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The multi-proxy study of sediment cores from Lake Isoba (43° 02′ N, 5° 18′ W; 1400 m a.s.l.) allows a detailed assessment of the past hydrological and environmental dynamics in north-western Iberia resulting from the interplay between climate variability and anthropogenic impact. The combination of diatom stratigraphy, sedimentology and high-resolution elemental geochemistry along with a robust chronological framework (established by 210Pb, 137Cs and 14C dating) provides a detailed environmental reconstruction for the past ~ 500 years. Abrupt changes in the fossil diatom assemblages indicate a high sensitivity of this small lake to past environmental change and allow identifying four major stages related to the main climate fluctuations of the Little Ice Age (LIA) and recent warming. High lake levels, enhanced runoff and higher productivity characterised the middle phase of the LIA (~ 1550 to 1630 CE), indicating an overall wet climate. Conversely, shallow lake levels, decreased runoff and relatively low productivity prevailed during the last phase of the LIA and the onset of the Industrial Era (~ 1630 to 1925 CE), likely due to colder and drier conditions. High lake levels and higher carbonate input occurred after ~ 1925 CE until the 1980s CE, when our data show an abrupt drop in lake levels probably caused by a regional negative rainfall anomaly related to climate warming during the past decades. Finally, since ~ 1997 CE a remarkable and abrupt increase in the lake nutrient load and turbidity is detected, probably associated with the replacement of transhumant sheep flocks with staying cattle. The main environmental changes reconstructed at Lake Isoba mostly agree with other palaeoclimatic records from northern Spain. However, the hydrological patterns reconstructed are opposed to those observed on the northern slopes of the Cantabrian Mountains. The recent and strong impact of land-use changes on the lake, causing more ecological disruptions than previous climate changes, is noteworthy and demonstrates the high sensitivity of mountain lakes to human activities in a global change context. Acknowledgements: This research was funded by the GECANT project “Climate and human drivers in the geoenvironmental evolution of the Cantabrian Region during the Anthropocene: integrating coastal, mountain lake and geomorphological records (CGL2017-82703-R) (AEI/FEDER, UE)”, the University of Bern and a ‘María Zambrano’ fellowship (Ministerio de Universidades/Universidad de Alcalá/European Union) to C.M-M. We thank the ‘Junta de Castilla y León’ (‘Servicio Territorial de Medio Ambiente de León’) and the administration of “Montañas de Riaño y Mampodre” Regional Park for issuing the permits to core Lake Isoba. André F. Lotter, Erika Gobet, Christoph Schwörer (University of Bern), Carlos Sierra-Fernández (University of León), Diego Baragaño (INDUROT-University of Oviedo), Santiago de Castro, María Galán, Mariano Torre (Junta de Castilla y León), Toño Barreda, Jaime Bonachea, Luis Echeandía, Lucía Agudo, Ana Belén Marín, Ignacio Varela (University of Cantabria), Elena Royo, Raquel López, Miguel Bartolomé, Alejandra Vicente de Vera, Blas Valero-Garcés (IPE-CSIC), Jaime Frigola (University of Barcelona), Lucía Arregui (Complutense University of Madrid), Aida Adsuar (IGEO-CSIC-UCM), Javier Sigró (Rovira i Virgili University) and Javier Martín-Chivelet (Complutense University of Madrid) are kindly acknowledged for their help with fieldwork, search for historical information and laboratory analyses. Thanks to the editors and two anonymous reviewers for their valuable comments and suggestions that contributed to improve the article. Funding: Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Open Access funding provided by University of the Basque Country. This study was financially supported by the GECANT project (CGL2017-82703-R) (AEI/FEDER, UE).

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG [Abstract] Understanding the environmental response to the last glacial termination in regions located in transitional climate zones such as the Atlantic Iberian mountains is crucial to estimate potential changes in regions affected by current glacial melting. We present an 8.5 m-long, solid last deglaciation and Holocene chronostratigraphic record including detailed sediment analysis from Lake Peixão, a pro-glacial lake in the Serra da Estrela (Central Portugal). The age–depth model relies on a Bayesian approach that includes 16 AMS 14C dates and 210Pb–137CS measurements, robustly dating the lake formation at 14.7 ± 0.32 cal. ka BP. This chronological reconstruction shows an average sedimentation rate of ca. 0.07 cm yr−1 (15 yr cm−1), enabling proxy analyses at decadal timescales. The sediment sequence is composed of five lithological units: (U1) coarse and unsorted fluvioglacial lacustrine deposits; (U2) massive fluvioglacial lacustrine deposits (863–790 cm below surface [bsf]; 14.7 ± 0.32–13.8 ± 0.12 cal. ka BP); (U3) water current fluvioglacial lacustrine deposits (790–766 cm bsf; 13.8 ± 0.12–12.9 ± 0.29 cal. ka BP); (U4) laminated/banded lacustrine deposits characterized by terrigenous deposits from ice-covered lake periods and episodic events of ice and snow melting (766–752 cm bsf; 12.9 ± 0.29–11.7 ± 0.15 cal. ka BP); and (U5) massive muddy lacustrine deposits (752–0 cm bsf; 11.7 ± 0.15 cal. ka BP–present). The occurrence of U2 to U4 deposits defines the transition from glacial cold (U1) to net warm postglacial conditions (U5). These climate transitions are marked by changes in sediments and the presence of very low sedimentation rate periods, possibly related to the Intra-Allerød Cold Period and the coldest phase of the Younger Dryas. Our results support the previously proposed timing of the retreat of the Serra da Estrela glaciers ca. 13.8 ± 0.12 cal. ka BP. The robust chronology of Lake Peixão highlights the potential of Iberian pro-glacial lakes for dating deglaciation processes and will lead to unprecedented decadal-to-centennial timescale palaeoclimate reconstructions in this region since the last glacial–interglacial transition. This work was supported by the Portuguese Foundation for Science and Technology – FCT, through the HOLMODRIVE project (PTDC/CTA-GEO/29029/2017). A. Hernandez is funded by the Spanish Ministry of Science and Innovation through the Ramón y Cajal Scheme [RYC2020-029253-I]. C. Martin-Puertas is funded by UKRI-FLF MR/W009641/1. G. Gil-Romera is funded by the DFG project FOR2358 ‘The Mountain Exile Hypothesis’. Pedro M. Raposeiro was funded by the Portuguese Science Foundation through contract DL57/2016/ICETA/EEC2018/25. Alexandre M. Ramos is funded by the Helmholtz ‘Changing Earth’ programme. Funding for open access charge: Universidade da Coruña/CISUG. The Estrela UNESCO Global Geopark is thanked for their support with field activities and permissions. The Parque Natural da Serra da Estrela (ICNF) provided research permits. Deutsche Forschungsgemeinschaft; FOR2358 Portugal. Fundação para a Ciência e a Tecnologia; DL57/2016/ICETA/EEC2018/25 Portugal. Fundação para a Ciência e a Tecnologia; PTDC/CTA-GEO/29029/2017 UK Research and Innovation; UKRI-FLF MR/W009641/1

In this paper we present the results of a multidisciplinary study performed in the Carrasqueira valley, a tributary of the River Sado (SW Portugal), aimed at characterising the Holocene environmental conditions during the late Mesolithic occupation of this valley. Our findings are based on a 13.5 m long sediment core (Arez3) collected on the alluvial plain close to a late Mesolithic shell midden, the Arapouco site. The results of the multiproxy analyses (texture, magnetic susceptibility, organic composition and chemistry, n-alkanes and palynology) point to a greater marine influence between ca. 8850 cal yrs. B.P. (at the core base) and ca. 7450 cal yrs. B.P. (at 750 cm below mean sea level (MSL)) and the existence of an environment similar to the present-day central estuarine basin. At this point in time, sedimentation rates were lower than the rate of sea-level rise, resulting in the formation of a drowned area with intertidal environments developing on the less incised margins. After 7040 cal yrs. B.P. the contribution of organic matter from terrestrial plants and freshwater phytoplankton to the sediment increased, reflecting a change in the sedimentary pattern, with the estuarine environments progressively giving way to freshwater environments. After the Middle Holocene (ca. 6530 cal yrs. B.P.), negative shifts of δ15N to values ~0‰ point to hyper-eutrophication and cyanobacteria bloom episodes under backswamp conditions. According to these results, the estuarine environment prevailed in the area until 7040 cal yrs. B.P. (5090 cal yrs. B.C.; 390 cm below MSL), i.e., during the Mesolithic occupation of the valley, allowing for the occurrence and for the exploitation of marine shellfish and fish by these hunter-gatherer communities at the proximity of the downstream occupation areas, This work was done with-in the PhD grant funded by FCT (SFRH/ BD/110270/2015) attributed to Ana Maria Costa between 2016 and 2019 and took advantage of financial support from the projects SimTIC (HAR2017-82557-P) financed by the Spanish Ministry of Science and Innovation, Back to Sado (PTDC/HIS-ARQ/121592/2010) funded by FCT. The authors would also like to acknowledge the support of the Instituto Dom Luiz - IDL (UIDB/50019/2020)

