A study on existence of dinoflagellates cysts and detection harmful kind of them in marine sediments of Hormozgan province

Some dinoflagellates produce cysts in harsh environmental condition, which sink on the surface of bottom sediments. These cysts have an important ecological role in distribution of dinoflagellates species, survival in bad condition and in genetic recombination (when they are formed in the process of sexual reproduction). To find dinoflagellate cysts in marine sediments of Hormozgan province, sampling was done in 27 stations in 2012. Samples were transported to laboratory under dark condition and then analyzed. The cyst of three orders of dinoflagellates and two genera of diatoms were identified in sediment samples. The observed dinoflagellate cysts were in the orders Peridiniales (59% or 53 cysts), Gonyaulacales (28% or 25 cysts) and Gymnodiniales (2% or 2 cysts ) respectively. The Peridiniales cyst were identified (19% or 17 cysts) at order level taxon, [37% or 33 cysts at genus level taxon (Protoperidinium 20% (or 18 cysts) and Scrippsiella 17% (or 15 cysts)] and 3% (or 3 cysts) at species level taxon (including Ensiculifera carinata, Scrippsiella irrigularis and Scrippsiella (cf. trochoidea)). The Gonyaulacales cysts were identified (22% or 20 cysts) at order level taxon, 5% or 4 cysts) were as genus Alexandrium and 1% or 1 cyst were as genus Alexandrium affine. The Gymnodiniales cysts were identified (2% or 2 cysts) at order level taxon. Moreover, 10 cysts (11%) were unknown dinoflagellates cysts which were mostly calcareous cysts. A significant numbers of diatoms cysts (belonging to genera Coscinodiscus and Surirella) were also identified in sediment samples.