Diversity of the cladocerans (Crustacea, Branchiopoda) in the Republic of Tyva, Russian Federation

Biodiversity Data Journal 13: e163656 doi: 10.3897/BDJ.13.e163656 Data Paper Diversity of the cladocerans (Crustacea, Branchiopoda) in the Republic of Tyva, Russian Federation Nadezhda Kirova , Valeria Kirova , Alexey Kotov ‡ Tuvinian Institute for the Exploration of Natural Resources of the Siberian Branch of Russian Academy of Sciences, Kyzyl, Russia § National Research Nuclear University MEPhI, Moscow, Russia | A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, Moscow, Russia Corresponding author: Valeria Kirova ([email protected]) Academic editor: Sameer Padhye Received: 30 Jun 2025 | Accepted: 16 Sep 2025 | Published: 06 Oct 2025 Citation: Kirova N, Kirova V, Kotov A (2025) Diversity of the cladocerans (Crustacea, Branchiopoda) in the Republic of Tyva, Russian Federation. Biodiversity Data Journal 13: e163656. https://doi.org/10.3897/BDJ.13.e163656 Abstract Background The cladoceran fauna is well studied across the Palaearctic, but remains poorly known in the Republic of Tyva, Russia. Our database represents the results of the faunistic survey of the cladocerans in this region performed during almost 30 years (1993–2022). A total of 902 sites were investigated, most of them being located in mountain areas (49°45' – 53°46' North latitude and 88°49' – 98°56' East longitude). The dataset includes the cladocerans sampled from permanent and temporary waterbodies with varying depths, altitudes and salinity levels. Sampling was conducted using plankton nets and then samples were transported to the Tuvinian Institute for Exploration of Natural Resources of the Siberian Branch of RAS for identification and further examined at the A.N. Severtsov Institute of Ecology and Ecology RAS. Species were identified, based on recent monographs and juvenile specimens (sometimes indeterminable, based on morphological methods) were excluded from the dataset. The dataset was published as a ‡ § | © Kirova N et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Darwin Core Archive in GBIF. For each sampling event, the coordinates of the location, date and collector are recorded. New information The dataset contains information on zooplankton and microzoobenthos from numerous permanent and temporary waterbodies in the Republic of Tyva, Russian Federation. Previously, the region’s cladoceran fauna was poorly studied. Our core data table includes 3,599 records representing 76 species from 902 locations. The most species-rich families are Chydoridae (30 species from 17 genera) and Daphniidae (26 species from 5 genera). No invasive species were detected. The results of this study contribute to a deeper understanding of the plankton and microzoobenthos communities in the Central Asian mountain regions. Keywords field studies, occurrence, Palaearctic, species richness, benthos, zooplankton, biodiversity, GIB Introduction Water fleas (Crustacea, Cladocera) are common in various types of continental waterbodies and often dominate in freshwater zooplankton and microzoobenthos (Dumont and Negrea 2002). Moreover, they serve as model organisms in various branches of biological science (Lampert 2011, Smirnov 2017). However, their study is uneven across different regions of the world, including within the Palaearctic. The northern regions, particularly Europe and the Far East, are relatively well studied (Alonso 1996, Kotov et al. 2011, Korovchinsky et al. 2021a). In contrast, hydrobiologists have paid much less attention to the southern regions of Central Asia, such as the Middle Asian countries, Mongolia and southern Siberia (Alonso 2010, Dadykin et al. 2024). These regions are home to several major mountain ranges, including the Pamirs, Tien Shan and Sayans. Mountain ecosystems are known for their unique fauna, often containing local endemics. During the Pleistocene glacial cycles, several refugia for microscopic freshwater organisms were located here (Hewitt 2000, Zuykova et al. 2019). Despite this, relatively few studies on Cladocera focus on these areas. The Republic of Tyva is amongst such underexplored