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The Daphnia longispina complex (Crustacea: Cladocera) contains several keystone freshwater species such as D. longispina O.F. Müller ( D. rosea Sars is a junior synonym), D. galeata Sars, D. cucullata Sars, and D. dentifera Forbes. The complex is common throughout the Holarctic, but there are several geographic regions where local forms have been assigned to European species names based on a superficial morphological resemblance. Here we examine the species status of a form that was previously assigned to D. rosea from a montane bog pond on Honshu, Japan. We used two nuclear non-coding loci (nDNA), mitochondrial sequences (the ND2 protein-coding region) and morphology for evidence. The mitochondrial gene evidence supported the existence of a divergent lineage that is more closely related to D. galeata than to D. dentifera . However, morphology and the nuclear DNA data indicated a lineage that is most closely related to D. dentifera . As our evidence supported the existence of a cohesive divergent lineage, we described a new species, Daphnia japonica sp. nov. Recognition of local and subalpine diversity in this group is critical as ongoing anthropogenic disturbance has been associated with introductions, local extirpations, and hybridization., Competing Interests: The authors declare that they have no competing interests., (© 2022 Kotov and Taylor.)

Only a small proportion of the world's crustacean taxa is adapted to limno-terrestrial microhabitats that are disconnected from conventional surface waterbodies. In rare occasions, water films on terrestrial tropical and subtropical vegetation may also harbour specialised cladocerans. Bryospilus Frey, 1980 (Chydoridae) is the only genus within the class Branchiopoda that is specialised to living almost exclusively in water-saturated terrestrial moss patches, leaf litter, and phytotelms. The remarkable waterflea lineage, which has a suite of highly unusual characters within the family, has been found in terrestrial habitats in rainforests of West Africa, South and Central America, and New Zealand. We discovered a new moss-inhabiting chydorid from western India, Bryospilus (Indobryospilus) bharaticus n. sp. , the first representative of the genus from the Oriental Region. Its morphology and behaviour are highly unusual for a species of Bryospilus. In comparison to its congeners, the new species can swim and it has significantly less oligomerisation, with three terminal setae on the antennal endopod instead of two and seven exopod setae on the third limb instead of six, among other features. We define a new subgenus Indobryospilus nov. and we amend the genus Bryospilus. The new species is a living evolutionary connection, characterised by a phenotype which provides us with new clues about evolutionary transitions in the only terrestrial branchiopod genus. Our results are informative beyond Cladocera, as the morphology of this species provides insights about the evolution and parallelisms of aquatic crustaceans that have specialised in limno-terrestrial habitats. We revisit the morphology of the genus, the disjunct biogeographical pattern with a potential ancient signature, and discuss the functional adaptations of these cladocerans to life on land, as well as convergences with subterranean lineages. A new key to the world species of Bryospilus species is included. [ABSTRACT FROM AUTHOR]

The Cerrado is home of the headwaters of some important Brazilian basins. Such biome has a high diversity of animal and plant species with a high degree of endemism. This premise is well documented for microcrustaceans of the Superorder Cladocera, although many areas still need sampling. In this context, the objective of the present investigation was to evaluate the geographic distribution and richness of Cladocera in the Cerrado biome. The analyzed data were obtained from the authors database on Brazilian Cladocera and distributed according to the hydrographic regions comprised in the biome. Species distribution models were used to determine the areas with the highest probability of occurrence of Cladocera. We analyzed 125 publications, resulting in 2829 records. In total, we obtained 161 taxa, belonging to 48 genera and seven families. Regarding the Hydrographic Regions, Paraná presented the highest richness, followed by TocantinsAraguaia and São Francisco. Our result indicates that most studies are concentrated in certain areas. Furthermore, the species distribution models indicated that transition areas between biomes have the highest probability of occurrence of genera and families. Our results indicate significant gaps in the knowledge, making it necessary to expand inventories and ecological studies in areas still unsampled. [ABSTRACT FROM AUTHOR]

Thirty-five cladocerans species are recorded from La Española lagoon in the Orinoquia region of Colombia; all are new records for Meta Department and 10 for Colombia. With the addition of these new reports, the total number of cladocerans for Colombia and the Meta department is increased by 124 and 38 species, respectively. The cladoceran fauna from the surveyed area is represented mainly by widespread species, commonly found in the Neotropical regions, but local morphological data are scarce in the regional literature. Brief diagnostic description of 18 species of cladoceran fauna recorded of the Meta department-Colombia are provided together with illustrations of taxonomically significant appendages, morphological remarks, notes on the variability of some species, and their distribution. [ABSTRACT FROM AUTHOR]

The enigmatic acid-resistant mesofossil genus Kuqaia is emended, a new species (Kuqaia scanicus) is instituted, and three established species are described from the Lower Jurassic (lower Pliensbachian) of the Kävlinge BH-928 core, in southern Sweden. Kuqaia has a distribution across the middle northern latitudes of Pangaea and is restricted to Lower to lower Middle Jurassic strata. Morphological characters support Kuqaia being the ephippia (resting egg/embryo cases) of Cladocera (Crustacea: Branchiopoda), and a probable early stem-group taxon of the Daphnia lineage. The paleoecology of the small planktonic crustaceans indicate purely fresh-water environments, such as lakes or ponds, all occurrences being in continental deposits, and the Kuqaia specimens possibly represent dry-season resting eggs. Chemical analyses of these and similar fossils, and of extant invertebrate eggs and egg cases are recommended to improve resolution of the biological affiliations of such mesofossil groups. [ABSTRACT FROM AUTHOR]

