Marc Ventura | CSIC (Consejo Superior de Investigaciones Científicas-Spanish National Research Council) (original) (raw)

Papers by Marc Ventura

Environmental Science & Technology, 2003

Polycyclic aromatic hydrocarbons (PAH) were measured in bulk atmospheric deposition collected in ... more Polycyclic aromatic hydrocarbons (PAH) were measured in bulk atmospheric deposition collected in three remote areas of Europe during 1997-1998. Mean total PAH fluxes over a period of 18 months were 1560 ( 750 and 1150 ( 630 ng m -2 mo -1 in the Pyrenees and the Alps, respectively. In the Caledonian mountains (Scandinavia) the observed mean fluxes were 1900 ( 940 ng m -2 mo -1 (6 month collection). Similar qualitative PAH compositions (p values <0.05) in the bulk atmospheric deposition have been observed between sites, which are dominated by the more volatile parent compounds. The main differences between lakes are related to the high molecular weight compounds. Atmospheric deposition of PAH to these remote sites appears to be independent of their concentrations in the atmosphere, which are similar between sites (in the range of 1.8-3.0 ng‚m -3 ), being controlled mainly by particle deposition, followed by precipitation and air temperature. A multilevel regression model including these three variables accounted for 74% of the total variability in total PAH bulk deposition; however, the contribution of each variable in the model is compound and site-dependent. The deposition of high molecular weight PAH depends more on particle deposition and precipitation, whereas air temperature is the main factor controlling the deposition fluxes of the low molecular weight PAH.

Through an extensive bibliographic search in historical archives and personal interviews to local... more Through an extensive bibliographic search in historical archives and personal interviews to local elderly people, we have attempted to describe the origin, the historical utilisation and the actual potential distribution of the fish species in the lakes of the Aiguestortes and Estany de Sant Maurici National Park. The first documented records in these lakes have been dated to the end of the sixteenth century. Traditional use of the species was related with alimentary requirements, but also it was used as an alternative economic resource. Traditional utilisation is significantly changed during the second half of the last century (s. XX), when important introductions related with leisure fishing activities are recorded, not only with allochtonous stocks of Brown trout but also with other exotic salmonids such as rainbow trout, brook trout and the cyprinid European minnow. As a result, only a 28% of the lakes have remained fish-less.

Biological Conservation, 2013

High mountain lakes are naturally fishless, although many have had introductions of non-native fi... more High mountain lakes are naturally fishless, although many have had introductions of non-native fish species, predominantly trout. Predation on native fauna by introduced trout involves profound ecological changes. The objective of this study was to reconstruct the historical process of trout introduction in 520 high mountain lakes >0.5 ha of the southern Pyrenees and quantify which particular factors either environmental or anthropogenic, best explained their present distribution and lake conservation status. The first written evidence of trout introductions dated back to 1371 AD. By 1900, trout had been introduced to 26.5% of lakes during preceding centuries. A subsequent wave of introductions began in 1960 when stocking led to trout becoming established in 52.5% of lakes. From 1900 to 1950, walking distance from nearby urban centres was the dominant factor explaining 29-60% of the variation in trout distribution, indicating that trout introductions were in lakes closer to human settlements. In contrast, with the onset of modern fish management that took place during the period 1960-2000, the most significant factors were both the management practices and lake characteristics which are likely related with the probability of survival of the fish populations. After 2000, the remaining fishless lakes were those of highest altitudes, and the shallowest and those with the lowest surface area. The recent fishing ban in protected areas of National Parks has resulted in a stabilization of the number of lakes with fish, suggesting that this is the only reliable management policy to avoid new introductions and preserve the conservation status of high mountain lakes.

Ecology and Evolution, 2015

Aiming to elucidate whether large-scale dispersal factors or environmental species sorting prevai... more 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.

Freshwater Biology, 2009

2. For all taxonomic groups we found a hierarchical structure in the community assemblage using d... more 2. For all taxonomic groups we found a hierarchical structure in the community assemblage using distinct scales of lake clustering (number of k-means groups) based on species composition similarity (Hellinger distance). We determined the optimal partition in assemblage types (ie number of lake clusters) for each taxonomic group by maximising the sum of the taxon indicative value (IndVal) and performed discriminant analyses, using environmental variables not conditioned by geographical patterns. Relevant environmental variables differed among and within ...

Spheroidal carbonaceous particles (SCPs) are produced only from high temperature combustion of fo... more Spheroidal carbonaceous particles (SCPs) are produced only from high temperature combustion of fossil-fuels. In mountain lake systems, they provide an unambiguous indicator of atmospheric deposition. In order to compare depositional fluxes of SCPs between mountain areas experiencing various pollutant regimes, intensive bulk deposition sampling was undertaken at five sites across Europe. Catchment soil cores and lake sediment cores were also taken at each site to compare SCP storage over the post-industrial period. Atmospheric, sediment and soil SCP data showed similar patterns. Highest contamination was found in Scotland, Slovakia and Spain with the Austrian site intermediate and the mid-Norwegian site least contaminated. A high proportion of accumulated SCPs were found to be stored in catchment soils at each site. Therefore, a significant increase in soil erosion, possibly as a result of future climate change, could lead to the input of large quantities of catchment stored SCPs and, by implication, other atmospherically deposited contaminants to the lake ecosystem.

