from the ship's owners.

TERRA.WIRE