Seasonality of the bloom-forming heterotrophic dinoflagellate Noctiluca scintillans in the Gulf of Oman in relation to environmental conditions

The Gulf of Oman is a semi-enclosed Gulf under the influence of the Arabian Gulf in the North, the Arabian Sea in the south, and experiences the reversal of the seasonal monsoons. Despite the increase in fish mortality during recent years, there are few short- term studies investigating the causative agents for such effects. Previous studies have occasionally linked the bloom-forming dinoflagellate Noctiluca scintillans to fish kill in the Gulf of Oman. In order to understand the mechanistic processes that are involved in the bloom formation of Noctiluca scintillans, hydrographic, biological and meteorological parameters have been investigated at two stations, the Fahal Island (F) and the Offshore (OFF) in the coastal water of Muscat from July 2005 to February 2006. The preliminary results suggest that Noctiluca scintillans abundance in the Gulf of Oman persists throughout the year but at different depths with bloom formation starting from early winter and reach a maximum during the spring period. The bloom formation is likely attributed to changes in hydrographic and biological factors and their spatial distribution is due to wind intensity and direction.