Arellano L., Fernandez P., Fonts R., Rose N.L., Nickus U., Thies H., Stuchlik E., Camarero L., Catalan J., Grimalt J.O. (2015) Increasing and decreasing trends of the atmospheric deposition of organochlorine compounds in European remote areas during the last decade. Atmospheric Chemistry and Physics. 15: 6069-6085.EnllaçDoi: 10.5194/acp-15-6069-2015
Bulk atmospheric deposition samples were collected between 2004 and 2007 at four high-altitude European sites encompassing east (Skalnaté Pleso), west (Lochnagar), central (Gossenköllesee) and south (Redòn) regions, and analysed for legacy and current-use organochlorine compounds (OCs). Polychlorobiphenyls (PCBs) generally showed the highest deposition fluxes in the four sites, between 112 and 488 ng m-2 mo-1, and hexachlorobenzene (HCB) the lowest, a few ng m-2 mo-1. Among pesticides, endosulfans were found at higher deposition fluxes (11-177 ng m-2 mo-1) than hexachlorocyclohexanes (HCHs) (17-66 ng m-2 mo-1) in all sites except Lochnagar that was characterized by very low fluxes of this insecticide. Comparison of the present measurements with previous determinations in Redòn (1997-1998 and 2001-2002) and Gossenköllesee (1996-1998) provided for the first time an assessment of the long-term temporal trends in OC atmospheric deposition in the European background areas. PCBs showed increasing deposition trends while HCB deposition fluxes remained nearly constant. Re-emission of PCBs from soils or as a consequence of glacier melting and subsequent precipitation and trapping of the volatilized compounds may explain the observed PCB trends. This process does not occur for HCB due to its high volatility which keeps most of this pollutant in the gas phase. A significant decline of pesticide deposition was observed during this studied decade (1996-2006) which is consistent with the restriction in the use of these compounds in most of the European countries. In any case, degassing of HCHs or endosulfans from ice melting to the atmosphere should be limited because of the low Henry's law constants of these compounds that will retain them dissolved in the melted water. Investigation of the relationship between air mass trajectories arriving at each site and OC deposition fluxes showed no correlation for PCBs, which is consistent with diffuse pollution from unspecific sources as the predominant origin of these compounds in these remote sites. In contrast, significant correlations between current-use pesticides and air masses flowing from the south were observed in Gossenköllesee, Lochnagar and Redòn. In the case of Redòn, the higher proportion of air masses from the south occurred in parallel to higher temperatures, which did not allow us to discriminate between these two determinant factors of pesticide deposition. However, in Gossenköllesee and Lochnagar, the relationship between pesticide concentration and southern air masses was univocal, reflecting the impact of regions with intensive agricultural activities. © Author(s) 2015.
Jarque S., Quiros L., Grimalt J.O., Gallego E., Catalan J., Lackner R., Pina B. (2015) Background fish feminization effects in European remote sites. Scientific Reports. 5: 0-0.EnllaçDoi: 10.1038/srep11292
Human activity has spread trace amounts of chemically stable endocrine-disrupting pollutants throughout the biosphere. These compounds have generated a background level of estrogenic activity that needs to be assessed. Fish are adequate sentinels for feminization effects as male specimens are more sensitive than humans to exogenous estrogenic compounds. High mountain lakes, the most distant environments of continental areas, only receive semi-volatile compounds from atmospheric deposition. We analyzed the expression levels of estrogen-regulated genes in male fish from these mountain lakes in Europe. Incipient feminization involving expression of estrogen receptor and zona radiata genes revealed a widespread diffuse estrogenic impact. This effect was correlated with the concentrations of some organochlorine compounds in fish and was consistent with the persistent occurrence of these tropospheric pollutants in the most remote planet regions. These results should be of general concern given the increasing endocrine disruption effects in human populations. © 2015, Nature Publishing Group. All rights reserved.
Pahissa J., Catalan J., Morabito G., Dorflinger G., Ferreira J., Laplace-Treyture C., Girbea R., Marchetto A., Polykarpou P., de Hoyos C. (2015) Benefits and limitations of an intercalibration of phytoplankton assessment methods based on the Mediterranean GIG reservoir experience. Science of the Total Environment. 538: 169-179.EnllaçDoi: 10.1016/j.scitotenv.2015.08.042
The status of European legislation regarding inland water quality after the enactment of the Water Framework Directive (WFD) originated scientific effort to develop reliable methods, primarily based on biological parameters. An important aspect of the process was to ensure that quality assessment was comparable between the different Member States. The Intercalibration process (IC), required in the WFD ensures the unbiased application of the norm. The presented results were developed in the context of the 2nd IC phase. An overview of the reservoir type definition of the Lake Mediterranean Geographical Intercalibration Group, where four types were considered divided by both alkalinity and climate, together with the results for selection of Maximum Ecological Potential sites (MEP) are presented. MEP reservoirs were selected based on pressure and biological variables. Three phytoplankton-based assessment methods were intercalibrated using data from Mediterranean countries. The Mediterranean Assessment System for Reservoirs Phytoplankton (Spain), the New Mediterranean Assessment System for Reservoirs Phytoplankton (Portugal and Cyprus) and the New Italian Method (Italy) were applied. These three methods were compared through option 3 of the Intercalibration Guide. The similarity of the assessments was quantified, and the Good/Moderate (GM) boundaries assessed. All three methods stood as comparable at the GM boundary except for the MASRP in siliceous wet reservoirs, which was slightly stricter. Finally, the main taxonomic groups represented in the phytoplankton community at MEP conditions were identified, as well as their main changes with an increasing trophic status. MEP sites are dominated by chrysophytes in siliceous wet reservoirs and by the diatoms Cyclotella and Achnanthes in calcareous ones. Cyanobacteria take over the community in both calcareous and siliceous wet reservoirs as eutrophication increases. In summary, the relevance and reliability of the quality assessment methods compared were confirmed both from an ecological perspective and a health risk management point of view. © 2015 Elsevier B.V.