Saltmarshes are a valuable wildlife habitat and play a key role in shoreline protection; given their potential in carbon sequestration and storage, these areas might also play a significant role within mitigation strategies to climate change. Natural saltmarshes can adapt to various disturbances through a series of feedbacks. However, land use changes and human occupation can alter the marsh natural dynamics diminishing their resilience.Aerial photographs have been used to study marsh vegetation and map its evolution since the late 70’s and have proven to be a key source of information. This technique facilitates the study of wetlands on a monthly, yearly, or decadal timescales. Historical photographs can be used to identify past trends and support the implementation of monitoring programs on vast wetland areas.In the region of the Tróia peninsula in the Sado estuary (SW Portugal), historical aerial photographs are available for the past 70 years. Using these photographs, this work attempts to answer the following questions: (1) How have the saltmarshes of Sado estuary change since the 1940’s? (2) How have marsh geomorphology and anthropogenic pressure contributed to these changes? (3) Is the variation of sea level in the Portuguese coast an important factor in marsh evolution?From the saltmarshes that were studied, only two increase in size; all the other saltmarshes suffer substantial losses in total area. All combined, these saltmarshes shrunk over 30 ha (≈27%) in the past 70 years. Availability of accommodation space and level of protection seem to be the key factors in saltmarsh resilience. There appears to be a link between the rise of the mean sea-level and the colonization of terrestrial areas, as well as with the disappearance of the saltmarsh islands. The effect of direct human action on the saltmarshes can also be observed in some of the studied areas.While this is a regional study – mostly intended to understand how the marshes of this area have evolve - it also serves a larger purpose, to emphasize the importance of aerial historical photographs as a source of information about this environment. Unlike other countries, in Portugal aerial photographs are used mostly for coastal erosion assessment, having been used only a couple of times to study marshes. Considering how many estuaries exist in Portugal, and the importance of these areas for the future of our coasts, it is essential to start using all the tools available in their study and in the creation of conservation, naturalization and recovery plans.This research was funded by Portuguese Foundation for Science and Technology, I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020 + PTDC/CTA-GEO/28412/2017 and Ph.D. Grants PD/BD/106074/2015 + PD/BD/142781/2018.

Salt marshes are highly valued coastal environments for different services: coastline protection, biodiversity, and carbon storage (blue carbon). However, they are vulnerable to climate changes, particularly sea-level rise (SLR). For this reason, it is essential to project the evolution of marsh areas until the end of the century. This work presents the results of applying a reduced complexity two-dimensional rule-based model developed by the authors: SMRM (Simplified Marsh Response Model). The model requires four parameters: a high-resolution digital terrain model (DTM) (LiDAR survey from 2011), local tidal levels (modeled from Setúbal-Tróia tide gauge), at least one SLR scenario (IPCC RCP4.5, FCUL MOD.FC_2b and NOAA Extreme were used) and accretion rates (determined through the analysis of 210Pb and 137Cs isotopic activity from a core in one of the studied marshes). Furthermore, additional parameters such as the error of the DTM (RMSE) or the acceleration of SLR and accretion rates can be added. The process is done through a MATLAB script and the output is a Geotiff file. The presented results are for the estuarine margin of the Tróia sandspit salt marshes (Sado estuary, Portugal – 40 km south of Lisbon), where six marsh patches(Caldeira de Tróia (CT-N (North) and CT-S (South)), Malha da Costa (MC-N and MC-S) and Comporta (Cmp-N and Cmp-S)) are present, totalizing an area of 109 ha.Projections indicate that a significant reduction in the marsh area is expected until 2100, that will be transformed in tidal flats/subtidal areas. Depending on the chosen SLR scenario, the losses will be between 6 (IPCC RCP4.5) and 84 % (NOAA Extreme) in area. If sea-level rises around 1 m until the end of the century (FCUL MOD.FC_2b), a loss of 36 % in global area is expected. The evolution will not be similar along the sandspit. The most mature marshes (MC-S, TC-N and TC-S) will be more resilient to SLR. These projections consider that the surrounding areas will not be occupied until the end of the century, reducing the probability of these areas disappearing in the future. In fact, limited saltmarsh displacement to inland will occur (between 4 and 35 ha – from IPCC RCP4.5 to NOAA Extreme) to adjacent areas with low slopes.The influence of each parameter was also evaluated in this work through a sensitivity analysis. The results indicate that SLR is the most significant parameter to consider, followed by accretion rates and the error of the DTM. The main conclusion is that the studied salt marshes could be resilient to conservative SLR scenarios but not to more severe projections, even if they have space landwards to expand.This research was funded by Portuguese Foundation for Science and Technology, I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020 + PTDC/CTA-GEO/28412/2017 and Ph.D. Grants PD/BD/142781/2018 + PD/BD/106074/2015.

The infilling of coastal incised river valleys is an important sedimentary record that holds imprinting’s of depositional environments and sea-level variations. Notwithstanding, the stratigraphic record is difficult to interpret once: i) incised valley coastal areas preserve information both from marine and fluvial processes; ii) the morphology of the valley can derive from a simple incision cycle (e.g. LGM) or be the result of multiple incisions during pre-LGM Quaternary low-stands; iii) the stratigraphic sequence depends on the type of estuary, wave-, tide-or mixed-dominated estuary; iv) palaeomorphology; v) fluvial discharge; and vi) sediment availability. To bypass these issues, several proposals have been published to help in the interpretation of incised valley stratigraphic successions and the identification of estuarine deposits preserved in depth.The Sado estuary is the second large estuary in Portugal (after the Tagus estuary) occupying an area of ca. 200 km2 combining both the external and internal domains. It is one of the most important wetlands in Europe concerning biodiversity being protected by law since 1980. At present it hosts important industries and serves as a stage for the development of other traditional economic activities. As a coastal wetland, the Sado estuary is highly sensitive to climatic and sea level changes. Notwithstanding the Sado valley morphology, its morphological and environmental evolution and the fluvial and estuarine responses to sea level changes are still poorly understood.The present study aims to characterise the palaeomorphology, morphological and estuarine evolution and sedimentary infilling in the upper areas of the estuarine zone located in the Sado (Alcácer do Sal) channel by combining information retrieved from sedimentary cores, geotechnical descriptions and Electric Resistivity Tomography (ERT) profiles. Geotechnical and ERT information reveal a deep incised palaeovalley reaching depths of 38 m and 24 m below MSL between Alcácer do Sal and Laxique (ca. 45 and 65 km upstream the estuarine inlet, respectively). The ERT data points to the occurrence of coarse sedimentary deposits in depth between Vale do Guizo (ca. 52 km upstream the estuarine inlet) and Laxique. Environmental and ecological proxies analised in the sediments retrieved from the Sado channel and tributaries reflect marine influence in the area (ca. 52 km upstream the estuarine inlet) since at least 8850 cal BP. The maximum extension of marine influence was detected in Laxique during the Middle to Late Holocene transition. Brackish conditions at this upstream location may have occurred earlier, but the coarseness of the sediment infilling prevented its recovery using coring devices and, consequently, its palaeoenvironmental characterization. Marine influence prevailed until 4000 cal BP at Laxique, from when the aggradation and progradation of the alluvial plain started. The aggradation of the alluvial plain began later (3250 cal BP) at Arapouco (ca. 50 km upstream the estuarine inlet).This research was funded by the Portuguese Foundation for Science and Technology, I.P./MCTES through national funding (PIDDAC) – UIDB/50019/2020 – Instituto Dom Luiz and by the Spanish Ministry of Science and Innovation through the project SimTIC (HAR2017-82557-P).

