Comunidades de diatomeas epipélicas en las lagunas de alta montaña de Sierra Nevada (Granada, España)

Se aborda el estudio de las diatomeas epipélicas que se desarrollan en la mayoría de las lagunas de alta montaña del Parque Nacional de Sierra Nevada. El catálogo florístico de las diatomeas epipélicas de Sierra Nevada contiene un total de 63 táxones de 29 géneros distintos, entre los que destacan por su mayor abundancia Encyonema minutum (Hilse)D.G.Mann, Nitzschia sublinearis Hustedt, Pinnularia microstauron (Ehrenberg) Cleve, Tabellaria flocculosa (Roth) Kutzing, y Staurosirella pinnata (Ehrenberg) Williams & Round. Si bien una serie de especies son típicamente epipélicas, tales como Navicula schoenfeldii Hustedt y Pinnularia subcapitata Greg., otras se desarrollan en este ambiente como hábitat secundario. Los análisis de agrupación y correspondencias llevados a cabo a partir de los inventarios obtenidos de las 25 lagunas estudiadas, nos permiten establecer dos comunidades de diatomeas claramente diferenciadas. La de distribución más general está formada por pequeñas especies fragilarioides, tales como Staurosirella pinnata, Pseudostaurosira pseudoconstruens y Tabellaria flocculosa. Este grupo de especies que se presenta en la mayoría de las lagunas de Sierra Nevada, más o menos someras y generalmente con borreguiles y con niveles de nitrógeno medio-altos y concentraciones de sílice variables. La otra agrupación, constituida por especies rafidiales está presente en las lagunas más profundas y sin borreguiles, las especies más características son Nitzschia sublinearis y Encyonema minutum de distribución muy general. Navicula radiosa está presente también en las lagunas más profundas. Solo una laguna (muy somera y con ricos borreguiles) presenta una comunidad epipelica constituida exclusivamente por Pinnularia microstauron.We have studied the epipelic diatoms of high mountain lakes in the Sierra Nevada National Park. The floristic list of the epipelic diatoms of Sierra Nevada has a total number of 63 taxa belonging to 29 different genera, of which most abundant are Encyonema minutum (Hilse) D.G.Mann, Nitzschia sublinearis Hustedt, Pinnularia microstauron (Ehrenberg) Cleve, Tabellaria flocculosa (Roth) Kutzing, and Staurosirella pinnata (Ehrenberg) Williams & Round. Part of the studied species are typically epipelic such as Navicula schoenfeldii Hustedt and Pinnularia subcapitata Greg., whilst others found in these lakes use this environment as a secundary habitat. The similarity cluster and correspondence analysis made on the inventory obtained from the 25 studied lakes, allow us to establish two different diatom communities. The one with the most general distribution is composed of small fragilariod species such as Staurosirella pinnata, Pseudostaurosira pseudoconstruens (Marciniak) D.G.Mann and Tabellaria flocculosa. This group of species is present in a wide range of lakes, more or less shallow, generally with meadows, with high-medium nitrogen concentration and variable silicon levels. The other assemblage, made up of raphidial species, is present in a more limited group of lakes (mainly closed lakes) which are generally deeper and mainly without meadows, the most characteristic species being Nitzschia sublinearis and Encyonema minutum. Navicula radiosa Kützing is present also in larger deeper lakes. Only one lake (very shallow and with rich meadow vegetation) presents an epipelic community made up of Pinnularia microstauron

Changes in epilithic diatom assemblages in a Mediterranean high mountain lake (Laguna de La Caldera, Sierra Nevada, Spain) after a period of drought

The epilithic diatom assemblages studied in the high mountain lake “La Caldera” (Granada, Spain) from 1996 to 1998 went through two clearly different stages. The initial one, in 1996, corresponded to the reflooding of the basin after a severe drought and was composed mainly of the colonising species Fragilaria rumpens, together with a lesser presence of Nitzschia sublinearis and Hantzschia amphioxys. The predominant presence of F. rumpens at the end of the summer of 2006 coincided with low species diversity (values of Shannon and Wiener Index: 0.3-0.6). During the following two years another assemblage established itself, dominated by Achnanthidium minutissimum, which is considered to be more stable and widespread among the lakes of the Sierra Nevada. The most notable subdominant species (less than 20% of relative abundance) in this assemblage were: Encyonema minutum, Encyonopsis microcephala and Navicula cryptocephala. The diversity values during this second period were much higher than in the first: 1.0-2.2. Nutrient concentrations were measured separately in the limnetic (epilimnetic) and benthic (epilithic) environments. These abiotic parameters show that the dynamics of ammonia and silica were much the same in both, showing a gradual decrease from the beginning to the end of the study period. Epilimnetic phosphorus followed a similar pattern to ammonia and silica. In the epilithon, nitrates and phosphates increased during the first year, only to descend notably during the second. The effect of other environmental parameters such as temperature and the preceding drought on the dynamics of the diatom assemblage are discussed. Ratio DIN:SRP let us test the different degrees of phosphorus limitation in epilithon and epilimnion environments; our results suggest that phosphorus limitation of primary production in high mountain lakes is much more severe in the limnetic environment that it is in the epilithon.Chemical analyses were funded by the European project Mountain Lake Research (MOLAR)

