Picos De Europa National Park Research Articles

Multi-Analytical Techniques to Define the Mineralogical and Petrophysical Characteristics and Provenance of Siliceous Lithic Findings: The Case Study of La Calvera Rock Shelter (Cantabria, Spain)

This archaeometric study aims at characterizing the archaeological finds belonging to the lithic industry from La Calvera rock shelter (Camaleño, Cantabria) and at hypothesizing the possible provenance of each material. The site, located in the mountainous area of Picos de Europa National Park (more than 1000 m a.s.l.) close to the megalithic complex of Peña Oviedo, is characterized by the presence of hearths and charcoal remains, ancient pottery, and a rich lithic assemblage composed of siliceous rocks dating back to >8000 BP and linked to the first Holocene occupations of the Cantabrian Mountains. For the study of the rock shelter’s lithic assemblage, a multi-analytical approach was used: SEM-EDS and XRD analyses were performed to define the microtextural characteristics of samples and to identify the amorphous/crystalline phases; physical and mechanical tests were conducted to define the petrophysical properties (density, porosity, imbibition and saturation indexes, mechanical strength) of the samples. Preliminary data of chemical compositions, obtained by portable XRF, are also presented. The results show that the different siliceous materials (quartzite, cherts, hyaline quartz) can be distinguished through the basic analytical techniques used here. In addition, most of the archaeological samples have mineralogical and petrographic features similar to the natural samples coming from nearby outcrops, corroborating the hypothesis of a local material supply. The presence of local sources of useful raw materials could have favoured the site’s occupation. Finally, the diverse compositional and textural feature of the analysed materials result in different mechanical properties (porosity, density, hardness, workability), so they likely had different uses and technical functions.

Correction of phenology-induced effects in forest canopy height models based on airborne laser scanning data. Insights from the deciduous mountain forests in Picos de Europa National Park in Spain

The comparison of ALS time-series is an important element of modern landscape conservation planning, especially to monitor forest ecosystems. Modellers must evaluate phenology when comparing ALS-based maps of ground elevation or canopy height between years. We showcase the scenario using a National Park in the North-West of Spain where bi-temporal ALS has been used to map deciduous mountain forests. We compare the 2010 and 2021 surveys using the same algorithms to interpret ALS data and to generate actionable products for managers, mainly digital terrain models and canopy height models. We implemented a hybrid approach to correct the discrepancies between the surveys, showing the problems arising from differences in phenology or the selection of the scaling. We quantified around 5% of the area suffered from >1 m difference in DTM and higher impact on CHM values. With the hybrid method, modellers can highly reduce the uncertainty when comparing two ALS surveys and derivable products. We provided a solid graphical and analytical diagnosis of these emerging problems in the context of multi-temporal ALS surveys testing the hybrid approach at two resolutions: 1 and 2 m, fine-grained scales. The assessment of phenology-induced effects is important under the context of nationwide ALS survey programmes currently in operation and on high-demand. Finally, we discuss and frame the hybrid-approach as a well-suited vector of canopy gap detection methods to support conservation planning and enforce species-specific habitat improvements.

The Effects of COVID-19 Pandemic on Spanish Protected Areas: the Case of Picos de Europa National Park

Protected areas are complex social-ecological systems; thus, they were unavoidably impacted by COVID-19. Spain is one of the most diverse countries in terms of biodiversity in the European Union and the second most visited country in 2019 and third touristic destination worldwide. Understanding the effects of the pandemic in Spanish protected areas is very important to discuss new possibilities on how to drive sustainable development on these conserved spaces and how to manage them in the event of external shocks and uncertain scenarios. Therefore, the aim of this study is to have a better understanding of the effects and opportunities of the pandemic on Spanish protected areas. To address this concern, a qualitative analysis is conducted based on an assessment of secondary literature and relevant interviews. Picos de Europa national park was chosen as case study because of its unique features. This study shows the drawbacks of the pandemic in Picos de Europa in terms of management operations, drastic fluctuation of visitors, loss of tourism revenues, vulnerability of neighboring communities, missed opportunities in conservation and education and pressure on nature. On the other hand, it poses opportunities in terms of technology, innovation, fundings, lessons learned, rise in educational and conservation activities and more awareness on the environment and rural surroundings. This study suggests that is difficult to find a win-win solution that includes the targets of nature conservation, viability of local economies and tourism activities in Picos de Europa. Ideas for management options that focus on dealing with the negative outcomes of the pandemic are suggested.