The Serra da Estrela range in Central Portugal is a key region to explore the Last Glacial termination in the Atlantic region of Iberia. We present the Late Glacial and Holocene record of Lake Peixão to reconstruct past environmental and climatic conditions at decadal timescales. We retrieved an 8.5m long core in the central and deepest zone of the lake. From the base to the top, the sediment core is composed of i) a thick layer (aprox. 0.5 m) of gravel-to-sand quartz clasts; ii) an alternation of one meter thick grey to pale-brown sandy deposits; and iii) homogeneous dark brown and pale-brown organic-rich muddy facies (ca. 7 meters). Using a Bayesian statistical model based on 16 radiocarbon dates using pollen concentrated samples and 210Pb measurements, we have developed an age-depth model covering the last ca. 14.6 ka, recording the onset of the lake at that time. Lake and mire records previously published in the area generally support this chronology for the formation of proglacial lakes. In addition, the proposed timing for the disappearance of the Serra da Estrela glaciers has been based on Cosmic-Ray Exposure dating (in situ cosmogenic 36Cl) of exposed moraine boulders and glacially polished bedrock surfaces. These results indicate that the end of the glacier’s presence in Serra da Estrela occurred at ca. 14.2 ka BP (during the Bølling-Allerød Interstadial). Therefore our results broadly suport the timing of the end of the deglaciation at the Serra da Estrela and highlight the value of lake sedimentary records. Moreover, the availability of last termination and Holocene highly-resolved sediments from Lake Peixão is likely to record very valuable evidence of climatic and environmental changes at decadal timescales extending from the last deglaciation, through the Holocene. This new multi-proxy data of the Lake Peixão sedimentary sequence will enable comparisons to other decadal-resolved records and support further investigations from the Mediterranean Iberian region.The financial support for this work was possible through the following FCT project: HOLMODRIVE—North Atlantic Atmospheric Patterns Influence on Western Iberia Climate: From the Late Glacial to the Present (PTDC/CTA-GEO/29029/2017).

Our study evaluates differences in the distribution and ecology of genetic variants within several ecologically important diatom species that are also key for Water Framework Directive monitoring of European rivers: Fistulifera saprophila (FSAP), Achnanthidium minutissimum (ADMI), Nitzschia inconspicua (NINC) and Nitzschia soratensis (NSTS). We used DADA2 to infer amplicon sequence variants (ASVs) of a short rbcL barcode in 531 environmental samples from biomonitoring campaigns in Catalonia and France. ASVs within each species showed different distribution patterns. Threshold Indicator Taxa ANalysis revealed three ecological groupings of ASVs in both ADMI and FSAP. Two of these in each species were separated by opposite responses to calcium and conductivity. Boosted regression trees additionally showed that both variables greatly influenced the occurrence of these groupings. A third grouping in FSAP was characterized by a negative response to total organic carbon and hence was better represented in waters with higher ecological status than the other FSAP ASVs, contrasting with what is generally assumed for the species. In the two Nitzschia species, our analyses confirmed earlier studies: NINC preferred higher levels of calcium and conductivity. Our findings suggest that the broad ecological tolerance of some diatom species results from overlapping preferences among genetic variants, which individually show much more restricted preferences and distributions. This work shows the importance of studying the ecological preferences of genetic variants within species complexes, now possible with DNA metabarcoding. The results will help reveal and understand biogeographical distributions and facilitate the development of more accurate biological indexes for biomonitoring programmes. info:eu-repo/semantics/acceptedVersion

Aim Temperate forests are currently facing multiple stresses due to climate change, biological invasions, habitat fragmentation and fire regime change. How these stressors interact with each other influences how, when and whether ecosystems recover, or whether they adapt or transition to a different ecological state. Because forest recovery or collapse may take longer than a human lifetime, predicting the outcomes of different stressor combinations remains difficult. A clearer vision of future forest trajectories in a changing world may be gained by examining collapses of forests in the past. Here, we use long-term ecological data to conduct a post-mortem examination of the decline of maritime pine forests (Pinus pinaster Ait.) on the SW Iberian Peninsula 7000-6500 years ago. Location Portugal and Spain. Methods We compared four palaeoecological records-two with pine declines and two without-using a multiproxy approach. Bioclimatic differences between the four sites were explored. Proxies for past vegetation and disturbance (fire and grazing) were compared with independent palaeoclimatic records. We performed functional traits analysis and used phase plots to examine the causes of pine decline. Results The pine decline represents a critical transition in SW Iberia, which lies close to maritime pine's bioclimatic limits. Prolonged drought likely killed trees and suppressed the fires that normally stimulate pine germination and pinewood recovery. Increased grazing pressure facilitated the rapid spread of resprouter shrubs. These competed with pine trees and ultimately replaced them. Our data highlight complex interactions between climate, fire, grazing and forest resilience. Main Conclusions The pine decline occurred at least a century after post-fire resprouters overtook obligate seeders in the vegetation, constituting an early-warning signal of forest loss. Fire suppression, resprouter encroachment and grazing may threaten the persistence of Mediterranean forests as droughts become more frequent and extreme. PTDC/AAC--CLI/108518/2008 info:eu-repo/semantics/publishedVersion

We applied DNA metabarcoding to evaluate the ecology of genetic variants within several diatom species that are important for biomonitoring. Benthic diatoms are widely used as bioindicators for biomonitoring programmes, including those for European rivers demanded by Water Framework Directive (WFD). Morphological identification of diatoms at species level is required for assessing the ecological status in biomonitoring programmes. However, this is a time-consuming task and requires expert knowledge. In addition, closely related species, which sometimes are scarcely distinguishable on the basis of their morphology, can show different ecological preferences; these may even vary within a single diatom species. Not being able to identify the different ecological preferences shown by the genetic variants of a single species or closely related species, might have consequences for biomonitoring programmes, especially if such differences occur within common species. The key diatom species that we studied were: Fistulifera saprophila (FSAP), widely regarded as a marker for elevated nutrient levels, organic pollution and hence poor ecological status; Achnanthidium minutissimum (ADMI), which usually indicates good ecological status; and Nitzschia inconspicua (NINC) and N. soratensis (NSTS), two species that are widely separated phylogenetically but almost impossible to distinguish in the light microscope. Our dataset was based on high-throughput sequencing using a 312-bp rbcL marker. We used the denoising pipeline DADA2 to infer amplicon sequence variants (ASVs) from 554 environmental samples from river biomonitoring campaigns in Catalonia (NE Spain) and France. Ecological groupings of ASVs were distinguished according to their environmental responses given by Threshold Indicator Taxa ANalysis (TITAN); the environmental parameters that most influenced the occurrence of these groupings were tested using boosted regression trees. We could distinguish three different ecological groupings of ASVs within ADMI and three within FSAP. In each species two of the groupings were clearly separated by their opposite responses to calcium and conductivity and boosted regression trees showed that for three out of four of these groupings, these two variables were among the most important variables for explaining the ASV distributions. The third grouping in FSAP had a negative response to total organic carbon and a positive response to altitude and hence was better represented in less organically polluted waters and higher ecological status than is generally assumed for FSAP. Our analyses did not identify ecological groupings of ASVs within NINC and NSTS but confirmed earlier studies, based on more limited sampling, that indicated different preferences of these species. Conductivity and calcium were the variables that most influenced the occurrence of NINC and NSTS, NINC being better distributed in waters with higher levels of calcium and conductivity than NSTS. Our findings indicate the potential use of DNA metabarcoding for distinguishing the ecological preferences of genetic variants within a single species or closely related species. This information, coupled with the broad knowledge generated over many years using traditional microscope-based identifications, will facilitate the development of more accurate biological indexes for the biomonitoring programmes of the future.

