Phylogeography and conservation genetics of Lake Qinghai scaleless carp Gymnocypris przewalskii

Distribution of microplastics in benthic sediments of Qinghai Lake on the Tibetan Plateau, China

Although several studies of microplastics (MPs) with size <5 mm in lake sediments focused on lakeshore areas, there have been no studies of distributions of MPs from lakeshores to the center of a lake. To test our hypothesis that MPs decrease from lakeshore to the center, a study was conducted on the largest brackish lake on the remote and high-altitude Tibetan Plateau, China. Abundances and characteristics of MPs in 14 samples of surface sediment collected from a river bay, a lake bay, and a lake central area were investigated. Distributions were influenced by river inflow, tourism, and minimal activity of humans, respectively around Qinghai Lake. The mean abundance of MPs in sediments of Qinghai Lake was 393 ± 457 items/kg, dry mass (dm). Based on the range of MP abundances in surface sediments of lakes worldwide, Qinghai Lake was classified as being moderately polluted with MPs. The dominant color, shape, size, and polymer type of MPs in sediments were transparent, fiber, 0.05-1 mm, and polypropylene, respectively. The river bay had a mean abundance of MPs two-fold greater than either the bay or central area of the lake. This indicates that the river catchment caused more pollution with MPs, while the central area of the lake was not a sink for MPs. Spatial trends of MPs in sediments from the shore to the center of the lake differed among areas, and were significantly related to wind, lake current, sedimentation rate, water- and sediment-properties, water depth, and proximity to land sources of MPs.

Diversity and distribution of fish in the Qilian Mountain Basin

The Qilian Mountain Basin, on the north-eastern edge of the Qinghai-Tibet Plateau (QTP), supports a high diversity of native and endemic fish. However, the detailed species inventory and distribution patterns concerning fish in the whole Basin remain unknown, which hinders the conservation of biodiversity and assessment of ecological health. We compiled a comprehensive species richness and distribution database of freshwater fish in the Qilian Mountain Basin, based on field investigations and exhaustive data collection from 50 rivers or lakes. Then, we elucidated a distribution pattern using clustering and ordination analyses based on a β_dissim matrix with species presence/absence data. A total of 79 freshwater fish species within eight orders, 17 families and 42 genera were recorded. The Qilian Mountain Basin could be grouped into six systems, which match the six Basins (i.e. Heihe River Basin, HHR; Qaidam Basin, QDM; Qinghai Lake Basin, QHL; Shule River Basin, SLR; Shiyang River Basin, SYR; Yellow River Basin, YR), based on the fish distribution pattern. Additionally, the spatial pattern of species distribution showed the distance decay of taxonomic similarity. Our results demonstrate that riverine connectivity resulting from historical processes plays a vital role in shaping the freshwater ichthyofauna of High Central Asia. These findings will be valuable for future systematic conservation of fish in the Qilian Mountain Basin.