Chydorus Sphaericus Research Articles

Interactive effects shape the dynamics of Chydorus sphaericus (O.F. Müller, 1776) population in a shallow eutrophic lake

Interactive effects shape the dynamics of Chydorus sphaericus (O.F. Müller, 1776) population in a shallow eutrophic lake

Embryogeny of Pleuroxus aduncus (Jurine, 1820) and Chydorus sphaericus S. Lato (Müller, 1776) indicate on conservative instars development among family Chydoridae (Crustacea, Cladocera, Anomopoda)

The embryogenesis of the family Chydoridae, in which 60 genera are recognized, is poorly understood compared to that of the family Daphniidae, which contains only five genera. Therefore, studies of the evolution of Anomopoda suffer from a paucity of data on chydorids. Here, I studied the embryogenesis of two cladocerans, Pleuroxus aduncus and Chydorus sphaericus s. lato of the Chydoridae, using scanning electron microscopy. Various ontogenetic stages were compared with those of Dunhevedia crassa, as described by Kotov etal. (2013). I confirmed an evolutionarily conserved pattern of instar development among these three species. Cladoceran families were analysed in relation to their numbers of thoracopods, an important taxonomic trait, and the numbers of thoracopods in ancestral states were proposed. Chydorus sphaericus s. lato lacks six thoracopods in the adult stage, but this study revealed their brief presence during embryonic development.

Işıklı Gölü (Çivril-Denizli/Türkiye) zooplankton dağılımı ve kompozisyonunun trofik durum değerlendirmesi ile araştırılması

In this study, the zooplankton distribution and composition of Işıklı Lake, located in the Inner West Anatolia region of Türkiye, were examined monthly between 2003-2005. Zooplankton samples were collected with Hydro-Bios plankton net (55 µm) at the surface and fixed in formaldehyde (4 %). Physiological parameters such as surface water temperature, pH, dissolved oxygen, and conductivity were also measured. Also, the frequency index (F %) and the Brachionus / Trichocerca (QB/T) were determined to assess the trophic composition of Lake Işıklı. A total of 49 species have been identified. Rotifera (55 %), Cladocera (27 %) and Copepoda (18%) were represented by the species. The maximum species was found in May 2004 (21 species), while the minimum was found in October 2003 (5 species). Asplanchna priodonta, Keratella cochlearis, Keratella tecta, Polyarthra dolichoptera, Synchaeta pectinata, Bosmina longirostris and Chydorus sphaericus are common species in the lake. The water temperature varied between 3.9-24.6 °C; pH ranged from 8.1 to 8.8; the electrical conductivity ranged from 341 µS/cm to 434 µS/cm; the dissolved oxygen values changed from 5.8 mg/L to 11.1 mg/L. According to the frequency index (F %), the most dominant species are B. longirostris (74 %), K. cochlearis (62 %), A. priodonta (54 %), and C. sphaericus (51 %). A total of 20 species are reported for the first time from the region. Newly reported species from the lake were: the rotifers, A. priodonta, Brachionus angularis, Brachionus calyciflorus, Colurella colurus, Keratella quadrata, Lecane clostrocerca, Lecane ludwigi, Lecane luna, Lecane lunaris, Lecane ohioensis, Lecane quadridentata, Lecane sp., Mytilina mucronata, Notholca acuminata, Notholca squamula, Trichotria tetractis, the cladocerans Acroperus harpae, Daphnia cucullata, and the copepods Eucyclops macrurus and Megacyclops gigas. Considering the Brachionus / Trichocerca (QB/T) ratio according to the Sládeček (1983) index, the lake showed mesotrophic features.

One more step in solving the Chydorus puzzlea morphological comparison between Chydorus tilhoi Rey & Saint-Jeans, 1969 and Chydorus sphaericus (O.F. Mller, 1776) (Crustacea: Cladocera).