The authors acknowledge COST Action ES 1105 "CYANOCOST Cyanobacterial blooms and toxins in water resources: Occurrence impacts and management" and COST Action Global Change Biology ES 1201 NETLAKE -Networking Lake Observatories in Europe" for contributing to this study through networking and knowledge sharing with European experts in the field. We acknowledge the members of the Global Lake Ecological Observatory Network (GLEON) for their collaborative spirit and enthusiasm that inspired the grassroots effort of the EMLS. E.M. was supported by a grant from the Swiss State Secretariat for Education, Research and Innovation to Bas Ibelings and by supplementary funding from University of Geneva. We thank Wendy Beekman for the nutrient analysis. We thank Pieter Slot for assisting with the pigment analysis. We thank Dr. Ian Jones for valuable feedback on an earlier version of the manuscript. We thank the Leibniz Institute of Freshwater Ecology and the Aquatic Microbial Ecology Group for logistic and technical support of J. Fonvielle and H.-P. Grossart, and the Leibniz Association for financial support. H.P. was supported by the US National Science Foundation (1840715, 1831096). A.C.'s work was funded by the Spanish Agencia Estatal de Investigacion and EU funds through the project CLIMAWET (CGL2015-69557-R). The collection of data for Lough Erne and Lough Neagh were funded by the Department of Agriculture, Environment and Rural Affairs, Northern Ireland. We are grateful to Kristiina Vuorio from the Freshwater Centre of the Finnish Environment institute for her help in organizing, collecting and analysing samples by the University of Jyvaskyla and to Gerald Dorflinger from the Water Development Department of Cyprus for his assistance with the sampling in Cyprus and for granting the CUT team permission to use WDD's equipment. Finally, we would like to thank the numerous other assistants that helped realizing each local survey. Open access funding provided by Universite de Geneve., To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L-1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4 degrees C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature., European Cooperation in Science and Technology (COST) ES 1105 ES 1201, Swiss State Secretariat for Education, Research and Innovation, University of Geneva, Leibniz Association, National Science Foundation (NSF) 1840715 1831096, Spanish Agencia Estatal de Investigacion, European Commission CGL2015-69557-R, Department of Agriculture, Environment and Rural Affairs, Northern Ireland

Bromine (Br) cycling in natural wetlands is highly complex, including abiotic/biotic processes and multiphase inorganic/organic Br-species. Wetland ecosystems receive Br primarily from the ocean, functioning as either sinks or sources of Br, with the overall imbalance largely decided by the prevailing climate. Aiming to trace the present-day transport of oceanogenic Br (i.e., derived from salt-water spray-droplets) and its uptake and storage in brackish and freshwater wetlands, we surveyed waters, autochthonous plants, and soils/sediments from coastal marshes and mountain peatlands in the westernmost fringe of northern Portugal. The calculated enrichment factors of bromide (Br−) relative to chloride in rainfall (EFsea = 16.8–75.3), rivers (EFsea = 1.3–13.9) and wetland waters, superficial (EFsea = 5.8–13.1) and interstitial (EFsea = 2.1–8.9), increased towards the inland highlands. We hypothesized that these values derived mostly from a known Br autocatalytic (heterogeneous) chemical cycle, starting at the seawater-aqueous interface and progressing in altitude. Br-bearing air masses are carried far from the Atlantic Ocean by moist westerlies, with Br− rainout from the atmosphere supplying the neighbouring mountain peatlands. Average [Br] in sampled wetland soils/sediments (111–253 mg/kg) agreed with values from other coastal regions, and they were directly correlated with the abundance of organic matter, varying irrespective the [Br−] of interstitial waters (129 μg/L–79 mg/L). According to the computed bioconcentration factors, the aqueous component was the major source of Br for all plant species investigated (BFplant/water = 2.1–508.0), as described elsewhere. However, Br contents in plants (14–173 mg/kg) evidenced interspecific differences, also suggesting a divergence from the acknowledged halophytic-glycophytic “model”. As plants are recognized producers of Br volatile molecules (e.g., methyl bromide, CH3Br), we interpreted translocation factors less than one in vascular species as explanatory of phytovolatilization rather than restriction of Br− upward movement in plants. Further investigation is needed, since considerable intrinsic plant variations in CH3Br emissions are mentioned in the literature.

Coastal back‐barrier perched lakes are freshwater bodies that are elevated over sea‐level and are not directly subjected to the inflow of seawater. This study provides a detailed reconstruction of the Doniños back‐barrier perched lake that developed at the end of a small river valley in the rocky coast of the north‐west Iberian Peninsula during the Holocene transgression. Its sequence stratigraphy was reconstructed based on a core transect across the system, the analyses of its lithofacies and microfossil assemblages, and a high‐resolution radiocarbon‐based chronology. The Doniños perched lake was formed ca 4·5 ka bp. The setting of the perched lake was favoured by Late Holocene sea‐level stabilization and the formation of a barrier and back‐barrier basin, which was contemporaneous with the high systems tract period. This basin developed over marine and lagoonal sediments deposited between 10·2 ka bp and 8·0 ka bp, during rapidly rising sea‐level characteristic of the transgressive systems track period. At 1·1 ka bp, the barrier was breached and the perched lake was partially emptied, causing the erosion of the back‐barrier basin sediments and a significant sedimentary hiatus. Both enhanced storminess and human intervention were likely to be responsible for this event. After 1 ka bp, the barrier reclosed and the present‐day lake was reformed, with the water level reaching as high as 5 m above mean sea‐level. The depositional evolution of the Doniños system serves as a model of coastal back‐barrier perched lakes in coastal clastic systems that have developed over gently seaward‐dipping rugged substrates at small distances from the shoreline and under conditions of rising sea‐level and high sediment supply. A review of estuaries, back‐barrier lagoons, pocket beaches and back‐barrier perched lakes in the rocky coast of north‐west Spain shows that the elevation of the bedrock is the main factor controlling the origin and evolution of these systems., This study was funded by the Spanish Ministry of Economy and Competitiveness through the projects CONSOLIDER‐ Ingenio 2010 GRACCIE (CSD2007‐00067), RapidNAO (CGL2013‐40608‐R) and PaleoMODES (CGL2016‐75281‐C2‐1‐R). AH and ML were supported by the Portuguese Science Foundation (FCT) through post‐doctoral SFRH/BPD/79923/2011 and SFRH/BPD/82103/2011, respectively. RC is grateful for a PhD fellowship from the Xunta de Galicia (Plan I2C) co‐financed by the European Social 94 Fund.

Luisa Riato was supported by a Coaltech Research Association Research Fellowship. J.C. Taylor is the recipient of South African National Research Foundation (NRF) incentive funding.

A previously unknown member of the Bacillariaceae was discovered almost simultaneously in four different brackish coastal wetlands on the Atlantic and Mediterranean coasts of the Iberian Peninsula. It appears to tolerate a wide range of salinities but was never common in samples where it occurred. The frustules were consistently hantzschioid (i.e. with the raphe systems always on the same side of the frustule) and the valve outline was asymmetrical about the apical plane, two features that have until recently been considered characteristic of Hantzschia. Molecular phylogenies based on rbcL and LSU rDNA indicated, however, that the new species does not belong in Hantzschia but among the several disparate lineages that comprise the paraphyletic genus Nitzschia. This finding, coupled with the recent discovery of other diatoms with constant hantzschioid symmetry but with a morphology very similar to the type species of Nitzschia, is discussed in relation to the status and characterization of Hantzschi...

Information on the response of temporary depressional wetland diatoms to human-induced disturbances is a limited and important component for the development of temporary wetland biological assessments in human-modified landscapes. Establishing a reference condition of variation due to natural disturbances in depressional wetlands using diatoms is necessary for further investigations of anthropogenic impacts. We examined the temporal and spatial responses of epiphytic diatom communities to natural environmental disturbances within three least disturbed wetlands in the Mpumalanga Province, South Africa. Alkalinity, Na+ and Cl−, water depth and total relative evapotranspiration (ETo) accounted for the highest proportion of temporal variation in composition of epiphytic diatoms, as revealed by canonical correspondence analysis (CCA). Alkalinity, Na+, and Cl− explained a much higher proportion of species variation, using partial CCA. A simple WA with inverse deshrinking produced reasonably robust models for Na+ (r boot 2 = 0.71), depth (r boot 2 = 0.64) and alkalinity (r boot 2 = 0.46), not for Cl− and ETo. We determined species optima and tolerances for Na+, depth and alkalinity which can facilitate identification of anthropogenic impacts based on changes of indicator taxa assemblages. Our study provides a basis for newly developed quantitative tools to be used in biomonitoring studies and evaluations of reference conditions for temporary wetland management.

