Introduction of non-native organisms in to the oceans through ballast water is widely recognized as an ecological concern. The International Maritime Organization (IMO) has come up with stringent regulations for the release of ballast water into oceans and expect ships to install ballast water treatment system (BWTS) to satisfy the standards set. IMO D-2 regulations and United States Coast Guard- Environmental Technology Verification program are quantitative of the plankton in the ballast water. Critical care is needed in sampling as inappropriate sample with wrong representation will yield false negative results. In this study the effect of stirring the water and a central perforated tube in the sampling tank on the count of plankton are evaluated. On mixing the contents of the tanks before recovering the samples, the phytoplankton count in the samples enhanced by ~20% while the zooplankton count got doubled. Moreover, the electric pump used had 12-15% mortality rate on the zooplankton (Artemia).

Ballast water, phytoplankton, Artemia, fluorescein diacetate, chloromethyl fluorescein diacetate.