Bloom occurrence and phylogeny of Gonyaulax polygramma (Dinophyceae) isolated from south east coast of Iran (Oman Sea)

Harmful blooms of dinoflagellates in southeastern Iran have been increased in recent years. A dense bloom of dinoflagellate species occurred in the Ramin coast after South West Monsoon (SWM) in southeastern Iran. In order to molecular and morphological species identification of the bloom, sampling was done in October 2017, in the phycolab; the dominant bloom-forming species was isolated into a unialgal culture and kept under 12L: 12D and 25°C. The result showed the dominant bloom-forming species belonged to the genus Gonyaulax that co-occurred with the Levanderina fissa, Scrippsiella trochoidea, and Prorocentrum micans species with the lower density. Phytoplankton density was 15×106 cells l-1. Morphological features and nucleotide sequences of the species were similar to Gonyaulax polygramma with 97% bootstrap support. This is the first record of a red tide incident triggered by G. polygramma in the northern Oman Sea, which was associated with changed water color and foam formation. This species is cosmopolitan in coastal waters, which can form harmful algal blooms (HABs).