Large-scale patterns of turnover and basal area change in Andean forests

General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment) and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century

Climate change and Saharan dust drive recent cladoceran and primary production changes in remote alpine lakes of Sierra Nevada, Spain

Recent anthropogenic climate change and the exponential increase over the past few decades of Saharan dust deposition, containing ecologically important inputs of phosphorus (P) and calcium (Ca), are potentially affecting remote aquatic ecosystems. In this study, we examine changes in cladoceran assemblage composition and chlorophyll-a concentrations over the past ~150 years from high-resolution, welldated sediment cores retrieved from six remote high mountain lakes in the Sierra Nevada Mountains of Southern Spain, a region affected by Saharan dust deposition. In each lake, marked shifts in cladoceran assemblages and chlorophyll-a concentrations in recent decades indicate a regional-scale response to climate and Saharan dust deposition. Chlorophyll-a concentrations have increased since the 1970s, consistent with a response to rising air temperatures and the intensification of atmospheric deposition of Saharan P. Similar shifts in cladoceran taxa across lakes began over a century ago, but have intensified over the past ~50 years, concurrent with trends in regional air temperature, precipitation, and increased Saharan dust deposition. An abrupt increase in the relative abundance of the benthic cladoceran Alona quadrangularis at the expense of Chydorus sphaericus, and a significant increase in Daphnia pulex gr. was a common trend in these softwater lakes. Differences in the magnitude and timing of these changes are likely due to catchment and lake-specific differences. In contrast with other alpine lakes that are often affected by acid deposition, atmospheric Ca deposition appears to be a significant explanatory factor, among others, for the changes in the lake biota of Sierra Nevada that has not been previously considered. The effects observed in Sierra Nevada are likely occurring in other Mediterranean lake districts, especially in softwater, oligotrophic lakes. The predicted increases in global temperature and Saharan dust deposition in the future will further impact the ecological condition of these ecosystemsMinisterio de Educación y Ciencia (MEC), Grant/Award Number: AP2007-00352; Programa Nacional de Movilidad de Recursos Humanos de Investigaci on (MICINN); Ministerio de Medio Ambiente (MMA), Grant/Award Number: 87/2007; Ministerio de Econom ıa, Industria y Competitividad (MINECO), Grant/Award Number: CGL2011-23483; Natural Sciences and Engineering Research Council of Canad

The CARMENES search for exoplanets around M dwarfs. Two temperate Earth-mass planet candidates around Teegarden’s Star

