bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metals and altitude drive genetic diversity of chironomids in Andean streams
Authors: Loayza‐Muro Raúl A. , de Baat Milo L. , Palomino Edwin J. , Kuperus Peter , Kraak Michiel H. S. , Admiraal Wim , Breeuwer Johannes A. J. 
Published: October 2013

Summary

Andean streams cover steep altitude gradients and locally leach metal‐rich bedrock, creating highly selective habitat conditions. Chironomids are among the few dominant insect taxa present under the harshest conditions in Andean high altitude streams, but it remains unclear whether their dominance is due to the adaptive capacity of a few species (population differentiation) or to a diversity of species with different capacities to cope with environmental extremes (species composition). Therefore, the aim of this study was to assess whether metals and altitude drive the genetic diversity of chironomids in Andean streams.

We measured metal concentrations and altitude‐related conditions, such as UV‐B radiation, water temperature and oxygen, in reference and metal‐rich streams located at both 3000 and 4000 m a.s.l. The genetic composition of the chironomid communities from these streams was determined by mitochondrial cytochrome oxidase I (COI) gene sequencing, and a phylogenetic tree was constructed.

The concentrations of all metals were higher in the metal‐rich streams than in the references streams. The UV‐B radiation level at 4000 m was notably higher than at 3000 m, while the water temperature followed the opposite trend. At 3000 m, the reference site was inhabited by six putative species, completely different from the three present at 4000 m. Only one putative species, which did not occur at the reference sites, was present at both the metal‐rich sites at 3000 and 4000 m.

The differences in putative species composition between 3000 and 4000 m indicated a strong sorting of species according to altitude. However, the unique putative species present at the metal‐rich sites at both 3000 and 4000 m indicated that altitude‐driven selection was overridden by the extreme selection pressure exerted by metal exposure. We conclude that altitude limits the distribution of chironomid taxa, but metal selection leads to predominance of a unique metal‐tolerant taxon.
Differences in feeding behaviour amongChironomusspecies revealed by measurements of sulphur stable isotopes and cadmium in larvae
Authors: Proulx Isabelle , Hare Landis 
Published: October 2013

SummaryWe set out to determine the feeding behaviours of 15Chironomusspecies collected from 16 boreal forest lakes by measuring cadmium (Cd) and stable isotopes of carbon (C), nitrogen (N) and sulphur (S) in larvae.Measurements of S stable isotopes and Cd discriminated betweenChironomusspecies that feed mainly on oxic particles from those that feed mainly on anoxic particles. Our results suggest thatC. dilutus,C. entis,C. plumosusandC. staegerifeed mainly on oxic particles (in the water column, in sediment or both), whereasC. anthracinus,C. bifurcatus,C. cucini,C. decorus‐group sp. 2,C. harpi,C. nr. atroviridis(sp. 2i),C. ochreatus,C. spp.NAI‐NAIIIandC. ‘tigris’feed mainly on anoxic sediments.In our study lakes, larval C isotopic signatures were relatively high, which suggests that they feed little on methanotrophic bacteria. Although larval C and N signatures differed between some sympatricChironomusspecies, these differences were not consistent among lakes. The absence of a trend among lakes suggests that lake‐specific factors determine larval C and N signatures.Differences in feeding habits and Cd concentrations among sympatric (cohabiting)Chironomusspecies suggest that pooling them in ecological, palaeolimnological or ecotoxicological studies could obscure trends in nature, thereby limiting their use as monitors of climate change or pollution.
A behavioral comparison of the common laboratory rat strains Lister Hooded, Lewis, Fischer 344 and Wistar in an automated homecage system
Authors: Clemens L. E. , Jansson E. K. H. , Portal E. , Riess O. , Nguyen H. P. 
Published: October 2013