A number of species of Chydorus Leach, 1816 (Crustacea: Cladocera) need improvements in their taxonomy much more than any other genus within the family Chydoridae Dybowsky & Grochowski, 1894 emend. Frey, 1967, which makes the systematics of the genus still a puzzle that lacks several pieces. Here, we redescribe the African species Chydorus tilhoi Rey & Saint-Jeans, 1969 and compare its morphology with that of Chydorus sphaericus (O.F. Mller, 1776). The two taxa might be easily differentiated because C. tilhoi has a single and relatively large major head pore with a wide rim, labral keel elongated with a large spine, and postabdomen with postanal part elongated, narrowing distally and with denticles near its anal margin, organized in groups. These morphological traits are absent in C. sphaericus. Chydorus tilhoi and C. sphaericus also differ in the morphology of the first (Inner Distal Lobe setae), third (exopodite proportion), and fifth (exopodite shape) limbs. Based on the literature and our observations, the limb morphology of C. tilhoi has important similarities with that of C. breviceps, C. nitidulus and C. dentifer, and their translocation to a new genus seems to be a fundamental piece in the puzzle of Chydorus.

Zooplankton of Volga River reservoirs: structure, abundance and dynamics

The taxonomic structure and spatial distribution of the late-summer zooplankton in the Volga River from the upper Ivankovo reservoir to Volga Delta near Astrakhan during the period 2020–2021 were studied. Zooplankton biomass in the most of the Volga reservoirs was dominated by cladoceran Daphnia galeata and copepod Mesocyclops leuckarti (up to 45–84%). However different dominant species were observed in the Volgograd reservoir. Cladocerans Chydorus sphaericus and Bosmina cf. longispina formed there up to 43% of the total zooplankton biomass. Rotifers and Ponto-Caspian copepod Heteroscope caspian are dominated in the Volga River below the dam of the Volzhskaya hydropower plant (56% and 18% of the total zooplankton biomass respectively). Among the invasive species, most abundant are East Asian copepod Thermocyclops taihokuensis (up to 230 thsd. ind./m3 and locally 90% of the total biomass) and North American copepod Acanthocyclops americanus (up to 86 thsd. ind./m3 and 35% of the total biomass). The maximum abundance of the zooplankton (0.8–1.6 g/m3) was observed in the Upper Volga reservoirs while the minimum abundance (0.1–0.2 g/m3) – in the Lower Volga. The maximum abundance of zooplankton (0.8–3.3 g/m3) was recorded in the mouth areas of the reservoir tributaries, while the minimum abundance (0.1–1.4 g/m3) – in the pelagic zone of the reservoirs. A decrease in the zooplankton community biomass from Upper to Lower Volga was observed in all biotopes. A negative correlation between the community abundance and daily water inflow into the reservoirs and a positive correlation between the community abundance and water temperature were revealed. Long-term variations in zooplankton biomass and their relationship with water body trophic state, thermal and oxygen regimes were discussed.

Determination of Bayındır Dam Lake (Ankara) Zooplankton Fauna

Zooplankton samples were collected from four stations in Bayındır Dam Lake between April 2022 and January 2023 using a 60 μm plankton net with horizontal and vertical hauls, and some water quality parameters (water temperature, pH, dissolved oxygen, and conductivity) were determined in-situ. The annual mean water temperature, dissolved oxygen, pH and conductivity were 17.64±7.64 °C, 7.92±0.18 mgL-1, 9.26±1.00 mgL-1, 368.52±24.69 µS cm-1 respectively. Water quality parameters were within normal limits for most aquatic organisms. A total of 87 species were recorded in the reservoir, including 66 rotifers (75.86%), 15 cladocerans (17.24%) and 6 copepods (6.90%). A total of 22 families from Rotifera, 5 families from Cladocera and 2 families from Copepoda were recorded. Brachionidae and Lecanidae (Rotifera) having most of the species were the richest families with 10 species each. With 8 Chydoridae species from Cladocera and 5 Cyclopoidae species from Copepoda, they were discovered to be the most numerous family. It was determined that the dam lake zooplankton consisted of widely distributed cosmopolitan and eutrophication indicator species.