Abstract Water fleas of the genus Daphnia have been a model system for hundreds of years and is among the best studied ecological model organisms to date. Daphnia are planktonic crustaceans with a cyclic parthenogenetic life-cycle. They have a nearly worldwide distribution, inhabiting standing fresh- and brackish water bodies, from small temporary pools to large lakes. Their predominantly asexual reproduction allows for the study of phenotypes excluding genetic variation, enabling us to separate genetic from non-genetic effects. Daphnia are often used in studies related to ecotoxicology, predator-induced defence, host–parasite interactions, phenotypic plasticity and, increasingly, in evolutionary genomics. The most commonly studied species are Daphnia magna and D. pulex, for which a rapidly increasing number of genetic and genomic tools are available. Here, I review current research topics, where the Daphnia model system plays a critical role.

The Taxonomic Catalog of the Brazilian Fauna (CTFB) is an initiative involving the effort of hundreds of researchers in several institutions, including international partners. Its main objective is to make public and give free access to a checklist of valid species occurring in Brazil. This catalog includes information on Cladocera, a group of microcrustaceans that occupy inland water and marine ecosystems. In this study, we evaluated the Cladocera part of the Brazilian Fauna Catalog. Among the taxa described or reported, we observed 155 valid species (37 endemic) and 61 genera (2 endemic) distributed in 11 families. European researchers represented 50% of all the authors involved in descriptions of species, and European collections keep most primary types, although many species have types that have been lost or not designed. Brazilian researchers were involved with a large number of descriptions, especially in the last 15 years. Our findings indicated that Cladocera taxa were observed in all hydrographic regions (Paraná with 119 species), biomes (Atlantic Forest with 126 species) and states, except state of Rondônia. The catalogue of Brazilian cladoceran fauna should be improved, as there are still large geographic ranges to be sampled in Brazil. [ABSTRACT FROM AUTHOR]

Freshwater microcrustaceans in the southern part of the Kamchatka Peninsula are relatively well-known, however, little research has focused on the northern part of the peninsula. Moreover, relatively few data are available on small water bodies, since most of the studies focused on large lakes and estuarine waters. Here, we present the first data on the microcrustaceans of Karaginsky Island (Kamchatka, Russia) and the adjacent mainland. A total of 100 species, including Branchiopoda, Copepoda, Ostracoda and Amphipoda, were observed in the studied area, which significantly expands our knowledge about the local fauna. Thirty-five species were newly recorded for the Kamchatka Peninsula, and three taxa were new for the whole territory of Russia. At least four taxa showed striking deviations from the typical morphology. The general faunistic composition of Karaginsky Island appears to be typical of Northeast Asia, with a prevalence of Palearctic and cosmopolitan taxa and a smaller proportion of East Asian and Beringian endemics. The faunistic diversity of Karaginsky Island is still not completely revealed, and more surveys are needed to have accurate estimations of biodiversity there. [ABSTRACT FROM AUTHOR]

The gene FoxO plays an important role in regulating individual growth and development, cell survival, and senescence, mainly through transcriptional regulation and the signal transduction pathway. In this study, the full-length cDNA sequence of the FoxO gene was cloned from Daphnia pulex. FoxO was silenced by RNA interference. The expression levels of the senescence-related genes FoxO , Akt , and Sir2 were analysed before and after interference by real-time polymerase chain reaction and Western blotting. Meanwhile, the production of an ephippium in D. pulex was evaluated before and after interference. The expression of FoxO and protein abundance decreased after interference. The number of ephippia produced in the Akt interference group was higher than in the two control groups, and the expressions of the senescence-related genes Akt and Sir2 decreased after interference. The results indicate that FoxO regulated senescence, primarily through the phosphorylation of Akt and acetylation of Sir2 , thereby affecting the reproductive transformation of D. pulex. [ABSTRACT FROM AUTHOR]

The embryonic stages of the anomopod Bosmina longirostris of the family Bosminidae were elucidated by scanning electron microscopy. Along with the corresponding stages of Bosmina coregoni described by Kotov (2001), these findings have enabled a comparison to Dunhevedia crassa , as a representative species of the family Chydoridae, and to Eurycercus lamellatus of the family Eurycercidae. In general, the developmental patterns are similar in these four species, particularly from blastulation to the first instar. The principal difference during embryogenesis is that in D. crassa and B. longirostris five thoracopods (six in E. lamellatus) are differentiated already with endo- and exopodites. [ABSTRACT FROM AUTHOR]