regions. The first records of crustaceans from this region date back to the early 20 century (Sars 1903). During the Soviet era, a number of publications related to fisheries in Tyva appeared (Greze and Greze 1958, Gundrizer 1975). th 2Kirova N et al A systematic study of Tuvinian water fleas began in the 1990s. Since then, several papers have been published (Kotov 1999, Kirova 2021, Sinev et al. 2021, Kirova and Oydup 2022). However, only a small proportion of the region’s waterbodies have been sampled so far. A detailed study of the cladoceran fauna in Tyva is urgently needed and a formal inventory is the first step in this direction. General description Purpose:The aim of this paper was to describe the current cladoceran fauna of the Republic of Tyva, based on a recently published dataset, which contains results of the survey in this region performed during almost 30 years (1993–2022) (Kirova et al. 2024). Project description Title:Diversity of the cladocerans (Crustacea, Branchiopoda) in the Republic of Tyva, Russian Federation Personnel:Nadezhda A. Kirova, Valeria O. Kirova, Alexey A. Kotov Study area description:The studies encompassed the Republic of Tyva (Russian Federation), covering the basins of the Yenisey River, the Great Lakes Depression and the Selenga River (49°45' – 53°46' North latitude and 88°49' – 98°56' East longitude) (Figs 1, 2). Figure 1. Location scheme (49°45' – 53°46' North latitude and 88°49' – 98°56' East longitude) of the studied waterbodies in the Republic of Tuva.  Diversity of the cladocerans (Crustacea, Branchiopoda) in the Republic ... 3 Sampling methods Description:The presented dataset on the taxonomic composition and abundance of cladocerans in the Republic of Tyva is based on the authors' original samples. The species list includes only native species; no invasive species were recorded. Sampling description:All samples were collected using plankton nets from the shore and from a boat in the case of large lakes and reservoirs (Fig. 3). Species identification was carried out, based on the latest guides to cladocerans (Korovchinsky et al. 2021a). Species lists were checked against GBIF Backbone Taxonomy (2021) (GBIF Secretariat 2023). Quality control:Species identification was primarily based on the latest monographs, developed with the participation of A.A. Kotov (Kotov et al. 2010, Korovchinsky et al. 2021a). Juvenile specimens were identified to the genus level and excluded from this dataset. In the course of our previous studies on the cladocerans of Tyva, several papers were published in international journals (Kotov 1999, Kirova 2021, Sinev et al. 2021, Kirova and Oydup 2022), reporting several new records for Russia. The taxonomic nomenclature is given in accordance with the taxonomic checklist of GBIF Backbone Taxonomy (GBIF Secretariat 2023); scientific names were further validated using the GBIF species matching tool. To facilitate publication on the GBIF network, the records were formatted in accordance with Darwin Core specifications (Wieczorek et al. 2012). Step description:Zooplankton samples were collected by filtering water through a plankton net, either in the sublittoral zone or open water from a boat. The samples were Figure 2. Layout of the studied waterbodies in the Republic of Tuva.  4Kirova N et al concentrated to 100 ml and fixed in a 4% formalin solution according to conventional method (Korovchinsky et al. 2021a). Zooplankton specimens were initially examined using a Leica MZ7.5 stereoscopic microscope (Leica Microsystems, Germany). Individual specimens were picked with a plastic pipette, placed in drops of a glycerol-water solution (1:1) and analysed using an Figure 3. Waterbodies of the Republic of Tyva, Russian Federation. A Lake Chagytay, Ulug-Khem depression; B Lake Sut-Khol, Alash Plateau; C Lake Azas, Todzhin depression; D former sand quarry near River Ulug-O, Todzha; E Biy-Khem basin; Sayano-Shushenskoe Reservoir; F River Durgen, mid-stream, Ulug-Khem depression; G River Mezhegey, Ulug-Khem depression; H River Tapsa floodplain, Biy-Khem basin. Photos by N.A. Kirova.  Diversity of the cladocerans (Crustacea, Branchiopoda) in the Republic ... 