Microcrustacean Species Research Articles

Post-senescence reproductive rebound in Daphnia associated with reversal of age-related transcriptional changes.

A long-lived species of zooplankton microcrustaceans, Daphnia magna, sometimes exhibits late-life rebound of reproduction, briefly reversing reproductive senescence. Such events are often interpreted as terminal investments in anticipation of imminent mortality. We demonstrate that such post-senescence reproductive events (PSREs) neither cause nor anticipate increased mortality. We analyze an RNAseq experiment comparing young, old reproductively senescent, and old PSRE Daphnia females. We first show that overall age-related transcriptional changes are dominated by the increased transcription of guanidine monophosphate synthases and guanylate cyclases, as well as two groups of presumed transposon-encoded proteins, and by a drop in transcription of protein synthesis-related genes. We then focus on gene families and functional groups in which full or partial reversal of age-related transcriptional changes occur. This analysis reveals a reversal, in the PSRE individuals, of age-related up-regulation of apolipoproteins D, lysosomal lipases, and peptidases as well as several proteins related to mitochondrial and muscle functions. While it is not certain which of these changes enable reproductive rejuvenation, and which are by-products of processes that lead to it, we present some evidence that post-senescence reproductive events are associated with the reversal of age-related protein and lipid aggregates removal and apoptosis.

Substantial unrealised global biodiversity of continental microcrustaceans

Abstract Freshwater ecosystems provide essential services for human well-being, with their conservation success reliant on the precise quantification of biodiversity. Diplostraca (= Cladocera) and Copepoda are diverse groups of microcrustaceans in aquatic ecosystems, important for a multitude of these services. We examined biodiversity trends of these groups, utilizing a comprehensive dataset, approximately 2341 studies, spanning from the early 19th Century to the present day, aiming at predicting the total number of microcrustacean species that will have been described by 2100. Descriptions increased until the 1900s, surged, and then declined after 1975. The predictive models indicate that by the year 2100, an additional 16–68% of cladoceran species and 37–126% of copepod species are likely to be identified, representing a significant portion of currently unrealised biodiversity. Eighteen prolific authors contributed to a quarter of these descriptions, with the rest spread among numerous authorities. Based on our extrapolation, the total number of microcrustacean species could potentially exceed 6114 by 2050 and 9046 by 2100, notwithstanding extinctions. These findings, which point to a significant amount of unrealised biodiversity, underscore the need to refine biodiversity estimates beyond conventional expert opinion. Such accuracy is crucial for addressing the underappreciated scale of the current biodiversity crisis.

Linking hydrological connectivity with the richness and composition of aquatic invertebrates across the Paraná River floodplain, Argentina

Lateral hydrological connectivity can affect the community characteristics by promoting dispersal of organisms between the river and its floodplain. We investigated the species richness, specific diversity, and relative abundance of microcrustaceans transported by the flood and the macroinvertebrates retained by Pontederia crassipes Mart. roots in five floodplain lakes with different connectivity within the RAMSAR Site Humedales Chaco. Due to differences in the slopes of the floodplain studied, the connectivity was determined by the topographic location of each lake, rather than by the distance from the river. During the hydrological connection, there was a transverse gradient in the physical and chemical characteristics of the water, with an increase in the electrical conductivity and a decrease in dissolved oxygen and suspended solids in the more isolated sites. A total of 62 species of microcrustaceans (48 cladocerans and 14 copepods) and 63 taxa of macroinvertebrates were identified. The microcrustaceans had high species richness in the three most connected lakes, whereas the macroinvertebrates had a peak in taxa richness in the lakes with intermediate connectivity. The low beta diversity (βw) for both microcrustaceans (14.63 %) and macroinvertebrates (16.9 %) indicated that taxa richness varied little between sites with different hydrological connectivity. In both assemblages, cluster analysis based on the similarity of the relative abundance grouped the three sites more connected and separated from the less connected sites. Our results suggest that species richness followed different patterns in different assemblages across the lateral gradient and that the hydrological connectivity was more related to the relative abundance of microcrustaceans and macroinvertebrates than to the classical measures of βw. Species diversity indices did not vary between sites. The high total species richness of invertebrates is mainly a result of the spatial arrangement of the different floodplain lakes.