Geographical indications in cheese mountain areas: Opportunity or threat to landscape and environmental conservation? The case of Cabrales (Spain)

This paper examines the impact of Geographical Indications in cheese mountain areas, exploring their potential to contribute to landscape and environmental sustainability by drawing on field work and documental evidences from Cabrales (Asturias, NW Spain). The Cabrales mountain, nestled in the Picos de Europa National Park, embraces a millenary culture linked to the elaboration of an intense flavor blue cheese. The commercial success of this cheese motivated, 40 years ago, the creation of the Cabrales Protected Designation of Origin (PDO). From that moment on, the implementation of certain control measures that affect the production process, together with the increase in demand, led to the disappearance of small producers and to the intensification of livestock management practices. Cheese producers took the opportunity that the PDO label gave them, and the PDO provided the context in which cheese production became an effective barrier against the degradation of the rural system. However, nowadays the intensification of livestock management practices constitutes the main threat to landscape and environmental conservation. Therefore, Local administrators and stakeholders should consider the need to reinforce the idea of a product whose quality is linked to environmental and landscape sustainability through the maintenance of the traditional extensive management practices.

A new species of Pseudomoraria from an alpine spring of Picos de Europa, North of Spain

Pseudomoraria triglavensis was described by Brancelj (1994) from specimens collected in a high-alpine reservoir at the Triglav National Park (NW Slovenia) at an altitude of 1690 m a.s.l. During an expedition in the Picos de Europa National Park (N Spain) in 2018, a new species of Pseudomoraria was collected in an epikarst spring (Fuente Escondido), below the ice cave of Altaiz at an altitude of 2112 m a.s.l. The new species can be easily distinguished from Pseudomoraria triglavensis by the presence of an inner seta on the edopodite 1 of female and male pereopod 1; absence of the outer spine on the exopodite 2 of the third and fourth female pereopods; four, instead of five setae on the second endopodite of the fourth female pereopod; and the female furca lacks the ventral distal patch of spinules characteristic of P. triglavensis. In the male, the new species differs from its congeners by the position and shape of the apophysis of the second edopodite of the pereopod 3, which is positioned in the outer, instead of the inner margin, and is bent around the distal inner spine; the second exopodite of the pereopod 4 has spines/setae, lacking the innermost seta which is present in P. triglavensis. The female armature of the pereopod 5 is highly variable, with 4-6 setae/spines on the exopod and 4-6 setae on the baso-endopod. According to Brancelj (1994), P. triglavensis could not be included in any genus known at the time and concluded, based on the armature of the pereopod 5 of both sexes, that it would be most closely related to Moraria. We disagree with this author and propose a close relationship of this genus with the genus Hypocamptus Chappuis, 1929 sharing similar male pereopod segmentation and armature. In addition, the species belonging to both genera are a characteristic for the fauna of the alpine water bodies. It is not yet clear the phylogenetic relationship between the two genera, but evidences suggest that Pseudomoraria may be a junior synonym of Hypocamptus.

A System of Indicators for Socio-Economic Evaluation and Monitoring of Global Change: An Approach Based on the Picos de Europa National Park

National Parks are spaces that are of great interest for evaluating and monitoring global environmental change as these parks encompass natural, cultural, and rural features, along with ecological processes, which are subject to social or economic changes that are much more difficult to track outside of these spaces. To do this, it is necessary to have a sufficient set of data and indicators to monitor the effects of global change in the short, mid, and long term. The majority of indicators have been developed to monitor the bio-geophysical environment; socio-economic indicators of global change for National Parks are much more limited. The aim of this paper is to present a system of indicators for socio-economic evaluation and monitoring of global change for the Picos de Europa National Park. This park has two unique features: it has one of the two systems of socio-economic indicators developed for the Spanish National Parks, and it is practically the only one of Spain’s 16 National Parks with human populations living within its boundaries. Many of the indicators specifically developed for this park can be used for other national parks that have similar characteristics.