AbstractBehavioral characterization is an important part of establishing novel animal models, but classical behavioral tests struggle to reveal conclusive results due to problems with both reproducibility and validity. On the contrary, automated homecage observations are believed to produce robust outcomes that relate more to natural animal behavior. However, information on the behavior of background strains from such observations, which could provide important reference material, is rare. For this reason, we compared the behavior of the commonly used Lister Hooded, Lewis, Fischer 344 and Wistar rats during 70 h of exposure to an automated homecage system at 2, 4 and 6 months of age. We found considerable strain differences in metabolic parameters, novelty‐induced and baseline activity‐related behavior as well as differences in the development of these parameters with age. The results are discussed in terms of advantages and disadvantages of the system compared to classical behavioral tests, as well as the system's ability to recreate common findings in literature.
Higher temperature sensitivity for stable than for labile soil organic carbon – Evidence from incubations of long‐term bare fallow soils
Authors: Lefèvre Romain , Barré Pierre , Moyano Fernando E. , Christensen Bent T. , Bardoux Gérard , Eglin Thomas , Girardin Cyril , Houot Sabine , Kätterer Thomas , van Oort Folkert , Chenu Claire 
Published: October 2013

AbstractThe impact of climate change on the stability of soil organic carbon (SOC) remains a major source of uncertainty in predicting future changes in atmospheric CO2 levels. One unsettled issue is whether the mineralization response to temperature depends on SOC mineralization rate. Long‐term (>25 years) bare fallow experiments (LTBF) in which the soil is kept free of any vegetation and organic inputs, and their associated archives of soil samples represent a unique research platform to examine this issue as with increasing duration of fallow, the lability of remaining total SOC decreases. We retrieved soils from LTBF experiments situated at Askov (Denmark), Grignon (France), Ultuna (Sweden), and Versailles (France) and sampled at the start of the experiments and after 25, 50, 52, and 79 years of bare fallow, respectively. Soils were incubated at 4, 12, 20, and 35 °C and the evolved CO2 monitored. The apparent activation energy (Ea) of SOC was then calculated for similar loss of CO2 at the different temperatures. The Ea was always higher for samples taken at the end of the bare‐fallow period, implying a higher temperature sensitivity of stable C than of labile C. Our results provide strong evidence for a general relationship between temperature sensitivity and SOC stability upon which significant improvements in predictive models could be based.
Nesting and acoustic ecology, but not phylogeny, influence passerine urban tolerance
Authors: Cardoso Gonçalo C. 
Published: October 2013

AbstractUrbanization is one of the most extensive and ecologically significant changes happening to terrestrial environments, as it strongly affects the distribution of biodiversity. It is well established that native species richness is reduced in urban and suburban areas, but the species traits that predict tolerance to urbanization are yet little understood. In birds, one of the most studied groups in this respect, evidence is appearing that acoustic traits influence urban living, but it remains unknown how this compares to the effects of more obvious ecological traits that facilitate urban living. Therefore, it remains unclear whether acoustic communication is an important predictor of urban tolerance among species. Here, with a comparative study across 140 European and North American passerines, I show that high song frequency, which is less masked by the low‐frequency anthropogenic noise, is associated with urban tolerance, with an effect size over half that of the most important ecological trait studied: off‐ground nesting. Other nesting and foraging traits accepted to facilitate urban living did not differ for species occurring in urban environments. Thus, the contribution of acoustic traits for passerine urban tolerance approximates that of more obvious ecological traits. Nonetheless, effect sizes of the biological predictors of urban tolerance were low and the phylogenetic signal for urban tolerance was null, both of which suggest that factors other than phenotypic traits have major effects on urban tolerance. A simple possibility is exposure to urbanization, as there was a higher proportion of urban‐tolerant species in Europe, which is more urbanized than North America.
Carbon–Temperature–Water change analysis for peanut production under climate change: a prototype for the AgMIP Coordinated Climate‐Crop Modeling Project (C3MP)
Authors: Ruane Alex C. , McDermid Sonali , Rosenzweig Cynthia , Baigorria Guillermo A. , Jones James W. , Romero Consuelo C. , DeWayne Cecil L. 
Published: October 2013