Non-indigenous species may pose a threat to native ecosystems worldwide. In aquatic environments, invasives may have a negative impact on human food security and livelihoods. Several water fleas (Crustacea: Branchiopoda: Cladocera) are notorious invasive alien species influencing large freshwater lake systems and even inland seas. In the current review, we discuss the state of knowledge regarding non-indigenous species in the Cladocera and their invasiveness potential in different continents. We argue that the potential impacts and occurrence of cladoceran exotics may be higher than generally assumed. We critically review 79 cases from literature sources, involving 61 cladoceran taxa where records outside of their natural distribution ranges were previously interpreted as invasions. We assessed the probability of natural range expansions versus human-mediated introductions and we discuss several major corridors of invasion. We estimate human-mediated transportations for at least 43 taxa (out of 61; ca 70%), while other cases can be seen as natural expansions of their distribution ranges (not necessarily/not likely human-mediated) and/or taxonomical confusion. We confirm non-indigenous presence in recipient regions for at least 41 cladoceran taxa, of which several are true invasives (i.e., with negative impacts on native ecosystems). The majority are zooplankters with effects on pelagic freshwater ecosystems, yet we also report on introductions by littoral taxa. We argue that cryptic introductions of cladocerans are taking place on a global scale, yet they remain under the radar. We highlight several striking case studies, such as the Ponto–Caspian onychopods that have invaded the Baltic Sea and the Laurentian Great Lakes, and several clones of the anomopod genera Daphnia and Bosmina that have successfully colonised new environments, causing equilibria shifts in native aquatic worlds. At the same time, we dispel some myths about taxa that were misconstrued as invasive in certain localities. Based on our review, the first of its kind for freshwater zooplankton, future environmental monitoring tools including molecular techniques and detailed surveys with rigorous and critical taxonomical assessments may help to provide a clearer picture on the extent of invasiveness of cladocerans. [ABSTRACT FROM AUTHOR]

Water fleas of the genus Daphnia have been a model system for hundreds of years and is among the best studied ecological model organisms to date. Daphnia are planktonic crustaceans with a cyclic parthenogenetic life-cycle. They have a nearly worldwide distribution, inhabiting standing fresh- and brackish water bodies, from small temporary pools to large lakes. Their predominantly asexual reproduction allows for the study of phenotypes excluding genetic variation, enabling us to separate genetic from non-genetic effects. Daphnia are often used in studies related to ecotoxicology, predator-induced defence, host–parasite interactions, phenotypic plasticity and, increasingly, in evolutionary genomics. The most commonly studied species are Daphnia magna and D. pulex, for which a rapidly increasing number of genetic and genomic tools are available. Here, I review current research topics, where the Daphnia model system plays a critical role. [ABSTRACT FROM AUTHOR]

A study of the water fleas (Crustacea: Cladocera) in man-made lakes in the northeast part of the United Arab Emirates revealed five species: Ceriodaphnia cf. cornuta Sars, 1885; Daphnia (Ctenodaphnia) arabica Neretina, Al Neyadi et Hamza, 2022; Moina cf. micrura Kurz, 1875; Anthalona mediterranea (Yalim, 2005); Coronatella anemae Van Damme et Dumont, 2008. The morphologies of the four taxa are described in detail, except that of D. Arabica, which has been described previously. The phylogenies of the C. cornuta and M. micrura species groups were reconstructed based on sequences of the COI mitochondrial gene and the possible divergence age of the Arabian clades was estimated based on molecular clocks with paleontological calibration. We concluded that the C. cornuta complex was differentiated in the Upper Jurassic to Lower Cretaceous. The splitting off of clades containing the Arabian population took place during the Oligocene to Miocene. The M. micrura species group was differentiated in the Upper Cretaceous, and the splitting off of clades including Arabian populations took place around the Oligocene. Therefore, the clades (of different hierarchical orders) in the Arabian Peninsula are very old compared to clades of similar rank in northern Eurasia, which usually have Late Pleistocene history. Most of our sampled water bodies were newly constructed man-made reservoirs. As revealed, the phylogroups are locally distributed, and we hypothesized that they are colonists from surrounding natural water bodies inhabited by the relicts of older fauna that survived after the great climate aridization and then occupied newly available (man-made) biotopes. [ABSTRACT FROM AUTHOR]

The class Branchiopoda, whose origin dates back to Cambrian, includes ~ 1200 species which mainly occupy freshwater habitats. The phylogeny and systematics of the class have been debated for long time, until recent phylogenomic analyses allowed to better clarify the relationships among major clades. Based on these data, the clade Anostraca (fairy and brine shrimps) is sister to all other branchiopods, and the Notostraca (tadpole shrimps) results as sister group to Diplostraca, which includes Laevicaudata + Spinicaudata (clam shrimps) and Cladoceromorpha (water fleas + Cyclestherida). In the present analysis, thanks to an increased taxon sampling, a complex picture emerges. Most of the analyzed mitogenomes show the Pancrustacea gene order while in several other taxa they are found rearranged. These rearrangements, though, occur unevenly among taxa, most of them being found in Cladocera, and their taxonomic distribution does not agree with the phylogeny. Our data also seems to suggest the possibility of potentially homoplastic, alternative gene order within Daphniidae. [ABSTRACT FROM AUTHOR]

Base metal smelting activity around Sudbury (Ontario, Canada) has persisted for over a century, emitting metals and acidifying contaminants that affected lakes downwind of smelter stacks. Although considerable research has been directed toward the paleolimnological study of diatoms and chrysophytes in the region, relatively little comparable work has been completed on invertebrates. Here, cladoceran (Branchiopoda: Cladocera) assemblages are compared using a paleolimnological "top-bottom approach", comparing preimpact and recent assemblages. Spatiotemporal differences were likely driven by acidification-related stressors and legacy effects of metal contamination. The replacement of the Daphnia longispina complex with the Daphnia pulex complex is attributable to diminished lake-water calcium concentrations. Increased abundances of early colonist taxa demonstrate that many acidified lakes have not fully recovered. Regional stressors further complicate recovery and the interpretation of temporal changes. Finally, clustering of recent cladoceran assemblages reflects the effects of modern multiple stressors and persistent historical stressors. This study shows that acidification history partially explains differences in cladoceran assemblages, but also that multiple stressors will likely continue to influence assemblage composition and recovery in Sudbury lakes. Defining appropriate reference conditions, considering historical and modern stressors, will be important when assessing the extent and trajectory of ecosystem recovery from widespread anthropogenic impacts. [ABSTRACT FROM AUTHOR]