From Forest Dynamics to Wetland Siltation in Mountainous Landscapes: A RS-Based Framework for Enhancing Erosion Control

Human activities have caused a significant change in the function and services that ecosystems have provided to society since historical times. In mountainous landscapes, the regulation of services such as water quality or erosion control has been impacted by land use and land cover (LULC) changes, especially the loss and fragmentation of forest patches. In this work, we develop a Remote Sensing (RS)-based modelling approach to identify areas for the implementation of nature-based solutions (NBS) (i.e., natural forest conservation and restoration) that allow reducing the vulnerability of aquatic ecosystems to siltation in mountainous regions. We used time series Landsat 5TM, 7ETM+, 8OLI and Sentinel 2A/2B MSI (S2) imagery to map forest dynamics and wetland distribution in Picos de Europa National Park (Cantabrian Mountains, northern Spain). We fed RS-based models with detailed in situ information based on photo-interpretation and fieldwork completed from 2017 to 2021. We estimated a forest cover increase rate of 2 ha/year comparing current and past LULC maps against external validation data. We applied this forest gain to a scenario generator model to derive a 30-year future LULC map that defines the potential forest extent for the study area in 2049. We then modelled the distribution of wetlands to identify the areas with the greatest potential for moisture accumulation. We used an S2 mosaic and topography-derived data such as the slope and topographic wetness index (TWI), which indicate terrain water accumulation. Overall accuracy scores reached values of 86% for LULC classification and 61% for wetland mapping. At the same time, we obtained the potential erosion using the NetMap software to identify potential sediment production, transport and deposition areas. Finally, forest dynamics, wetland distribution and potential erosion were combined in a multi-criteria analysis aiming to reduce the amount of sediment reaching selected wetlands. We achieved this by identifying the most suitable locations for the conservation and restoration of natural forests on slopes and in riparian areas, which may reduce the risk of soil erosion and maximise sediment filtering, respectively. The results show a network pattern for forest management that would allow for controlling erosion effects across space and time at three levels: one, by reducing the load that originates upslope in the absence of forest cover; two, by intersecting runoff at watercourses related to sediment transport; and three, by a lack of former barriers, by trapping erosion near to the receiving wetland systems, main river axes and contributing streams. In conclusion, the proposed methodology, which could be transferred to other mountain regions, allows to optimise investment for erosion prevention and wetland conservation by using only very specific areas of the landscape for habitat management (e.g., for NBS implementation).

Abandonment of cultural landscapes: butterfly communities track the advance of forest over grasslands

Rural landscapes in Europe have suffered considerable land-use change in the last 50 years, with agricultural intensification in western regions and land abandonment in eastern and southern regions. The negative impacts of agricultural intensification on butterflies and other insects in western Europe have been well studied. However, less is known about the impacts of abandonment on mountain and humid areas of eastern and southern Europe, where landscapes have remained more natural. We sampled butterfly communities in the Picos de Europa National Park (Spain), a region which is undergoing a process of rural abandonment. 19 hay meadows with different periods of abandonment were studied (long-term 18 years or mid-term abandoned, 3–7 years) and compared to meadows continuously managed in a traditional way. We examined how local meadow characteristics and landscape variables affected butterfly community response to abandonment. Butterfly communities were affected by abandonment, with an overall increase in the density of individuals in the long term. Community composition appears to undergo major change over time, with a species turnover of around 50% in the first few years of abandonment, rising to around 70% after 18 years of abandonment. There was a tendency for species with higher preference for closed habitats to increase their densities as time since abandonment proceeded. Landscape variables had a major impact on butterfly communities, stronger than the effect of meadow management. Community preference for closed habitats was associated with higher forest cover in the surroundings of the meadows, but heterogeneous landscapes (in their composition or configuration) mitigated this effect.Implications for insect conservationOur findings suggest that we should ensure that communities have time to react to the diverse stressors imposed by global change. Facilitating survival to all kinds of functional and taxonomic groups implies promoting landscape heterogeneity and connectivity.

Host contribution to parasite persistence is consistent between parasites and over time, but varies spatially.

