First circumpolar assessment of Arctic freshwater phytoplankton and zooplankton diversity : Spatial patterns and environmental factors

Arctic freshwaters are facing multiple environmental pressures, including rapid climate change and increasing land-use activities. Freshwater plankton assemblages are expected to reflect the effects of these stressors through shifts in species distributions and changes to biodiversity. These changes may occur rapidly due to the short generation times and high dispersal capabilities of both phyto- and zooplankton. Spatial patterns and contemporary trends in plankton diversity throughout the circumpolar region were assessed using data from more than 300 lakes in the U.S.A. (Alaska), Canada, Greenland, Iceland, the Faroe Islands, Norway, Sweden, Finland, and Russia. The main objectives of this study were: (1) to assess spatial patterns of plankton diversity focusing on pelagic communities; (2) to assess dominant component of beta diversity (turnover or nestedness); (3) to identify which environmental factors best explain diversity; and (4) to provide recommendations for future monitoring and assessment of freshwater plankton communities across the Arctic region. Phytoplankton and crustacean zooplankton diversity varied substantially across the Arctic and was positively related to summer air temperature. However, for zooplankton, the positive correlation between summer temperature and species numbers decreased with increasing latitude. Taxonomic richness was lower in the high Arctic compared to the sub- and low Arctic for zooplankton but this pattern was less clear for phytoplankton. Fennoscandia and inland regions of Russia represented hotspots for, respectively, phytoplankton and zooplankton diversity, whereas isolated regions had lower taxonomic richness. Ecoregions with high alpha diversity generally also had high beta diversity, and turnover was the most important component of beta diversity in all ecoregions. For both phytoplankton and zooplankton, climatic variables were the most important environmental factors influencing diversity patterns, consistent with previous studies that examined shorter temperature gradients. However, barriers to dispersal may have also played a role in limiting diversity on islands. A better understanding of how diversity patterns are determined by colonisation history, environmental variables, and biotic interactions requires more monitoring data with locations dispersed evenly across the circumpolar Arctic. Furthermore, the importance of turnover in regional diversity patterns indicates that more extensive sampling is required to fully characterise the species pool of Arctic lakes.Peer reviewe

Influence of the Water Level in the Yenisei River on the Ecosystem of its Anabranch within the City of Krasnoyarsk

Расположенная в черте города Красноярска в 35 км ниже Красноярской ГЭС Абаканская протока р. Енисей является, с одной стороны, важным рекреационным водоемом, а с другой стороны, подвержена нескольким типам антропогенного воздействия (зарегулирование дамбой, поступление ливневых и теплых вод, наличие садкового рыбоводного хозяйства), ухудшающего ее рекреационные свойства из-за чрезмерного зарастания макрофитами и скоплений метафитона нитчатой водоросли рода Spirogyra, ухудшения органолептических и микробиологических показателей воды. Природные климатические факторы способны существенно модифицировать влияние антропогенных факторов, что представляет интерес в плане прогнозирования и принятия решений по ликвидации негативных явлений. Целью работы является оценка влияния режима уровня воды р. Енисей в весенне-летний период на экосистему протоки через сравнение данных в многоводный (2021) и средневодный (2020) годы. Гидрофизические, гидрохимические и гидробиологические измерения проводили с мая по август 2020 и 2021 гг. сверху вниз на станциях левобережья: 1 – выше дамбы (фон), 2 – ниже дамбы, 3 – напротив выпуска теплых вод ТЭЦ, 4 – пляж, ниже рыбоводных садков. В 2021 г. вода в протоку поступала только снизу (к ст. 4 и 3), так как водопропускные трубы в теле плотины были засыпаны. В 2021 г., по сравнению с 2020 г., на зарегулированном участке протоки значительно увеличились численность и биомасса фито- и зоопланктона, возросла первичная продукция планктона, а аналогичные показатели фитоперифитона и зообентоса, напротив, снизились по причине их формирования на свежезалитых грунтах. Метафитон отсутствовал, но в августе спирогира стала доминировать в биомассе фитоперифитона. Концентрации нитрит-иона в воде увеличились в зарегулированной части протоки, а нитрат-иона и общего фосфора – на всех станциях протоки, в том числе и на фоновой, получающей воды из Красноярского водохранилища. Наблюдаемая в 2021 г. «вспышка трофии» в планктоне ст. 3 и 4 обусловлена длительным (полтора месяца) удержанием высокого уровня воды в протоке, позволившим использовать биоте вымываемые из затопленных берегов органические вещества и биогены, и аналогична таковой в экотонных зонах выклинивания подпора водохранилищ. Ежегодное увеличение концентраций минеральных форм азота и общего фосфора на нижних станциях, по сравнению с другими станциями, вероятно, обусловлено эвтрофирующим влиянием садкового рыбоводного хозяйстваLocated within the city of Krasnoyarsk, 35 km downstream of the Krasnoyarsk Hydropower Plant, the Abakanskaya anabranch of the Yenisei River, on the one hand, is an important recreational water body and, on the other hand, is subject to several types of anthropogenic impact (regulation by a dam, inflow of storm and warm waters, fish farming). These impacts worsen its recreational properties due to excessive growth of macrophytes and metaphytic filamentous algae of the genus Spirogyra, causing deterioration of organoleptic and microbiological parameters of water. Natural climatic factors can significantly modify the influence of anthropogenic factors, which is of interest in terms of forecasting and decision-making about the elimination of negative factors. The aim of the present work is to assess the influence of the water level regime of the Yenisei River in the spring–summer period on the anabranch ecosystem by comparing the data for the high-water (2021) and medium-water (2020) years. Hydrophysical, hydrochemical, and hydrobiological measurements were carried out from May to August 2020 and 2021 at locations on the left bank: 1 – upstream of the dam (reference), 2 – downstream of the dam, 3 – opposite the outlet of warm water, 4 – at the beach, downstream of the fish farm. In 2021, water entered the anabranch only from downstream (to locations 4 and 3), since the culverts in the dam body were filled up. In 2021, compared to 2020, the abundance and biomass of phyto- and zooplankton in the regulated section of the anabranch significantly increased, the primary production of plankton increased, but the corresponding parameters of phytoperiphyton and zoobenthos, on the contrary, decreased due to their formation on freshly flooded soils. Metaphyton was absent, but in August, Spirogyra began to dominate in the phytoperiphyton biomass. Nitrite ion concentrations in the water increased in the regulated part of the anabranch, and the nitrate ion and total phosphorus concentrations increased at all locations, including the reference location, receiving water from the Krasnoyarsk Reservoir. The plankton “abundance outbreak” observed in 2021 at locations 3 and 4 was caused by the water level in the anabranch remaining high over a long period (one and a half months), which made it possible for the biota to use organic matter and nutrients washed out from the flooded banks; the outbreak was similar to those occurring in the ecotone zones of inputs to the upper parts of reservoirs. The annual increase in the concentrations of mineral forms of nitrogen and total phosphorus at the lower locations compared with other locations was probably due to the eutrophic influence of fish farmin