AbstractClimate change is projected to push the limits of cropping systems and has the potential to disrupt the agricultural sector from local to global scales. This article introduces the Coordinated Climate‐Crop Modeling Project (C3MP), an initiative of the Agricultural Model Intercomparison and Improvement Project (AgMIP) to engage a global network of crop modelers to explore the impacts of climate change via an investigation of crop responses to changes in carbon dioxide concentration ([CO2]), temperature, and water. As a demonstration of the C3MP protocols and enabled analyses, we apply the Decision Support System for Agrotechnology Transfer (DSSAT) CROPGRO‐Peanut crop model for Henry County, Alabama, to evaluate responses to the range of plausible [CO2], temperature changes, and precipitation changes projected by climate models out to the end of the 21st century. These sensitivity tests are used to derive crop model emulators that estimate changes in mean yield and the coefficient of variation for seasonal yields across a broad range of climate conditions, reproducing mean yields from sensitivity test simulations with deviations of ca. 2% for rain‐fed conditions. We apply these statistical emulators to investigate how peanuts respond to projections from various global climate models, time periods, and emissions scenarios, finding a robust projection of modest (<10%) median yield losses in the middle of the 21st century accelerating to more severe (>20%) losses and larger uncertainty at the end of the century under the more severe representative concentration pathway (RCP8.5). This projection is not substantially altered by the selection of the AgMERRA global gridded climate dataset rather than the local historical observations, differences between the Third and Fifth Coupled Model Intercomparison Project (CMIP3 and CMIP5), or the use of the delta method of climate impacts analysis rather than the C3MP impacts response surface and emulator approach.
Sustained effects of atmospheric [CO2] and nitrogen availability on forest soilCO2efflux
Authors: Oishi A. Christopher , Palmroth Sari , Johnsen Kurt H. , McCarthy Heather R. , Oren Ram 
Published: October 2013

AbstractSoilCO2efflux (Fsoil) is the largest source of carbon from forests and reflects primary productivity as well as how carbon is allocated within forest ecosystems. Through early stages of stand development, both elevated [CO2] and availability of soil nitrogen (N; sum of mineralization, deposition, and fixation) have been shown to increase gross primary productivity, but the long‐term effects of these factors onFsoilare less clear. Expanding on previous studies at the Duke Free‐AirCO2Enrichment (FACE) site, we quantified the effects of elevated [CO2] and N fertilization onFsoilusing daily measurements from automated chambers over 10 years. Consistent with previous results, compared to ambient unfertilized plots, annualFsoilincreased under elevated [CO2] (ca. 17%) and decreased with N (ca. 21%). N fertilization under elevated [CO2] reducedFsoilto values similar to untreated plots. Over the study period, base respiration rates increased with leaf productivity, but declined after productivity saturated. Despite treatment‐induced differences in aboveground biomass, soil temperature and water content were similar among treatments. Interannually, low soil water content decreased annualFsoilfrom potential values – estimated based on temperature alone assuming nonlimiting soil water content – by ca. 0.7% per 1.0% reduction in relative extractable water. This effect was only slightly ameliorated by elevated [CO2]. Variability in soil N availability among plots accounted for the spatial variability inFsoil, showing a decrease of ca. 114 g C m−2 yr−1per 1 g m−2increase in soil N availability, with consistently higherFsoilin elevated [CO2] plots ca. 127 g C per 100 ppm [CO2] over the +200 ppm enrichment. Altogether, reflecting increased belowground carbon partitioning in response to greater plant nutritional needs, the effects of elevated [CO2] and N fertilization onFsoilin this stand are sustained beyond the early stages of stand development and through stabilization of annual foliage production.
Evidence for key enzymatic controls on metabolism of Arctic river organic matter
Authors: Mann Paul J. , Sobczak William V. , LaRue Madeleine M. , Bulygina Ekaterina , Davydova Anna , Vonk Jorien E. , Schade John , Davydov Sergei , Zimov Nikita , Holmes Robert M. , Spencer Robert G. M. 
Published: October 2013