Most parasites and pathogens infect multiple hosts, but a great deal of variation exists in the role of those hosts in persistence of infection. Understanding which hosts are most important in maintaining parasites can provide a clearer target for infection control. Recently developed empirical and theoretical approaches provide a way to quantify the relative contribution of hosts within a community and place them in a multi-host framework to better direct control efforts. Amphibians provide a framework for better understanding multi-host-multi-parasite dynamics. Two well-studied amphibian parasites, Batrachochytrium dendrobatidis (Bd) and Ranavirus, infect multiple host species and exhibit a great deal of heterogeneity in how they affect hosts. We used these two parasites and a community of five amphibian species to investigate the relative importance of hosts in parasite persistence, and how any patterns varied spatially and temporally. At two sites (Lake Ercina and Lake Lloroza in the Picos de Europa National Park, Spain) we collected data on the prevalence and shedding rate of parasite infection for both Bd and Ranavirus, and the abundance of each species' life stages. We used these data to parameterize a recently developed modeling framework, which was used to quantify the relative contribution of each host to the community reproductive number, R0 . By comparing each host-category over time and between sites we were able to identify consistencies in which host was responsible for the maintenance of these two parasites. Within a site one species consistently contributed the most to the persistence of both parasites. This consistency did not transfer between sites, the maintenance host species being different for each. At one site (Ercina), life stages of the common midwife toad, Alytes obstetricans, acted as the maintenance host for both Bd and Ranavirus. In contrast, at the second site, Lloroza, the alpine newt, Ichthyosaura alpestris, fulfilled that role. A single host species was responsible for infection persistence of both parasites at each lake. Attempts to control the infection levels and impacts of multiple parasites can benefit from a community epidemiology approach, and provide clarity on which hosts are the foci of mitigation efforts. However, at a small spatial scale, the target host may vary according to the physical qualities of those sites and the demographics of the host community.

Identification of technological/metabolic/environmental profiles of cheeses with high GABA contents

γ-aminobutyric acid (GABA) is reported to reduce blood pressure and stress when provided as a nutritional supplement. GABA, however, appears naturally in cheese in varying amounts. The present work recorded its concentration in 100 samples of 37 European cheese varieties. Subsequent multivariate analysis identified two technological/metabolic/environmental (TME) profiles associated with a high GABA-content: 1) mature, artisanal, blue cheeses made in the Picos de Europa National Park area from raw cow's milk (or a mixture including it) under the influence of a montane oceanic climate - the TME profile of the Cabrales Protected Designation of Origin (PDO), Gamonedo PDO and Picon Bejes-Tresviso PDO varieties; and 2) aged hard cheeses made from raw sheep's milk under the influence of a temperate continental climate, with Manchego PDO and Zamorano PDO cheeses the hallmark varieties. These findings may help the cheese manufacture industry design functional GABA-enriched cheeses.

Change in landscape and ecosystems services as the basis of monitoring natural protected areas: a case study in the Picos de Europa National Park (Spain).

Services provided by protected areas (PAs) are based on their natural heritage, as stated in the conservation objectives, and many depend on their landscape, the spatial pattern of land cover patches. We study changes in the service provision of a PA based on its landscape changes. As services are defined according to the conservation objectives of the PA, this can be used in monitoring the PA conservation status. Using easily accessible historical land cover maps, landscape changes over time are identified and assessed according to changes in services provision, based on the PA conservation objectives. The PA under study is one of the oldest in Europe. Almost 80years after its initial declaration, it was increased by incorporating surrounding areas. This helps to understand to what extent the oldest PA has conserved its environmental heritage, compared with what happened in the area most recently protected and not subjected to previous conservation regime. As expected in an area managed for conservation, changes in services in the older PA are small. But changes in the recently included area are also small and very similar to those ones. As change in ecosystem services are based on landscape changes, they do not relate only to the increase or decrease in the spatial distribution of single land covers but also on their joint spatial arrangement. This allows us to assess trade-offs among services provided by different land covers implied in landscape changes.

