50 research outputs found

    Combining remote sensing and field mapping methods to study the vegetation dynamics within a coastal wetland and determine the habitat effects of a threatened bird species (Emberiza schoeniclus witherbyi)

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    [EN] Coastal wetlands are highly dynamic changing ecosystems because of the effects of meteorology, wildlife interactions and human activities. They are one of the world's most threatened ecosystems, and threats to them drive the most specialist species to unfavorable conservation status and population trends. Therefore, it is important to frequently monitor the coverage changes of the different vegetation types to understand these species' population dynamics. However, frequent and detailed cartography entails costly efforts. Here, satellite images with field mapping were combined to create vegetation classification maps for past years from SPOT-5 images in the Pego-Oliva coastal wetland (Spain) and obtained classification accuracies above 85%. Together with habitat selection models, this information was used to understand the changes in the habitat of a threatened bird species, the Eastern Iberian reed bunting (Emberiza schoeniclus witherbyi), whose population has sharply declined in recent decades in Spain. A statistically significant reduction in reed-rush patches (positively selected habitat) and an increase in homogeneous reed patches (negatively selected habitat) were observed in those areas where the species disappeared as breeders. This study shows the potential of remote sensing and GIS techniques for the a posteriori monitoring of variation in the habitats available for threatened species to set up management and conservation measures.The authors thank the authorities of the Marjal Pego-Oliva Natural Park for providing the facilities to work in protected areas and for the relevant permits. This study has been funded by projects CGL2005-02041/BOS and CGL2010-21933-C02-02 from the Spanish Ministry of Education and Science. P. Vera was granted research support by Spanish Ornithological Society/BirdLife in 2008. Nacho Encabo and Marcial Marin helped with the fieldwork in 2006 and 2007.Carrasco, L.; Vera, P.; Belda, E.; Monrós, JS. (2017). Combining remote sensing and field mapping methods to study the vegetation dynamics within a coastal wetland and determine the habitat effects of a threatened bird species (Emberiza schoeniclus witherbyi). Journal of Coastal Research. 34(1):42-49. https://doi.org/10.2112/JCOASTRES-D-16-00194.1S424934

    Effects of migratory status and habitat on the prevalence and intensity of infection by haemoparasites in passerines in eastern Spain

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    The Iberian peninsula is a suitable place to study the effects of migratory condition on the prevalence of blood parasites in avian communities as resident, local populations cohabit with migratory species and with abundant vector populations. In this study we examined the incidence of avian blood parasites in three localities in the Mediterranean region (east Spain), in relation to the migratory status of the species. We analyzed 333 blood smears from 11 avian species, and obtained an overall prevalence of 9.6%. The prevalence of parasites varied among the different species studied, although intensity of infection did not. Our results are discussed in terms of population dynamics and abundance of Diptera vectors able to transmit blood parasites to other birds

    Characterization of the gas-liquid interfacial waves in vertical upward co-current annular flows

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    [EN] For more than fifty years, hundreds of research works have focused on the study of annular flow because of its huge importance in many industrial processes, for instance, chemical, petroleum, etc., being of particular interest in nuclear industry. Specifically, interfacial waves play a vital role in the mass, momentum and energy transference processes between gas and liquid phases. This paper describes the new experimental measurements of vertical upward co-current two-phase gas-liquid flow carried out in a tube with an inner diameter of 44 mm. The liquid film thickness and the major characteristics of the interfacial waves have been measured using a non-intrusive instrument, a conductance probe. The physical phenomenon in which this device is based is the change in the electrical conductivity between air and water, i.e., the electrical signal collected in the sensor receiver depends on the thickness of the liquid film layer. The experimental measurements range from 2000 to 3500 l/min for the gas volumetric flow rate, and from 4 to 10 l/min for the liquid volumetric flow rate. Correlation of the experimental measurements of liquid film thickness and the major properties of the interfacial waves have been analyzed using non-dimensional numbers. An important part of the document focuses on the comparison of the experimental data and the fitting correlations against several of the most widely used expressions. Throughout this paper, in addition to present all the available correlations, the existing scattering found when comparing against other expressions have been also confirmed, underlining the existence of gaps of knowledge even today. Emphasize that the proposed correlations are the ones that better fit the data of all experimental series carried out under the present study for the analyzed variables, with almost all the experimental points covered by the +/- 10% error bands of the new correlations.The authors are indebted to the plan of I+D support of the EXMOTRANSIN project ENE2016-79489-C2-1-P.Cuadros-Orón, JL.; Rivera-Durán, Y.; Berna, C.; Escrivá, A.; Muñoz-Cobo, JL.; Monrós-Andreu, G.; Chiva, S. (2019). Characterization of the gas-liquid interfacial waves in vertical upward co-current annular flows. Nuclear Engineering and Design. 346:112-130. https://doi.org/10.1016/j.nucengdes.2019.03.008S11213034