[Abstract] The species composition of diatom assemblages was studied in five unpolluted thermo-mineral springs in Galicia (NW Spain). Three are considered hot and two cold, and some contain hydrogen sulphide. A total of 68 taxa (24 genera) have been recorded. The Shannon–Wiener diversity index (H′) ranged between 0.63 and 2.01. The nMDS ordination showed that diatom assemblage composition was influenced mostly by conductivity, temperature and hydrogen sulphide concentration. Diatom assemblages found in the Galician springs differed from those in springs of other geographical locations with similar physical and chemical characteristics. The most species-rich genera were Nitzschia and Achnanthidium with 10 and 8 species, respectively. Achnanthidium exiguum and Achnanthidium saprophilum had the widest distribution. Denticula thermalis and Achnanthidium caledonicum were found in environments with relatively low mineralization and low temperature, whereas Rhopalodia gibberula, Rhopalodia operculata and Fragilaria crotonensis were found in mineral-rich springs with high temperatures. Achnanthidium exiguum, A. saprophilum, Achnanthes coarctata, Achnanthes exigua var. elliptica, Mayamaea atomus, Eunotia implicata, Gomphonema minusculum, Gomphonema minutum and Cosmioneis pusilla were present in the spring with high H2S content.

Estuaries are sensitive to changes in global to regional sea level, to climate-driven variation in rainfall and to fluvial discharge. In this study, we use source and environmentally sensitive proxies together with radiocarbon dating to examine a 7-m-thick sedimentary record from the Sado estuary accumulated throughout the last 3.6 kyr. The lithofacies, geochemistry and diatom assemblages in the sediments accumulated between 3570 and 3240 cal. BP indicate a mixture between terrestrial and marine sources. The relative contribution of each source varied through time as sedimentation progressed in a low intertidal to high subtidal and low-energy accreting tidal flat. The sedimentation proceeded under a general pattern of drier and higher aridity conditions, punctuated by century-long changes of the rainfall regime that mirror an increase in storminess that affected SW Portugal and Europe. The sediment sequence contains evidence of two periods characterized by downstream displacement of the estuarine/freshwater transitional boundary, dated to 3570-3400 cal. BP and 3300-3240 cal. BP. These are intercalated by one episode where marine influence shifted upstream. All sedimentation episodes developed under high terrestrial sediment delivery to this transitional region, leading to exceptionally high sedimentation rates, independently of the relative expression of terrestrial/marine influences in sediment facies. Our data show that these disturbances are mainly climate-driven and related to variations in rainfall and only secondarily with regional sea-level oscillations. From 3240 cal. BP onwards, an abrupt change in sediment facies is noted, in which the silting estuarine bottom reaches mean sea level and continued accreting until present under prevailing freshwater conditions, the tidal flat changing to an alluvial plain. The environmental modification is accompanied by a pronounced change in sedimentation rate that decreased by two orders of magnitude, reflecting the loss of accommodation space rather than the influence of climate or regional sea-level drivers. FCT by Spanish Ministry of Science and Innovation [SFRH/BD/110270/2015, HAR2014-51830-P, HAR2011-29907-C03-00] FCTPortuguese Foundation for Science and Technology [PTDC/HISARQ/121592/2010] Instituto Dom Luiz-IDL [UID/GEO/50019/2013] info:eu-repo/semantics/publishedVersion

We examine the Holocene environmental changes in a wet dune slack of the Portuguese coast, Poco do Barbarroxa de Baixo. Lithology, organic matter, biological proxies and high-resolution chronology provide estimations of sediment accumulation rates and changes in environmental conditions in relation to sea-level change and climate variability during the Holocene. Results show that the wet dune slack was formed 7.5 cal. ka BP, contemporaneous with the last stages of the rapid sea-level rise. This depositional environment formed under frequent freshwater flooding and water ponding that allowed the development and post-mortem accumulation of abundant plant remains. The wetland evolved into mostly palustrine conditions over the next 2000 years, until a phase of stabilization in relative sea-level rise, when sedimentation rates slowed down to 0.04 mm yr(-1), between 5.3 and 2.5 cal. ka BP. Later, about 0.8 cal. ka BP, high-energy events, likely due to enhanced storminess and more frequent onshore winds, caused the collapse of the foredune above the wetlands' seaward margin. The delicate balance between hydrology (controlled by sea-level rise and climate change), sediment supply and storminess modulates the habitat's resilience and ecological stability. This underpins the relevance of integrating past records in coastal wet dune slacks management in a scenario of constant adaptation processes. Faculdade de Ciencias da Universidade de Lisboa [FCT UID/GEO/50019/2013]

Current diatom assessments of shallow lakes typically use littoral epiphytic diatoms as bioindicators for eutrophication pressure. However, challenges in establishing robust ecological assessments still exist because of the natural pressures that shallow lakes are subjected to which are difficult to quantify (e.g., water-level fluctuations or wave action). Information on the spatial and temporal variability of epiphytic communities within a shallow lake is limited although important for the development of robust bioassessment protocols. We compared epiphytic diatom taxa and functional group compositions between the littoral and pelagic zone of three least-disturbed shallow lakes in the northeastern part of South Africa along a temporal gradient. In comparison to the pelagic zone, the littoral zone was characterized by almost double in species richness. Temporal variability was significantly higher for littoral diatom communities and littoral water physico-chemistry than those of the pelagic. Overall, water depth was a good predictor of the epiphytic diatom taxa and functional group composition. We also found that pelagic diatom taxa and functional groups correlated better with pelagic physico-chemistry than littoral diatoms to littoral physico-chemistry. This could be attributed to un-modeled factors related to natural physical pressures that will have more of an impact on littoral habitats than less exposed pelagic habitats. Given these findings, using pelagic epiphytic diatoms as a bioindicator in shallow lake monitoring programs could be more efficient than littoral diatoms at providing robust ecological assessments due to their relatively low variability.

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains. © 2018 by the authors. Licensee MDPI, Basel, Switzerland., The authors acknowledge COST Action ES 1105 “CYANOCOST—Cyanobacterial blooms and toxins in water resources: Occurrence impacts and management” and COST Action ES 1201 “NETLAKE—Networking Lake Observatories in Europe” for contributing to this study through networking and knowledge sharing with European experts in the field. Evanthia Mantzouki was supported by a grant from the Swiss State Secretariat for Education, Research and Innovation (SERI) to Bas Ibelings and by supplementary funding from the University of Geneva. We thank Clare Ahnlund, Ena Suarez and Irene Gallego for helping out with the Swiss survey. We thank Wendy Beekman and Els J. Faassen for the nutrient and toxin analysis.

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment., The authors acknowledge COST Action ES 1105 “CYANOCOST – Cyanobacterial blooms and toxins in water resources: Occurrence impacts and management” and COST Action ES 1201 “NETLAKE – Networking Lake Observatories in Europe” for contributing to this study through networking and knowledge sharing with European experts in the field. Evanthia Mantzouki was supported by a grant from the Swiss State Secretariat for Education, Research and Innovation (SERI) to Bas Ibelings and by supplementary funding from University of Geneva. We thank Wendy Beekman for the nutrient analysis and the University of Wageningen for covering the costs of this analysis from the personal funding of dr. Miquel Lürling. We thank Pieter Slot for assisting with the pigment analysis and the University of Amsterdam for covering the costs of the analysis through funding from the group of Prof. Jef Huisman and dr. Petra Visser (IBED). We would like to thank the Environmental Data Initiative for covering the cost of archiving the EMLS dataset. We would like to thank the Leibniz Institute of Freshwater Ecology and Inland Fisheries, Dept. of Experimental Limnology and the Aquatic Microbial Ecology Group for logistic and technical support of J. Fonvielle and H.-P. Grossart; and the Leibniz Association for financial support. The collection of data for Lough Erne and Lough Neagh were funded by the Department of Agriculture, Environment and Rural Affairs, Northern Ireland.

