1. Broad-scale assessment of biodiversity is needed for detection of future changes across substantial regions of the Arctic. Presently, there are large data and information gaps in species composition and richness of the freshwater planktonic and meiobenthos communities of the Russian Arctic. Analysis of these data is very important for identifying the spatial distribution and temporal changes in species richness and diversity of rotifers, cladocerans, and copepods in the continental Russian Arctic.2. We investigated biogeographic patterns of freshwater plankton and meiobenthos from c. 67° to 73°N by analysing data over the period 1960-2017. These data include information on the composition of rotifers, cladocerans, and copepods obtained from planktonic and meiobenthic samples, as well as from subfossil remains in bottom sediments of seven regions from the Kola Peninsula in the west, to the Indigirka River Basin (east Siberia) in the east. 3. Total richness included 175 species comprised of 49 rotifer genera, 81 species from 40 cladoceran genera, and 101 species from 42 genera of calanoid, cyclopoid, and harpacticoid copepods. Longitudinal trends in rotifer and micro-crustacean diversity were revealed by change in species composition from Europe to eastern Siberia. The most common and widespread species were 19 ubiquitous taxa that included Kellicottia longispina (Rotifera), Chydorus sphaericus s. lat. (Cladocera), Heterocope borealis, Acanthocyclops vernalis, and Moraria duthiei (Copepoda). The highest number of rare species was recorded in the well-studied region of the Bolshezemelskaya tundra and in the Putorana Plateau.4. The total number of copepod and rotifer species in both Arctic lakes and ponds tended to increase with latitude. Relative species richness of copepods was positively associated with waterbody area, elevation, and precipitation, while relative species richness of cladocerans was positively related to temperature. This result is consistent with known thermophilic characteristics of cladocerans and the cold tolerance properties of copepods, with the former being dominant in shallow, warmer waterbodies of some western regions, and the latter being dominant in This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

We present the presence/absence species list (Table 1) of rotifer, cladoceran, and copepod (Calanoida, Harpacticoida, and Cyclopoida) fauna from seven Arctic regions of Russia (the Kola Peninsula, the Pechora River Delta, the Bolshezemelskaya tundra, the Polar Ural, the Putorana Plateau, the Lena River Delta, and the Indigirka River Basin) based on our own and literature data. Our own records were obtained by analyzing samples of zooplankton, meiobenthos, and two cores of bottom sediments (from the Kola Peninsula and the Bolshezemelskaya tundra lakes) that we collected once in July or August in 1992, 1995–2017. To supplement the list, we used relevant literature with periods of research from the 1960s to the 2010s. The list is almost identical to “Dataset 2: Zooplankton and Meiofauna across Arctic Regions of Russia”, which was analyzed but not published in [1] . The detailed analysis of this list revealed the specific composition of the aquatic fauna associated with the climatic and geographical factors [1] . The data provide information on the current state of biodiversity and species richness in Arctic fresh waters and can serve as the basis for monitoring these environments and predicting how they are likely to change in the future.

Поступила в редакцию 07.06.17 Фролова Лариса Александровна, кандидат биологических наук, доцент кафедры зоологии и общей биологии Казанский (Приволжский) федеральный университет ул. Кремлевская, д. 18, г. Казань,

This paper presents the results of the hydrochemical, hydrobiological, and paleolimnological studies of 17 Arctic lakes in the Pechora River delta. Water samples and surface sediments were collected during the 2020 summer expedition to the Nenets State Nature Reserve. Based on the chemical composition of their waters, the studied lakes belong to the chloride class, sodium group II. Overall, they are characterized by shallow depths typical of this region, low mineralization (below 200 mg/L) and water hardness, as well as high dissolved oxygen levels. To assess the ecological status of the lakes, cladocerans and their subfossil remains, which have been widely recognized as reliable indicators for tracking long-term changes in the development of freshwater ecosystems, were analyzed. A total of 23 cladoceran taxa were identified. The dominant species were Bosmina longispina (Leydig, 1860) and Chydorus cf. sphaericus (Müller, 1776)either of these species, often displacing each other, prevailed in the lakes. Other cladoceran species were low-abundant and found sporadically: Sida crystallina (Müller, 1776), Pleuroxus uncinatus (Baird, 1850), Coronatella rectangula (Sars, 1862), and Bythotrephes longimanus (Leydig, 1860). The study also reports the first finding of Rhynchotalona latens (Sarmaja-Korjonen, Hakojarvi and Korhola, 2000), a rare glacial relict species with a narrow distribution range, in this region of Russia. The zoogeographical analysis of the data obtained on the identified taxa showed that species typical of the Palearctic and Holarctic zones prevail in the cladoceran communities under study.

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