Blooms of pollution indicator micro-alga (Synedra acus) in Northern Arabian Sea along Karachi, Pakistan

Abstract

Sewage water from Karachi and agricultural runoff from adjacent lands put lots of pollutants and nutrients in coastal waters of Karachi. Appearance of algal blooms in new geographical areas is being frequently reported and is attributed to increased marine pollution and climatic changes. For the current monitoring study, fortnightly phytoplankton samples were collected from polluted as well as cleaner localities along Karachi coast by using a phytoplankton net of 40μm mesh size. Standard parameters like Temperature, salinity, pH, rainfall were also recorded. Samples were analyzed qualitatively using phase-contrast microscope. Unusual, non-toxic and irregular blooms of a pollution indicator micro alga, Synedra acus has been frequently observed, suppressing existence of all other phytoplankton. This irregular appearance could not be related with any oceanographic parameters under study. These results reflect the presence of suspect factors (nutrients, environmental pollutants and climatic conditions) that might have governed synedra acus to bloom in this part of the northern Arabian Sea.