Insights on the Existence of Ancient Glacial Refugee in the Northern Black/Azov Sea Lowland, with the Description of the First Stygobiotic Microcrustacean Species of the Genus Niphargus Schiödte, 1849 from the Mouth of the Don River

A new species of the genus Niphargus Schiödte, 1849 (Crustacea: Amphipoda: Niphargidae), co-existing with other stygobiotic amphipods, Diasynurella kiwi Marin and Palatov, 2023 and Pontonyx donensis (Martynov, 1919) (Crangonyctidae), is described from a small spring on a shore of Kiziterinka River in Rostov-on-Don City in the mouth of the Don River. Two of the three species in the studied spring, D. kiwi and the discovered Niphargus, belong to microcrustaceans not exceeding the total body size of 3 mm. The new species, Niphargus rostovi sp. nov., represents one of the smallest species within the genus and is mostly related to the Greek Niphargus karkabounasi Ntakis, Anastasiadou, Zakšek and Fišer, 2015, which is also not reaching the body size of 3 mm. One more related undescribed species is found on the Crete Island by the molecular genetic data. These species represent a separate phylogenetic lineage within the “carpathicus” species complex, which diverged from the congeners in the Late Miocene for more than 10 Mya. At the same time, the speciation within the ingroup started about 5–6 Mya, obviously correlating with the drainage of the Euxinian basin of the Eastern Paratethys, connecting the lower Don and southern Greece areas. Niphargus potamophilus Birštein, 1954 is also first recorded from the mouth of the Belbek River in the Crimean Peninsula, closing the known area from the Kuban River delta to Rostov-on-Don area and further along the western coast of the Black Sea to Bulgaria. Analysis of the recent records of long-time lineages of endemic/subterranean/stygobiotic animals unable to disperse for long distances assumed that glacial refugium existed at the mouth of the Don River, along with the South Caucasus (Colchis) and the southern Caspian (Hyrcania), where many species have survived several periods of glaciation since the late Miocene.

Freshwater microcrustaceans of Hispaniola: new records and potential as biological control agents

Some species of freshwater microcrustaceans have been widely used for biological control of mosquito larval populations. These zooplankton communities play an important role against some species of mosquitoes by exerting competitive pressure or predation. However, zooplankters are scarcely studied in many Caribbean islands such as Hispaniola. The goal of this study was to improve the knowledge of these microcrustaceans in order to better understand the biodiversity and ecology of this Antillean Island. Samples of zooplankton were taken from 28 ponds in the northern Dominican Republic during 2020. The total richness of microcrustaceans was 25 species, comprising 17 copepods and 8 cladocerans. Most of the collected species were previously described for the island, and some of them are registered as potential biological controllers of mosquito larvae populations. Five genera (including 6 species) of microcrustaceans that inhabit the ponds are recorded for the first time for Hispaniola: Simocephalus Schoedler, 1858; Pleuroxus Baird, 1853; Ilyocryptus G.O. Sars, 1861; Apocyclops Lindberg, 1942; and Diacyclops Kiefer, 1927. Here, we discuss these new findings in relation to the competitive and/or predatory potential of these species against mosquito larvae. The present study improves the knowledge of biodiversity in ponds in the Dominican Republic.

Identification of Microcrustaceans as Potential Bioindicators of Arsenic in Tropical Water Bodies.

We investigated microcrustaceans inhabiting arsenic contaminated and non-contaminated freshwater to identify potential bioindicators of arsenic contamination in the tropical freshwater of Matehuala in northern Mexico. We collected water, sediment, and zooplankton, at five sampling points during three sampling campaigns. We determined water temperature, pH, electrical conductivity, dissolved oxygen, alkalinity, salinity, and total arsenic concentration in water. Additionally, we determined total arsenic and arsenic speciation in sediment samples. We identified microcrustaceans and determined abundance, richness, and Shannon Index. We also investigated relationships and correlations between physiochemical and ecological variables. Results showed that arsenic concentrations in freshwater ranged from 0.001 to 53.23mg/L, while total arsenic in sediments ranged from 10.37 to 2472.84mg/kg as As + 5. Six microcrustacean species were found in highly and moderately contaminated water (Latonopsis australis, Eucyclops chihuahuensis, Acanthocyclops americanus, Pleuroxus (Picripleuroxus) quasidenticulatus, Macrocyclops albidus, and Paracyclops chiltoni), while five species were found in arsenic-free water (Simocephalus punctatus, Alona glabra, Eucyclops leptacanthus, M. albidus, and P. quasidenticulatus). An inverse relationship was observed between microcrustacean richness and arsenic. However, the scope of the data did not allow for a strong and significant correlation. Nevertheless, among the species inhabiting As-free water, S. punctatus showed potential to be further tested as a bioindicator of As contamination in Matehuala. Identification of potential bioindicators could help monitor water quality and increase understanding of the incorporation and toxicity of As in freshwater-sensitive and freshwater-metallotolerant microcrustaceans, which, in turn, might help us to understand As incorporation in the food web.