A catalog of Bacillariophyceae for the rivers of NW of Spain is made for the first time. It includes a re-examination of the taxa reported in previous publications, taxa cited during the last years of the rivers of the Galicia-Costa Hydrographic Demarcation, and a revision of the taxonomy, in line with the systematic and nomenclature changes, which have occurred mainly in recent years. The epilethic diatoms of the river basins of Galicia-Costa were sampled during the years 2005, 2006, and 2007, in May-June and September. The study was carried out in 41 localities distributed along 31 rivers, samples were taken in upstream and downstream sections. Diatom communities were compared in all upstream sections of these rivers draining from siliceous substrates. We identified 141 taxa of diatoms from the coast of Galicia. In this paper we present 15 new citations for Galicia, two for Spain and three for the Iberian Peninsula, in addition to a new species recently described. The dominant taxa are: Achnanthidium minutissimum, Achnanthes subhudsonis, Karayevia oblongella, Cocconeis placentula var. euglypta, Gomphonema rhombicum, and Navicula minima. Achnanthes subhudsonis was the most abundant species during the spring and summer months. The remaining species showed no relevant changes regardless of the time of year. The results indicate that the river diatoms of Galicia are an important component of the diversity of the ecosystem. Se realiza por primera vez un catálogo de Bacillariophyceae para los ríos del NW de España. Se incluyen un nuevo examen de los táxones recogidos en publicaciones anteriores, datos de táxones citados durante los últimos años de los ríos de la demarcación hidrográfica de Galicia-Costa y una revisión de la taxonomía, en consonancia con los cambios sistemáticos y nomenclaturales, que se han producido sobre todo durante los últimos años. Se estudiaron las diatomeas epilíticas de las cuencas de los ríos de Galicia-Costa entre los años 2005, 2006 y 2007, durante dos temporadas diferentes: mayo-junio y septiembre. El estudio se llevó a cabo en 41 localidades distribuidas a lo largo de 31 ríos, donde se tomaron muestras en tramos aguas arriba y aguas abajo. Las comunidades de diatomeas de estos ríos que drenan de sustratos silíceos fueron comparadas en todos los tramos de aguas arriba. Se identificaron 141 táxones de diatomeas de la costa de Galicia. En este trabajo presentamos 15 nuevas citas para Galicia, dos para España y tres para la Península Ibérica, además de una nueva especie recientemente descrita. Los táxones dominantes son: Achnanthidium minutissimum, Achnanthes subhudsonis, Karayevia oblongella, Cocconeis placentula var. euglypta, Gomphonema rhombicum, y Navicula minima. Achnanthes subhudsonis fue la especie más abundante durante los meses de primavera y verano. Las especies restantes no mostraron cambios pertinentes independientemente de la época del año. Los resultados indican que las diatomeas de los ríos de Galicia son un componente importante de la diversidad del ecosistema.

Water-level fluctuations (WLF) often represent one of the greatest impacts on the development of lake ecosystems. In the year 1931, the Trentino Hydroelectric Company (SIT) requested the hydroelectric use of water bodies in the Upper and Middle Sarca basin. The largest and deepest lakes were dammed to increase lake volume and exploited since mid 1950s. This research uses the sediment record of two small lakes in close proximity to each other (Garzone and Serodoli) in northern Italy, used for hydroelectric power generation to determine the dependence of diatom-assemblage dynamics on WLF that have taken place over the last 60 years. Historical WLF are clearly reflected in the lithological composition and grain-size variations of the sediment cores. During the regression and transgression phases, the boundaries between the erosion, transport and accumulation zones fluctuated, causing redistribution of previously accumulated sediments, and their return into the lake’s cycling of biogeochemical matter. The water-level changes not only caused distinct taxonomic shifts in the diatom communities, which were dominated by different species in the core sections of each lake, but also significant shifts in the composition of the diatoms’ ecological, morphofunctional and life-form groups. Diatoms with a low- and high-profile attachment type were the dominant morphological forms in the upper core levels, where the most extreme fluctuations in water level had occurred. Increased turbulent mixing caused by WLF favours the presence of large, heavily silicified centric diatoms, while more stable levels would select for smaller centric diatoms through thermal stratification.

Acid mine drainage (AMD) from coal mining in the Mpumalanga Highveld region of South Africa has caused severe chemical and biological degradation of aquatic habitats, specifically depressional wetlands, as mines use these wetlands for storage of AMD. Diatom-based multimetric indices (MMIs) to assess wetland condition have mostly been developed to assess agricultural and urban land use impacts. No diatom MMI of wetland condition has been developed to assess AMD impacts related to mining activities. Previous approaches to diatom-based MMI development in wetlands have not accounted for natural variability. Natural variability among depressional wetlands may influence the accuracy of MMIs. Epiphytic diatom MMIs sensitive to AMD were developed for a range of depressional wetland types to account for natural variation in biological metrics. For this, we classified wetland types based on diatom typologies. A range of 4–15 final metrics were selected from a pool of ~ 140 candidate metrics to develop the MMIs based on their: (1) broad range, (2) high separation power and (3) low correlation among metrics. Final metrics were selected from three categories: similarity to reference sites, functional groups, and taxonomic composition, which represent different aspects of diatom assemblage structure and function. MMI performances were evaluated according to their precision in distinguishing reference sites, responsiveness to discriminate reference and disturbed sites, sensitivity to human disturbances and relevancy to AMD-related stressors. Each MMI showed excellent discriminatory power, whether or not it accounted for natural variation. However, accounting for variation by grouping sites based on diatom typologies improved overall performance of MMIs. Our study highlights the usefulness of diatom-based metrics and provides a model for the biological assessment of depressional wetland condition in South Africa and elsewhere.

We have studied the phycological diversity at the Natural Park of Serra da Enciña da Lastra (Ourense, Spain) and present here the algae checklist of the Galir river, the only permanent fluvial course in the area. This geographical zone is a SCI (Site of Community Importance) and is located within an European Nature Reserve belonging to the “Nature 2000” network. Despite its environmental importance there is no previous phycological survey to this study. We collected samples in three points along the river, and measured physical and chemical water parameters (pH, conductivity, temperature, and dissolved oxygen). The checklist includes 88 taxa: 6 Cyanophyta, 4 Rhodophyta, 60 Heterokontophyta (58 Bacillariophyceae, 2 Xantophyceae), 1 Dinophyta, 2 Euglenophyta, and 15 Chlorophyta. Within the Rhodophyta we highlight the presence of Lemanea condensata, as a new record to the Iberian Peninsula. In addition, we have identified 8 new records for Galicia and 14 for Ourense Se ha estudiado la diversidad ficológica del río Galir, el único curso fluvial permanente del Parque Natural Serra da Enciña da Lastra (Orense, España). Es un Lugar de Importancia Comunitaria (LIC) incluido en la red de espacios naturales “Natura 2000”. A pesar de su importancia ambiental, no hay ningún estudio ficológico previo al presente. El catálogo de la flora ficológica incluye táxones recogidos de tres puntos del río y se han tenido en cuenta algunos parámetros físicoquímicos del agua: pH, conductividad, temperatura y oxígeno disuelto. El catálogo florístico incluye 88 táxones: 6 Cyanophyta, 4 Rhodophyta, 60 Heterokontophyta (58 Bacillariophyceae y 2 Xantophyceae), 1 Dinophyta, 2 Euglenophyta y 15 Chlorophyta. Entre las Rhodophyta destaca Lemanea condensata, por ser nueva cita para la Península Ibérica. Además, se han encontrado 8 nuevas citas para Galicia y 14 para la provincia de Orense This study was funded by the Consellería de Medio Ambiente e Desenvolvemento Sostible de la Xunta de Galicia (PGIDIT05RFO20002PR) SI

International audience; With the aim of evaluating cause-effect relationships between metal pollution and biofilm structure and function, a translocation study was performed in a metal-polluted stream (the Osor stream “la riera d’Osor”, NE Spain). Biofilm responses were measured as temporal changes in chl-a fluorescence param-eters, pigment composition and diatom species composition. Biofilms from a non-polluted site were translocated to four downstream sites presenting a gradient of metal pollution, corresponding to scenar-ios of low and moderate metal pollution. Metal effects (Zn bioaccumulation, Fe bioaccumulation and Zn in water) were distinguished from other stressors (phosphate concentration in water). Based on the results obtained, a fast bioaccumulation of Zn (after few hours of exposure) was linked to a decrease in photosyn-thetic efficiency and an enhancement of mechanisms of protection through the xanthophyll cycle. After longer exposure, differences in Zn and Fe bioaccumulation and Zn water concentration between sites were linked to diatom community changes; decrease in diatom cell biovolume, along with a decrease in the IPS index of diatoms. Based on our results, we recommend including Zn in the list of priority pollutant substances of the European Water Framework Directive (2000/60/EC), due to its occurrence and toxic-ity. In addition, our study supports the use of chl-a fluorescence parameters together with the analysis of photosynthetic pigments of biofilms as suitable functional endpoints of early toxicity. Furthermore, diatom community studies are recommended for their clear response after chronic exposure. However, new diatom indices beyond the use of the IPS are required to increase their sensitivity to metal pollution, e.g. to identify the damage caused by moderate to low metal pollution.