Zooplankton in the Technogenic Aquatic Ecosystem of the North Crimean Canal, the Longest in Europe

The construction and use of navigation and irrigation canals are among the common human alterations in landscapes and ecosystems. The North Crimean Canal (NCC) is the longest in Europe; its main branch is 403 km, and the total of all its branches exceeds 10,000 km. It is a main driver of the significant environmental changes in an all-arid part of Crimea. No zooplankton studies in the canal have been carried out up to this time at all. In 2022, zooplankton was studied in different sites from May to October. Total zooplankton abundance fluctuated between 170 and 19,560 ind. m−3, and wet biomass between 0.75 and 1057 mg m−3. In total, 11 Rotifera species, 11 Cladocera species, and 15 Copepoda species, including 2 Harpacticoida, 5 Calanoida, and 8 Cyclopoida, were found in plankton. The most common Rotifera species were Brachionus calyciflorus, Euchlanis dilatate, and Keratella cochlearis. Among Cladocera, Chydorus sphaericus, Bosmina longirostris, and Coronatella rectangular have the highest frequency of occurrence. In Copepoda, these were Acanthocyclops vernalis, Eurytemora affinis, and Nitocra typica. Among the 37 species found in NCC, 10 were not previously noted in the water bodies of Crimea. Among rotifers, they were Ploesoma hudsoni, Polyarthra dolichoptera, Pompholyx complanata, Synchaeta grandis, and Synchaeta stylata. Bosminopsis zernowi, Rhynchotalona rostrata, and Scapholeberis mucronata were not noted before among Cladocera. Eurytemora lacustris and Cyclops smirnovi were first found in Crimea among Copepoda. New technogenic aquatic ecosystems such as NCC are the “gateway” for the invasion of alien species into the new regions.

Chromosome-scale genome assembly of the freshwater cladoceran crustacean Chydorus sphaericus: A resource for discovery of genes responsive to ecological challenges

The genus Chydorus Leach 1816 (family Chydoridae) is a diverse and ecologically important taxon within freshwater ecosystems. Despite having been widely used in ecological, evolutionary and eco-toxicological studies, no high-quality genomic resource is available for any member of the genus. Here, we present a high-quality chromosome-level assembly of the C. sphaericus genome by combining 7.40 Gb (∼ 50 × coverage) PacBio reads, 19.28 Gb (∼ 135 × coverage) Illumina paired-end reads, and 34.04 Gb Hi-C reads. Our genome assembly is approximately 151 Mb, with contig and scaffold N50 lengths of 1.09 Mb and 13.70 Mb, respectively. The assembly captured 94.9% of the complete eukaryotic BUSCO. Repetitive elements accounted for 17.6% of the genome, and 13,549 protein-coding genes were predicted (based on transcriptome sequencing data, ab-initio or homology-based prediction), of which 96.4% have been functionally annotated in the NCBI-NR database. We identified 303 gene families specific to C. sphaericus, mainly families enriched in functions related to immune response, visual senses and detoxification. Interestingly, we also found 53 significantly expanded gene families in C. sphaericus, mostly with functions related to detoxification. This high-quality assembly genome will act as a reference genome for C. sphaericus and benefit studies on functional and comparative genomics of Chydorus and other crustaceans.