Water, Air, and Soil Pollution, 2001

Limnology and Oceanography, 2000

High-altitude lakes are exposed to high fluence rates of solar ultraviolet radiation (UVR; 290-40... more High-altitude lakes are exposed to high fluence rates of solar ultraviolet radiation (UVR; 290-400 nm) and contain low concentrations of dissolved organic carbon (DOC). While in most lowland lakes, DOC can be used to predict UV transparency with sufficient accuracy, current models fail to estimate UVR in clear alpine lakes. In these lakes, phytoplankton may contribute significantly to the UV attenuation either as particles or as a source of chromophoric dissolved organic matter (CDOM) with distinctive properties. We investigated a series of 26 lakes in the Alps and Pyrenees, situated at elevations ranging from 422 to 2,799 m above sea level and having DOC concentrations ranging from 0.2 to 3.5 mg L Ϫ1 . CDOM, as measured by the absorptivity of filtered lake water, explained most of the variability in the attenuation of underwater UVR among lakes (r 2 ϭ 0.94, P Ͻ 0.001). However, within-lake variation in the UV attenuation revealed a significant contribution from phytoplankton in deeper waters (UV attenuation increasing with chlorophyll a concentration; r 2 ϭ 0.97, P ϭ 0.002), only apparent when DOC concentrations were low (ϳ0.3 mg L Ϫ1 ). The DOC-specific absorptivity (a g *) was also important for characterizing the optical conditions in this series of lakes. Epilimnetic values of a g * were significantly lower in lakes located at high elevations (with low allochthonous CDOM inputs from the catchment), compared to lakes surrounded by trees and meadows. Moreover, a g * was generally lower in surface waters than in deeper water layers, suggesting the influence of photobleaching on UV transparency. The slope S of the exponential regression between CDOM absorptivity and wavelength did not show clear patterns, such as found in marine systems, and often presented lower values in the epilimnetic waters (in association with lower a g *). Collectively, our results suggest that in transparent alpine lakes, the dynamics of the CDOM pool and phytoplankton production will have a strong effect on temporal changes in UV underwater attenuation. Solar ultraviolet-B radiation (UVB; 290-320 nm) has increased during the last 15 yr over many Earth's locations as a consequence of the degradation of the stratospheric ozone layer. Beside Antarctica, where the increment is notorious,

Limnetica, 2006

High mountain lakes offer research opportunities beyond what could be expected from their quantit... more High mountain lakes offer research opportunities beyond what could be expected from their quantitative relevance in the Earth system. In this article we present a brief summary of the research carried out in the lakes of the Pyrenees in the last twenty years by the group of limnology of the Centre for High Mountain Research (CRAM) of the University of Barcelona. The studies can be included in three main topics: life in extreme conditions, catchment-lake relationships and environmental changes.

Journal of Paleolimnology, 2002

Weather variation and climate fluctuations are the main sources of ecosystem variability in remot... more Weather variation and climate fluctuations are the main sources of ecosystem variability in remote mountain lakes. Here we describe the main patterns of seasonal variability in the ecosystems of nine lakes in Europe, and discuss the implications for recording climatic features in their sediments. Despite the diversity in latitude and size, the lakes showed a number of common features. They were ice-covered between 5-9 months, and all but one were dimictic. This particular lake was long and shallow, and wind action episodically mixed the water column throughout the ice-free period. All lakes showed characteristic oxygen depletion during the ice-covered-period, which was greater in the most productive lakes. Two types of lakes were distinguished according to the number of production peaks during the ice-free season. Lakes with longer summer stratification tended to have two productive periods: This is the third of 11 papers published in this special issue on the palaeolimnology of remote mountain lakes in Europe resulting from the MOLAR project funded by the European Union. The guest editor was Richard W. Battarbee.

Genome, 2008

As for most other organisms, genome size in zooplankton differs widely. This may have a range of ... more As for most other organisms, genome size in zooplankton differs widely. This may have a range of consequences for growth rate, development, and life history strategies, yet the causes of this pronounced variability are not settled. Here we propose that small genome size may be an evolutionary consequence of phosphorus (P) allocation from DNA to RNA under P deficiency. To test this hypothesis we have compared the two major groups of zooplankton, copepods and cladocerans, that have overlapping niches and body size. Relative to the cladocerans, copepods have a more complex life history and a lower mass-specific P content, while cladocerans tend to have higher P and RNA contents and higher specific growth rates and frequently experience P-limited growth, likely due to a shortage of P for ribosome synthesis. Cladocerans also generally have smaller genomes than copepods (1C = 0.17-0.63 pg DNAÁcell -1 vs. 1C = 0.10-10 pg DNAÁcell -1 ). Furthermore, cladocerans have a higher slope of the relationship of body size with DNA content (1.5 vs. 0.28 in copepods) and present almost 15-fold higher RNA:DNA ratios (24.8 in cladocerans vs. 1.6 in copepods). Hence, small genome size in cladocerans could reflect an evolutionary pressure towards ''efficient'' genomes to conserve a key element needed to maximize growth rate. We do not claim that this is a universal cause of genome size variability, but propose that streamlining of genomes could be related to P conservation rather than energy conservation. This could be relevant for a range of organisms that may suffer P-limited growth rates.