Measurement of the CP-violating phase ϕs in B¯s0→Ds+Ds− decays

We present a measurement of the CP-violating weak mixing phase ϕs using the decay B¯0s→D+sD−s in a data sample corresponding to 3.0 fb−1 of integrated luminosity collected with the LHCb detector in pp collisions at center-of-mass energies of 7 and 8 TeV. An analysis of the time evolution of the system, which does not use the constraint |λ|=1 to allow for the presence of CP violation in decay, yields ϕs=0.02±0.17(stat)±0.02(syst)  rad, |λ|=0.91+0.18−0.15(stat)±0.02(syst). This result is consistent with the standard model expectation

Measurement of the ηc(1S) production cross-section in proton–proton collisions via the decay ηc(1S) → pp¯

No abstract available

Search for the lepton flavour violating decay tau(-) -> mu(-)mu(+)mu(-)

A search for the lepton flavour violating decay $\tau^-\to \mu^-\mu^+\mu^-$ is performed with the LHCb experiment. The data sample corresponds to an integrated luminosity of $1.0\mathrm{\,fb}^{-1}$ of proton-proton collisions at a centre-of-mass energy of $7\mathrm{\,Te\kern -0.1em V}$ and $2.0\mathrm{\,fb}^{-1}$ at $8\mathrm{\,Te\kern -0.1em V}$. No evidence is found for a signal, and a limit is set at $90\%$ confidence level on the branching fraction, $\mathcal{B}(\tau^-\to \mu^-\mu^+\mu^-) < 4.6 \times 10^{-8}$.Comment: 20 pages, 10 figures, published as JHEP 02 (2015) 12

Measurement of the (eta c)(1S) production cross-section in proton-proton collisions via the decay (eta c)(1S) -&gt; p(p)over-bar

The production of the $\eta_c (1S)$ state in proton-proton collisions is probed via its decay to the $p \bar{p}$ final state with the LHCb detector, in the rapidity range $2.0 < y < 4.5$ and in the meson transverse-momentum range $p_T > 6.5$ GeV/c. The cross-section for prompt production of $\eta_c (1S)$ mesons relative to the prompt $J/\psi$ cross-section is measured, for the first time, to be $\sigma_{\eta_c (1S)}/\sigma_{J/\psi} = 1.74 \pm 0.29 \pm 0.28 \pm 0.18 _{B}$ at a centre-of-mass energy $\sqrt{s} = 7$ TeV using data corresponding to an integrated luminosity of 0.7 fb$^{-1}$, and $\sigma_{\eta_c (1S)}/\sigma_{J/\psi} = 1.60 \pm 0.29 \pm 0.25 \pm 0.17 _{B}$ at $\sqrt{s} = 8$ TeV using 2.0 fb$^{-1}$. The uncertainties quoted are, in order, statistical, systematic, and that on the ratio of branching fractions of the $\eta_c (1S)$ and $J/\psi$ decays to the $p \bar{p}$ final state. In addition, the inclusive branching fraction of $b$-hadron decays into $\eta_c (1S)$ mesons is measured, for the first time, to be $B ( b \rightarrow \eta_c X ) = (4.88 \pm 0.64 \pm 0.29 \pm 0.67 _{B}) \times 10^{-3}$, where the third uncertainty includes also the uncertainty on the $J/\psi$ inclusive branching fraction from $b$-hadron decays. The difference between the $J/\psi$ and $\eta_c (1S)$ meson masses is determined to be $114.7 \pm 1.5 \pm 0.1$ MeV/c$^2$.Comment: 20 pages, 3 figure