    Multi-needle capacitance probe for non-conductive two-phase flows

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    Despite its variable degree of application, intrusive instrumentation is the most accurate way to obtain local information in a two-phase flow system, especially local interfacial velocity and local interfacial area parameters. In this way, multi-needle probes, based on conductivity or optical principles, have been extensively used in the past few decades by many researchers in two-phase flow investigations. Moreover, the signal processing methods used to obtain the time-averaged two-phase flow parameters in this type of sensor have been thoroughly discussed and validated by many experiments. The objective of the present study is to develop a miniaturized multi-needle probe, based on capacitance measurements applicable to a wide range of non-conductive two-phase flows and, thus, to extend the applicability of multi-needle sensor whilst also maintaining a signal processing methodology provided in the literature for conductivity probes. Results from the experiments performed assess the applicability of the proposed sensor measurement principle and signal processing method for the bubbly flow regime. These results also provide an insight into the sensor application for more complex two-phase flow regimes

    A recipe for postfledging survival in great tits Parus major: be large and be early (but not too much)

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    Survival of juveniles during the postfledging period can be markedly low, which may have major consequences on avian population dynamics. Knowing which factors operating during the nesting phase affect postfledging survival is crucial to understand avian breeding strategies. We aimed to obtain a robust set of predictors of postfledging local survival using the great tit (Parus major) as a model species. We used mark–recapture models to analyze the effect of hatching date, temperatures experienced during the nestling period, fledging size and body mass on first-year postfledging survival probability of great tit juveniles. We used data from 5192 nestlings of first clutches ringed between 1993 and 2010. Mean first-year postfledging survival probability was 15.2%, and it was lower for smaller individuals, as well as for those born in either very early or late broods. Our results stress the importance of choosing an optimum hatching period, and raising large chicks to increase first-year local survival probability in the studied population.Secretaría de Estado de Investigación, Desarrollo e Innovación (Grant/Award Number: ‘CGL2013-48001-C2-1-P’)Peer reviewe

    Trophic ecology of Gymnodactylus geckoides Spix, 1825 (Squamata, Phyllodactylidae) from Caatinga, Northeastern Brazil

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    The diet of lizards is mainly composed of arthropods. It can be affected by biotic and abiotic factors, which influence the energy supply provided by the composition of the animal´s diet. The richness and abundance of many arthropod species can be influenced by environmental seasonality, especially in the Caatinga ecoregion, due to the rainfall regimes. The present study aims to describe aspects of the seasonal and morphological variation in the lizard Gymnodactylus geckoides diet and their energy content. We collected 157 individuals (63 females, 68 males, and 26 juveniles) at the Catimbau National Park, Northeastern Brazil, of which 72 were analyzed for the dry season and 59 for the rainy season. Our data indicates Isoptera to be the most common prey in G. geckoides’s diet. Energy content, prey number was higher in the dry season, whereas prey volume and glycogen content increased in the rainy season. Proteins and lipids did not show marked differences. The present study represents the first effort to understand variations in G. geckoide’s trophic ecology, indicating that this specie presents a wide variation in their diet, especially when considering seasonal factors, revealing their needs and restrictions according to prey availability and environmental conditions