AbstractPermafrost thaw in the Arctic driven by climate change is mobilizing ancient terrigenous organic carbon (OC) into fluvial networks. Understanding the controls on metabolism of this OC is imperative for assessing its role with respect to climate feedbacks. In this study, we examined the effect of inorganic nutrient supply and dissolved organic matter (DOM) composition on aquatic extracellular enzyme activities (EEAs) in waters draining the Kolyma River Basin (Siberia), including permafrost‐derived OC. Reducing the phenolic content of the DOM pool resulted in dramatic increases in hydrolase EEAs (e.g., phosphatase activity increased >28‐fold) supporting the idea that high concentrations of polyphenolic compounds in DOM (e.g., plant structural tissues) inhibit enzyme synthesis or activity, limiting OC degradation. EEAs were significantly more responsive to inorganic nutrient additions only after phenolic inhibition was experimentally removed. In controlled mixtures of modern OC and thawed permafrost endmember OC sources, respiration rates per unit dissolved OC were 1.3–1.6 times higher in waters containing ancient carbon, suggesting that permafrost‐derived OC was more available for microbial mineralization. In addition, waters containing ancient permafrost‐derived OC supported elevated phosphatase and glucosidase activities. Based on these combined results, we propose that both composition and nutrient availability regulate DOM metabolism in Arctic aquatic ecosystems. Our empirical findings are incorporated into a mechanistic conceptual model highlighting two key enzymatic processes in the mineralization of riverine OM: (i) the role of phenol oxidase activity in reducing inhibitory phenolic compounds and (ii) the role of phosphatase in mobilizing organic P. Permafrost‐derived DOM degradation was less constrained by this initial ‘phenolic‐OM’ inhibition; thus, informing reports of high biological availability of ancient, permafrost‐derived DOM with clear ramifications for its metabolism in fluvial networks and feedbacks to climate.
Anthropogenic nitrogen deposition in boreal forests has a minor impact on the global carbon cycle
Authors: Gundale Michael J. , From Fredrik , Bach Lisbet H. , Nordin Annika 
Published: October 2013

AbstractIt is proposed that increases in anthropogenic reactive nitrogen (Nr) deposition may cause temperate and boreal forests to sequester a globally significant quantity of carbon (C); however, long‐term data from boreal forests describing how C sequestration responds to realistic levels of chronic Nr deposition are scarce. Using a long‐term (14‐year) stand‐scale (0.1 ha) N addition experiment (three levels: 0, 12.5, and 50 kg N ha−1 yr−1) in the boreal zone of northern Sweden, we evaluated how chronic N additions altered N uptake and biomass of understory communities, and whether changes in understory communities explained N uptake and C sequestration by trees. We hypothesized that understory communities (i.e. mosses and shrubs) serve as important sinks for low‐level N additions, with the strength of these sinks weakening as chronic N addition rates increase, due to shifts in species composition. We further hypothesized that trees would exhibit nonlinear increases in N acquisition, and subsequent C sequestration as N addition rates increased, due to a weakening understory N sink. Our data showed that understory biomass was reduced by 50% in response to the high N addition treatment, mainly due to reduced moss biomass. A 15N labeling experiment showed that feather mosses acquired the largest fraction of applied label, with this fraction decreasing as the chronic N addition level increased. Contrary to our hypothesis, the proportion of label taken up by trees was equal (ca. 8%) across all three N addition treatments. The relationship between N addition and C sequestration in all vegetation pools combined was linear, and had a slope of 16 kg C kg−1 N. While canopy retention of Nr deposition may cause C sequestration rates to be slightly different than this estimate, our data suggest that a minor quantity of annual anthropogenic CO2 emissions are sequestered into boreal forests as a result of Nr deposition.
Future no‐analogue vegetation produced by no‐analogue combinations of temperature and insolation
Authors: Reu Björn , Zaehle Sönke , Bohn Kristin , Pavlick Ryan , Schmidtlein Sebastian , Williams John W. , Kleidon Axel 
Published: October 2013