The traditional and widely used ecomorphological spring classification—pool springs (limnocrenes), seepages (helocrenes), and flowing springs (rheocrenes)—is based mainly on the flow regime at the spring mouth. This clear distinction is based purely on environmental conditions, but how and to what extent these spring typologies are reflected by biological assemblages consisting of different taxonomic groups remains largely untested. Classification of habitats typically is based on one or few taxonomic groups. However, groups are likely to differ in their response to the environment, so different, equally valid classifications might result with different groups. We evaluated the responses and their congruence of a wide range of taxonomic groups to different spring types. Eighty-six springs in the Italian Alps were first classified based on environmental factors only. The consistency of this classification was tested using diatoms, bryophytes, vascular plants, nematodes, mollusks, oligochaetes, w...

In this study a biological classification based on diatom communities (a posteriori classification) was used to search for the most appropriate a priori classification in reference conditions, on the basis of 31 reference sites encompassing eight watersheds in the NE Iberian Peninsula. We considered three different a priori systems for comparison: (i) a typological classification (ecotypes and subecotypes) based on geomorphology and water flow; (ii) the watershed as a unit, irrespective of its size; and (iii) a classification based on the geographical distance between sites under the assumption that biological characteristics are increasingly similar in geographically closer sites. Classification in ecotypes and subecotypes was the most robust with minor differences between them. The watershed (hydrological units) classification was significant though weaker than the typological classification and there was a larger environmental variation within watersheds than within ecotypes. Finally, results showed that geographically closer sites were not more biologically similar in terms of diatom community composition. We can conclude that the ecotypological environmental-based classifications developed by the local water agency did adequately describe the biological classification based on epilithic diatoms.

A study was carried out to evaluate the sensitivity of different chlorophyll-a (chl-a) fluorescence parameters measured in freshwater biofilms as metal pollution biomarkers of short- and long-term metal exposures at environmentally realistic concentrations. A microcosm experiment was performed using indoor channels. Mature biofilms were exposed from hours to weeks to three different treatments: No-Metal, Zn (400 μg l−1); and Zn plus Cd (400 μg l−1 and 20 μg l−1, respectively). Metal concentration was based on a real case study: the Riou-Mort River (France). Biofilms exposed to Zn bioaccumulated similar Zn contents per dry weight to those exposed to the mixture (Zn plus Cd) causing a similar inhibition of the effective quantum yield $$(\Upphi_{\text{M}}^{\prime})$$ during the first hours of exposure. A reduction of the algal biomass, a shift in the community composition (a high reduction of diatoms), a reduction of the maximal quantum yield (ΦM) and a strong reduction of non-photochemical quenching (NPQ) were observed from day 14 until the end of the experiment (35 days). The results indicate that the effects of the metal mixture present in the Riou-Mort on biofilms could be attributed to Zn toxicity. The use of a set of chl-a fluorescence measurements, including photochemical and NPQ parameters, are recommended as a reliable biomarker tool box to evaluate both short- and long-term effects of metals on biofilms containing oxygenic photoautotrophs, suggesting its use in field applications.

The chronologies and sediment accumulation rates for a lake sediment sequence from Lough Carra (Co. Mayo, western Ireland) were established by applying the constant initial concentration (CIC) and constant rate of supply (CRS) hypotheses to the measured (210)Pb(excess) profile. The resulting chronologies were validated using the artificial fallout radionuclides (137)Cs and (241)Am, which provide independent chronostratigraphic markers for the second half of the 20th century. The validity of extrapolating the derived CIC and CRS dates below the (210)Pb dating horizon using average sedimentation rates was investigated using supplementary paleolimnological information and historical data. Our data confirm that such an extrapolation is well justified at sites characterised by relatively stable sedimentation conditions.

The expected response of fluvial biofilms to the environment and metal pollution prevailing under different discharge conditions was investigated. The relationship between inter-annual hydrological variability and metal concentration in water and sediments was explored in Mediterranean rivers (Catalonia, NE Spain) affected by low but chronic metal pollution, using monitoring data provided by the Catalan Water Agency (ACA). During the period investigated (2000-2006), metal pollution was characterized by low water concentrations and high concentrations in sediments. The most consistent pattern was observed for sediment cadmium (Cd) concentrations, showing a positive relationship with annual discharge, reaching values of environmental concern (above ecotoxicological benchmarks). A different pattern was observed for Cu, Zn, and As increasing with flow in some sites and decreasing in others. While Cd seems to proceed from diffuse sources being washed by surface runoff, Zn, Pb, and As may proceed from either diffuse or point-sources in the different river sites investigated. The relevance of diffuse metal pollution in the area of study indicates that polluted landfills runoff might be an important source of metals causing repetitive pulses of high metal concentration in the receiving water courses. The experimental results presented demonstrate that metal effects in fluvial biofilms may be accumulative, increasing the toxicity after repetitive pulse exposures. Since draughts and extreme rain events are expected to increase at higher latitudes due to global change, the sources of metal pollution, its final concentration and potential effects on the fluvial ecosystem may also change following the patterns expected for human-impacted Mediterranean rivers. © 2010 Springer Science+Business Media B.V. Family Process Institute Sixth Framework Programme: MODELKEY 511237-2 GOCE, KEYBIOEFFECTS MRTN-CT-2006-035695 Ministry of Education and Science: FLUVIALFITOMARC CGL2006-12785, FLUVIALMULTISTRESS CTM2009-14111-CO2-01-745 Acknowledgments The ‘‘Serveis Científics i Tècnics’’ at the University of Girona provided its facilities and technical help for ICP-MS metal analysis. The research was funded by the Spanish Ministry Science and Education (FLUVIALFITOMARC CGL2006-12785 and FLUVIALMULTISTRESS CTM2009-14111-CO2-01-745), and the EC Sixth Framework Program (MODELKEY 511237-2 GOCE and KEYBIOEFFECTS MRTN-CT-2006-035695). Alexandra Serra and Berta Bonet benefit from a FPI grant of the Spanish Ministry Science and Education. Güluzar Atli benefit from an Erasmus grant between the University of C¸ ukurova (Turkey) and the University of Girona (Spain).

A catalog of Bacillariophyceae for the rivers of NW of Spain is made for the first time. It includes a re-examination of the taxa reported in previous publications, taxa cited during the last years of the rivers of the Galicia-Costa Hydrographic Demarcation, and a revision of the taxonomy, in line with the systematic and nomenclature changes, which have occurred mainly in recent years. The epilethic diatoms of the river basins of Galicia-Costa were sampled during the years 2005, 2006, and 2007, in May-June and September. The study was carried out in 41 localities distributed along 31 rivers, samples were taken in upstream and downstream sections. Diatom communities were compared in all upstream sections of these rivers draining from siliceous substrates. We identified 141 taxa of diatoms from the coast of Galicia. In this paper we present 15 new citations for Galicia, two for Spain and three for the Iberian Peninsula, in addition to a new species recently described. The dominant taxa are: Achnanthidium minutissimum, Achnanthes subhudsonis, Karayevia oblongella, Cocconeis placentula var. euglypta, Gomphonema rhombicum, and Navicula minima. Achnanthes subhudsonis was the most abundant species during the spring and summer months. The remaining species showed no relevant changes regardless of the time of year. The results indicate that the river diatoms of Galicia are an important component of the diversity of the ecosystem.