Zooplankton of some rivers of the Podkamennaya Tunguska river catchment (Yenisei river catchment)

The article reports the results of studies of zooplankton communities сonducted in 2017–2020 in some rivers of the Podkamennaya Tunguska river catchment. Zooplankton samples were selected and processed according to generally accepted methods. The taxonomic composition was determined for the first time (except for the Kamo River). The taxonomic composition included 48 taxa: Rotifera — 21, Cladocera — 16, Copepoda — 13. The greatest species diversity of zooplankton was recorded in the Tohomo, Tetere and Taiga rivers — 18–26 taxa, the smallest — in the Ter, Levoe Cheremo and Levaya Tokura rivers — one species each. In most rivers there were rotifers Euchlanis dilatata, and crustaceans — Acroperus harpae, Chydorus sphaericus. In general, rotifers and cladocerans played a significant role in the zooplankton of the studied rivers. The average abundance and biomass of zooplankton organisms varied from 22 to 2673 ind./m3 and from 0.001 to 29.63 mg/m3, respectively. Zooplankton was most developed in the Tetere river due to the abundance of large cladoceras of the genus Alona, Daphnia longispina, Eurycercus lamellatus, Simocephalus vetulus. Low the average abundance was in the rivers Maliy Yurubchen, Levaya Tokura, biomass — Verhvnya Madra, Dugungna, Maliy Yurubchen, Yurubchen, Tes, Levoe Cheremo, Levaya Tokura characterized by a relatively high flow rate and limited supply of organic and biogenic substances that determine the development of the invertebrate food supply. According to the quantitative characteristics of zooplankton, the rivers of the Podkamennaya Tunguska river catchment are characterized as poor in feed.

Cladocera and Copepoda (Cyclopoida, Calanoida) of the mountain part of the Stryi river basin (Ukrainian Carpathians)

The Cladocera, Cyclopoida and Calanoida species diversity of the mountain part of the Stryi river basin is described. The objects of research were found in 48 lenthic water bodies (Zhuravlyne lake, Yavirske reservoir, numerous ponds, puddles, swamps, springs, and wells) and on 7 sections of the Stryi and Yablunka rivers. 24 species of Cladocera, 23 Cyclopoida, and 1 Calanoida are found. The most diverse is the fauna of Lake Zhuravlyne, which is located in the Skole Beskydy National Nature Park. 56% of the species diversity of the mentioned groups is noted in ponds, 42% in puddles and swamps, 8% in springs and wells, 15% in rivers, 10% in Yavirske reservoir, 44% in Zhuravlyne. The fauna of the mountain part of the Stryi river basin includes 44% of the Cladocera, Cyclopoida and Calanoida species diversity of the territory of the Ukrainian Carpathians. Only Eudiaptomus transylvanicus is noted within Calanoida. Alona protzi, Eurycercus lamellatus, Simocephalus expinosus are found only in the study area within the Ukrainian Carpathians. The most common species in this area are Chydorus sphaericus (36% frequency of occurrence in the investigated lenthic water bodies) and Eucyclops serrulatus (55%). These species are the most common in the Ukrainian Carpathians as well. The highest total density of Cladocera and Cyclopoida was 253,5 thous.ind./m3. Daphnia obtusa, Alona protzi, Eucyclops subterraneus, Paracyclops poppei та Grateriella unisetigera are rare species for Lviv region. Eurycercus lamellatus, Simocephalus expinosus, Chydorus latus together with the previous species are rare for the Ukrainian Carpathians in total. 47% of the investigated lenthic water bodies are in oligosaprobic zone. The most valuable communities of the Cladocera, Cyclopoida and Calanoida exist in the Zhuravlyne lake, springs and wells near village Verkhnia Rozhanka, pools of the Vododilnyi masiff, riverbed of Stryi and the along-river reservoirs between the villages Zavadavivka and Yavora, and ponds near the village Dovge.