Journal of Paleolimnology, 2002

The ecosystem response of Lake Redó (Central Pyrenees) to fluctuations in seasonal air temperatur... more The ecosystem response of Lake Redó (Central Pyrenees) to fluctuations in seasonal air temperature during the last two centuries was investigated by comparison of reconstructed air temperatures with the sediment record. Fine slicing allowed a resolution of 3–6 years according to the 210Pb dating, although it was still difficult to easily investigate the response to air temperature forcing, since extreme fluctuations in temperature occur on interannual time-scales. However, the resolution was sufficient to show responses on decadal and century scales. An overall tendency to warming in mean annual temperature in the Central Pyrenees has been caused by summer and in particular by autumn increases. Many of the measured sediment variables apparently responded to these long term trends, but the significance of the relationships was highly conditioned by the structure of the data. The variables responding most on the finer time scales were the microfossils. For diatoms, chironomids and chrysophytes the main variability correlated to summer and to autumn temperatures. For two planktonic species, Fragilaria nanana and Cyclotella pseudostelligera, we found a link of their variability with temperature fluctuations in their growing months (September and October, respectively). This relationship appeared at a certain point during a general warming trend, indicating a threshold in the response. On the other hand, no significant changes in the dominant species could be linked to temperature, nor in any significant subgroup of the 180 diatom species present in the core. In contrast, for most chironomids (particularly Paratanytarsus austriacus, Heterotrissocladius marcidus and Micropsectra radialis) a negative relationship with summer temperature extended throughout the studied period. This response of the whole group gives chironomids a more robust role as indicators for recording temperature changes on long time-scales (e.g., through the Holocene) and for lake signal inter-comparison. Finally, our results indicated that, in all cases, there was a significant resilience to high frequency changes and hysteresis despite extreme fluctuations. Although we were dealing with organisms with one or many generations per year, their populations seemed to follow the decadal trends in air temperature.

The biological activity of the planktonic community of lake Redó, expressed in terms of carbon fl... more The biological activity of the planktonic community of lake Redó, expressed in terms of carbon fluxes, was measured and compared to the changes in DIC, DOC and POC in the water column. Planktonic photosynthesis ranged between c. 0.01 -0.3 µg C m -2 h -1 . Release of EOC phytoplankton was highly variable, between 5 and 80% of total fixation. Bacterial uptake of EOC ranged between 1-20% of total fixation. Bacterial activities were, in absolute numbers, very low: 0.005±0.003 µg C m -2 h -1 , in contrast with the higher grazing rates on bacteria of 0.036±0.021 µg C m -2 h -1 . Respiration and diffusion of CO 2 to the atmosphere seem to be the main processes controlling DIC concentration. DOC and POC concentrations were highly correlated, and their fluxes presented large fluctuations. These changes in DOC are larger than those due to the processes we have measured. Other processes that might affect DOC include diffusion from sediments, inputs from the catchment, uptake by mixotrophic algae and zooplankton, bacterial respiration, UV photoxidation, and flocculation. Lake Redó seems to act in general terms as an heterotrophic system: respiration is higher than photosynthesis, and the budget is balanced by the import of DOC and, to a lesser extent, POC. Most of the carbon seems to be ultimately released to atmosphere, since little is accumulated in sediments. The estimates of diffusive fluxes agreed with this hypothesis. At this stage, the comparison of biogeochemical budgets with biological activity measurements only serves as a rough approximation of the main pathways in the C cycling in the lake, and to point the issues that need further research in order to calculate the C budget in the lake with accuracy.

Environmental Pollution, 2005

Polychlorobiphenyls (PCBs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and DDT were e... more Polychlorobiphenyls (PCBs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and DDT were examined in the muscle of brown trout (Salmo trutta) from a high mountain lake located in the Pyrenees (Catalonia, Spain) that was used as a model of these lacustrine environments. Results indicate that fish age is the main factor of variability among specimens in this population that is subjected to atmospheric inputs of the organochlorine compounds (OC). Increases of 2- and 20-fold between fish aged 1 year and 15 years old are found. The observed pattern cannot be explained in terms of fish size, condition factor, or muscle lipid content. Higher molecular weight compounds (higher lipophilicity) are better correlated with fish age than low molecular weight compounds. A transformation from 4,4′-DDT to 4,4′-DDE occurs in fish after ingestion; this results in amplified age-dependent signals, especially in male specimens. In contrast, PCB congener #180 has lower age dependence than the general OC group, which could be due to its high hydrophobicity (log Kow > 7). In any case, selective accumulation of hydrophobic compounds is already observed among younger fish (age, 1 year). Due to this effect, the relative OC composition does not reflect the main OC pollutants in the lake waters.

Limnology and Oceanography, 2005

With the aim to determine the contribution of development and reproduction to the variability in ... more With the aim to determine the contribution of development and reproduction to the variability in the elemental composition of zooplankton, we measured the carbon (C), hydrogen (H), nitrogen (N), and phosphorus (P) elemental composition of the planktonic crustacean assemblage in an alpine lake for a whole seasonal cycle. The species included three distinct living modes: a cladoceran, Daphnia pulicaria; a cyclopoid copepod, Cyclops abyssorum; and a calanoid copepod, Diaptomus cyaneus. For the three species, reproduction was the main cause of elemental variability. Adult females of the three species lost from 32% to 48% of their initial absolute C and H content during reproduction, which corresponded to a similar decrease in their lipid and carbohydrate content. The N content did not change in any of the three species, nor did the protein and chitin content. Daphnia and Diaptomus lost 35% and 56%, respectively, of their initial absolute P content during reproduction, whereas the P content of Cyclops did not change. The three species stored energy compounds under unfavorable conditions for later use in offspring production, but only Diaptomus and Daphnia mobilized stored P. Corresponding stoichiometric changes with reproduction included a decrease in C : N ratio for the three species; an increase in N : P ratio for Daphnia adult females and adults of Diaptomus; and a C : P ratio increase in Diaptomus females and decline in Cyclops females. Differences in C : P ratio changes corresponded with differences in allocation to their respective reproductive tissues. Diaptomus males and Daphnia females did not change their C : P ratio with reproduction.

