The effect of Urmia lake water withdrawal on Artemia urmiana population structure

Abstract

Introduction: Urmia lake is the largest natural habitat of a unique species of Artemia named Artemia urmiana. The lake has about 5000 km2 surface area when full, was recorded as biosphere reservoir by UNESCO in 1975. During last two decades, irregular development of agriculture (80%) and reduced precipitation (20%) have decreased its surface area to about 1661 km2 in November 2018. This had either economical, social, environmental and pathogenic impacts on local people around Urmia lake or on Artemia population structure and its cysts.
Materials & Methods: In this study, the effects of water withdrawal on the lake Artemia population was studied during 26 months period from April 2018 to May 2020. Eight sampling sites were selected in northern and southern parts of the lake. Samplings were performed monthly. Several physicochemical factors were determined such as water temperature, transparency, salinity, water level, Total Dissolved Solids (TDS) and Electric Conductivity (EC). Furthermore, Artemia life stages including Nauplius, meta Nauplius, juvenile and adult densities were determined. Statistical analysis was carried out by PAST software version 3.04.
Result: The results showed that the level of Lake Urmia shows seasonal fluctuations during a year. In 2017, no adult, meta, young, and Nauplius Artemia species were observed in Urmia Lake due to the too low water depth, but from the beginning of 2018, biological forms of Artemia were observed in the lake as the water rose.
Conclusion: The results showed that reduced water level imposed decreased Artemia biomass and cysts density.