Response of zooplankton to inputs of terrestrial dissolved organic matter: Food quality constraints induced by microbes

AbstractTerrestrial inputs of dissolved organic matter (DOM) stimulate microbial growth by supplying organic carbon and DOM‐associated nutrients, and thus increase food availability for zooplankton. Terrestrial inputs of DOM might decrease the content of eicosapentaenoic acid (EPA) in particular organic matter (POM) due to an increase in biomass of EPA‐poor microbes, for example, heterotrophic bacteria and autotrophic cyanobacteria, thereby reducing food quality and filter‐feeding zooplankton's biomass. We performed a 26‐d mesocosm experiment where terrestrial DOM was manipulated by adding (treatments) and kept without adding (controls) 13C‐labeled maize leachate to evaluate the effect of food quality changes induced by terrestrial DOM inputs on zooplankton. DOM addition treatments had significantly higher concentrations of POM and Chlorophyll a relative to controls, but significant lower EPA content of POM, responding to increased biomass of bacteria and chlorophytes. Biomass and EPA content of filter‐feeding cladoceran Chydorus sphaericus was significantly reduced by terrestrial DOM addition. Stable isotope analyses showed 13C enrichments in bacteria and cryptophytes in the treatment of 13C‐labeled maize leachate, indicating a growth stimulation of heterotrophic microbes by organic carbon addition. Although the 13C enrichment in Chydorus evidenced the extensive use of terrestrial DOM by this cladoceran, positive relationships between Chydorus biomass and EPA content of POM suggest that terrestrial DOM inputs increase food quality constrains on filter‐feeding zooplankton. Our study suggests that the response of filter‐feeding zooplankton to inputs of terrestrial DOM depends on how the terrestrial inputs change the microbial communities and thus the food quality in the receiving aquatic ecosystems.

A checklist of Cladocera (Crustacea: Branchiopoda) of the Shatt Al-Arab River, Basrah, Iraq

About 51 species belonging to 2 Orders, 7 Families, and 20 Genera were recognized.The present review is based on ten systematic studies recording the species found in the region.The largest number of species recorded was 23 species at the Al-Qurnah station and 14 species ineach of the Al-Hartha and Al-'Ashar stations. It was found that the most common species in theShatt Al-Arab River were Chydorus sphaericus and Simocephalus (Simocephalus)vetuloides.

Biogeography and environmental drivers of zooplankton communities in permafrost-affected lakes on the Qinghai-Tibet Plateau

Global warming is accelerating permafrost thaw, forming new thermokarst lakes and substantially influencing the old ones. However, the biological communities in thermokarst lakes on the Qinghai-Tibet Plateau (QTP) are rarely studied. Here, we assessed the biogeographical patterns of zooplankton communities in 44 thermokarst lakes across the QTP. Across all lakes, 17 Cladocera and 13 Copepoda species were identified, with most of the lakes dominated by Cladocera. Chydorus sphaericus and Cyclops vicinus were the most frequently detected species. Both cladoceran and copepod communities had very low species richness and density, which lacked a clear spatial pattern but positively associated to dissolved oxygen. In general, species richness was negatively influenced by seston particle quantity while the density was positively influenced by water nutrient concentrations. Cladoceran and copepod communities had a high β-diversity (0.89 and 0.91, respectively), which was dominated by species turnover. However, Cladocera had significantly lower β-diversity and turnover component than copepod communities. β-diversity of Cladocera and Copepoda showed a significant but weak distance decay relationship and also significantly correlated with longitude, latitude, mean annual temperature, as well as concentrations of seston particle carbon and nitrogen. In addition, their β-diversities differentially correlated to other environmental variables. Overall, the results suggested that the geographical barriers, climate, and some local environmental variables are key factors in shaping the biogeography of zooplankton community. Although a general biogeographic pattern of zooplankton across the QTP cannot be drawn from this limited dataset, this study provided the first large spatial scale investigation and analyses of zooplankton biogeography in thermokarst lakes on the QTP. Given the important roles of zooplankton in aquatic ecosystems, this study could provide insights for understanding the influences of future environmental changes on thermokarst lake ecosystems.

