A historical data on the seasonal density variation of phytoplankton, zooplankton and Mnemiopsis leidyi in the South Caspian Sea

Abstract

The seasonal variation of phytoplankton, zooplankton (holoplankton) and ctenophore (Mnemiopsis leidyi) were investigated at eight transects from east to west in the South Caspian Sea. In spring (May), the most abundance of zooplankton was observed in the east area, where the temperature was over 19 °C, phytoplankton and M. leidyi were lower than 10 × 106 cells m-3 and 10 to 20 ind. m-3 respectively. In summer (August), the zooplankton and phytoplankton population increased by over 7000 ind. m-3 and over 50×106 cells m-3 in the east area respectively. When temperature was higher than 24 °C, M. leidyi increased in warm season (August) and also in November. Zooplankton and phytoplankton were elevated in winter and reached the maximum amount, while M. leidyi decreased sharply. In this study, we observed alterations in phytoplankton, zooplankton and M. leidyi in the South Caspian Sea from west to east along with the effects of temperature and seasonal variations on their distribution.

Keywords

• phytoplankton
• zooplankton
• mnemiopsis leidyi
• temperature
• caspian sea