Hydrogeology of the Picos de Europa National Park (northern of Spain)

The Picos de Europa National Park, with a total area of 675 km 2 , is located in the North of Spain, in the provinces of Asturias, Cantabria and León. Carbonated materials predominate in the North and central areas of the Park, whilst to the South rocks are mainly siliceous. The complex geological structure caused by the superposition of two orogenies has conditioned the presence of a very karstified limestone series more than 2 km thick. The karst development is really important and it is well known that the Picos de Europa high mountains contain 14 % of the deepest discovered caves in the world. As far as hydrological planning is concerned, the park is integrated into the 016.214 Picos de Europa-Panes and 016.218 Alto Deva-Alto Cares groundwater bodies. The geological formations present in the Picos de Europa National Park, considering the permeability characteristics of the materials, can be classified as either aquifers or aquitards. The main aquifer is karst in nature and includes a powerful series of carboniferous limestones with an O-E orientation. The presence of siliciclastic formations, which behave like aquitards, determine the compartmentalization of the aquifer into “smaller underground water bodies” (hereinafter SGWB, the acronym for the English terminology, “smaller groundwater bodies”) with dimensions of between 2 and 108 km 3 in volume. The piezometric level in the different SGWBs varies between 120 and 1,200 m a.s.l., descending in a staggered way to the North. It shouldbe noted that in the Central and Eastern Massifs the piezometry is more uniform and is located between 300 and 500 m a.s.l. To the northern of the limit of the park, the main points of discharge of the carbonated aquifer are located between 120 and 150 m a.s.l. The aquifer recharge, preferably by direct infiltration, has a clear snow influence. The karst springs jointly discharge the water from the surface runoff infiltrated into the aquifer and the groundwater that comes from the different SGWBs. The presence of siliciclastic units, with general W-E directions that function as permeability barriers has caused the circulation of the underground flow to be directed predominantly northwards, and therefore, has led to the main springs being located in the northern part of the park.

Karst Cave Geoheritage in Protected Areas: Characterisation and Proposals of Management of Deep Caves in the Picos de Europa National Park (Spain)

Caves are one of the most spectacular elements of karst with a high natural value, due to their singularity and high diversity of natural features. The Picos de Europa National Park (Spain) is a high mountain protected area that represents the highest density of deep caves of the World (12 deep caves/km2). This work analyses geoheritage linked to these caves as a part of broad projects to know and inventory the geological heritage of the Picos de Europa National Park. The methodology of work combines both geomorphological and geoheritage studies. Geomorphological study includes a caves inventory of the National Park, the characterization of the caves geomorphology and the selection of 14 caves with > 1-km depth as geosites, including an ice cave for its uniqueness. The geoheritage study is based on a four-forms system formed by selected indicators following the pressure-state-response (PSR) model. In the short term, management measures proposed for the deep karst caves of the National Park include enhancing the scientific research focused on karst and groundwater flow evolution and the palaeoclimatic variations of the region including ice cave monitoring. In the medium term, it should be adequate to re-design the public use system for the regulation and control of the visits to the caves and to emphasise the outstanding nature of the geoheritage linked to the endokarst of the National Park. Finally, in the long term, it would be necessary to design a visit system for expert speleological groups.

A new species of perennial Bromus (Bromeae, Poaceae) from the Iberian Peninsula.

During a survey of the genus Bromus for the ongoing Flora Iberica, B.picoeuropeanussp. nov., a new orophilous species of perennial Bromus from Picos de Europa National Park, was found, and it is described and illustrated here. This new species belongs to the Bromuserectus complex and differs from the other perennial species of this group occurring in the Iberian Peninsula in its well-developed rhizome, the small innovation leaves and all peduncles and branches shorter than the spikelets. B.picoeuropeanus grows on calcareous stony soils associated with dry places. We provide a description and illustrations of the new species and an identification key for the most related European perennial species belonging to the complex.

Biodiversity conservation effectiveness provided by a protection status in temperate forest commons of north Spain