Assemblages of Meiobenthic and Planktonic Microcrustaceans (Cladocera and Copepoda) from Small Water Bodies of Mountain Subarctic (Putorana Plateau, Middle Siberia)

The Putorana Plateau (Krasnoyarsk Territory, Russia) is one of the largest mountainous regions of subarctic Eurasia. Studies of aquatic ecosystems of this are far from complete. In particular, microcrustaceans (Cladocera и Copepoda) of the Putorana Plateau are poorly investigated, although they are one of the main components of meiobenthic and zooplanktonic communities and a target for monitoring of the anthropogenic influence and climate change. An open question is a biogeographical status of the crustacean fauna of the plateau. Additionally, it is unknown which environmental factors significantly affect benthic and planktonic crustacean assemblages? Based on the samples collected in tundra and forest tundra ponds in the western and central parts of the plateau, analysis of the composition of crustacean fauna and factors regulating the assemblage structure was performed. In total, 36 Cladocera and 24 Copepoda species were found. Of these, 23 taxa are new for the region, and four are new to science. Species richness of Copepoda is higher in the central part and on the western slopes of the plateau than in foothills, while number of the Cladocera species in contrast decreases in mountainous areas. Variations in meiobenthic assemblages are due to the research area, type of water supply and less affected by altitude above sea level. For planktonic assemblages the size of the water body and, to a lesser degree, by macrophytes species composition was significant. Almost 12.8% of microcrustacean species of the Putorana Plateau can be attributed to glacial relics. Crustacean fauna of the Putorana Plateau has a high species richness and distinguishes significantly from the fauna of both western and eastern regions of the Arctic. The specifics of faunal composition of the region are connected to the climatic features of Middle Siberia and the retaining of the Pleistocene fauna in some glacial refugia.

Water availability and quality determine temporal synchrony and beta diversity of microcrustaceans in temporary pools

Beta diversity patterns have been frequently used to investigate metacommunity structure. The metacommunity concept has focused primarily on the spatial beta component, but part of the unaccounted variation is likely associated with temporal beta patterns. Here, we examined the effect of seasonal variation in water availability on the spatiotemporal assembly of microcrustaceans living in temporary pools. Specifically, we sampled microcrustaceans in 5 pools monthly for 12 mo and tested how temporal fluctuations in physicochemical variables affected beta diversity. We also investigated whether species showed synchronous responses in tracking dry or wet conditions. Our study revealed that only those microcrustacean species associated with the wet season had temporally synchronous population dynamics. However, we did not find population synchrony in the dry season and in those comparisons including all microcrustacean species. Physicochemical variables such as pH, dissolved oxygen, and water transparency explained part of the spatial variation in beta diversity. These results suggest a strong influence of species sorting on metacommunity structure both in space and in time. Extreme climatic conditions, such as water scarcity, could affect population dynamics; thus, linking spatial and temporal patterns will be necessary to disentangle the effects of stochastic processes and environmental filtering on metacommunity dynamics.

The life-history fitness of F1 hybrids of the microcrustacean Daphnia pulex and D. pulicaria (Crustacea, Anomopoda).

Negative interaction between alleles that arise independently in diverging populations (i.e., Dobzhansky-Muller incompatibilities) can cause reduction of fitness in their hybrids. However, heterosis in hybrids can emerge if hybridization breaks down detrimental epistatic interaction within parental lineages. In this study, we examined the life-history fitness of the inter-specific F1s of two recently diverged microcrustacean species Daphnia pulex and D. pulicaria as well as intra-specific crosses of D. pulex. We identified heterosis in two out of five life-history traits in the inter-specific F1s. According to theories that heterosis can transiently emerge in early speciation, the observation of heterosis in these life-history traits suggests that there are no major genetic incompatibilities between these two species affecting these traits and that D. pulex and D. pulicaria are at an early stage of speciation.

Dangerous connections: biochemical and behavioral traits in Daphnia magna and Daphnia longispina exposed to ecologically relevant amounts of paracetamol.

