Abstract
The present paper deals with the impact of “Tasman Spirit” oil spill on marine primary producers which occurred near Karachi Harbour on July, 27th, 2003. One year long study in the affected area revealed that phytoplanktons were seriously affected by oil spill but not so much seaweeds and mangroves. Very low species diversity of phytoplankton was observed as compared to previous observations in the same and adjacent areas but the standing crop (phytoplankton abundance) was not affected. Large size species dominated over the smaller ones indicating adjustment to presence of low density oil on the surface of water. Centric diatoms out numbered the pennate forms and armoured dinoflagellates the naked forms. The seaweeds were less affected. The attached forms on the buoys and floating forms survived the spill. However, those growing attached to small rocky patches on the beach died due to deposition of thick layer of crude oil, but later recovered soon after the oil spill was over along with barnacles. The mangroves do not grow in the affected area nor did the oil reach the adjacent mangrove stands, therefore, its effect on them could not be studied. However, the mangrove propagules and seedlings drifted in the area were all damaged and killed, thereby affecting the benthic food chain ad also the reproductive potential of the mangroves of the adjacent areas.