Environmental Science & Technology, 2004

An integrated study encompassing the distribution of organochlorine compounds (OC) in water, food... more An integrated study encompassing the distribution of organochlorine compounds (OC) in water, food web (chironomids, terrestrial insects, cladocerans, mollusks, and cyanobacteria), and fish (brown trout) from a high mountain lake (Redon, Pyrenees) is reported. OC distributions in these compartments have been determined to assess their transport routes into fish. Food diets have been estimated by analysis of fish stomach content and food web stable isotopes (δ 13 C and δ 15 N). OCs with octanol-water partition coefficient (K ow ) higher than 10 6 showed lower concentrations in food than expected from theoretical octanol-water partition, indicating that the distribution of these compounds does not reach equilibrium within the life span of the food web organisms (ca. 1 year). On the other hand, the degree of biomagnification in fish increased with K ow , except in the case of the largest compound analyzed (seven chlorine substituents, PCB #180). OC exchange at fish gill and gut has been evaluated using a fugacity model based on the water, food, and fish concentrations. All compounds exhibited a net gill loss and a net gut uptake. A pseudostationary state was only achieved for compounds with log(K ow ) < 6. Calculation of fish average residence times for the compounds in apparent steady state gave values of days to a few weeks for HCHs, 1 year for HCB and 4,4′-DDE, and 2-3 years for 4,4′-DDT and PCB#28 and PCB#52. Residence times longer than one decade were found for the more chlorinated PCB.

The process-oriented catchment-scale model MAGIC was used to simulate water chemistry at Lake Red... more The process-oriented catchment-scale model MAGIC was used to simulate water chemistry at Lake Redó, a high mountain lake in the Central Pyrenees, Spain. Data on lakewater and atmospheric deposition chemistry for the period 1984-1998 were used to calibrate the model, which was then used to reconstruct past and to provide forecasts for three hypothetical future scenarios of deposition. Forecast scenarios considered several combinations of changes in S and N deposition due to abatement strategies, and in base cation deposition due to climate-induced changes in air-mass trajectories from northern Africa. Scenario 1 assumed constant deposition of base cations at the present level plus the expected decrease in S and N deposition resulting from reduced emissions; scenario 2 (best case) assumed an increase in base cation deposition plus the same decrease in S and N deposition as in scenario 1; scenario 3 (worst case) assumed a decrease in base cation deposition plus no decrease in S and N deposition. The hindcast indicated that during the past 140-year period changes in lake water chemistry have been significant for a remote mountain catchment, although no substantial acidification has occurred. In this regard Lake Redó can be described as a "non-sensitive lake" maintaining a reference condition. The forecasts indicated changes that do not affect this status, but the trends, even if slight, were different between scenarios. A slight decline in the surface water ANC is predicted by Scenario 3. The N budget indicates an unusually low retention in the catchment, which may result in enhanced sensitivity to further increased N deposition. Some of the discrepancy between modelled and measured Ca 2+ in lake water during 1984-98 could be explained by changes in rainfall amounts and by increased weathering rates due to increases in air temperature.

Water, Air, & Soil Pollution: Focus, 2002

Here we present the chemical trends of seven high altitude lakes, analysed within the AL:PE and M... more Here we present the chemical trends of seven high altitude lakes, analysed within the AL:PE and MOLAR Projects of the EU (1999) and selected on the basis of the availability of complete and reliable data for the period 1984–1999. The lakes are representative of the Scandinavian Alps, the Cairngorm Mountains in Scotland, the Alps and the Pyrenees. Significant trends were identified for some indicators of acidification, for instance pH and alkalinity, but not all lakes reacted similarly to decreasing depositions of sulphate and base cations. Differences in lake response are discussed in relation to recent variations of atmospheric deposition chemistry and associated changes in climatic conditions. Beside individual variations of the studied lakes, depending, among other things, on altitude and morphology, catchment characteristics and climate trends play a major role for the reaction of high altitude lakes on changes in atmospheric depositions.

We reconstructed the genetic structure of a planktonic crustacean Daphnia longispina living in hi... more We reconstructed the genetic structure of a planktonic crustacean Daphnia longispina
living in high mountain lakes and ponds in the Pyrenees to investigate whether it was
shaped by persistent founder effects originating shortly after the last glacial maximum
or by ongoing dispersal and effective migration (gene flow). We found that the genetic
structure can largely be explained by a single colonization event following gradual
deglaciation of the Pyrenees ~10 000–15 000 years ago. Nuclear genetic diversity
declined steeply from southeast to northwest, suggestive of serial colonization of available
habitats with advancing deglaciation. The spatial genetic structure suggests that
founder effects were major determinants of the present-day diversity, both at the catchment
level and at the level of individual water bodies, further supporting extremely
low effective migration rates. This study reveals a prime example of a founder effect
that is both long lasting and maintained at small spatial scales. Our data suggest a
process of isolation by colonization as a result of strong priority effects and monopolization.
We found evidence for the spread of haplotypes with Pyrenean ancestry across
the Palaearctic over distances up to 5500 km, although the local genetic structure after
colonization was hardly influenced by contemporary dispersal. Finally, our data also
suggest that mitochondrial mutation rates in the studied populations were seven times
higher than typically assumed. Overall, we show that founder effects can persist for
centuries even at small spatial scales at which the potential for dispersal is high.