Exposure of nontarget organisms to therapeutic agents can cause distinct toxic effects, even at low concentrations. Paracetamol is a painkiller drug, widely used in human and veterinary therapies, being frequently found in the aquatic compartment in considerable amounts. Its toxicity has already been established for some species, but its full ecotoxicological potential is still not sufficiently described. To characterize the ecotoxicity of paracetamol, the present study evaluated several parameters, such as acute immobilization (EC50 calculation), biochemical alterations, and behavioral effects, in two species of freshwater microcrustaceans of the genus Daphnia (D. magna and D. longispina). To increase the relevance of the data obtained, animals were exposed to levels of paracetamol similar to those already reported to occur in the wild. Data showed antioxidant responses in both species, namely an increase of catalase and GSTs activities in D. magna. On the contrary, effects of paracetamol on D. longispina included only an impairment of GSTs activity. Despite the absence of anticholinesterasic effects, behavioral modifications were also observed. This set of data indicates that realistic levels of paracetamol may trigger the activation of the antioxidant defense system of freshwater crustaceans, causing changes in behavioral traits (increase in swimming time, but with a reduction in swimming distance) of unknown etiology that are likely to affect normal life traits of wild populations.

Effects of PVC pipe leachates on the survival and reproduction of two micro-crustacean species Ceriodaphnia Cornuta and Daphnia Magna

The occurrence and impacts of plastic are among the most concerns on the environment, ecosystems, and human health in recent years. Plastic products may contain harmful additives (e.g. phthalate, bisphenol) which can easily be leached out of the surface of the plastic materials and enter the environment causing negative effects on organisms in aquatic ecosystems. However, the toxicity of the leached plastic additives on aquatic organisms including micro-crustaceans have not been fully understood. Therefore, this study aims to evaluate the chronic effects of the leachate from the polyvinyl chloride (PVC) water pipes at the concentration of 0, 10 and 100 mg PVC/L on the survival and reproduction of two micro-crustacean species: Daphnia magna, and Ceriodaphnia cornuta. The results showed that the leachate from PVC pipes at the concentration of 100 mg/L did not adversely affect on survival and reproduction of D. magna, but reduced up to 50% of the survival rate and 60% of the reproduction of C. cornuta. The tropical micro-crustacean species C. cornuta was more vulnerable than the temperate one, D. magna. The results revealed the potential health risks of the PVC water pipes C. cornuta was recommended to be used as a model organism for the toxicological investigation and environmental assessment.

Planktonic Microcrustacean Community Structure Varies with Trophic Status and Environmental Variables in Tropical Shallow Lakes in Malaysia

A study was conducted to evaluate planktonic microcrustacean species composition, abundance, and diversity in lakes with different trophic status and to determine the relationship between microcrustacean community structure and lake environmental conditions. This study hypothesized that there are correlations between eutrophication levels and microcrustacean community structures in a lake. Three shallow lakes of different trophic status (Sembrong, Putrajaya and Subang lakes) were selected for this study. Two-Way Analysis of similarities (ANOSIM) revealed differences in microcrustacean diversity and density amongst lakes, where the hypereutrophic condition in Sembrong lake resulted in the lowest diversity but the highest density of microcrustaceans. Similarity percentage (SIMPER) analysis identified the discriminator species among lakes where the domination of small-sized microcrustaceans was observed in lakes with high levels of eutrophication; the hypereutrophic Sembrong lake (Ceriodaphnia cornuta, 74.0%); the meso-eutrophic Putrajaya lake (Bosmina longirostris, 46.9%; C. cornuta, 19.4%). Chlorophyll a, total phosphorus and water transparency showed significant roles in the distribution of microcrustaceans. The canonical correspondence analysis (CCA) scores indicated that small-sized C. cornuta and B. longirostris were related to the eutrophic conditions of lakes. This study elucidated that the lake trophic status could be one of the main factors contributing to the community restructuring of microcrustaceans in tropical lakes.

Standard and biochemical toxicological effects of zinc pyrithione in Daphnia magna and Daphnia longispina

Chemical toxicity in the environment may be the consequence of exposure of living organisms to multiple substances, with distinct putative effects. Among this mulytiplicity of chemicals that occur in the wild, pharmaceutical drugs and antifoulers are prone to exert toxic effects on non-target organisms. To characterize the toxicity elicited by a compound of this specific class, the present study used standard and biochemical-based tools to quantify the toxic response of the antifouler and antidandruff zinc pyrithione in Daphnia magna and Daphnia longispina. The analised parameters were immobility, reproduction, behavioral alteration (swimming patterns), anti-oxidant defense (catalase activity), metabolism (GSTs activities), and neurotoxicity (ChE activity) after exposure to sublethal concentrations of this drug. Exposure to zinc pyrithione has been shown to have neurotoxic and oxidative effects, with changes in swimming behavior. There were no changes in reproductive traits of exposed individuals, from both species. The obtained data demonstrate that ecologically relevant levels of zinc pyrithione can deleteriously alter critical parameters in two distinct freshwater microcrustacean species, although with distinct toxicity patterns and outcomes.

