Non-Indigenous Cladocera (Crustacea: Branchiopoda): From a Few Notorious Cases to a Potential Global Faunal Mixing in Aquatic Ecosystems

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.O

Miocene cyclopid copepod from a saline paleolake in Mojave, California

There are remarkably few direct fossil records of Copepoda, which implies that current estimates of the lineage divergence times and inferences on the historical biogeography remain highly dubious for these small-sized crustaceans. The Cyclopidae, a predominantly freshwater copepod family with 1000+ species and distributed worldwide, has no fossil record at all. Recent collections from the middle Miocene Barstow Formation in Southern California resulted in ample material of finely preserved cyclopid fossils, including both adult and larval stages. To document the antennulary setation pattern in the adult and copepodid instars we used a coding system that is coherent between sexes and developmental stages. The majority of the cyclopid fossils, coming from saline lake environment, represent the modern genus Apocyclops, a euryhaline, thermophilic group occurring both in the New World and Old World. A new species Apocyclops californicus is described, based on the short medial spine and spiny ornamentation of the free segment of leg 5, spinule ornamentation of pediger 5, and well-developed protuberances of the intercoxal sclerite of leg 4. The presence of antennal allobasis and the features of the swimming legs unambiguously place the Miocene Apocyclops in the A. panamensis-clade, a predominantly amphi-Pacific group. The middle Miocene fossils with clear affinities to a subgroup of Apocyclops imply an early Miocene or Paleogene origin of the genus. Based on the geographic patterns of the species richness and morphology in Apocyclops and its presumed closest relative, genus Metacyclops, we hypothesize that: (i) the ancestor of Apocyclops, similar in morphology to some cave-dweller Metacyclops occurring today in the peri-Mediterranean region, might have arrived in North America from Europe via the Thulean North Atlantic bridge in the late Paleocene–early Eocene; (ii) Eocene termination of the Thulean land connection might have resulted in the divergence of Apocyclops from the Metacyclops stock

Hormonal induction of undescribed males resolves cryptic species of cladocerans

Cyclic parthenogens have a mixed breeding system with both meiotic and ameiotic eggs. Although investment in sexual stages is often synchronized with seasonal cycles, the degree of investment is a quantitative trait associated with habitat instability. Populations of cyclic parthenogens from stable environments, such as large lakes and oceans, generally show reduced or undetectable investment in males. Indeed, males of many species of lacustrine cyclic parthenogens are unknown to science. Methyl farnesoate (MF), a crustacean juvenile hormone, has been implicated as an inducer of male formation in Daphnia magna (Crustacea: Cladocera), a denizen of unstable habitats with marked sexual recruitment. Here, we show experimentally that MF induces male production in four distantly related lacustrine species of cladocerans under growth conditions unfavourable for male production. The males of three species are new to science. Unlike females, the anatomy of the previously unknown males of Bosmina (Lunobosmina) oriens permitted ready morphological diagnosis of sibling species and subfossils. The results suggest that the role for MF in the sex determination of cladocerans is general

Features of speech disorders in patients with acute ischemic stroke

Introduction. Various speech disorders that lead to impaired communication occur in 3050% of ischemic stroke (IS) survivors. Although most attention is traditionally paid to aphasia, speech disorders also include the following: dysarthria, dysphonia (isolated or in combination with dysarthria and/or dysphagia), fluency disorders, and non-specific speech disorders associated with the severity of condition and a cognitive disorder. Objective: to study the variety of speech disorders and their features in patients with acute IS. Materials and methods. We examined 69 right-handed patients with mild-to-moderate acute IS and NIHSS score of 412. The patients were enrolled in the study on days 17 of the IS. Results. We found aphasia in 27/69 patients (39.1%), dysarthria in 21/69 patients (30.4%), dysphonia (isolated or in combination with dysarthria) in 17/69 patients (24.6%), fluency disorders in 19/69 patients (27.5%; 2 patients with tachylalia and 17 patients with bradylalia). In addition, 30 patients (43.5%) had dysphagia (isolated or in combination with dysarthria). At the initial examination, patients admitted within the 17 days of the acute IS onset presented with global or severe sensory and motor aphasia. At the same time, we discovered a pronounced positive dynamics in speech recovery thanks to speech therapy sessions. A significant remission in a speech disorder component led to the development of cortical aphasia affecting either anterior or posterior language areas at the end of the most acute IS period, while aphasia severity reduced to mild or moderate. Conclusions. A fast reduction in aphasic disorders due to the speech therapy sessions suggests that the focal and connectional diaschisis are the basis for the severe speech disorders

