The Effects of Water Withdrawal and A. urmiana on Phytoplankton Communities in Urmia Lake (Northwest, Iran)

Urmia Lake is one of the largest permanent hypersaline lakes in the world. The lake can be characterized as an oligotrophic lake concerning phytoplankton production. Due to agriculture development and low precipitation in recent years in Urmia Lake’s basin, the water level has declined as much as 4 m compared to 15 years ago. Water level decline influence the phytoplankton population through increased water salinity. Furthermore, Artemia urmiana Gunther as the major zooplankton in hypersaline lakes may affected on phytoplankton populations. Therefore, the purpose of the present study was evaluation how A. urmiana impact on the phytoplankton structure in Urmia lake. Eight stations were selected in south and north parts of the lake. Sampling were performed monthly during May 2018 to June 2020. Phytoplankton structure were analysed by inverted microscopy. Environmental parameters water temperature, pH, salinity, water level, Total Dissolved Solids (TDS), Electric conductivity (EC) were determined in each sampling. Seasonal fluctuations of algal abundance influence A. urmiana population in temperate large hypersaline lakes such as Urmia Lake. However, A. urmiana grazing pressure has significant effects on microalgal density. This study indicated that salinity is not increased directly by water level decline in Urmia Lake.