    Similar dispersal patterns between two closely related birds with contrasting migration strategies

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    Studying dispersal is crucial to understand metapopulation and sink-source dynamics and invasion processes. The capability to disperse is especially important for species living in fragmented habitats like wetlands. We investigated the distribution of natal and breeding dispersal distances and philopatry in Spanish populations of two closely related reedbed-nesting birds, the Moustached Warbler Acrocephalus melanopogon and the Eurasian Reed Warbler Acrocephalus scirpaceus. These warblers are morphologically very similar, but differ in migration strategy and, in our study area, in population size. Our aims were to find the best model for dispersal distances and to assess the occurrence of intra- or interspecific differences in dispersal patterns. We used ringing data from the Spanish marking scheme and selected recaptures to avoid including migrating individuals. In both species, most individuals were philopatric but dispersing birds were able to cross large distances (up to more than 100 km), suggesting the capability to compensate for habitat fragmentation. We found the heavy-tailed Cauchy distribution to be the best conceptual description for our data, in all cases but natal dispersal of Moustached Warblers. Among Eurasian Reed Warblers, natal philopatry was lower than breeding philopatry. We found no significant interspecific differences. This does not confirm the hypothesis of higher dispersal ability in long distance migrants (like Eurasian Reed Warblers) than in resident/short distance migrant bird species (like Moustached Warblers). The similarity in dispersal patterns among the two warblers may be explained by their close phylogenetic relatedness, similar constraints imposed on both species by a patchy habitat or similar evolutionary pressures.We are grateful to the many ringers who collected the data during years of fieldwork in Spain. Francesco Ceresa is supported by an "Atraent talent'' grant from the University of Valencia.Ceresa, F.; Belda, E.; Monrós González, JS. (2016). Similar dispersal patterns between two closely related birds with contrasting migration strategies. Population Ecology. 58(3):421-427. doi:10.1007/s10144-016-0547-0S421427583Banco de datos de anillamiento del remite ICONA – Ministerio de Medio Ambiente (2015) Datos de anillamiento y recuperaciones en España. Ministerio de Agricultura, Alimentación y Medio Ambiente, SEO/BirdLife, ICO, EBD-CSIC y GOB. Madrid (in Spanish)Begon M, Townsend CR, Harper JL (2006) Ecology: from individual to ecosystems, 4th edn. Blackwell Publishing, OxfordBlomqvist D, Fessl B, Hoi H, Kleindorfer S (2005) High frequency of extra-pair fertilisation in the moustached warbler, a songbird with a variable breeding system. Behaviour 142:1133–1148Bohonak AJ (1999) Dispersal, gene flow, and population structure. Q Rev Biol 74:21–45Burnham KP, Anderson DR (2002) Model selection and multi-model inference: a practical information-theoretic approach. Springer Verlag, New YorkCantos FJ, Tellería JL (1994) Stopover site fidelity of four migrant warblers in the Iberian Peninsula. J Avian Biol 25:131–134Carrascal LM, Palomino D (2008) Las aves comunes reproductoras en España. Población en 2004–2006. SEO/BirdLife, Madrid (in Spanish with English abstract)Carrascal LM, Weykam S, Palomino D, Lobo JM, Díaz L (2005) Atlas Virtual de las Aves Terrestres de España. http://www.vertebradosibericos.org/atlasaves.html . Accessed 16 Feb 2016Castany J (2003) El carricerín real (Acrocephalus melanopogon) en el P. N. del Prat de Cabanes-Torreblanca. Doctoral thesis. University of Valencia, Valencia (in Spanish)Castany J, López G (2006) El carricerín real en España. I Censo Nacional (2005). SEO/BirdLife, Madrid (in Spanish with English abstract)Ceresa F, Belda EJ, Kvist L, Rguibi-Idrissi H, Monrós JS (2015) Does fragmentation of wetlands affect gene flow in sympatric Acrocephalus warblers with different migration strategies? J Avian Biol 46:577–588Cooper NW, Murphy MT, Redmond LJ, Dolan AC (2009) Density-dependent age at first reproduction in the eastern kingbird. Oikos 118:413–419Delignette-Muller ML, Dutang C (2015) fitdistrplus: An R Package for fitting distributions. J Stat Softw 64:1–34. http://www.jstatsoft.org/v64/i04/ . Accessed 2 Sep 2015Frankham R, Ballou JD, Briscoe DA (2010) Introduction to conservation genetics, 2nd edn. Cambridge University Press, CambridgeHengeveld R (1994) Small step invasion research. 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    Regression with Empirical Variable Selection: Description of a New Method and Application to Ecological Datasets