AbstractAimProjections of future climate change suggest that regional climates may evolve to states that are unlike any climate regime found on Earth today. These climates will impose novel constraints on plant species, and are likely to give rise to plant associations that are compositionally unlike any found on Earth today. Here, we explore whether the geographical distribution of previously mapped no‐analogue climates corresponds to the geographical distribution of simulated no‐analogue vegetation under scenarios of global warming.LocationGlobal landmasses.MethodsWe used JeDi, a process‐based vegetation model that accounts for ecophysiological trade‐offs in plant growth and survival, to identify the assembly of plant functional types into no‐analogue associations under scenarios of global warming. We compared the geographical distribution of these no‐analogue vegetation types with those of no‐analogue climates derived from seasonal temperature and precipitation. To better understand the climatic causes that lead to no‐analogue vegetation, we performed a set of JeDi simulation experiments and compared them, as well as selected climate indices, with the geographical distribution of no‐analogue vegetation. Finally, we explored the changes in plant characteristics leading to no‐analogue vegetation composition.ResultsIn our model simulations, a no‐analogue vegetation type emerged in Northern Eurasia due to the interacting effects of rising temperatures and the prolongation of the growing season, combined with stable patterns in the seasonal insolation cycle. Future tropical biomes experiencing novel temperature and precipitation regimes however, resemble contemporary vegetation despite significant losses of plant diversity.Main conclusionsOur modelling study shows how no‐analogue vegetation can emerge in response to novel climates produced by rising temperatures and stable insolation, while also suggesting that no‐analogue climates do not necessarily lead to no‐analogue vegetation types. This result underlines the importance of considering plant diversity and the need to integrate ecophysiological knowledge through process‐orientated models when projecting future vegetation.
Candida albicans adherence and proliferation on the surface of denture base materials
Authors: Koch Carola , Bürgers Ralf , Hahnel Sebastian 
Published: October 2013

ObjectiveThis study aimed to evaluate the adhesion and proliferation of Candida albicans on denture base materials with different resin chemistries.Materials and methodsStandardised specimens were prepared from different denture base materials (i.e. Palapress vario, Paladon 65, Castdon, Sherapress, Eclipse and Mucopren) and subjected to thermal cycling to simulate an artificial ageing process. After the determination of surface roughness and surface free energy, Candida albicans adherence and proliferation on the surface of denture base materials were simulated by subsequent incubation with Candida albicans ATCC 10231 for either 24 h or 196 h with and without prior simulation of salivary pellicle formation.ResultsRegardless of the presence of a salivary pellicle or the incubation time, the results indicate that the proliferation of Candida albicans is significantly dependent on the material that is used for the fabrication of denture bases (p < 0.001). A significantly higher proliferation of Candida albicans was observed on the surface of denture base materials with the highest polar contribution to surface free energy (i.e. Eclipse, Mucopren), and this result supports the assumption that there might be a relationship between the polar contribution to surface free energy of the substratum material and Candida albicans proliferation.ConclusionThe results obtained from this study indicate that Candida albicans proliferation in particular is not necessarily increased on denture base materials that are subjected to thermal cycling.
Multiple hydrocarbon charging events in Kuh‐e‐Mond oil field, Coastal Fars: evidence from biomarkers in oil inclusions
Authors: Shariatinia Z. , Feiznia S. , Shafiei A. , Haghighi M. , Mousavi Dehghani A. , Memariani M. , Farhadian N. 
Published: October 2013

AbstractOil inclusions were retrieved from dolomite and calcite fracture fills in upper, middle and lower reservoir zones in Kuh‐e‐Mond Field, Zagros Basin, Iran. They are assumed to be persevered samples of primary oil; hence, their biomarkers were analysed to determine the maturity gradient and source facies of petroleum at the time of migration. A variety of specific parameters were obtained including n‐alkanes, hopanes, steranes from aromatic hydrocarbons in oil inclusions and reservoir hydrocarbons petroleum. The Pr/Ph ratio varies from 0.5 to 1, which is indicative of dominant reducing conditions during source rock deposition. The fluid inclusion oils with dibenzothiophene/phenanthrene ratios ranging from 0.68 to 1.4, Pr/Ph ratios from 0.8 to 1.2 and with C34/C35 ratios of homohopanes in the range from 1.1 to 1.76, suggest regional variations of organic facies in their source rocks. Biomarker parameters obtained from fluid inclusion oils differ slightly from those of reservoired oil. The biomarker data indicate that the reservoir oil in the Kuh‐e‐Mond Field was generated and expelled predominantly from carbonate–marly sources deposited in anoxic environments. A terrestrial material source seems plausible here, and the presence of C29/C27 ααα 20R steranes supports this finding. The maturity levels of fluid inclusion oils inferred from C12+ parameters are slightly higher in the dolomite and calcite cements from the upper reservoir zone, which may be due to continuous reservoir filling.