Interpreting noble-gas concentrations as proxies for salinity and temperature in the world’s largest soda lake (Lake Van, Turkey)

AbstractSoda lakes are saline and alkaline ecosystems that are considered to have existed since the first geological records of the world. These lakes support the growth of ecologically and economically important microorganisms due to their unique geochemistry. Microbiota members of lakes are valuable models to study the link between community structure and abiotic parameters such as pH and salinity. Lake Van is the largest endroheic lake and in this study, bacterial diversity of lake water, sediment, and pearl mullet (inci kefali; Alburnus tarichi), an endemic species of fish which are collected from different points of the lake, are studied directly and investigated meticulously using a metabarcoding approach after pre-enrichment. Bacterial community structures were identified using Next Generation Sequencing of the 16S rRNA gene. The analysis revealed that the samples of Lake Van contain high level of bacterial diversity. Direct water samples were dominated by Proteobacteria, Cyanobacteria, and Bacteroidota, on the other hand, pre-enriched water samples were dominated by Proteobacteria and Firmicutes at phylum-level. In direct sediment samples Proteobacteria, whereas in pre-enriched sediment samples Firmicutes and Proteobacteria were determined at highest level. Pre-enriched fish samples were dominated by Proteobacteria and Firmicutes at phylum-level. In this study, microbiota members of Lake Van were identified by taxonomic analysis.

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A new species of Enchytraeus (Enchytraeidae, Oligochaeta) from the profundal of Lake Van, the world's largest soda Lake (Turkey, East Anatolia)

Zootaxa ◽

10.11646/zootaxa.4382.2.8 ◽

2018 ◽

Vol 4382 (2) ◽

pp. 367 ◽

Cited By ~ 1

Author(s):

NAİME ARSLAN ◽

TARMO TIMM ◽

VERÓNICA ROJO ◽

ANTÓN VIZCAÍNO ◽

RÜDIGER M. SCHMELZ

Keyword(s):

New Species ◽

Small Body ◽

Local Population ◽

Soda Lake ◽

Benthic Invertebrate ◽

Coi Gene ◽

Similar Species ◽

Lake Van ◽

Gene Trees ◽

Sampling Campaign

Enchytraeus polatdemiri sp. nov. (Enchytaeidae, Oligochaeta) was discovered in the framework of a sampling campaign of the benthic invertebrate fauna of the hyperalkaline Lake Van in Eastern Anatolia, Turkey, the third-largest closed lake and the largest soda lake on Earth. It was the only oligochaete species found in all samples. DNA sequencing included a fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene, and a fragment of the nuclear histone 3 (H3) gene. For comparison, specimens from laboratory cultures of E. albidus Henle, 1837, a widespread and morphologically similar species, were sequenced as well. The new species differs from E. albidus in comparatively small body size, 2 or 3 chaetae per bundle, saddle-shaped clitellum, absence of a copulatory field between the male pores and vasa deferentia usually not extending beyond the clitellum. The individual gene trees of COI and H3, as well as the combined phylogenetic analysis of both trees, recovered Enchytraeus polatdemiri sp. nov. as a monophyletic group within the genus Enchytraeus, closely related to E. albidus, but with an average p-distance for COI of 14.5 %. E. polatdemiri sp. nov. may have evolved from a local population of Enchytraeus albidus, a species well-adapted to changing salinity conditions, or from a common ancestor into an extremophile species that dwells and reproduces in the profundal of a strongly alkaline soda lake.

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The discovery of a microbialite-associated freshwater fish in the world’s largest saline soda lake, Lake Van (Turkey)

Zoosystematics and Evolution ◽

10.3897/zse.97.62120 ◽

2021 ◽

Vol 97 (1) ◽

pp. 181-189

Author(s):

Mustafa Akkuş ◽

Mustafa Sarı ◽

F. Güler Ekmekçi ◽

Baran Yoğurtçuoğlu

Keyword(s):

Morphological Difference ◽

Sequence Divergence ◽

Soda Lake ◽

Fish Population ◽

Stream Fishes ◽

Lake Van ◽

Undescribed Species ◽

Morphological Examination ◽

Mtdna Coi ◽

Endorheic Basin

Lake Van is the largest saline soda lake in the world and one of the world’s few endorheic lakes of greater than 3,000 km2 surface area. Despite its huge size, no fish species have so far been known to permanently occur in this lake due to its extreme environmental conditions. Here, we report the discovery of a fish population that permanently inhabits some of the unique microbialites of the lake, at a maximum depth of 13 m and about 500 m offshore. We tested whether this is an undescribed species or a new occurrence of a known species. A molecular and morphological examination showed that the newly discovered fish represents an isolated population of Oxynoemacheilus ercisianus, the only nemacheilid loach native to the freshwater tributaries of the Lake Van endorheic basin. Our further hypotheses on the prediction that (a) stream fishes would have a more anterior placement of fins than lake fishes were supported; but, that (b) stream fishes would be more slender bodied than their lake conspecifics was not supported. The lake dwelling population also shows very small sequence divergence (0.5% K2P distance) to its stream dwelling conspecific in the mtDNA-COI barcode region. The notable morphological difference with minute molecular divergence implies that the newly discovered population might have lost its link to freshwater during desiccation and transgressional phases of the Lake Van, and has adapted to a life on the microbialites.

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