Analysis of Cladocera (Crustacea: Branchiopoda) subfossil remains in lake sediments features prominently in paleolimnological studies. It is well known, however, that species composition in a taphocoenosis (assemblage of subfossil remains in sediments) does not represent perfectly that of the original living community (biocoenosis) from which it came. We analyzed the representation of different Cladocera skeletal components in sediments of 27 Russian water bodies to compare two methods of enumerating relative abundances of cladoceran remains: (1) recording the number of most abundant fragments of each taxon to represent the number of individuals, and (2) recording each fragment of a taxon as belonging to an individual specimen. Overall, for all cladoceran taxa and all water bodies sampled, proportions of different skeletal components differed from what would be expected based on those in live individuals. Carapaces were the most abundant component in 23 of 27 water bodies. Head shields were common, but predominated in only four samples, whereas postabdomens were rare, accounting for < 10% of the whole sample set. Several hypotheses are proposed to explain the different proportions of cladoceran skeletal remains in sediment samples. Both methods for counting remains yielded similar relative abundance estimates for different taxa, which can be regarded as evidence that both methods are adequate, with some exceptions. For example, Alona affinis was represented by a relatively high portion of postabdomens, a component that for other taxa was usually poorly represented. In general, recording of the total number of skeletal components, as compared to using the most abundant fragment method (MAF), slightly overestimates the significance of some taxa in the community. Disproportionate preservation of different skeletal components among cladoceran taxa does not compromise the results of cladoceran-based paleoecological analyses using either counting method, but should be considered when interpreting results. [ABSTRACT FROM AUTHOR]

In the aquaculture of fish and crustaceans, the indoor culture of M. macrocopa constitutes a requisite to produce a more effective feed for the larviculture of the cultured commercial species. The present study examined the efficiency of different diets on population density, survival, and productivity of M. macrocopa. The cladocerans [Cladocera: currently largely referred to as Diplostraca] were fed and enriched with seven diets, including Chlorella sp., agro-industrial residues (rice bran and soybean meal), bio-organic fertilizer (chicken manure and swiftlet waste), canola oil and artificial micro pellets. The diets were provided at a concentration of 500 mg/l for each diet. The M. macrocopa fed on rice bran had a higher population density, survival, productivity, and a promising higher nutrient quality than the test groups fed on the other dietary treatments used. This study has covered the most important aspects of nutritional requirements to produce live feed organisms, which would provide a comprehensive data set for an alternative solution of the best feed for M. macrocopa propagation and their utilization in hatcheries. Résumé: En aquaculture de poissons et de crustacés, l'élevage en intérieur de M. macrocopa constitue un prérequis pour produire une nourriture plus efficace pour la production de larves des espèces commerciales élevées. Cette étude examine l'efficacité de différents régimes sur la densité de population, la survie et la productivité de M. macrocopa. Les cladocères [Cladocère : actuellement largement nommé Diplostraca] ont été nourris et enrichis avec sept régimes, incluant Chlorella sp., des résidus agro-alimentaires (riz brun et farine de soja), engrais bio-organiques (fumier de poulet et déchets de salangane), huile de canola et micro granulés artificiels. Les régimes ont été donnés à une concentration de 500 mg/l chacun. Les M. macrocopa nourris avec le riz brun ont eu une densité de population, une survie, une productivité plus élevées, et une qualité nutritive potentiellement plus élevée que les groupes nourris avec les autres régimes testés. Cette étude s'est intéressée aux aspects les plus importants des besoins nutritionnels pour produire une nourriture vivante, et pourrait fournir un ensemble de données pour une solution alternative à une meilleure nourriture pour M. macrocopa et leur utilisation généralisée en écloseries. [ABSTRACT FROM AUTHOR]

A core of bottom sediments of 4.98 m depth has been taken from Lake Rubskoe, Ivanovo area (central part of the East European Plain). According to radiocarbon dating, the age of the lower layer of the core is 11 000 cal BP. A study of 23 samples has revealed the remains of 38 taxa of Cladocera (Crustacea: Branchiopoda). According to Lyubarsky's scale, there are no dominant taxa among the cladocerans; Chydorus cf. sphaericus (Müller, 1776) and Bosmina (Eubosmina) cf. longispina (Leydig, 1860) are subdominant taxa. Typical arctic species that had inhabited the lake at the earlier stages of its formation were replaced by taxa that preferred temperate conditions during the development of the water body. Four faunistic zones have been identified on the stratigrhaphic diagram of the cladoceran community of Lake Rubskoe. An increase in the proportion of Bosmina (Eubosmina) cf. longispina in the layers of 8500 cal BP may have been related to an increase of the pelagic area of the water body at that period. In many cases, it is obvious that the rates of certain taxa in the taphocoenosis of Lake Rubskoe correlate with the climatic changes reported at that time. [ABSTRACT FROM AUTHOR]