The establishment and maintenance of protected areas is the backbone of global conservation strategies to halt biodiversity loss. However, despite the more than 200,000 legally designated protected sites worldwide, the rate of species extinction has not decreased, for which some debate the real effectiveness of protected areas to preserve biodiversity. Using data from tropical areas, many studies have attempted to test the effectiveness of protected areas by comparing species richness in protected and neighbouring unprotected sites, without reaching a consensus. Here, we extend this line of research with data from temperate deciduous forests inside and outside Picos de Europa National Park and Biosphere Reserve (N Spain). Specifically we compare data from mixed broadleaved woodlands, beech forests (Fagus sylvatica L.) and Pyrenean oak (Quercus pyrenaica Willd.) forests. We conducted botanical inventories and recorded ecological data from 25 0.2-ha concentric plots distributed in forest commons inside the reserve and from other 25 similar plots established in neighbouring not protected forest commons. Data were used to construct a set of ecological indicators and evaluated using modelling methods. We found no significant differences in species composition between plots in protected and non-protected forest commons, likely due to the similar management criteria applied in both land uses. We found less active management outside the protected area, which helps to maintain stands in a semi-natural state. In contrast, we observed the presence of silvicultural treatments inside the protected area, although these treatments were non-intensive, promoting vegetation composition associated to late-successional ecosystems. We only detected significant differences between plots inside and outside the protected area when relation between species richness was analysed with reference to forest habitat type. Precisely, plots of beech forests inside Picos de Europa were more homogenous than plots outside the protected area, which may indicate that management practices inside the protected area do not favour tree species diversity. Non-intensive silviculture management in beech forests inside Picos de Europa seems to promote the presence of the dominant tree species Fagus sylvatica L., which in the absence of perturbations is characterized by conforming monospecific vegetation communities. Overall, our results do not support the idea that protected areas hold more biodiversity than surrounding forest commons. Conservation treatments applied in protected areas should promote the presence of species associated to disturbances, particularly in stands tending to homogeneous species composition at late-successional stages, as this may enhance their resilience under the current rapid global changes.

Tourism versus nature conservation: reconciliation of common interests and objectives — an analysis through Picos de Europa National Park

Nature tourism and particularly tourism in national parks have acquired significant importance in contemporary societies. Post-Fordist consumers have reevaluated the meanings of ‘nature’ and ‘natural spaces’ and now avoid standardization to seek singularity. Tourism in national parks is a consequence of this tendency and has both positive and negative aspects. The purpose of this sociological research is to describe the most relevant conflicts in the Picos de Europa National Park (Spain) involving the park’s conservation, local economic development, and tourism. Seven in-depth interviews and three focus groups were addressed to key local stakeholders. In this research were identified three chief areas of existing or potential inter-related conflicts and the main actors interacting with them. The first is on population, particularly, the negative consequences of depopulations on the local socio-economic development and the environment. A second source of conflicts identified is caused by the difficult conciliation between commercial exploitation and conservation of the protected natural area. More precisely, this specific form of tourism positively contributes to the economy of local communities whilst problems can arise for the conservation goals of National Parks. Thirdly, in this research is also analyzed the institutional governance and the inter and intra-governmental conflicts as well as with the Park’s management body. These findings provide important information for the improved management of tourism and conflicting interests in natural parks.

The influence of depth and macrophyte habitat on paleoecological studies using chironomids: Enol Lake (Spain) as a case study

Paleolimnological studies often rely on a single sediment core for reconstructing past environmental changes of an entire lake system. This involves a number of assumptions about the correct representativeness of the living assemblage by the subfossil assemblage. This paper is aimed at understanding the main drivers affecting the dispersion and transportation of Chironomidae head capsules, which may affect the correct interpretation of downcore changes through overrepresentation or underrepresentation of certain taxa. We analyzed the chironomid living assemblage of Enol Lake (Picos de Europa National Park, Spain) and compared the subfossil assemblage at different depths. We found a highly homogeneous composition and density of recent subfossil assemblage along the depth transect (i.e. dominance of the Tanytarsini Paratanytarsus austriacus-type), which would indicate that a single core retrieved at any depth would be representative of the lake community. However, the composition of the benthic living assemblage changed significantly with depth, suggesting the existence of a driving force behind the dominance of P. austriacus-type in the subfossil assemblage. We argue that the dense mats of Characeae present in the sublittoral area (from 2 to 8 m) are most likely responsible for this homogenization, since this is the preferred habitat of Paratanytarsus, which was found at very high densities at this depth. Thus, we conclude that the interpretation of past changes in the lake conditions should be made with caution due to the overrepresentation of P. austriacus-type head capsules along the depth transect. Our findings show that it is important to explore the relationship between the living and the recent subfossil fauna of each lake in paleolimnological studies, since understanding deposition and transport patterns can help to avoid misinferring past environmental and limnological conditions.