Сучасний стан зоопланктону Каховського водосховища

The current state of the quantitative and qualitative development of zooplankton in the Kakhovka Reservoir is examined. The species composition, the representation of taxonomic groups, the number and biomass of zooplankton in the summer period of 2020–2021 were determined. The average number of zooplankton in the summer of 2020 in the studied areas (Bilenke village, Bilenke-Malokaterynivka station, vicinity of Malokaterynivka village) was 40.833 units/m3 with the biomass 0.245 g/m3, in the summer of 2021 — 110,932 units/m3 with the biomass 0.652 g/m3. Rotifers formed the basis of the number and biomass of zooplankton in the summer of 2020 (76% and 86%). Cladocera both in number and biomass (5% and 7%) and copepod (18% and 6%, respectively) had a significantly lower level of development in the reservoir. Dreissena polymorpha larvae were found in a small amount (1%) and biomass (0.1%). In the summer period of 2021, rotifers also formed the basis of the number and biomass of zooplankton (72% and 68%). Cladocera both in number (8%) and biomass (14%), and the copepod (19% and 18%, respectively) reached a lower level of development in the reservoir. As in the previous year, the larva of D. polymorpha was found in a small amount (1%) and biomass (0.1%). In the summer of 2020, the basis of the number and biomass of rotifers was formed by: Asplanchna brightwelli (24% and 40%), Asplanchna priodonta (7% and 24%), Synchaeta pectinata (13% and 8%), Brachionus calyciflorus (6% and 6%), Euchlanis dilatata (6% and 2%, respectively), in the summer of 2021 A. brightwelli (16% and 27%), A. priodonta (5% and 19%), S. pectinata (12% and 8%), E. dilatata (7% and 2%), B. calyciflorus (6% and 6%), Brachionus diversicornis (5% and 2%, respectively). Chydorus sphaericus dominated in number (4%) and biomass (7%) among Cladocera in 2020, and C. sphaericus also dominated in number (7%) and biomass (12%) in 2021. In 2020, copepod in the reservoir are mainly represented by nauplial (17% and 6%) stages, and in 2021 by nauplial (12% and 4%) and copepod (4% and 3%) stages, as well as Diaptomus juv. (1% and 8%), Cyclops sp. (2% and 3%, respectively).

ГІЛЛЯСТОВУСІ (CLADOCERA) Й ВЕСЛОНОГІ (COPEPODA: CALANOIDA, CYCLOPOIDA) РАКОПОДІБНІ МАРМАРОСЬКИХ ГІР (УКРАЇНСЬКІ КАРПАТИ)

There are noted 11 species of plankton crustaceans (7 – Cladocera and 4 – Copepoda (Calanoida and Cyclopoida)) from the reservoirs of the Ukrainian part of the Marmarosh Mountains. 
 The high mountain glacial lake Kryvave, the forest lake of the overflow type (landslide) Shchevora, small swamp and some of the puddles are investigated. Lake Kryvave is located at an altitude of 1620 m above sea level in the glacial crust of Mt. Pip Ivan Marmarosky within the subalpine vegetation. Its size is 38.8 by 19.4 m, the maximum depth is 0.5 m. Lake Shchevora is located at an altitude of 1209 m above sea level in a hollow in a spruce forest with an admixture of beech. The size of the lake is 61.5 by 21.8 m. The recorded maximal depth is 1.6 m, but the lake might be much deeper.
 The most common species in this area are Chydorus sphaericus (O. F. Müller, 1776) and Acanthocyclops vernalis (Fischer, 1853). The others species has a more local distribution in the Marmarosh Mountains. Daphnia obtusa Kurz, 1874, Chydorus sphaericus, Acanthocyclops vernalis and Mixodiaptomus tatricus (Wierzejski, 1883) inhabited in the subalpine reservoirs upper 1515 m above sea level. These communities are typical for high mountain shallow reservoirs of Chornohora, Svydivets massifs too. This indicates that the hydrofauna of the Marmarosh Mountains belongs to the high mountain fauna of Carpathians.
 Mixodiaptomus tatricus, which inhabits the reservoirs of subalpine and alpine zones of southeastern Europe is specific stenotopic species to the communities of the Ukrainian Carpathians and is present by an isolated population in the reservoirs on the slopes of Mt. Pip Ivan Marmarosky. 
 The total density of planktonic crustaceans in the lakes is very low (0.5–1.3 thous. ind./m3), because of cold water, a small amount of organic matter, absence or lack of aquatic macrophytes. The most numerous planktonic crustaceans are in subalpine puddles – up to 138.5 thous. ind./m3. The total density of planktonic crustaceans in road puddles does not exceed 6 thous. ind./m3. The maximum density was reached Daphnia obtusa – to 54,5 and Chydorus sphaericus – to 51,3 thous. ind./m3 from other species.
 Lake Kryvave and the puddle on the slopes of Mt. Stig are oligosaprobic, while the other reservoirs are β-mesosaprobic.