Environmental Science & Technology, 2003

Polycyclic aromatic hydrocarbons (PAH) were measured in bulk atmospheric deposition collected in ... more Polycyclic aromatic hydrocarbons (PAH) were measured in bulk atmospheric deposition collected in three remote areas of Europe during 1997-1998. Mean total PAH fluxes over a period of 18 months were 1560 ( 750 and 1150 ( 630 ng m -2 mo -1 in the Pyrenees and the Alps, respectively. In the Caledonian mountains (Scandinavia) the observed mean fluxes were 1900 ( 940 ng m -2 mo -1 (6 month collection). Similar qualitative PAH compositions (p values <0.05) in the bulk atmospheric deposition have been observed between sites, which are dominated by the more volatile parent compounds. The main differences between lakes are related to the high molecular weight compounds. Atmospheric deposition of PAH to these remote sites appears to be independent of their concentrations in the atmosphere, which are similar between sites (in the range of 1.8-3.0 ng‚m -3 ), being controlled mainly by particle deposition, followed by precipitation and air temperature. A multilevel regression model including these three variables accounted for 74% of the total variability in total PAH bulk deposition; however, the contribution of each variable in the model is compound and site-dependent. The deposition of high molecular weight PAH depends more on particle deposition and precipitation, whereas air temperature is the main factor controlling the deposition fluxes of the low molecular weight PAH.

Through an extensive bibliographic search in historical archives and personal interviews to local... more Through an extensive bibliographic search in historical archives and personal interviews to local elderly people, we have attempted to describe the origin, the historical utilisation and the actual potential distribution of the fish species in the lakes of the Aiguestortes and Estany de Sant Maurici National Park. The first documented records in these lakes have been dated to the end of the sixteenth century. Traditional use of the species was related with alimentary requirements, but also it was used as an alternative economic resource. Traditional utilisation is significantly changed during the second half of the last century (s. XX), when important introductions related with leisure fishing activities are recorded, not only with allochtonous stocks of Brown trout but also with other exotic salmonids such as rainbow trout, brook trout and the cyprinid European minnow. As a result, only a 28% of the lakes have remained fish-less.

Biological Conservation, 2013

High mountain lakes are naturally fishless, although many have had introductions of non-native fi... more High mountain lakes are naturally fishless, although many have had introductions of non-native fish species, predominantly trout. Predation on native fauna by introduced trout involves profound ecological changes. The objective of this study was to reconstruct the historical process of trout introduction in 520 high mountain lakes >0.5 ha of the southern Pyrenees and quantify which particular factors either environmental or anthropogenic, best explained their present distribution and lake conservation status. The first written evidence of trout introductions dated back to 1371 AD. By 1900, trout had been introduced to 26.5% of lakes during preceding centuries. A subsequent wave of introductions began in 1960 when stocking led to trout becoming established in 52.5% of lakes. From 1900 to 1950, walking distance from nearby urban centres was the dominant factor explaining 29-60% of the variation in trout distribution, indicating that trout introductions were in lakes closer to human settlements. In contrast, with the onset of modern fish management that took place during the period 1960-2000, the most significant factors were both the management practices and lake characteristics which are likely related with the probability of survival of the fish populations. After 2000, the remaining fishless lakes were those of highest altitudes, and the shallowest and those with the lowest surface area. The recent fishing ban in protected areas of National Parks has resulted in a stabilization of the number of lakes with fish, suggesting that this is the only reliable management policy to avoid new introductions and preserve the conservation status of high mountain lakes.

Ecology and Evolution, 2015

Aiming to elucidate whether large-scale dispersal factors or environmental species sorting prevai... more 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.

Freshwater Biology, 2009

2. For all taxonomic groups we found a hierarchical structure in the community assemblage using d... more 2. For all taxonomic groups we found a hierarchical structure in the community assemblage using distinct scales of lake clustering (number of k-means groups) based on species composition similarity (Hellinger distance). We determined the optimal partition in assemblage types (ie number of lake clusters) for each taxonomic group by maximising the sum of the taxon indicative value (IndVal) and performed discriminant analyses, using environmental variables not conditioned by geographical patterns. Relevant environmental variables differed among and within ...

Spheroidal carbonaceous particles (SCPs) are produced only from high temperature combustion of fo... more Spheroidal carbonaceous particles (SCPs) are produced only from high temperature combustion of fossil-fuels. In mountain lake systems, they provide an unambiguous indicator of atmospheric deposition. In order to compare depositional fluxes of SCPs between mountain areas experiencing various pollutant regimes, intensive bulk deposition sampling was undertaken at five sites across Europe. Catchment soil cores and lake sediment cores were also taken at each site to compare SCP storage over the post-industrial period. Atmospheric, sediment and soil SCP data showed similar patterns. Highest contamination was found in Scotland, Slovakia and Spain with the Austrian site intermediate and the mid-Norwegian site least contaminated. A high proportion of accumulated SCPs were found to be stored in catchment soils at each site. Therefore, a significant increase in soil erosion, possibly as a result of future climate change, could lead to the input of large quantities of catchment stored SCPs and, by implication, other atmospherically deposited contaminants to the lake ecosystem.