5 Olympus CX41 light microscope (Olympus Corporation, Japan). After processing, all samples were stored in the first author’s personal collection for further taxonomic and morphological studies. Initially, all records were incorporated into the last author’s local database in Microsoft Access. They were then prepared for import to GBIF using Microsoft Excel. The dataset field names were chosen according to Darwin Core standards (Wieczorek et al. 2012). We have also calculated the rate of: 1) benthic-phytophylous taxa (Suppl. material 1) living in the macroptype thickets in the littoral zone, on the bottom or in the upper layer of bottom sediments (it is difficult to distinguish truly phytophylous and bottom species in case of the cladocerans, as many taxa could live in both biotopes); 2) planktonic taxa living in the water column both in pelagic or sublittoral zone; 3) neustonic taxa spending much time attached to the bottom side of the water surface film. Information on the mode of life was extracted from previously published data (Korovchinsky et al. 2021b). Unfortunately, to date, a zoogeographic analysis of our data seems to be premature as many revealed taxa represent, in reality, groups of non-revised congener species with presumably different geographic ranges and ecological preferences (Korovchinsky et al. 2021b). The rate of benthic-phytophylous/planktonic/neustonic taxa was 56.6/38.1/5.3 (in %) for the species and 60.0/38.4/6.6 for records; therefore, benthic-phytophylous taxa dominated in Tuva waterbodies (Fig. 4) similarly to other waterbodies of Eurasia (Kotov et al. 2013, Korovchinsky et al. 2021b. Eurybiotic benthic-phytophylous taxon Chydorus sphaericus was found in most waterbodies, while planktonic Daphnia longispina was very common in fresh waterbodies and Moina mongolica dominated in brackish waterbodies. Geographic coverage Description:The Republic of Tyva is located in the middle of the Asian continent, occupying a large territory (ca. 168,600 km ) in southern Siberia and bordering Mongolia in the south. Landscapes of the Republic are very diverse,including mountain ridges and plateaus (mountains occupy 82% of the territory) and intermountain river valleys (Sidorenko 1966). The main features of the landscape were formed there during the Caenozoic (Bazarov 1986). In general, Tyva is ringed by high mountains (the Sayan Mountains in the north and the East Siberian Mountains in the east), with the flat Tuva Basin located in its central and southern parts. The climate is sharply continental. Winters are long, frosty and windless; springs are short, clear, windy and dry; summers are short, cool and dry in the mountains, but hot and 2 6Kirova N et al dry in the lowlands; autumns are dry and sunny, with occasional periods of heat. Precipitation in the lowlands ranges from approximately 150 to 400 mm per year, while in mountainous areas, it varies from 400–600 mm to 800–1000 mm per year, with maximum precipitation occurring in summer. The frost-free period lasts 90–116 days and the growing season spans 150–160 days. Permafrost is common throughout the territory (Efimtsev 1957, Bakhtin 1968). Diverse latitudes and climates create a variety of aquatic environments, ranging from high-altitude mountain lakes to "lowland" rivers and temporary waterbodies at approximately 1000 m a.s.l. Most of the Republic of Tyva lies within the Ulug Khem (Yenisey River) Basin, which is formed by the confluence of the Biy Khem (Large Yenisey) and Kaa Khem (Little Yenisey). A smaller portion of the territory belongs to the endorheic Mongolian Great Lakes Depression, while a minor area is part of the Selenga River Basin. Approximately 6,700 lakes are recorded within the Republic. The diverse landscape and climatic conditions contribute to the seasonal hydrological dynamics across different types of waterbodies (Klopova 1957, Arakchaa and Kurbatskaya 1998). Coordinates:49°45' – 53°46' North latitude; 88°49' – 98°56' East longitude. Figure 4. Numbers of each taxon records in 902 locations in the Republic of Tuva: benthic-phytophylous (red), planktonic (blue) and neustonic (green) taxa.  