A comprehensive monitoring project (2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013) provided data on hydrology, hydromorphology, climatology, water physico-chemistry, sedimentology, macroinvertebrate community and fish diversity in the Kharaa River basin in northern Mongolia, thus enabling, for the first time, a detailed characterization of the stream landscapes. Surface waters were categorized into separate "water bodies" according to their identifiable abiotic and biocoenotic features, subsequently creating the smallest management sub-units within the river basin. Following the approach of the European Water Framework Directive (EC-WFD), in order to obtain a good ecological status (GES), four clearly identifiable water bodies in the Kharaa River main channel and seven water bodies consisting of the basin's tributaries were delineated. The type-specific undisturbed reference state of various aquatic ecosystems was identified in the assessment and used to set standards for OPEN ACCESSWater 2015, 7 3167 restoration goals. With regards to water quality and quantity, the upper reaches of the Kharaa River basin in the Khentii Mountains were classified as having a "good" ecological and chemical status. Compared with these natural reference conditions in the upper reaches, the initial risk assessment identified several "hot spot" regions with impacted water bodies in the middle and lower basin. Subsequently, the affected water bodies are at risk of not obtaining a level of good ecological and/or chemical status for surface waters. Finally, a matrix of cause-response relationships and stressor complexes has been developed and is presented here. The applicability of management approaches is discussed to better foster the development of a sustainable river basin management plan. The application of natural references states offers a sound scientific base to assess the impact of anthropogenic activities across the Kharaa River basin.

Autecologic information of aquatic insects in the river systems under extreme continental climatic conditions is limited. Therefore, the objective of this study was to analyze life cycles, larval development, densities, microhabitat distribution, and secondary production of two sympatric burrowing mayfly species, Ephemera orientalis and Ephoron nigridorsum, in the Kharaa River, Northern Mongolia. Both species were typically distributed within the middle reaches of the focus river, displaying significant different larval densities across the three study sites. Four distinct microhabitats for E. orientalis and E. nigridorsum were identified. The preferred habitats of both species were substrates composed of rocks, cobbles, or coarse gravels with variable smaller mineral fractions of finer sandy, muddy, or organic substrates beside. Based on larval body size distribution and the emergence period, it was concluded that E. orientalis has a univoltine winter life cycle. The estimated annual production of larvae at two investigated sites in the middle stretch of the river in the year 2009 was 1.65 and 2.25 g DW m−2 year−1. Biomass was 294.8 and 490.3 mg DW m−2, and the annual production to biomass rate (P/B) was 4.5 and 5.6 year−1, respectively. In contrast, E. nigridorsum displayed a univoltine summer life cycle with a very likely egg diapause of approximately 8 months. Annual production estimates were 5.27 and 7.89 g DW m−2 year−1, biomass was 281.2 and 443.2 mg DW m−2; the annual P/B rates were 17.9 and 18.7 year−1 at the two sites reflecting the extremely shortened life cycle of this species. We conclude that the two sympatric species showed a difference in life cycles but no separation in habitat selection.

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Abstract:Mongolia is not only a water-scarce but also a data-scarce country with regard to environmental information. At the same time, regional effects of global climate change, major land use changes, a booming mining sector, and growing cities with insufficient and decaying water and wastewater infrastructures result in an increasingly unsustainable exploitation and contamination of ground and surface water resources putting at risk both aquatic ecosystems and human health. For the mesoscale (≈15,000 km 2 ) model region of the Kharaa River Basin (KRB), we investigated (1) the current state of aquatic ecosystems, water availability and quality; (2) past and expected future trends in these fields and OPEN ACCESSWater 2015, 7 3487 their drivers; (3) water governance structures and their recent reforms; and (4) technical and non-technical interventions as potential components of an integrated water resources management (IWRM). By now, the KRB is recognized as one of the most intensively studied river basins of the country, and considered a model region for science-based water resources management by the Mongolian government which recently adopted the IWRM concept in its National Water Program. Based on the scientific results and practical experiences from a six-year project in the KRB, the potentials and limitations of IWRM implementation under the conditions of data-scarcity are discussed.