Water, Air, and Soil Pollution, 2001

Limnology and Oceanography, 2000

High-altitude lakes are exposed to high fluence rates of solar ultraviolet radiation (UVR; 290-40... more High-altitude lakes are exposed to high fluence rates of solar ultraviolet radiation (UVR; 290-400 nm) and contain low concentrations of dissolved organic carbon (DOC). While in most lowland lakes, DOC can be used to predict UV transparency with sufficient accuracy, current models fail to estimate UVR in clear alpine lakes. In these lakes, phytoplankton may contribute significantly to the UV attenuation either as particles or as a source of chromophoric dissolved organic matter (CDOM) with distinctive properties. We investigated a series of 26 lakes in the Alps and Pyrenees, situated at elevations ranging from 422 to 2,799 m above sea level and having DOC concentrations ranging from 0.2 to 3.5 mg L Ϫ1 . CDOM, as measured by the absorptivity of filtered lake water, explained most of the variability in the attenuation of underwater UVR among lakes (r 2 ϭ 0.94, P Ͻ 0.001). However, within-lake variation in the UV attenuation revealed a significant contribution from phytoplankton in deeper waters (UV attenuation increasing with chlorophyll a concentration; r 2 ϭ 0.97, P ϭ 0.002), only apparent when DOC concentrations were low (ϳ0.3 mg L Ϫ1 ). The DOC-specific absorptivity (a g *) was also important for characterizing the optical conditions in this series of lakes. Epilimnetic values of a g * were significantly lower in lakes located at high elevations (with low allochthonous CDOM inputs from the catchment), compared to lakes surrounded by trees and meadows. Moreover, a g * was generally lower in surface waters than in deeper water layers, suggesting the influence of photobleaching on UV transparency. The slope S of the exponential regression between CDOM absorptivity and wavelength did not show clear patterns, such as found in marine systems, and often presented lower values in the epilimnetic waters (in association with lower a g *). Collectively, our results suggest that in transparent alpine lakes, the dynamics of the CDOM pool and phytoplankton production will have a strong effect on temporal changes in UV underwater attenuation. Solar ultraviolet-B radiation (UVB; 290-320 nm) has increased during the last 15 yr over many Earth's locations as a consequence of the degradation of the stratospheric ozone layer. Beside Antarctica, where the increment is notorious,

Limnetica, 2006

High mountain lakes offer research opportunities beyond what could be expected from their quantit... more High mountain lakes offer research opportunities beyond what could be expected from their quantitative relevance in the Earth system. In this article we present a brief summary of the research carried out in the lakes of the Pyrenees in the last twenty years by the group of limnology of the Centre for High Mountain Research (CRAM) of the University of Barcelona. The studies can be included in three main topics: life in extreme conditions, catchment-lake relationships and environmental changes.

Journal of Paleolimnology, 2002

Weather variation and climate fluctuations are the main sources of ecosystem variability in remot... more Weather variation and climate fluctuations are the main sources of ecosystem variability in remote mountain lakes. Here we describe the main patterns of seasonal variability in the ecosystems of nine lakes in Europe, and discuss the implications for recording climatic features in their sediments. Despite the diversity in latitude and size, the lakes showed a number of common features. They were ice-covered between 5-9 months, and all but one were dimictic. This particular lake was long and shallow, and wind action episodically mixed the water column throughout the ice-free period. All lakes showed characteristic oxygen depletion during the ice-covered-period, which was greater in the most productive lakes. Two types of lakes were distinguished according to the number of production peaks during the ice-free season. Lakes with longer summer stratification tended to have two productive periods: This is the third of 11 papers published in this special issue on the palaeolimnology of remote mountain lakes in Europe resulting from the MOLAR project funded by the European Union. The guest editor was Richard W. Battarbee.

Genome, 2008

As for most other organisms, genome size in zooplankton differs widely. This may have a range of ... more As for most other organisms, genome size in zooplankton differs widely. This may have a range of consequences for growth rate, development, and life history strategies, yet the causes of this pronounced variability are not settled. Here we propose that small genome size may be an evolutionary consequence of phosphorus (P) allocation from DNA to RNA under P deficiency. To test this hypothesis we have compared the two major groups of zooplankton, copepods and cladocerans, that have overlapping niches and body size. Relative to the cladocerans, copepods have a more complex life history and a lower mass-specific P content, while cladocerans tend to have higher P and RNA contents and higher specific growth rates and frequently experience P-limited growth, likely due to a shortage of P for ribosome synthesis. Cladocerans also generally have smaller genomes than copepods (1C = 0.17-0.63 pg DNAÁcell -1 vs. 1C = 0.10-10 pg DNAÁcell -1 ). Furthermore, cladocerans have a higher slope of the relationship of body size with DNA content (1.5 vs. 0.28 in copepods) and present almost 15-fold higher RNA:DNA ratios (24.8 in cladocerans vs. 1.6 in copepods). Hence, small genome size in cladocerans could reflect an evolutionary pressure towards ''efficient'' genomes to conserve a key element needed to maximize growth rate. We do not claim that this is a universal cause of genome size variability, but propose that streamlining of genomes could be related to P conservation rather than energy conservation. This could be relevant for a range of organisms that may suffer P-limited growth rates.