Гіллястовусі (Cladocera) й веслоногі (Copepoda: Calanoida, Cyclopoida) ракоподібні масивів Руна, Боржава, Вододільний (Українські Карпати)

15 species of plankton crustaceans (7 – Cladocera and 8 – Copepoda (Calanoida and Cyclopoida)) from reservoirs of the Runa, Borzhava, and Vododilnyi massifs are noted. The objects of research were found in 13 of the studied reservoirs within the Runa massif, Vodiv­kania and Preluchnyi areas, as well as the upper stream of Husnyi and Zhdenievka rivers; five inhabited reservoirs were found in the Borzhava massif, and three in the Vododilnyi one. Pond size measurements of the Velyka Trustsia and two Borzhava lakes were carried out. The natural glacial origin of the Velyka Trustia lake which is located to the northwest of the top of the Runa massif is doubtful. Most likely it was formed by the erection of artificial dams. Chydorus sphaericus (OF Müller, 1776) and Daphnia obtusa Kurz, 1874 (Cladocera) are the most common species in the investigated area. The highest density of plankton crustaceans was recorded in the reservoirs of natural origin: the Borzhava lake 1 – 170.3 thous. ind./m3, in the meadow puddle of the Vododilnyi massif – 253.5 thous. ind./m3. Daphnia obtusa dominates in these communities with 55–97 % of the total number of crustacean plankton. Under the condition of a low number of reservoirs in this area a high concentration of aquatic diversity, which was observed in single aquatic habitats within the massifs of Runa, Borzhava, and Vododilnyi is very valuable. Their value ability enhances the importance of the reservoirs’ conservation level in preserving the biodiversity of mountain areas. The presence of stenobiotic and endemic hydrobiont taxa (Daphnia obtusa Kurz, 1874, Mixodiaptomus tatricus (Wierzejski, 1883)) indicates that these reservoirs deserve the preservation of the existing natural abiotic conditions of their ecosystems without further increasing the level of anthropogenic pressure. Water bodies of the Vododilnyi massif are oligosaprobic, single water bodies of the Runa and Borzhava massifs are oligosaprobic, while the other reservoirs are β-mesosaprobic. Vehicle and motorbike tourism is the main current negative factor of anthropogenic pressure in the water basins and reservoirs of the studied area. This impact influences the stable existence of natural aquatic ecosystems to a high extent, as all such reservoirs are located on the roadside or close to dirt roads.

Investigation of groundwater zooplankton fauna from water wells in Yayladağ district of Hatay province in Turkey

Some water quality parameters (water temperature, conductivity, dissolved oxygen and pH) and zooplankton fauna were investigated in 10 water wells where the study was conducted. In this study, 14 species of Rotifera (46.67%), 10 species of Copepoda (33.33%), and 6 species of Cladocera (20%) were identified. It was found that the widely distributed species Rotaria neptunia (in 7 wells), Keratella quadrata (in 5 wells), Daphnia curvirostris (in 8 wells), Coronatella rectangula (in 6 wells), Chydorus sphaericus and Pleuroxus aduncus (in 5 wells each), Megacyclops viridis (in 8 wells) and Tropocyclops prasinus (in 6 wells). The most species (14 species) were found in well 8, followed by wells 3, 5, 7 and 9 with 11 species. In general, it was determined that there was a significant and positive relationship between zooplankton species diversity and abundance, and water quality parameters.