Anthropogenic and climatic factors enhancing hypolimnetic anoxia in a temperate mountain lake

Oxygen depletion (temporal or permanent) in freshwater ecosystems is a widespread and globally important environmental problem. However, the factors behind increased hypolimnetic anoxia in lakes and reservoirs are often diverse and may involve processes at different spatial and temporal scales. Here, we evaluate the combined effects of different anthropogenic pressures on the oxygen dynamics and water chemistry of Lake Enol, an emblematic mountain lake in Picos de Europa National Park (NW Spain). A multidisciplinary study conducted over a period of four years (2013–2016) indicates that the extent and duration of hypolimnetic anoxia has increased dramatically in recent years. The extent and duration of hypolimnetic anoxia is typical of meso-eutrophic systems, in contrast with the internal productivity of the lake, which remains oligo-mesotrophic and phosphorus-limited. This apparent contradiction is ascribed to the combination of different external pressures in the catchment, which have increased the input of allochthonous organic matter in recent times through enhanced erosion and sediment transport. The most important among these pressures appears to be cattle grazing, which affects not only the import of carbon and nutrients, but also the lake microbiology. The contribution of clear-cutting, runoff channelling, and tourism is comparatively less significant. The cumulative effects of these local human impacts are not only affecting the lake metabolism, but also the import of sulfate, nitrate- and ammonium-nitrogen, and metals (Zn). However, these local factors alone cannot explain entirely the observed oxygen deficit. Climatic factors (e.g., warmer and drier spring and autumn seasons) are also reducing oxygen levels in deep waters through a longer and increasingly steep thermal stratification. Global warming may indirectly increase anoxia in many other mountain lakes in the near future.

Chironomid communities as indicators of local and global changes in an oligotrophic high mountain lake (Enol Lake, Northwestern Spain)

<p>The benthos of the high mountain Enol Lake (Picos de Europa National Park, Spain) was analyzed in order to understand the spatiotemporal factors and patterns controlling its current Chironomidae community. In total, more than 14,000 chironomid larvae were identified, belonging to 27 taxa. The results have pointed out the presence of 3 main chironomid assemblages in the lake: i) littoral community, which is mainly controlled by temperature and oxygen seasonal changes, ii) <em>Chara</em>-dominant community, which is mainly controlled by the presence and abundance of Characeae in the lake, and iii) profundal community, which is affected by low oxygen levels caused by sediment and organic matter discharge to the lake due to human pressures in the lake basin. We provide valuable insights for the managers to understand the current ecological status of Enol Lake and to evaluate which measures should be implemented to preserve or improve it. Moreover, our results constitute an essential step forward to improve the interpretation of the past changes of the lake by means of the subfossil chironomid community. </p>

Organic geochemical evidence of postglacial paleoenvironmental evolution of the Comeya peatland (Asturias, N Spain)

Comeya peatland is located in Picos de Europa National Park (N. Spain) at 851m above sea level, representing the continuous postglacial infill of a hollow (growth rate=0.4mm/yr) during the last 15,000cal.yrBP. Three intervals can be distinguished in the profile: the bottom one, with ash content close to 90%, which is previous to the peatland installation in the area and is followed by an interval with oscillating ash content (30–60%) probably related to alluvial fan sedimentation. The uppermost one corresponds to the peat deposit with ash content generally close to 10%. The present day vegetation consists of Sphagnum species with herbaceous plants and heathers. The study comprises the analysis of some biomarkers with potential as palaeoenvironmental proxies quantified by gas chromatography/mass spectrometry, supported by bulk δ13C and δ15N isotopic. The biomarker assemblage is dominated by the n-alkanes and methyl-ketones with medium-to-high molecular weight and odd number of carbons. The biomarker ratios indicate an enrichment in Sphagnum characteristic compounds at 120–250cm (3150–6350cal.yrBP) reflecting more humid conditions. This episode coincides with higher C/N atomic ratio, higher values of δ13C and lower of δ15N. The wetter conditions of this interval are also shown by the depleted δD values of the n-alkane, particularly those related with mosses as (n-C23 and n-C25) and the enriched δ13C values of both n-alkanes and methyl-ketones.Segregation of δ13C values has been observed for homologues series in Comeya peat with medium molecular weight n-alkanes typical of mosses living in waterlogged environments, being enriched in δ13C values compared with higher molecular weight n-alkanes typical of woody and herbaceous plants of drier habitats. This study has shown a slight enrichment of δ13C values of methyl-ketones compared to n-alkanes, the differences being not conclusive to support a common or different origin for both compound classes.