Journal of Paleolimnology, 2002

The ecosystem response of Lake Redó (Central Pyrenees) to fluctuations in seasonal air temperatur... more The ecosystem response of Lake Redó (Central Pyrenees) to fluctuations in seasonal air temperature during the last two centuries was investigated by comparison of reconstructed air temperatures with the sediment record. Fine slicing allowed a resolution of 3–6 years according to the 210Pb dating, although it was still difficult to easily investigate the response to air temperature forcing, since extreme fluctuations in temperature occur on interannual time-scales. However, the resolution was sufficient to show responses on decadal and century scales. An overall tendency to warming in mean annual temperature in the Central Pyrenees has been caused by summer and in particular by autumn increases. Many of the measured sediment variables apparently responded to these long term trends, but the significance of the relationships was highly conditioned by the structure of the data. The variables responding most on the finer time scales were the microfossils. For diatoms, chironomids and chrysophytes the main variability correlated to summer and to autumn temperatures. For two planktonic species, Fragilaria nanana and Cyclotella pseudostelligera, we found a link of their variability with temperature fluctuations in their growing months (September and October, respectively). This relationship appeared at a certain point during a general warming trend, indicating a threshold in the response. On the other hand, no significant changes in the dominant species could be linked to temperature, nor in any significant subgroup of the 180 diatom species present in the core. In contrast, for most chironomids (particularly Paratanytarsus austriacus, Heterotrissocladius marcidus and Micropsectra radialis) a negative relationship with summer temperature extended throughout the studied period. This response of the whole group gives chironomids a more robust role as indicators for recording temperature changes on long time-scales (e.g., through the Holocene) and for lake signal inter-comparison. Finally, our results indicated that, in all cases, there was a significant resilience to high frequency changes and hysteresis despite extreme fluctuations. Although we were dealing with organisms with one or many generations per year, their populations seemed to follow the decadal trends in air temperature.

The biological activity of the planktonic community of lake Redó, expressed in terms of carbon fl... more The biological activity of the planktonic community of lake Redó, expressed in terms of carbon fluxes, was measured and compared to the changes in DIC, DOC and POC in the water column. Planktonic photosynthesis ranged between c. 0.01 -0.3 µg C m -2 h -1 . Release of EOC phytoplankton was highly variable, between 5 and 80% of total fixation. Bacterial uptake of EOC ranged between 1-20% of total fixation. Bacterial activities were, in absolute numbers, very low: 0.005±0.003 µg C m -2 h -1 , in contrast with the higher grazing rates on bacteria of 0.036±0.021 µg C m -2 h -1 . Respiration and diffusion of CO 2 to the atmosphere seem to be the main processes controlling DIC concentration. DOC and POC concentrations were highly correlated, and their fluxes presented large fluctuations. These changes in DOC are larger than those due to the processes we have measured. Other processes that might affect DOC include diffusion from sediments, inputs from the catchment, uptake by mixotrophic algae and zooplankton, bacterial respiration, UV photoxidation, and flocculation. Lake Redó seems to act in general terms as an heterotrophic system: respiration is higher than photosynthesis, and the budget is balanced by the import of DOC and, to a lesser extent, POC. Most of the carbon seems to be ultimately released to atmosphere, since little is accumulated in sediments. The estimates of diffusive fluxes agreed with this hypothesis. At this stage, the comparison of biogeochemical budgets with biological activity measurements only serves as a rough approximation of the main pathways in the C cycling in the lake, and to point the issues that need further research in order to calculate the C budget in the lake with accuracy.

Environmental Pollution, 2005

Polychlorobiphenyls (PCBs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and DDT were e... more Polychlorobiphenyls (PCBs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and DDT were examined in the muscle of brown trout (Salmo trutta) from a high mountain lake located in the Pyrenees (Catalonia, Spain) that was used as a model of these lacustrine environments. Results indicate that fish age is the main factor of variability among specimens in this population that is subjected to atmospheric inputs of the organochlorine compounds (OC). Increases of 2- and 20-fold between fish aged 1 year and 15 years old are found. The observed pattern cannot be explained in terms of fish size, condition factor, or muscle lipid content. Higher molecular weight compounds (higher lipophilicity) are better correlated with fish age than low molecular weight compounds. A transformation from 4,4′-DDT to 4,4′-DDE occurs in fish after ingestion; this results in amplified age-dependent signals, especially in male specimens. In contrast, PCB congener #180 has lower age dependence than the general OC group, which could be due to its high hydrophobicity (log Kow > 7). In any case, selective accumulation of hydrophobic compounds is already observed among younger fish (age, 1 year). Due to this effect, the relative OC composition does not reflect the main OC pollutants in the lake waters.

Limnology and Oceanography, 2005

With the aim to determine the contribution of development and reproduction to the variability in ... more With the aim to determine the contribution of development and reproduction to the variability in the elemental composition of zooplankton, we measured the carbon (C), hydrogen (H), nitrogen (N), and phosphorus (P) elemental composition of the planktonic crustacean assemblage in an alpine lake for a whole seasonal cycle. The species included three distinct living modes: a cladoceran, Daphnia pulicaria; a cyclopoid copepod, Cyclops abyssorum; and a calanoid copepod, Diaptomus cyaneus. For the three species, reproduction was the main cause of elemental variability. Adult females of the three species lost from 32% to 48% of their initial absolute C and H content during reproduction, which corresponded to a similar decrease in their lipid and carbohydrate content. The N content did not change in any of the three species, nor did the protein and chitin content. Daphnia and Diaptomus lost 35% and 56%, respectively, of their initial absolute P content during reproduction, whereas the P content of Cyclops did not change. The three species stored energy compounds under unfavorable conditions for later use in offspring production, but only Diaptomus and Daphnia mobilized stored P. Corresponding stoichiometric changes with reproduction included a decrease in C : N ratio for the three species; an increase in N : P ratio for Daphnia adult females and adults of Diaptomus; and a C : P ratio increase in Diaptomus females and decline in Cyclops females. Differences in C : P ratio changes corresponded with differences in allocation to their respective reproductive tissues. Diaptomus males and Daphnia females did not change their C : P ratio with reproduction.