Resonant phonon-magnon interactions in free-standing metal-ferromagnet multilayer structures

We analyze resonant magneto-elastic interactions between standing perpendicular spin wave modes (exchange magnons) and longitudinal acoustic phonon modes in free-standing hybrid metal-ferromagnet bilayer and trilayer structures. Whereas the ferromagnetic layer acts as a magnetic cavity, all metal layers control the frequencies and eigenmodes of acoustic vibrations. The here proposed design allows for achieving and tuning the spectral and spatial modes overlap between phonons and magnons that results in their strong resonant interaction. Realistic simulations for gold-nickel multilayers show that sweeping the external magnetic field should allow for observing resonantly enhanced interactions between individual magnon and phonon modes in a broad range of frequencies spanning from tens of GHz up to several hundreds of GHz, which can be finely tuned through the multilayer design. Our results would enable the systematic study and the deep understanding of resonantly enhanced magneto-elastic coupling between individual phonon and magnon modes up to frequencies of great contemporary fundamental and applied interest.Comment: 9 pages, 6 figure

Predicting the invasive potential of the cladoceran Daphnia lumholtzi Sars, 1885 (Crustacea: Cladocera: Daphniidae) in the Neotropics: are generalists threatened and relicts protected by their life-history traits?

Invasive species are one of the major threats to biodiversity, which is aggravated in poorly known groups, such as cladocerans. Daphnia lumholtzi Sars (Cladocera: Anomopoda: Daphniidae) is currently invading the Neotropical region, and there are few records of this process. Our goal was to predict the invasive scenario for D. lumholtzi in the Neotropics using species distribution modelling and to assess the climatic overlap of the invader with the native species. We trained our MaxEnt model using occurrence records from native and invaded areas and projected it in the Neotropics. Additionally, we compared the climatic niche of some native species with the invader’s niche. Our model showed high environmental suitability in areas connected by the lowland Paraná River Basin (southwestern Brazil, eastern Argentina and Uruguay), in south-central Chile and Atlantic coastal areas. Widely distributed native species showed climatic overlap with the invader, while relict species did not. Daphnia lumholtzi thrives in warm and stable environments (e.g. the Paraná River basin), which of concern because the invader could already be spreading in that area. Native species could suffer due to climatic niche similarity, while natural barriers and local environmental conditions may protect relict species. We urge the need for further studies to understand this invasion process more fully.   </p

Mesozoic fossils (>145 Mya) suggest the antiquity of the subgenera of Daphnia and their coevolution with chaoborid predators

<p>Abstract</p> <p>Background</p> <p>The timescale of the origins of <it>Daphnia </it>O. F. Mueller (Crustacea: Cladocera) remains controversial. The origin of the two main subgenera has been associated with the breakup of the supercontinent Pangaea. This vicariance hypothesis is supported by reciprocal monophyly, present day associations with the former Gondwanaland and Laurasia regions, and mitochondrial DNA divergence estimates. However, previous multilocus nuclear DNA sequence divergence estimates at < 10 Million years are inconsistent with the breakup of Pangaea. We examined new and existing cladoceran fossils from a Mesozoic Mongolian site, in hopes of gaining insights into the timescale of the evolution of <it>Daphnia</it>.</p> <p>Results</p> <p>We describe new fossils of ephippia from the Khotont site in Mongolia associated with the Jurassic-Cretaceous boundary (about 145 MYA) that are morphologically similar to several modern genera of the family Daphniidae, including the two major subgenera of <it>Daphnia</it>, i.e., <it>Daphnia </it>s. str. and <it>Ctenodaphnia</it>. The daphniid fossils co-occurred with fossils of the predaceous phantom midge (Chaoboridae).</p> <p>Conclusions</p> <p>Our findings indicate that the main subgenera of <it>Daphnia </it>are likely much older than previously known from fossils (at least 100 MY older) or from nuclear DNA estimates of divergence. The results showing co-occurrence of the main subgenera far from the presumed Laurasia/Gondwanaland dispersal barrier shortly after formation suggests that vicariance from the breakup of Pangaea is an unlikely explanation for the origin of the main subgenera. The fossil impressions also reveal that the coevolution of a dipteran predator (Chaoboridae) with the subgenus <it>Daphnia </it>is much older than previously known -- since the Mesozoic.</p