Despite extensive records of chemical recovery, relatively little is known about recovery of aquatic biota in Sudbury (Ontario, Canada). Cladocera (Branchiopoda) are key components of lake food webs, and understanding spatial patterns in their assemblages may emphasize ecosystem recovery challenges. Paleolimnological techniques complement and provide long-term context to modern monitoring. Cladoceran remains from the surface sediments of 67 lakes across a gradient of smelter impacts were examined to determine which measured limnological factors most influenced assemblage composition. Lakes were divided into four categories by acidification histories and location: Acidified (pH < 6) Urban, Non-urban Acidified, Acidified Killarney, and Reference (pH > 6) lakes. Specific conductance, nutrients, alkalinity, and lake depth significantly structured assemblages. Most assemblages were dominated by generalist taxa. Relative abundances of Alona taxa varied strongly along alkalinity and pH gradients. Lakes with high metal concentrations were generally less diverse and dominated by generalist taxa, although metals often co-occurred with other stressors. Recovery targets could be affected by these chemical factors. These data provide useful information for future environmental inferences from cladocerans in metal smelting regions. [ABSTRACT FROM AUTHOR]

Cladocerans, also referred to as "water fleas", are a special group of crustacean zooplankton, noteworthy for their highly nutritive value as "natural live feed" in aquaculture practices and also for maintaining ecosystem stability. Geographically, in eastern India, the district West Midnapore in West Bengal is a part of unique red lateritic soil region known as the "Rarh belt" or "Rarh Bengal". Due to this characteristic edaphic and topographical feature the biodiversity status of the wetlands herein are of special significance. An attempt was made to record the cladoceran species diversity in three ecologically contrasting freshwater bodies (a fishpond, a village pond, and a forest pond) in Garhbeta I block, in the northern fringe of West Midnapore district, West Bengal, India. The study revealed the presence of a total of 16 cladoceran species among the three study sites. Chydoridae (56%) was found to be the dominant family followed by Moinidae (19%). The fish pond (13 species) contained the highest species diversity followed by the forest pond (10 species) and village pond (eight species) respectively. The study showed that cladoceran species diversity seemed to be positively correlated with presence of nutrients. The species diversity was associated with the eutrophication status, ecosystem stability and productivity levels of the wetlands. The maximum species diversity was found in the pre-monsoon and least in the monsoon period. Thus, increase in temperature indicated a positive correlation with species diversity. The Shannon-Weiner index (H') value ranged between 1.81 and 2.50 among the three sites, indicating overall moderately stable ecosystems. The one-way ANOVA results indicated that the variation in H' value across different seasons was not statistically significant, but statistically significantly differed among different sites. Similar trends were seen for species evenness index and other diversity indices as well. Bray-Curtis cluster analysis based on species distribution indicated Site I and Site III were more similar as compared to Site II. However, as the recorded species count was less than the overall species diversity (63 species) recorded in the region, further studies are recommended for greater exploration of the group in the area. [ABSTRACT FROM AUTHOR]

Biological invasions are known to be among the most important threats to the long-term conservation of native biota, and their effects might be even more difficult to contrast when they are cryptic, i.e., when the non-native invaders cannot be easily recognised based on morphology, and can thus be confused with native taxa. Such cryptic invasions are known to widely occur in the cladoceran genus Daphnia O.F. Müller, 1785, so that the actual distribution and status of most species and lineages need to be checked with a genetic approach. In the frame of this work, we investigated if the Sicilian populations of D. (Daphnia) pulex Leydig, 1860 belonged to the allochthonous North American lineage, which is known to occur in several regions of the Palearctic and Afrotropical biogeographical regions, or rather to the autochthonous European lineage of the species. The molecular results obtained, based on a fragment of the mitochondrial gene encoding for NADH subunit dehydrogenase 5 (ND5), allowed us to rule out the allochthonous status of the species, confirming the presence of autochthonous relictual lineages of D. pulex in Sicily. The native status of these populations is in agreement with their local distribution, limited to natural and poorly-impacted water bodies mostly located in wooded areas at medium and high altitudes. The current local distribution of D. pulex in Sicily is possibly linked to the end of the last glacial maximum and the onset of warmer climatic conditions in the early Holocene, which led the species to take refuge in colder microthermal refugia located at high altitudes, determining their current relictual distribution. [ABSTRACT FROM AUTHOR]

In Yellowknife (Northwest Territories, Canada), roaster stack emissions from historic gold mining activities, particularly Giant Mine (1948–2004), have left a legacy of arsenic contamination in lakes. We examined Cladocera (Branchiopoda, Crustacea) subfossil remains in the recent and pre-industrial sediments of 23 lakes (arsenic gradient of 1.5–750 µg/l) within a 40 km radius of Giant Mine to provide a snapshot of regional change in Cladocera since pre-1850. We found that littoral and benthic taxa dominated the recent assemblages in high-[As] lakes (surface water [As] > 100 µg/l), while pelagic Bosmina was dominant in lakes with lower [As]. Cladocera richness and diversity were positively correlated with [As] (P = 0.004, R2 = 0.39; and P = 0.002, R2 = 0.46, respectively), except for four lakes with [As] > 100 µg/l. The lakes that showed the most pronounced changes in Cladocera since pre-1850 were those affected by both metal(loid) pollution and urban development, where complete shifts in the dominant taxa occurred. Lakes that were most heavily impacted by arsenic emissions did not experience notable shifts in Cladocera assemblages. Our study suggests that changes in Cladocera assemblages in mining-impacted subarctic lakes are modulated by local, lake-specific limnological conditions and the interaction of multiple stressors. [ABSTRACT FROM AUTHOR]