Environmental Science & Technology, 2004

An integrated study encompassing the distribution of organochlorine compounds (OC) in water, food... more An integrated study encompassing the distribution of organochlorine compounds (OC) in water, food web (chironomids, terrestrial insects, cladocerans, mollusks, and cyanobacteria), and fish (brown trout) from a high mountain lake (Redon, Pyrenees) is reported. OC distributions in these compartments have been determined to assess their transport routes into fish. Food diets have been estimated by analysis of fish stomach content and food web stable isotopes (δ 13 C and δ 15 N). OCs with octanol-water partition coefficient (K ow ) higher than 10 6 showed lower concentrations in food than expected from theoretical octanol-water partition, indicating that the distribution of these compounds does not reach equilibrium within the life span of the food web organisms (ca. 1 year). On the other hand, the degree of biomagnification in fish increased with K ow , except in the case of the largest compound analyzed (seven chlorine substituents, PCB #180). OC exchange at fish gill and gut has been evaluated using a fugacity model based on the water, food, and fish concentrations. All compounds exhibited a net gill loss and a net gut uptake. A pseudostationary state was only achieved for compounds with log(K ow ) < 6. Calculation of fish average residence times for the compounds in apparent steady state gave values of days to a few weeks for HCHs, 1 year for HCB and 4,4′-DDE, and 2-3 years for 4,4′-DDT and PCB#28 and PCB#52. Residence times longer than one decade were found for the more chlorinated PCB.

The process-oriented catchment-scale model MAGIC was used to simulate water chemistry at Lake Red... more The process-oriented catchment-scale model MAGIC was used to simulate water chemistry at Lake Redó, a high mountain lake in the Central Pyrenees, Spain. Data on lakewater and atmospheric deposition chemistry for the period 1984-1998 were used to calibrate the model, which was then used to reconstruct past and to provide forecasts for three hypothetical future scenarios of deposition. Forecast scenarios considered several combinations of changes in S and N deposition due to abatement strategies, and in base cation deposition due to climate-induced changes in air-mass trajectories from northern Africa. Scenario 1 assumed constant deposition of base cations at the present level plus the expected decrease in S and N deposition resulting from reduced emissions; scenario 2 (best case) assumed an increase in base cation deposition plus the same decrease in S and N deposition as in scenario 1; scenario 3 (worst case) assumed a decrease in base cation deposition plus no decrease in S and N deposition. The hindcast indicated that during the past 140-year period changes in lake water chemistry have been significant for a remote mountain catchment, although no substantial acidification has occurred. In this regard Lake Redó can be described as a "non-sensitive lake" maintaining a reference condition. The forecasts indicated changes that do not affect this status, but the trends, even if slight, were different between scenarios. A slight decline in the surface water ANC is predicted by Scenario 3. The N budget indicates an unusually low retention in the catchment, which may result in enhanced sensitivity to further increased N deposition. Some of the discrepancy between modelled and measured Ca 2+ in lake water during 1984-98 could be explained by changes in rainfall amounts and by increased weathering rates due to increases in air temperature.

Water, Air, & Soil Pollution: Focus, 2002

Here we present the chemical trends of seven high altitude lakes, analysed within the AL:PE and M... more Here we present the chemical trends of seven high altitude lakes, analysed within the AL:PE and MOLAR Projects of the EU (1999) and selected on the basis of the availability of complete and reliable data for the period 1984–1999. The lakes are representative of the Scandinavian Alps, the Cairngorm Mountains in Scotland, the Alps and the Pyrenees. Significant trends were identified for some indicators of acidification, for instance pH and alkalinity, but not all lakes reacted similarly to decreasing depositions of sulphate and base cations. Differences in lake response are discussed in relation to recent variations of atmospheric deposition chemistry and associated changes in climatic conditions. Beside individual variations of the studied lakes, depending, among other things, on altitude and morphology, catchment characteristics and climate trends play a major role for the reaction of high altitude lakes on changes in atmospheric depositions.

We reconstructed the genetic structure of a planktonic crustacean Daphnia longispina living in hi... more We reconstructed the genetic structure of a planktonic crustacean Daphnia longispina
living in high mountain lakes and ponds in the Pyrenees to investigate whether it was
shaped by persistent founder effects originating shortly after the last glacial maximum
or by ongoing dispersal and effective migration (gene flow). We found that the genetic
structure can largely be explained by a single colonization event following gradual
deglaciation of the Pyrenees ~10 000–15 000 years ago. Nuclear genetic diversity
declined steeply from southeast to northwest, suggestive of serial colonization of available
habitats with advancing deglaciation. The spatial genetic structure suggests that
founder effects were major determinants of the present-day diversity, both at the catchment
level and at the level of individual water bodies, further supporting extremely
low effective migration rates. This study reveals a prime example of a founder effect
that is both long lasting and maintained at small spatial scales. Our data suggest a
process of isolation by colonization as a result of strong priority effects and monopolization.
We found evidence for the spread of haplotypes with Pyrenean ancestry across
the Palaearctic over distances up to 5500 km, although the local genetic structure after
colonization was hardly influenced by contemporary dispersal. Finally, our data also
suggest that mitochondrial mutation rates in the studied populations were seven times
higher than typically assumed. Overall, we show that founder effects can persist for
centuries even at small spatial scales at which the potential for dispersal is high.