Surface water samples were collected in March 2009 from five selected stations (between 14° 46.851′ to 15° 26.851′ N and 42° 54.850′ to 42° 57.138′ E) in the coastal waters of the Yemeni Red Sea. The coastal waters of Al-Hodeidah is highly polluted and eutrophicated causing regular blooms of the dinoflagellate Noctiluca miliaris. The effect of pollution was reflected on phytoplankton abundance and species diversity in the sewage-fed area, north of Al-Hodeidah. The non-polluted coastal waters off Al-Saleef supported rich phytoplankton coupled with high species diversity and richness. No signs of temperature-influenced floral disturbance were noticed in the coastal waters which received thermal effluents from a steam power station at Ras Al-Katheeb.

Microalgae, blooms, pollution, species diversity