СЕЗОННАЯ ДИНАМИКА ЗООПЛАНКТОНА ШЕКСНИНСКОГО ВОДОХРАНИЛИЩА (ВОЛОГОДСКАЯ ОБЛАСТЬ)

The paper analyzes the seasonal dynamics of the composition, structure, and abundance of zooplankton in different parts of the Sheksna Reservoir in 2016–2020. The zooplankton in the reservoir includes 107 species (Rotifera – 41, Cladocera – 41, Copepoda – 25). The authors have found 88 species in Lake Beloye and 90 species in the river part of the reservoir. 7 species in the lake and 17 in the river part of the reservoir have been found for the first time. The communities of different parts of the reservoir are similar in terms of zooplankton composition (76%). The highest level of dominance (0.32–0.38) of zooplankton is observed during the ice period. In Lake Beloye, this figure is higher than in the river part of the reservoir. A small set of species (Kellicottia longispina, Keratella cochlearis, Eudiaptomus gracilis) is characterized by high density in all seasons of the year. Some species are dominant only in certain periods. In summer, rotifers of the genus Polyarthra and Mesocyclops leuckarti dominate the entire water area of the reservoir. Lake Beloye is dominated by Daphnia galeata and Chydorus sphaericus in summer. The composition of the dominant zooplankton complex in different parts of the reservoir is similar in certain seasons. Only in May, the structure of the dominant complex of the lake and river sections of the reservoir differs. The ratio of dominants in Lake Beloye in May is similar to the ice period. The maximum abundance of zooplankton in the reservoir is recorded in summer. From May to November the largest number of copepods is observed. In March, rotifers dominate. Cladocera were noted as dominants only in the lake part of the reservoir. The seasonal dynamics of the structure and abundance of zooplankton generally corresponds to those in the 1970s and early 2000s.

Zooplankton Diversity and Water Quality Assessment of Lentic Waters of Jammu, India

An attempt was made to study the abiotic parameters of three water bodies of Jammu region along with their impact on distribution and presence of zooplankton. The total of 49 organisms belonging to five groups of zooplankton viz Protozoa, Rotifera, Cladocera, Copepoda and Ostracoda were identified. Of the three stations, ostracods were recorded from station 1 only. Phylum Rotifera was observed to be dominant in all the three stations. Many pollution indicator species like Brachionus calyciflorus, Brachionus angularis, Keratella tropica, Polyarthra vulgaris, Filinia longiseta, Moina brachiata, and Chydorus sphaericus were recorded from Station 1. Both biotic and abiotic components indicate that station 1 is progressing towards eutrophication.

Multiple Recent Colonizations of the Australian Region by the Chydorus sphaericus Group (Crustacea: Cladocera)

Biotic introductions are an ongoing disruption for many ecosystems. For passively dispersed freshwater zooplankton, transcontinental introductions have been common but are poorly studied in the southern hemisphere. Here we assess the hypothesis of recent introduction for populations of the Chydorus sphaericus group (Crustacea: Cladocera) in Australia. We analyzed 254 sequences (63 original sequences) from the cytochrome oxidase I region of mitochondrial DNA of Chydorus sp., which included global representation. Three Australian populations were connected with separate clades in the northern hemisphere, suggesting multiple colonization events for Australia. The timescale of the divergences was consistent with recent (Quaternary) dispersal. As Australian populations are exposed to migrating birds from the northern hemisphere, both avian and anthropogenic sources are candidates for dispersal vectors. We concluded that recent cross-hemisphere dispersal in the Chydorus sphaericus group is more common than previously believed.