Search for the doubly charmed baryon Ω cc +

Abstract: A search for the doubly charmed baryon Ωcc+ with the decay mode Ωcc+ → Ξc+K−π+ is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment from 2016 to 2018, corresponding to an integrated luminosity of 5.4 fb−1. No significant signal is observed within the invariant mass range of 3.6 to 4.0GeV/c2. Upper limits are set on the ratio R of the production cross-section times the total branching fraction of the Ωcc+ → Ξc+K−π+ decay with respect to the Ξcc++→Λc+K−π+π+ decay. Upper limits at 95% credibility level for R in the range 0.005 to 0.11 are obtained for different hypotheses on the Ωcc+ mass and lifetime in the rapidity range from 2.0 to 4.5 and transverse momentum range from 4 to 15 GeV/c

Spatial and Temporal Dynamics of Anabaena flos-aquae Akinetes in Bottom Sediments of a Small Siberian Reservoir

Spatial distribution of akinetes of Anabaena flos-aquae (cyanobacteria) in littoral bottom sediments of a small Siberian reservoir was studied. Akinete abundance in bottom sediments is found to be related with type of sediments and presence of higher water plants. The highest abundance of akinetes was observed in silty sediments at stations located in higher plants bed (mainly emerged plants Typha latifolia L. and Phragmites australis (Cav.) Trin. ex Steud.). These results demonstrate that macrophyte beds could increase the size of the potential cyanobacterial inoculum by accumulation of akinetes in shallow bottom sediments and, as a result, favour cyanobacterial bloom development. In addition, seasonal dynamics of Anabaena flos-aquae, including vegetative cells and akinetes, in bottom sediments and water column in open water and littoral of the reservoir was studied. Dynamics of Anabaena abundance in the water column at the central station and littoral stations were very similar, but the number of cells in the littoral achieved higher year maximum than that at the central station. The highest seasonal peak of vegetative cells and akinetes in the water column was observed at the littoral station, located in emerged higher plants bed. However, at this part of the reservoir lowest intensity of akinete production was recorded. Deposition of akinetes to bottom sediments occurred both in open water and littoral. Nevertheless, seasonal dynamics of akinetes in bottom sediments differed between these sites. At the central station accumulation of akinetes in bottom sediments occurred throughout the summer, but in the littoral abundance of akinetes decreased just after their sedimentation. Hence, abundance of akinetes in the littoral sediments of the reservoir is markedly lower than that in the deeper central part

Spatial and Temporal Dynamics of Anabaena flos-aquae Akinetes in Bottom Sediments of a Small Siberian Reservoir

Spatial distribution of akinetes of Anabaena flos-aquae (cyanobacteria) in littoral bottom sediments of a small Siberian reservoir was studied. Akinete abundance in bottom sediments is found to be related with type of sediments and presence of higher water plants. The highest abundance of akinetes was observed in silty sediments at stations located in higher plants bed (mainly emerged plants Typha latifolia L. and Phragmites australis (Cav.) Trin. ex Steud.). These results demonstrate that macrophyte beds could increase the size of the potential cyanobacterial inoculum by accumulation of akinetes in shallow bottom sediments and, as a result, favour cyanobacterial bloom development. In addition, seasonal dynamics of Anabaena flos-aquae, including vegetative cells and akinetes, in bottom sediments and water column in open water and littoral of the reservoir was studied. Dynamics of Anabaena abundance in the water column at the central station and littoral stations were very similar, but the number of cells in the littoral achieved higher year maximum than that at the central station. The highest seasonal peak of vegetative cells and akinetes in the water column was observed at the littoral station, located in emerged higher plants bed. However, at this part of the reservoir lowest intensity of akinete production was recorded. Deposition of akinetes to bottom sediments occurred both in open water and littoral. Nevertheless, seasonal dynamics of akinetes in bottom sediments differed between these sites. At the central station accumulation of akinetes in bottom sediments occurred throughout the summer, but in the littoral abundance of akinetes decreased just after their sedimentation. Hence, abundance of akinetes in the littoral sediments of the reservoir is markedly lower than that in the deeper central part