Zooplankton standing stock off south of Great Nicobar Island during an oil spill incident and after

Abstract

An intensive sampling was carried out in the oil plume area between lat. 5 degrees 56' to 6 degrees 42'N and long. 93 degrees 10' to 94 degrees 30'E. For a comparative study, samples were also collected along the international oil tanker route along the 5 degrees 45'N latitude from 82 degrees E to 92 degrees E longitude. The biomass values noted tow weeks after the oil spill along the oil tanker route (negligible to 50 ml/100 m sup(3)) and in the vicinity of the island (2.45 to 70 ml/100 m sup(3)) suggested that the standing stock was not much affected as there was no trace of any oil in these areas after two weeks of the accident. This may be due to the natural dispersion and disintegration of oil, associated with the local winds and south-westerly currents. Zooplankton biomass was relatively high 8 months after the oil spill and it ranged from 5.62 to 72.3 ml/100 m sup(3) along the tanker route and 2.32 to 83.3 ml/100 m sup(3) at the oil spilled site. This may either be due to the full recovery of the environment or the normal seasonal variations. Later observations did not show any eventual damage to the faune and flora as expected.