A three-year record of red tides in Chabahar coastal waters (North of Gulf of Oman)

Seven phytoplankton species (Alexandrium sp., Prorocentrum micans, Cochlodinium (aka Margalefidinium) polykrikoides, Mesodinium rubrum, Akashiwo sanguinea, Gonyaulax
polygramma, Ceratium sp.) were found as the main cause of Harmful algal blooms (HABs) in a three-year record of red tides in Chabahar coastal waters (North of Gulf of Oman). Autumnal blooms of Gonyaulax polygramma and Prorocentrum micans are reported for the first time in the region. The most frequent bloom events were caused by Akashiwo sanguinea (i.e. 4 times) and Mesodinium rubrum (i.e. 3 times). The highest observed density was at Oct 2017 caused by Akashiwo sanguinea (15.3*106/ litre). The recorded temperature range was from 24.4 to 31.5°C and the DO ranged widely from 3.9 to 11.2 mg/liter. In conclusion, HABs occurrences are not associated with the expansion of one particular species but with multiple taxa and there is aد suitable environmental condition for HABs in the autumn and spring in the region.