The relation between environmental parameters of Hormuzgan coastline in Persian Gulf and occurrence of the first harmful algal bloom of Cochlodinium polykrikoides (Gymnodiniaceae)



 Cochlodinium polykrikoides was
bloomed in the Persian Gulf for the first time in September 2008, started from
the Strait of Hormuz and then spread out towards the northern parts covering
most of the areas of the Gulf and lasted 8 months. In order to find out
environmental conditions during the bloom, a monthly sampling program was
carried out in seven surface stations in 2008-2009. At each station, three
samples (triplicates) were collected for phytoplankton analysis and also one
sample for environmental analyses, including salinity, chlorophyll a and nutrients.
Blooms of C. polykrikoides were observed with a
seawater temperature of 20.1 to 31.0 °C,
salinity 37.0-40.1 ppt and nutrient concentration ranges during the bloom and red tide were 0.064-0.707 mg/l nitrate + nitrite
and 0.001-1.66 mg/l phosphate, respectively. Maximum of C. polykrikoides abundance was measured 26 × 106 cells L-1 in
October 2008. Kruscal wallis test demonstrated a significant difference
in densities and chlorophyll-a in different months and seasons not in different
stations. This study showed increase of temperature (>31.0 °C) stopped bloom and red tide due to C.
polykrikoides in both the eastern and middle sampling stations but in the
western stations was determined decrease in nutrient amounts as the major
factor therefore increased nutrient of coastal waters, and environmental
conditions could have efficacy the occurrence of this dinoflagellate.