The branchiopod Eurycercus lamellatus is widely distributed in Norwegian lakes, ranging from coastal to alpine areas. On the Hardangervidda mountain plateau in southern Norway, E. lamellatus was searched for in 144 lakes in 11 catchments in the western and 16 catchments in the central and eastern areas. Their occurrence is mainly based on the diet of brown trout Salmo trutta. Eurycercus lamellatus was recorded in 25% and 70% of the lakes in these two areas, respectively. This may be due to striking differences in the environmental conditions, with more dilute water and lower water temperatures in western areas, and hence shorter growing seasons. The occurrence of E. lamellatus in central and eastern catchments increased with lake size, being found in 65% and 85% of lakes with a surface area of 400 mm). However, under high predation pressure, E. lamellatus also contributed significantly to the diet of larger fish. The abundance of E. lamellatus seems to vary highly on a yearly basis in one of the lakes (Sandvatn). Even though E. lamellatus is described as a typical littoral species, it was common down to depths of 15 m.

In 2018, the water flea, Ilyocryptus spinifer Herrick 1882 (Cladocera, Ilyocryptidae), was found for the first time in the Vetluga River, Nizhny Novgorod Region, European Russia. This species with a benthic phytophilic mode of life belongs to the southern thermophilous complex of cladocerans and shows a circumtropical distribution pattern. So far, I. spinifer has never been found in Europe, sporadic records of this species were known only from few southern regions in the Asian part of Russia. The invasion of I. spinifer to relatively high latitudes may be related to a natural distribution range expansion due to global climate warming, to transfers via migratory birds, and/or with ballast waters in ships. In any case, further monitoring of the revealed populations is very important to control the water ecosystem conditions in Russia and other countries. [ABSTRACT FROM AUTHOR]

Carcasses of mammals with well-preserved soft tissues from the permafrost of Siberia and northern North America are among the most important sources of our knowledge on Quaternary environments. However, the potential of this information source is far from being exhausted. The objective of this study is to reveal and describe the remains of freshwater invertebrates in the hair and gut contents of large Pleistocene mammals stored for a long time in museum collections. We have studied the gut contents of two mammoths, as well as the hair of two other mammoths, one woolly rhinoceros, four bison, and two horses. Remains of invertebrates were found in the gut contents of both mammoths, as well as in the hair of two mammoths and the woolly rhinoceros, while no remains were detected in the bison and horse hair. Among the remains of microscopic invertebrates, the most common are branchiopod crustaceans, namely the ephippia of Daphnia sp., Simocephalus sp., the head shields and valves of Chydoridae (Cladocera), and the mandibles of tadpole shrimps (Notostraca). Based on our current level of knowledge, we are able to identify only a limited number of Pleistocene branchiopods. Studies on Recent taxa with the aim to develop identification keys to the aforementioned groups are needed, as they could significantly expand the potential of palaeoecological analysis. [ABSTRACT FROM AUTHOR]

A new technique for the optimization of the taxonomic study of cephalic openings in Branchiopoda is proposed here. The study of the cephalic openings in the various taxa that constitute this clade is of great importance. This is true not only for taxonomic studies, being fundamental for species identification in the Chydoridae, but also for phylogenetic and physiological investigations. For this, currently available protocols include the use of electron microscopic analysis, using the whole specimen, or the use of optical microscopy, by removing the cephalic shield from the specimen and mounting it on slides. This work presents a simple technique for the study of cephalic openings in Branchiopoda, facilitating their study, particularly for those associated with the Chydoridae. [ABSTRACT FROM AUTHOR]

Cladocera (Crustacea: Branchiopoda) quickly respond to changes in environmental conditions and their remains are usually found in large amounts in lacustrine sediments, which make them an important biological proxy in paleolimnological studies. Variations in species composition have been used to infer paleo-climate and paleo-environmental variables including lake depth, eutrophication, and deforestation. However, despite their advantages as bioindicators in the study of past conditions, they are underutilized in paleolimnological research in Central America due to limited knowledge about their diversity and the morphological differences between the subfossil remains of different taxa. In order to address this issue, we described and analyzed cladoceran remains from 56 waterbodies located in Mexico, Guatemala, El Salvador, and Honduras. Here, we provide a description of the remains from 10 different taxa that belong to the Sididae, Bosminidae, Daphniidae, Macrothricidae, and Ilyocryptidae families. [ABSTRACT FROM AUTHOR]

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Use of subfossil cladoceran remains for paleolimnological studies in Mesoamerica, especially in Central America, is constrained by the poorly known composition of cladoceran communities. We examined sediments from 56 waterbodies in Central America (Guatemala, El Salvador, Honduras) and the Yucatan Peninsula (Mexico), and provide illustrations and descriptions of the remains of Chydoridae from the region, emphasizing their diagnostic traits. In total, 36 Chydoridae taxa, representing 24 genera, were recognized. The illustrations and descriptions of chydorid subfossils included here will enable paleolimnologists to recognize and identify such remains in lake sediment cores, thereby facilitating paleoenvironmental inferences from lake sites in Mesoamerica. Furthermore, data included here expand knowledge about the geographic distributions of Neotropical chydorids. [ABSTRACT FROM AUTHOR]

