Coexistence of Sexual and Parthenogenetic Artemia Populations in Lake Urmia and Neighbouring Lagoons

Abstract

We studied the Artemia populations existing in Lake Urmia (north-western Iran), one of the largest habitats of Artemia in the world, in order to settle the long-standing controversy over the sexual status of the endemic Artemia populations. Experiments were carried out in the laboratory and in the field. Cysts, collected from different sites of the lake and peripheral lagoons, were hatched and cultured to adults in the laboratory. Adult sexual and parthenogenetic animals were isolated and newly hatched nauplii from them were cultured to maturity in different salinities, ranging from 15 -80 ppt. Survival levels and percentage of animals attaining adulthood were measured over a period of 30 days. In the field experiment, cysts taken from Lake Urmia were hatched and the resulting nauplii were inoculated into six earthen ponds (80 -140 ppt) constructed in the vicinity of the lake. Population composition in each pond was determined over a period of two years. Results indicated that both sexual and parthenogenetic Artemia coexist in Lake Urmia. While the lake itself is dominated by sexual Artemia, the asexual populations were found to be restricted to particular areas in or near the lake. Artemia appearing seasonally in the lagoons adjacent to the lake were exclusively parthenogenetic. Parthenogens could grow, mature and reproduce at very low salinities (15 -33 ppt), whereas higher salinities (above 50 ppt) were required for A. urmiana to attain sexual maturity. We consider salinity to be a major abiotic factor determining the distribution of these sexually different populations within and outside the lake.

Updating Geographic Distribution of Artemia urmiana Günther, 1890 (Branchiopoda: Anostraca) in Europe: An Integrated and Interdisciplinary Approach

“…urmiana co-exists with an Artemia parthenogenetic strain in Lake Urmia (AGH et al, 2007), but the similitude of the Lake Koyashskoe parthenogenetic strain with that of Lake Urmia is yet to be demonstrated.…”

Inbreeding and outbreeding depression in geographical parthenogensHeterocypris incongruensandEucypris virens(Crustacea: Ostracoda)

“…Fitness value is context dependent and both measurement of inbreeding depression and comparison between sexual and asexual lineages of the same species provided variable and sometimes contrasting results (Browne et al 1988;Barata et al 1996;Jokela et al 1997;Vrijenhoek & Pfeiler 1997;Negovetic et al 2001;Agh et al 2007;Wolinska & Lively 2008;Lehto & Haag 2010). Differences may have different explanations: methodological (comparing asexuals to their closest available sexual relatives not necessarily the ones from which they originated), or biological (parthenogens of intraspecific hydrid origin or asexual polyploids).…”

Comparison of the diameter of the frontal knobs in Artemia urmiana Günther, 1899 (Anostraca)

“…A. urmiana only occurs in Urmia Lake Baxevanis et al, 2006), and it can coexist there with A. parthenogenetica Bowen & Sterling, 1978(cf. Abatzopoulos et al, 2006Agh et al, 2007).…”