Research Article: The Study on Dinocysts in the southern coastal waters of Caspian Sea

Algal cysts data has the potential to link with environmental parameters. In the pelagic zone, various factors such as sediment turbulence, the unusual rising of temperature, and nutrient can cause the entrance of surface sediment cysts into the water column. This paper aims to study dinocysts fluctuation in the southern part of the Caspian Sea. ۵۶۳ water samples were collected during a period from ۲۰۰۹ to ۲۰۱۳ as well as a year from ۲۰۱۸ to ۲۰۱۹. The dinocysts were identified by reliable references. Analysis of variance was used to determine significant differences in dinocysts abundance between the seasons, depths, layers, and regions. The microscopic results showed that the cysts of Dissodinium pseudolunula, Pyrocystis sp., and Gonyaulax polyedra were identified. The percentage of presence frequency of cysts in years of ۲۰۰۹-۲۰۱۰, ۲۰۱۱-۲۰۱۲, ۲۰۱۲-۲۰۱۳, and ۲۰۱۸-۲۰۱۹ were obtained ۴۶, ۴, ۹, and ۳۴%, respectively. The different stages of the Dissodinium pseudolunula and Pyrocystis sp. cysts formed the highest percent frequency of presence. The cyst of Gonyaulax polyedra (as an indicator of warm water) was increased in the water column compared to previous years, which probably is a reflection of increases in sea surface temperature in this region.

Keywords:

Dinocyst , Environmental indicators , Southern Caspian Sea , Iran