Abstract: The present study investigated the morphology and taxonomy of marine centric diatom Chaetoceros lorenzianus from Karachi Harbor, Pakistan for the first time for the first time during the incident of Tasman Spirit Oil Spill (2003) in the area. Phytoplankton samples were collected from 5 different locations from the study area. Chaetoceros lorenzianus was found only at one station collected after Tasman Spirit Oil Spill. Moreover morphometric measurements of present record showed narrow range as compared to the records investigated by other workers.
Fig.: Chaetoceros lorenzianus (SEM, pair of sibling cells in girdle view): A, Scale bar: 10 µm; B, Sibling cells with long setae. Scale bar: 20 µm; C, Sibling valves with wide aperture. Scale bar: 5 µm.