Distribution of planktonic microcrustaceans (Cladocera and Copepoda) in lentic and lotic environments from the semiarid region in northeastern Brazil

Abstract The present study aimed to inventory the biodiversity of planktonic microcrustaceans (Cladocera and Copepoda) in 44 environments from the semiarid region of Brazil, increasing the knowledge about zooplankton community, including phytophilous species. Between 2011 and 2017, organisms were collected in a non - systematic way in the states of Rio Grande do Norte, Pernambuco, Ceará and Paraíba. A total of 60 species of planktonic microcrustaceans were identified, of which 52 were cladocerans and eight were copepods. The basin that presented the highest richness was Pajeú River with 41 species. Nevertheless, the extrapolated number of species shows an increasing tendency for this basin. The genus composition was different between the basins, with Moxotó basin (Pernambuco) being isolated from the others, probably since lagoons were the only type of environment sampled in this basin. Richness and abundance patterns were higher for the basins where sampling was mainly performed in lentic environments, such as Pajeú and Moxotó. Microcrustacean inventories and long-term studies need to be conducted more frequently to better understand the biodiversity of continental aquatic ecosystems in the semiarid region of Brazil.

Composition, characteristics and long-term variability of the freshwater microcrustacean fauna of the Faroe Islands

ABSTRACTDespite the accessibility of the Faroe Islands, faunistic research on their numerous lakes and ponds is quite rare. The biota of Faroese freshwaters is still underexplored, and its specific traits raise many questions. In the present survey, 32 microcrustacean species were observed, 8 of which were new to the Faroese fauna. The obtained species list shows that Cladocera species prevail over Copepoda here, which is not typical of northern territories. This fact is due to (1) the extraordinarily warm climate of the Faroe Islands compared to other areas at similar latitudes because of the heating effect of the surrounding North Atlantic Current and (2) the lack of calanoid species, which have never been found in the freshwaters of the Faroe Islands. The diachronic analysis of the species diversity and composition over the centuries of research on the archipelago showed no evidence of the impact of global climate change on the fauna.

Zooplankton associated with phytotelms and treefrogs in a neotropical forest

ABSTRACT Assumptions about the distribution of zooplankton communities in various ecosystems are often limited by lack of data on dispersal mechanisms. Many studies on frog-mediated passive dispersal have been developed in bromeliads, but they usually focus on ostracods and annelids. We investigated the potential for external phoresy of zooplankton (rotifers, cladocerans, copepods) by treefrogs in bromeliad phytotelms. Our hypotheses are that (1) zooplankton composition on frogs’ skin and in phytotelm tanks is similar, and (2) frogs with larger body size carry more propagules of these invertebrates. We filtered phytotelm water (10 to 150 mL) using plankton net (45 µm), and fixed invertebrates with 4% formalin. Frogs were actively collected in and around bromeliads (up to ~1.5 m radius) and then washed with distilled water. Fourteen species of rotifers and three of crustaceans were registered in phytotelm water and frog bodies. We captured 17 frogs with a snout-vent length (SVL) ranging from 2 to 5 cm and belonging to five species: Pristimantis ramagii (Boulenger, 1888), Dendropsophus decipiens (A. Lutz, 1925), Scinax auratus (Wied-Neuwied,1821), S. pachycrus (Miranda-Ribeiro, 1937) and S. x-signatus (Spix, 1824). Among them, 12 (70.59%) had propagules adhered to their bodies, of which the majority (ten individuals) had active zooplankton forms, while only two had dormant eggs. Ten rotifer and two microcrustacean species were recorded adhered to frogs. The zooplankton composition differed between phytotelms and anuran skin, and frog body size does not explain the number of propagules carried, refuting both hypotheses. However, evidence of dispersal was found due to the high number of propagules adhered to anurans. Our study provides evidence that frogs may be potential dispersers of dormant and active forms of zooplankton in bromeliads, through external phoresy.

New and previously known species of Copepoda and Cladocera (Crustacea) from Svalbard, Norway – who are they and where do they come from?