Diversity of the cladocerans (Crustacea, Branchiopoda) in the Republic ... 7 Taxonomic coverage Description:The dataset contains information on 76 species from 35 genera documented in the Republic of Tuva, with each record georeferenced. The following families are represented: Bosminidae, Cercopagididae, Chydoridae, Daphniidae, Eurycercidae, Holopedidae, Ilyocryptidae, Leptodoridae, Macrothricidae, Moinidae, Polyphemidae and Sididae. The dataset comprises a total of 3,599 records (Dadykin et al. 2024). The umber of revealed species represents 27% of the total number of species in the whole of Northern Eurasia (76 vs. 287, see Korovchinsky et al. (2021a)) and 28% of the species in the Palaearctic (Kotov et al. 2013). This number is comparable with that for Tajikistan (75, see Dadykin et al. (2024)) which also includes mountain and lowland portions. Fortunately, no non-indigenous taxa were identified. However, it should be noted that only a morphological approach was used and molecular methods could potentially detect such taxa within cryptic species complexes. Temporal coverage Notes:The presented dataset contains information on the diversity of cladocerans in the Republic of Tyva during the vegetation seasons of 1993 to 2022 in the Yenisey and Selenga River Basins and in the Depression of Great Mongolian Lakes. Collection data Collection name:The zooplankton collections of the Tuvinian Institute for the Exploration of Natural Resources of the Siberian Branch of Russian Academy of Sciences and the collection of the laboratory for aquatic ecology and invasions of A.N. Severtsov Institute of Ecology and Ecology of RAS. Usage licence Usage licence:Other IP rights notes: CC BY 4.0 Data resources Data package title:Diversity of the cladocerans (Crustacea, Branchiopoda) in the Republic of Tyva, Russian Federation Resource link: https://doi.org/10.15468/ns642b 8Kirova N et al Alternative identifiers: https://www.gbif.org/dataset/fca47d2f-0188-4c55-b46a-20aa0 5ed76c7 Number of data sets:1 Data set name:Diversity of the cladocerans (Crustacea, Branchiopoda) in Republic of Tyva, Russian Federation Download URL: https://api.gbif.org/v1/occurrence/download/request/0080518-2505 25065834625.zip Data format:Darwin Core Description: The dataset provides information on 76 species from 35 genera found in the Republic of Tuva, each documented with corresponding geographic coordinates (Kirova et al. 2024). These taxa belong to the following families: Bosminidae (2 species from 1 genus), Cercopagididae (1 species from 1 genus), Chydoridae (30 species from 17 genera), Daphniidae (26 species from 5 genera), Eurycercidae (1 species from 1 genus), Holopedidae (1 species from 1 genus), Ilyocryptidae (2 species from 1 genus), Leptodoridae (1 species from 1 genus), Macrothricidae (5 species from 3 genera), Moinidae (5 species from 1 genus), Polyphemidae (1 species from 1 genus) and Sididae (2 species from 2 genera). The dataset comprises 3,599 records. Each observation in the dataset includes basic metadata: location (latitude and longitude), observation date, observer name and identifier. Coordinates were recorded in situ using a Garmin eTrex 32x (Garmin Ltd., USA). Column label Column description type The nature or genre of the resource. eventID An identifier for the set of information associated with an event (something that occurs at a place and time). eventDate The date when material from the trap was collected or the range of dates during which the trap collected material. basisOfRecord The specific nature of the data record. occurrenceID An identifier for the Occurrence (as opposed to a particular digital record of the occurrence). continent The name of the continent in which the location occurs. country Country of the sampling site. countryCode The standard code for the country in which the Location occurs. stateProvince The name of the next smaller administrative region than country (state, province, canton, department, region etc.) in which the location occurs. higherGeography The name of geographic sub-regions. Diversity of the cladocerans (Crustacea, Branchiopoda) in the Republic ... 9