The embryological development of Ceriodaphnia reticulata Dumont & Pensaert, 1983 and Scapholeberis rammneri Jurine, 1820 were investigated using scanning electron microscopy. A carapace spine did not develop and there was no fusion of the first antennae. These are apparent apomorphies of Daphnia Müller, 1785 , which suggests that the common ancestor of Daphniidae Straus, 1820 did not have a carapace spine during its embryological development, and its first antennae were short and separated during embryogenesis. Morphological evidence thus appears congruent with molecular interpretations showing that Scapholeberis Schoedler, 1858 is basal to other genera of Daphniidae, Ceriodaphnia being a sister taxon to Daphnia. [ABSTRACT FROM AUTHOR]

The purpose of this study is to analyze the taxonomic composition of the branchiopod crustaceans (Crustacea: Branchiopoda) from the assemblage of animal and plant remains recovered from fossil mammoth hair found in the Allaikha River basin, Sakha Republic, Russian Federation. We studied the hair structure. AMS radiocarbon dating of both the hair itself and the remains demonstrated their different ages. We found different animal and plant remains in the hair taphocoenosis. The most diverse and numerous remains belong to branchiopod crustaceans: resting eggs and distal portions of the mandibles of Anostraca, distal portions of the mandibles of Notostraca, filtering limbs of some Anostraca or Daphniidae, ephippia of Daphnia (Daphnia) curvirostris, Daphnia (Ctenodaphnia) atkinsoni, and D. (C.) magna. No representatives of D. (Ctenodaphnia) now occur in northeastern Eurasia, but our findings of numerous ephippia in the fossil hair of two mammoths, one from the Allaikha River and the other, studied previously, from the Bol'shaya Chukochya River basin (see Kirillova et al., 2016), show that Daphnia (Ctenodaphnia) taxa occurred in the region at least in the past and were probably common and widely distributed there. The reasons for the extinction of Daphnia (Ctenodaphnia) in northeastern Eurasia require additional special study. We also emphasize the need for further studies of the morphology of ephippia, resting eggs, and mandibles of recent Branchiopoda, which would be essential for adequate identification of Pleistocene remains. [ABSTRACT FROM AUTHOR]

Daphnia pulex is a freshwater microcrustacean that is known for its cyclical parthenogenesis. In D. pulex , parthenogenetic reproduction switches to sexual reproduction when the living conditions worsen. However, this transformation also occurs over age under favourable living conditions. Thus, there might be a relationship between aging and reproductive conversion. We performed Illumina RNA sequencing, generating 51 712 680 and 59 854 588 raw reads from 1 day-old D. pulex and 25 day-old D. pulex , respectively. From these reads, 60 776 transcripts were assembled and 36 569 (60.15%) unigenes were annotated. A number of significantly differentially expressed genes associated with growth, aging, and reproduction were identified and Quantitative real-time PCR for six genes confirmed the transcriptome data. RNA interference (RNAi) of the caspase-3 gene (casp3) that is a key gene for growth, development, aging, and reproduction, was conducted, which achieved an 80% reduction in casp3 mRNA expression. Meanwhile, the mRNA expression of upstream genes jnk and akt , and sir2 (encoding a substrate of casp3) were also detected. The change of jnk mRNA expression before and after RNAi was not significant (P > 0.05) and the mRNA levels of sir2 decreased, while akt increased after casp3 RNAi (P < 0.05). The results indicated the interrelationships of some genes in the senescence pathway and helped to identify the molecular mechanism of the aging progress in D. pulex. Overall, the difference in mRNA expression profile during aging of D. pulex forms a basis for further studies aimed at understanding the role of the transcriptional level in regulating aging and reproductive transformation. [ABSTRACT FROM AUTHOR]

Based on the specimens collected in four surveys at eight sites in major rivers in Vinh Long province during 2013 through 2014, the total of eighteen species of cladoceran, belonging to 14 genera, 7 families and 2 orders, were recorded. The cladocerans fauna in Vinh Long province is moderately diverse, and almost all the species were common. Among eighteen species, Grimaldina brazzai Richard, 1892 is a rare species. A total of four females specimens of species G. brazzai were collected at the Co Chien river, but male specimens were absent. The specimens were morphologically identified as G. brazzai described first by Richard (1892), followed by Brook (1959), Idris (1983), Smirnov (1992) and Hollwedel (2003). Grimaldina brazzai is currently the only one species in the genus Grimaldina and has been recorded in several tropical countries, such as Brazil, Cambodia, Indonesia, Laos, Malaysia, Philippines, Singapore and Thailand. They occur in lakes and rice fields, but population of this species is very limited in nature. In Vietnam, this species was previousely recorded in the South of Vietnam, but has not been described so far. [ABSTRACT FROM AUTHOR]

Since early 2000 years, the knowledge about the taxonomy of Aloninae (Cladocera: Chydoridae) has been in rapid progress. For this reason, the most of Brazilian fauna was affected concerning nomenclature, besides an increase in the number of known genera and species. Thus, in this study, we bring an updated species list of Aloninae in Brazil, as well as identification keys based in current nomenclature and morphological standards. Our finding pointed to the occurrence of 46 valid species, belonging to 21 genera and three groups of Alona sensu lato. Two of these genera are endemic to Brazil. So far, South-East Asia and Brazil have the most well-studied Aloninae fauna in the entire planet. [ABSTRACT FROM AUTHOR]