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    Despite recent papers on problems associated with full-model and stepwise regression, their use is still common throughout ecological and environmental disciplines. Alternative approaches, including generating multiple models and comparing them post-hoc using techniques such as Akaike's Information Criterion (AIC), are becoming more popular. However, these are problematic when there are numerous independent variables and interpretation is often difficult when competing models contain many different variables and combinations of variables. Here, we detail a new approach, REVS (Regression with Empirical Variable Selection), which uses all-subsets regression to quantify empirical support for every independent variable. A series of models is created; the first containing the variable with most empirical support, the second containing the first variable and the next most-supported, and so on. The comparatively small number of resultant models (n = the number of predictor variables) means that post-hoc comparison is comparatively quick and easy. When tested on a real dataset – habitat and offspring quality in the great tit (Parus major) – the optimal REVS model explained more variance (higher R2), was more parsimonious (lower AIC), and had greater significance (lower P values), than full, stepwise or all-subsets models; it also had higher predictive accuracy based on split-sample validation. Testing REVS on ten further datasets suggested that this is typical, with R2 values being higher than full or stepwise models (mean improvement = 31% and 7%, respectively). Results are ecologically intuitive as even when there are several competing models, they share a set of “core” variables and differ only in presence/absence of one or two additional variables. We conclude that REVS is useful for analysing complex datasets, including those in ecology and environmental disciplines

    Differential Expression of PGC-1α and Metabolic Sensors Suggest Age-Dependent Induction of Mitochondrial Biogenesis in Friedreich Ataxia Fibroblasts

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    11 pages, 6 figures. PMID:21687738[PubMed] PMCID: PMC3110204BACKGROUND: Friedreich's ataxia (FRDA) is a mitochondrial rare disease, which molecular origin is associated with defect in the expression of frataxin. The pathological consequences are degeneration of nervous system structures and cardiomyopathy with necrosis and fibrosis, among others. PRINCIPAL FINDINGS: Using FRDA fibroblasts we have characterized the oxidative stress status and mitochondrial biogenesis. We observed deficiency of MnSOD, increased ROS levels and low levels of ATP. Expression of PGC-1α and mtTFA was increased and the active form of the upstream signals p38 MAPK and AMPK in fibroblasts from two patients. Interestingly, the expression of energetic factors correlated with the natural history of disease of the patients, the age when skin biopsy was performed and the size of the GAA expanded alleles. Furthermore, idebenone inhibit mitochondriogenic responses in FRDA cells. CONCLUSIONS: The induction of mitochondrial biogenesis in FRDA may be a consequence of the mitochondrial impairment associated with disease evolution. The increase of ROS and the involvement of the oxidative phosphorylation may be an early event in the cell pathophysiology of frataxin deficiency, whereas increase of mitochondriogenic response might be a later phenomenon associated to the individual age and natural history of the disease, being more evident as the patient age increases and disease evolves. This is a possible explanation of heart disease in FRDA.This work was supported by grants SAF2008-01338, SAF2006-01047 and SAF2009-07063 from the Ministerio de Ciencia e Innovación and financial support from the CIBERER (Biomedical Network Research Center for Rare Diseases). A.G. thanks the Conselleria de Educación of the Generalitat Valenciana for the financial support by grants GVPRE/2008/154. A.B.-A. is the recipient of a JAE-CSIC predoctoral fellowship. The CIBERER is an initiative of the Instituto de Salud Carlos III and INGENIO 2010.Peer reviewe
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