The Design Technique for Power Management Unit of the Tag IC for Radio Frequency Identification of Critical Infrastructure Objects

The ultra-high frequency (UHF) tag IC’s main part of the power management unit (PMU) design technique is presented. The technique is a step-by-step algorithm for designing a PMU and consists of five interrelated stages. At the first stage, the requirements for the parameters of the PMU (output voltage, output DC power, efficiency, output capacitor capacity) and the Q-factor of the tag analog front-end are determinates. At the second stage, the design of an electrical circuit of a voltage multiplier (VM) is carried out. VM is required to convert the voltage of the input radio frequency (RF) signal into an DC voltage. During the third stage, the design of the electrical circuit of the DC voltage limiter is carried out, which is necessary to reduce the output voltage of VM to a safe level. The result of stage 4 is an electrical circuit of surge protection designed to provide the required level of immunity of the tag IC to the effects of electrostatic discharge and a high-power RF signal. As part of the final stage, the evaluation and alignment with the required Q-factor value of the tag IC analog front-end is carried out. The proposed technique can be used for the development of domestic UHF tag ICs (ISO 18000-6C, GJB 7377.1, etc.) based on CMOS technological processes, including ICs designed for radio frequency identification of critical infrastructure objects. Using the presented technique, the design of a PMU with an estimated efficiency value of 70%, an estimated Q-factor of the analog front-end of less than 15 at an RF input signal power of -12.7 dBm was performed

Taphonomic phenomenon of ancient hair from Glacial Beringia:perspectives for palaeoecological reconstructions

An accumulation of mammoth hair, discovered in the Bol'shaya Chukochya River valley (northeast Yakutia, Russia), was found to contain remains of terrestrial and aquatic organisms, including plants, insects, crustaceans, birds and mammals. Radiocarbon dating indicated that this post-mortem taphocoenosis represented multiple time periods. The mammoth hair was dated to older than 45 ka BP, the plants were dated to 12 750 +/- 50 a BP (which corresponds to a shift in the environmental conditions and landscapes during the formation of thermokarst in northeastern Russia) and the bird feathers were dated to 4115 +/- 40 a BP. A scenario of the formation of this fossil assemblage is proposed, covering the MIS 3-1 time range. The hair also yielded various Arctic branchiopod crustaceans, which inhabit shallow temporary water bodies and therefore are important for reconstruction of palaeoenvironments. The cladoceran subgenus Daphnia (Ctenodaphnia), currently absent from the Asian part of Beringia, is reported from this region for the first time. The study demonstrates that the discovered permafrostpreserved hair is a unique repository of Ice Age organisms.</p

Efficiency of Finding Muon Track Trigger Primitives in CMS Cathode Strip Chambers

In the CMS Experiment, muon detection in the forward direction is accomplished by cathode strip chambers~(CSC). These detectors identify muons, provide a fast muon trigger, and give a precise measurement of the muon trajectory. There are 468 six-plane CSCs in the system. The efficiency of finding muon trigger primitives (muon track segments) was studied using~36 CMS CSCs and cosmic ray muons during the Magnet Test and Cosmic Challenge~(MTCC) exercise conducted by the~CMS experiment in~2006. In contrast to earlier studies that used muon beams to illuminate a very small chamber area ($< \! 0.01$~m$^2$), results presented in this paper were obtained by many installed CSCs operating {\em in situ} over an area of $\approx \! 23$~m$^2$ as a part of the~CMS experiment. The efficiency of finding 2-dimensional trigger primitives within 6-layer chambers was found to be~$99.93 \pm 0.03\%$. These segments, found by the CSC electronics within $800$~ns after the passing of a muon through the chambers, are the input information for the Level-1 muon trigger and, also, are a necessary condition for chambers to be read out by the Data Acquisition System