In recent years, an increase in knowledge about the diversity and biogeography of Brazilian Cladocera fauna has been evident. To keep up with these changes, it is opportune to carry out an update of the taxonomy and biogeography for the main cladoceran groups. Since 2008, some progress has been observed in Ilyocryptidae, with reports of four new taxa. In this study, an updated checklist of Ilyocryptidae from Brazil is provided, with a diagnosis for each cited taxon, as well as an identification key. Some of these taxa are considered rare; however, this issue might be an artifact of sampling. As this is the first in a series of papers compiling current information about Brazilian Cladocera, an identification key to orders and families occurring in Brazil is also provided. [ABSTRACT FROM AUTHOR]

Abstract: Aim: To understand modern and past aquatic community responses to climate‐induced shifts in productivity and ultraviolet radiation (UV) exposure. Location: Tree line ecotone from north boreal forest to subarctic tundra in northeastern Finnish Lapland. Taxon: Cladocera (Crustacea: Branchiopoda). Methods: Thirty‐one small and shallow lakes were examined for summer epilimnetic communities (SEC) and surface sediment fossil integrative communities (FIC) of Cladocera for species distribution and their environmental correlations. A 700‐year down‐core sediment sequence from a tree line lake (Námmájávri) was analysed for FICs and cladoceran‐inferred UV absorbance (ABSUV, indicative of melanin pigmentation) for evidence of long‐term community and photoprotective responses and compared with records of palaeotemperature, solar intensity, and composite sediment biogeochemistry by variance partitioning analysis. Results: The SECs were primarily correlated with specific UV absorbance (indicative of UV exposure) and total phosphorus and FICs by mean July air temperature and total nitrogen. The Námmájávri FICs showed subtle changes with a directional shift between the 19th and 21st centuries and were mostly explained by solar intensity. ABSUV exhibited increases during the 18th and 20th centuries, being related to variation in sediment biogeochemistry, which was indicative of changes in auto‐ versus allochthonous production. Main conclusions: The ecotonal distribution of cladocerans is sensitive to temperature, nutrients, and allochthonous carbon, which is closely linked with UV exposure. The long‐term community shifts and photoprotection have been governed by solar intensity and biogeochemical shifts through lake water optics, attributable to direct UV impact or climate‐mediated intensification in photodegradation of allochthonous carbon. Estimations of the dual effects and mechanisms of increasing temperatures and UV on subarctic lakes and their biota remain challenging as their individual impacts on key species were partly contradictory. [ABSTRACT FROM AUTHOR]

Present study was conducted to assess thePhysico-chemical characteristicsand plankton diversity in Nanaksagar reservoir, located in Tarai region of Uttarakhand. Monthly samplings were conducted at three selected sites duringAugust 2016 to March 2017. The floristic composition of Nanaksagar reservoir contained 23 phytoplanktontaxa belonging to 5 major taxonomic groups namely Chlorophyceae, Bacillariophyceae, Cyanophyceae, Euglenophyceae and Dinophyceae. The maximum numbers of species were contributed by Chlorophyceae. The density of phytoplankton ranged between 90000 and 231333 cells/ litre. Highest value was found in the month of February 2017 while lowest density of phytoplankton were recorded in August 2016. Phytoplankton was found to be positively correlated with zooplankton (0.90), transparency (0.30), specific conductivity (0.34), pH (0.47), DO (0.83) and total alkalinity (0.77). 14 zooplankton taxa belonging to three taxonomic groups namely Rotifera, Cladocera and Copepoda were collected from the reservoir during the investigation period. Maximum number of species was contributed by Cladocera. The population abundance ranged between 2417 and 14067 organisms/litre. Highest zooplankton count was recorded in February at site S1 and lowest in August at site S2. Zooplankton was found to be positively correlated with phytoplankton (0.90), transparency (0.49), specific conductivity (0.18), pH (0.78), DO (0.87) and total alkalinity (0.80). [ABSTRACT FROM AUTHOR]

Comparative analysis of the ontogeny of representatives of two sister taxa (Cladocera and Cyclestherida) showed that the paedomorphic morphology of cladocerans (the small number of thoracic segments and segments of branches of antennae II, and the reduction of the carapace) was caused by the cessation of development of the somatic structures at early larval stages of ontogeny. It is demonstrated that this stop is not associated with the accelerated development of the reproductive system (progenesis), since it takes place long prior to the beginning of reproduction. In accordance with this fact, the past hypotheses that cladocerans evolved from the reproducing larvae of the ancestral form or that they are early maturing metanauplii should be recognized as erroneous. Cyclestheria. The origin of Cladocera from a Cyclestheria-like ancestor should be regarded as neotenic, taking into consideration the extended interpretation of this term. [ABSTRACT FROM AUTHOR]

This series of communications is aimed to report on a study of the water fleas (Crustacea, Cladocera) of Central Yakutia. This first communication provides brief descriptions of the representatives of the families Sididae, Daphniidae, and Ophryoxidae, namely Sida crystallina (O.F. Müller 1776), Diaphanosoma orghidani orghidani Negrea 1982, Diaphanosoma amurensis Korovchinsky et Sheveleva 2009, Diaphanosoma brachyurum (Liévin 1848), Scapholeberis mucronata (O.F. Müller 1776), Scapholeberis rammneri Dumont et Pensaert 1983, Megafenestra cf. nasuta (Birge 1879), Simocephalus cf. serrulatus (Koch 1841), and Ophryoxus kolymensis Smirnov 1992. Remarks are given on the occurrence of these taxa in Northern Eurasia. [ABSTRACT FROM AUTHOR]