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In Lake Urmia area, northwestern Iran, parthenogenetic Artemia and the bisexual Artemia urmiana Günther 1890 are found to occupy different ecological niches determined by salinity. Given the fluctuations of the lake over geological times, we thus hypothesized that species identification of Artemia cysts, buried in the sediments, can provide information on lake conditions in the past. Therefore, encysted embryos of Artemia were recovered from lake sediments by augering at a site near the present shoreline. Cysts and associated plant remains from two studied levels yielded radiocarbon ages in the range 5,000-6,700 YBP. For determination of the type of Artemia, the constant synonym mutation in exon-7 of the Na/K ATPase gene was verified, and the diameter of the recovered cysts was compared with that of modern cysts from the Lake Urmia region. The results show that the cysts represent a parthenogenetic type of Artemia, whose cyst diameter is somewhat different from that of present-day local parthenogenetic Artemia. The present study firstly confirms the stability of DNA in ancient Artemia cysts for molecular analysis. Moreover, it suggests variation in Lake Urmia's conditions over time, and based on comparison with salinity preferences of contemporary Artemia populations, it more specifically suggests that Lake Urmia was a brackish lake dominated by a parthenogenetic Artemia population in the geological period sampled. It finally illustrates how, like in the study of freshwater propagule banks, paleogenetic analysis of Artemia DNA recovered from sediment cores can be used as a tool in the paleoecological study of generally highly fluctuating saline habitats. [ABSTRACT FROM AUTHOR]

The development of the molar surface in post-embryonic stages of Artemia urmiana and A. parthenogenetica was studied using scanning electron microscopy (SEM). Cysts of both species have been collected from Urmia Lake, Iran, and its adjacent lagoons and were hatched and raised under laboratory conditions. The cuticular teeth on the molar surface appeared in stage L9 in A. urmiana but at L3 in A. parthenogenetica. While the appearance and development of the molar surface of those species were different during metanaupliar and post-metanaupliar stages, the morphology was similar in post-larval stages. Thus, these species can be distinguished based on the morphology of the molar surface and by the appearance of adult characteristics, all readily apparent in early phases of their respective life cycles. [ABSTRACT FROM AUTHOR]