Arctic landscapes are characterised by an immense number of fresh and brackish water habitats – lakes, ponds and puddles. Due to a rather harsh environment, there is a limited number of species inhabiting these ecosystems. Present biological communities are impacted and changed by recent climate-driven regime shifts. New species may appear, and existing communities may become supressed or even disappear depending on how their ecological needs interact with ongoing changes. This study provides data on presently existing and probably recently arriving fresh and brackish water microcrustacean species in Norwegian High Arctic - Svalbard archipelago. The study focused on two taxa groups, Cladocera and Copepoda and altogether we found seven taxa new for Svalbard: Alona werestschagini, Polyphemus pediculus, Diaptomus sp., Diacyclops abyssicola, Nitokra spinipes, Epactophanes richardi and Geeopsis incisipes. Compared with an existing overview for the area, our study increased the number of species by more than 20 %, and some of the new species have never been found that far north. Finally, we present a complete and critically updated revised species list of fresh and brackish water cladocerans and copepods for Svalbard.

Notes on Halicyclops (Copepoda, Cyclopoida, Cyclopidae) from Colombia and the western Caribbean: a new record with a key to species of Group “B” sensu Rocha (1991)

Three species of brackish waters microcrustaceans are herein recorded; they belong to the cyclopoid copepod genus Halicyclops and were collected from a coastal system in northern Colombia: H. exiguus Kiefer, 1934, H. venezuelaensis Lindberg, 1954, and H. hurlberti Rocha, 1991. The former has intraspecific variations that deserve further study. The finding of the latter species, previously known from the Eastern Tropical Pacific, represents a new record for Colombia and the Caribbean Sea Basin in the Northwestern Tropical Atlantic. With the finding of H. hurlberti the number of species of Halicyclops known from the Neotropical region and Colombia increases to 20 and 5, respectively. The regional diversity of the genus is probably underestimated. A key to species of the genus belonging to group “B” sensu Rocha (1991) is also provided.

Assessing Cladocera and Copepoda individual disturbance levels in hydrologically dynamic environment

Microcrustacean species (Cladocera, Copepoda) as a significant component of the plankton assembly play diverse roles in floodplain ecosystems and cope with the heterogenic environment differently. Since alterations in the hydro regime are considered disturbance events for zooplankton development, we assessed whether and to what extent are Cladocera and Copepoda exposed to disturbances caused by hydro regime alterations in a floodplain lake. To evaluate the disturbance levels for individual microcrustacean assemblage in different water layers and between different hydrological phases, we applied the abundance/biomass comparison (ABC) method. Recorded microcrustacean assemblages highly depended on the hydrological state of the waterbody and diverged accordingly. Cladocera demonstrated to be more sensitive to change in specific environmental parameters like conductivity, temperature and transparency, while Copepoda exhibited no limitation by ecological variables. Although both groups were influenced by the bottom–up and top–down control, different disturbance intensity was recorded for the individual microcrustacean class. An undisturbed condition during isolation of the Lake allowed Cladocera to reach equilibrium while both microcrustacean groups exhibited moderate to high levels of disturbance following inundation. Regarding disturbance intensity, Cladocera expressed a weak distinction following hydro regime and water layer replacement. On the other hand, Copepoda disturbance levels notably depended on the position in the water column within a specific hydrological phase. Results of the ABC analyses gave a good representation of a real community dispersal in the studied Lake. However, more research is needed to re-evaluate here given levels of disturbance properly.

The first data on the freshwater microcrustaceans of Shokalsky Island (Russian Arctic).

BackgroundInformation on freshwater invertebrates of the Russian Arctic is very scarce, especially concerning insular biota. The species composition of microcrustaceans (Cladocera, Copepoda) of many arctic islands is still unknown and have never been explored. Here we report the results of the first investigation of the zooplankton of the Shokalsky Island (Yamalo­Nenets Autonomous Okrug, Russia).Information on freshwater invertebrates of the Russian Arctic is very scarce, especially concerning insular biota. The species composition of microcrustaceans (Cladocera, Copepoda) of many arctic islands is still unknown and have never been explored. Here we report the results of the first investigation of the zooplankton of the Shokalsky Island (Yamalo­Nenets Autonomous Okrug, Russia).New informationThe new records reported here are novel for the region and significantly expand the knowledge of the high­-latitude aquatic biota. We studied the species composition of Cladocera and Copepoda of 21 freshwater habitats located on the south­western part of Shokalsky Island. We found 15 species of microcrustaceans in total and all of them are reported for the first time here. Also, the obtained data expand the existing ranges of distribution of some species and report several new taxa for the whole Yamalo­Nenets region of Russia.