Context.Teegarden’s Star is the brightest and one of the nearest ultra-cool dwarfs in the solar neighbourhood. For its late spectral type (M7.0 V),the star shows relatively little activity and is a prime target for near-infrared radial velocity surveys such as CARMENES.Aims.As part of the CARMENES search for exoplanets around M dwarfs, we obtained more than 200 radial-velocity measurements of Teegarden’sStar and analysed them for planetary signals.Methods.We find periodic variability in the radial velocities of Teegarden’s Star. We also studied photometric measurements to rule out stellarbrightness variations mimicking planetary signals.Results.We find evidence for two planet candidates, each with 1.1M⊕minimum mass, orbiting at periods of 4.91 and 11.4 d, respectively. Noevidence for planetary transits could be found in archival and follow-up photometry. Small photometric variability is suggestive of slow rotationand old age.Conclusions.The two planets are among the lowest-mass planets discovered so far, and they are the first Earth-mass planets around an ultra-cooldwarf for which the masses have been determined using radial velocities.We thank the referee Rodrigo Díaz for a careful review andhelpful comments. M.Z. acknowledges support from the Deutsche Forschungs-gemeinschaft under DFG RE 1664/12-1 and Research Unit FOR2544 “BluePlanets around Red Stars”, project no. RE 1664/14-1. CARMENES isan instrument for the Centro Astronómico Hispano-Alemán de Calar Alto(CAHA, Almería, Spain). CARMENES is funded by the German Max-Planck-Gesellschaft (MPG), the Spanish Consejo Superior de InvestigacionesCientíficas (CSIC), the European Union through FEDER/ERF FICTS-2011-02 funds, and the members of the CARMENES Consortium (Max-Planck-Institut für Astronomie, Instituto de Astrofísica de Andalucía, LandessternwarteKönigstuhl, Institut de Ciències de l’Espai, Institut für Astrophysik Göttingen,Universidad Complutense de Madrid, Thüringer Landessternwarte Tautenburg,Instituto de Astrofísica de Canarias, Hamburger Sternwarte, Centro de Astro-biología and Centro Astronómico Hispano-Alemán), with additional contribu-tions by the Spanish Ministry of Economy, the German Science Foundationthrough the Major Research Instrumentation Programme and DFG ResearchUnit FOR2544 “Blue Planets around Red Stars”, the Klaus Tschira Stiftung, thestates of Baden-Württemberg and Niedersachsen, and by the Junta de Andalucía.Based on data from the CARMENES data archive at CAB (INTA-CSIC). Thisarticle is based on observations made with the MuSCAT2 instrument, devel-oped by ABC, at Telescopio Carlos Sánchez operated on the island of Tener-ife by the IAC in the Spanish Observatorio del Teide. Data were partly col-lected with the 150-cm and 90-cm telescopes at the Sierra Nevada Observa-tory (SNO) operated by the Instituto de Astrofísica de Andalucía (IAA-CSIC).Data were partly obtained with the MONET/South telescope of the MOnitoringNEtwork of Telescopes, funded by the Alfried Krupp von Bohlen und HalbachFoundation, Essen, and operated by the Georg-August-Universität Göttingen,the McDonald Observatory of the University of Texas at Austin, and the SouthAfrican Astronomical Observatory. We acknowledge financial support from theSpanish Agencia Estatal de Investigación of the Ministerio de Ciencia, Inno-vación y Universidades and the European FEDER/ERF funds through projectsAYA2015-69350-C3-2-P, AYA2016-79425-C3-1/2/3-P, AYA2018-84089, BES-2017-080769, BES-2017-082610, ESP2015-65712-C5-5-R, ESP2016-80435-C2-1/2-R, ESP2017-87143-R, ESP2017-87676-2-2, ESP2017-87676-C5-1/2/5-R, FPU15/01476, RYC-2012-09913, the Centre of Excellence ”Severo Ochoa”and ”María de Maeztu” awards to the Instituto de Astrofísica de Canarias (SEV-2015-0548), Instituto de Astrofísica de Andalucía (SEV-2017-0709), and Cen-tro de Astrobiología (MDM-2017-0737), the Generalitat de Catalunya throughCERCA programme”, the Deutsches Zentrum für Luft- und Raumfahrt throughgrants 50OW0204 and 50OO1501, the European Research Council through grant694513, the Italian Ministero dell’instruzione, dell’università de della ricerca andUniversità degli Studi di Roma Tor Vergata through FFABR 2017 and “Mis-sion: Sustainability 2016”, the UK Science and Technology Facilities Council through grant ST/P000592/1, the Israel Science Foundation through grant848/16, the Chilean CONICYT-FONDECYT through grant 3180405, the Mexi-can CONACYT through grant CVU 448248, the JSPS KAKENHI through grantsJP18H01265 and 18H05439, and the JST PRESTO through grant JPMJPR1775

CIBERER : Spanish national network for research on rare diseases: A highly productive collaborative initiative

Altres ajuts: Instituto de Salud Carlos III (ISCIII); Ministerio de Ciencia e Innovación.CIBER (Center for Biomedical Network Research; Centro de Investigación Biomédica En Red) is a public national consortium created in 2006 under the umbrella of the Spanish National Institute of Health Carlos III (ISCIII). This innovative research structure comprises 11 different specific areas dedicated to the main public health priorities in the National Health System. CIBERER, the thematic area of CIBER focused on rare diseases (RDs) currently consists of 75 research groups belonging to universities, research centers, and hospitals of the entire country. CIBERER's mission is to be a center prioritizing and favoring collaboration and cooperation between biomedical and clinical research groups, with special emphasis on the aspects of genetic, molecular, biochemical, and cellular research of RDs. This research is the basis for providing new tools for the diagnosis and therapy of low-prevalence diseases, in line with the International Rare Diseases Research Consortium (IRDiRC) objectives, thus favoring translational research between the scientific environment of the laboratory and the clinical setting of health centers. In this article, we intend to review CIBERER's 15-year journey and summarize the main results obtained in terms of internationalization, scientific production, contributions toward the discovery of new therapies and novel genes associated to diseases, cooperation with patients' associations and many other topics related to RD research

A giant exoplanet orbiting a very-low-mass star challenges planet formation models

Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts constraints on the planet accretion and migration rates. Disk instabilities may be more efficient in forming planets than previously thought

CARMENES: high-resolution spectra and precise radial velocities in the red and infrared

SPIE Astronomical Telescopes + Instrumentation (2018, Austin, Texas, United States