Taranu Z.E., Gregory-Eaves I., Leavitt P.R., Bunting L., Buchaca T., Catalan J., Domaizon I., Guilizzoni P., Lami A., Mcgowan S., Moorhouse H., Morabito G., Pick F.R., Stevenson M.A., Thompson P.L., Vinebrooke R.D. (2015) Acceleration of cyanobacterial dominance in north temperate-subarctic lakes during the Anthropocene. Ecology Letters. 18: 375-384.EnllaçDoi: 10.1111/ele.12420
Increases in atmospheric temperature and nutrients from land are thought to be promoting the expansion of harmful cyanobacteria in lakes worldwide, yet to date there has been no quantitative synthesis of long-term trends. To test whether cyanobacteria have increased in abundance over the past ~ 200 years and evaluate the relative influence of potential causal mechanisms, we synthesised 108 highly resolved sedimentary time series and 18 decadal-scale monitoring records from north temperate-subarctic lakes. We demonstrate that: (1) cyanobacteria have increased significantly since c. 1800 ce, (2) they have increased disproportionately relative to other phytoplankton, and (3) cyanobacteria increased more rapidly post c. 1945 ce. Variation among lakes in the rates of increase was explained best by nutrient concentration (phosphorus and nitrogen), and temperature was of secondary importance. Although cyanobacterial biomass has declined in some managed lakes with reduced nutrient influx, the larger spatio-temporal scale of sedimentary records show continued increases in cyanobacteria throughout the north temperate-subarctic regions. © 2015 John Wiley & Sons Ltd/CNRS.
Tromer R.M., Barbosa M.B., Bartumeus F., Catalan J., Da Luz M.G.E., Raposo E.P., Viswanathan G.M. (2015) Inferring Lévy walks from curved trajectories: A rescaling method. Physical Review E - Statistical, Nonlinear, and Soft Matter Physics. 92: 0-0.EnllaçDoi: 10.1103/PhysRevE.92.022147
An important problem in the study of anomalous diffusion and transport concerns the proper analysis of trajectory data. The analysis and inference of Lévy walk patterns from empirical or simulated trajectories of particles in two and three-dimensional spaces (2D and 3D) is much more difficult than in 1D because path curvature is nonexistent in 1D but quite common in higher dimensions. Recently, a new method for detecting Lévy walks, which considers 1D projections of 2D or 3D trajectory data, has been proposed by Humphries et al. The key new idea is to exploit the fact that the 1D projection of a high-dimensional Lévy walk is itself a Lévy walk. Here, we ask whether or not this projection method is powerful enough to cleanly distinguish 2D Lévy walk with added curvature from a simple Markovian correlated random walk. We study the especially challenging case in which both 2D walks have exactly identical probability density functions (pdf) of step sizes as well as of turning angles between successive steps. Our approach extends the original projection method by introducing a rescaling of the projected data. Upon projection and coarse-graining, the renormalized pdf for the travel distances between successive turnings is seen to possess a fat tail when there is an underlying Lévy process. We exploit this effect to infer a Lévy walk process in the original high-dimensional curved trajectory. In contrast, no fat tail appears when a (Markovian) correlated random walk is analyzed in this way. We show that this procedure works extremely well in clearly identifying a Lévy walk even when there is noise from curvature. The present protocol may be useful in realistic contexts involving ongoing debates on the presence (or not) of Lévy walks related to animal movement on land (2D) and in air and oceans (3D). © 2015 American Physical Society.
de Mendoza G., Ventura M., Catalan J. (2015) Environmental factors prevail over dispersal constraints in determining the distribution and assembly of Trichoptera species in mountain lakes. Ecology and Evolution. 5: 2518-2532.EnllaçDoi: 10.1002/ece3.1522
Aiming to elucidate whether large-scale dispersal factors or environmental species sorting prevail in determining patterns of Trichoptera species composition in mountain lakes, we analyzed the distribution and assembly of the most common Trichoptera (Plectrocnemia laetabilis, Polycentropus flavomaculatus, Drusus rectus, Annitella pyrenaea, and Mystacides azurea) in the mountain lakes of the Pyrenees (Spain, France, Andorra) based on a survey of 82 lakes covering the geographical and environmental extremes of the lake district. Spatial autocorrelation in species composition was determined using Moran's eigenvector maps (MEM). Redundancy analysis (RDA) was applied to explore the influence of MEM variables and in-lake, and catchment environmental variables on Trichoptera assemblages. Variance partitioning analysis (partial RDA) revealed the fraction of species composition variation that could be attributed uniquely to either environmental variability or MEM variables. Finally, the distribution of individual species was analyzed in relation to specific environmental factors using binomial generalized linear models (GLM). Trichoptera assemblages showed spatial structure. However, the most relevant environmental variables in the RDA (i.e., temperature and woody vegetation in-lake catchments) were also related with spatial variables (i.e., altitude and longitude). Partial RDA revealed that the fraction of variation in species composition that was uniquely explained by environmental variability was larger than that uniquely explained by MEM variables. GLM results showed that the distribution of species with longitudinal bias is related to specific environmental factors with geographical trend. The environmental dependence found agrees with the particular traits of each species. We conclude that Trichoptera species distribution and composition in the lakes of the Pyrenees are governed predominantly by local environmental factors, rather than by dispersal constraints. For boreal lakes, with similar environmental conditions, a strong role of dispersal capacity has been suggested. Further investigation should address the role of spatial scaling, namely absolute geographical distances constraining dispersal and steepness of environmental gradients at short distances. © 2015 The Authors.
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