1. A variety of species richness measures have been used to assess the effects of environmental degradation on biodiversity. Such measures can be highly influenced by sample size, sampling effort, habitat type or complexity, however, and typically do not show monotonic responses to human impact. In addition to being independent of the degree of sampling effort involved in data acquisition, effective measures of biodiversity should reflect the degree of taxonomical relatedness among species within ecological assemblages and provide a basis for understanding observed diversity for a particular habitat type. Taxonomic diversity or distinctness indices emphasize the average taxonomic relatedness (i.e. degree of taxonomical closeness) between species in a community. 2. Eutrophication of freshwater ecosystems, mainly due to the increased availability of nutrients, notably phosphorus, has become a major environmental problem. Two measures of taxonomic distinctness (Average Taxonomic Distinctness and Variation in Taxonomic Distinctness) were applied to surface sediment diatoms from 45 lakes across the island of Ireland to examine whether taxonomic distinctness and nutrient enrichment were significantly related at a regional scale. The lakes span a range of concentrations of epilimnic total phosphorus (TP) and were grouped into six different types, based on depth and alkalinity levels, and three different categories according to trophic state (ultra-oligotrophic and oligotrophic; mesotrophic; and eutrophic and hyper-eutrophic). 3. The taxonomic distinctness measures revealed significant differences among lakes in the three different classes of trophic state, with nutrient-rich lakes generally more taxonomically diverse than nutrient-poor lakes. This implies that enrichment of oligotrophic lakes does not necessarily lead to a reduction in taxonomic diversity, at least as expressed by the indices used here. Furthermore, taxonomic distinctness was highly variable across the six different lake types regardless of nutrient level. 4. Results indicate that habitat availability and physical structure within the study lakes also exert a strong influence on the pattern of taxonomic diversity. Overall the results highlight problems with the use of taxonomic diversity measures for detecting impacts of freshwater eutrophication based on diatom assemblages. © 2008 The Authors.

Water-level fluctuations (WLF) in lakes and rivers, especially their extent, frequency and duration, are dominant forces controlling the functioning of these ecosystems. In particular, WLF play an important role in the lake’s littoral and aquatic–terrestrial interface processes. WLF may take place on different spatial and temporal scales under natural conditions but water levels have been artificially modified in regulated lakes, and their impacts are expected to be enhanced within the actual global change scenarios with forthcoming management problems. This article presents an overview on the literature published on this important topic since 1991 by using journals indexed in the ISI Web of Knowledge. The overall objective was to examine temporal and spatial trends in publications on WLF, the specific aspect of WLF concerned and their main effects. Throughout the article we have used case studies to illustrate different effects of WLF on the variety of lake habitats and indicators that have been studied. Overall, the number of papers published on the subject since the 1990s has risen steadily, when less than ten papers were published each year; until 2006 and peaking in 2005. The greatest number of papers on WLF has been carried out in Europe and North America (c. 73%). These data also showed that the effects of WLF have not been studied equally for different groups of organisms. There is a greater interest on macrophytes, which are the most studied group of organisms (18.4% of the papers). Nearly 7% of the papers deal with algae, and zooplankton and invertebrates account for a 7% followed by fish. WLF effects on ecosystems are very complex, and the biological effects in lakes are greatest in shallow water and littoral areas, where even small changes in water levels can result in the conversion of large areas of a standing-water environment in air exposed habitats. Finally, these data might serve to highlight knowledge gaps still existing on this topic and, in particular, some of the approaches that can potentially contribute to solve several of these lacunae are explored.

A key issue in the implementation of the Water Framework Directive is the classification of streams and rivers using biological quality parameters and type-specific reference conditions. Four groups of stream types were defined in NE Spain on the basis of 152 diatom samples by means of detrended correspondence analysis and classification techniques. Diatom analysis was restricted to epilithic taxa, and the sites included gradients ranging from near-natural streams to sites with poor ecological quality. The main gradient shows a clear separation of sites in relation to the degree of human influence: polluted streams (mainly located in the lowlands) differ from streams in mountainous areas and in the Pyrenees. A second gradient is related to physiographical features. Headwater streams can be distinguished by their catchment geology. The type-specific diatom taxa for the stream types studied were determined by using indicator species analysis (IndVal). The type-specific taxa from near-natural streams are coincident with the indicator taxa for high ecological status. Human impact reduced the typological heterogeneity of the diatom community composition. Overall, the diatom communities in NE Spain exhibit a regional distribution pattern that closely corresponds with that observed in river systems elsewhere. Physiographical differences are only evident in undisturbed sites, while nutrient enrichment and other human disturbances may mask the regional differences in the distribution of diatom communities.

Palaeolimnological data from six mesotrophic, eutrophic and hypertrophic lakes in the Irish Ecoregion, in the form of microfossil (cladocera, diatoms and pollen) and sediment chemistry data from radiometrically dated sediment cores, were used to reconstruct past variations in lake water quality and catchment conditions. Basal sediments from sediment cores from the six sites ranged in age from the late 18th century to the early 20th century. A weighted averaging partial least squares regression model was developed to reconstruct past epilimnetic total phosphorus concentrations. The results indicate that all but one of the study sites currently are in a far more productive state compared with the beginning of the sediment core record and that those same five lakes have experienced accelerated enrichment post c. 1980. Two of the sites demonstrated long-term enrichment, in one case beginning in the late 19th century, while both eutrophication and oligotrophication have occurred at three sites. The results highlight the difficulties in applying a general temporal end-point for reference conditions and demonstrate that productive lakes in the Irish Ecoregion have complex, locally specific and often long histories of enrichment. These may not be responsive to reduced external loadings of phosphorus and, as a result, restoration could prove particularly challenging. The results also provide evidence of the ways in which palaeolimnological techniques can assist implementation of the EU Water Framework Directive.

Summary 1 The European Union (EU) Water Framework Directive (WFD) requires that member states establish type-specific reference conditions for all waterbodies, including freshwater lakes. This presents a problem in those locations where human activity has resulted in significant changes to the biological, chemical and physical characteristics of waterbodies. 2 Seventy-six oligotrophic and meso-oligotrophic [0–19 µg total phosphorus (TP) L−1] lakes thought to be relatively unimpacted by human activity have been nominated as candidate reference lakes (CRL) by the Irish Environmental Protection Agency. This research has used palaeolimnological (lake sediment-based) techniques to test the actual and historical ecological site-specific status of a representative selection of these CRL. Where the temporal record of sedimentation was sufficiently long, the study adopted c. 1850 ad as the primary baseline date for reference conditions. 3 Short sediment cores were obtained from the deepest parts of 35 CRL, and chronologies were established from profiles of spheroidal carbonaceous particles (SCP). Twenty-two cores of sediment appeared to date back to c. 1850 on the basis of SCP concentrations. Unless the SCP chronologies suggested otherwise, diatom assemblages present in top and bottom samples from the cores were used as proxies of, respectively, present-day and reference conditions. Past lake water pH (DI-pH) and TP concentration (DI-TP) were inferred from the diatom data. Higher resolution sampling (up to five sediment samples per core) was adopted at seven sites where the SCP-based chronology was more robust and for at least one core from each of the most common types of CRL. Sediment chemistry data were determined to identify possible anthropogenic drivers of the observed changes in the diatom assemblages. 4 Ordination and dissimilarity measures identified the main patterns of variation in the diatom data. Eleven of 34 CRL for which diatom data were available showed little or no change in biological status between core top and bottom samples. Core bottom samples in six of these dated back to pre- or c. 1850 and reference (and high ecological) status could therefore be confirmed in these cases. The estimated age of core bottom samples in the remaining five cores was in the period just after c. 1850 to c. 1950 ad (four cores) or was impossible to determine (one core). Twenty-three (68%) of the CRL sampled showed biologically important deviation from the reference condition, with acidification and nutrient enrichment seemingly the main causes of change. Catchment disturbance, notably peat erosion possibly linked to recent afforestation, also appeared to have been a factor in some cases. 5 Synthesis and applications. This study provides the first systematic examination of changes to water quality in (perceived) pristine lakes over the last c. 150 years for Ireland, and demonstrates the potential of palaeolimnology to support the implementation of the WFD. The results indicate that diatom communities in low alkalinity lakes have been particularly altered, and acidification and nutrient enrichment appear to have been important drivers for some lakes. Furthermore, higher resolution results call into question the validity of applying c. 1850 as the date for reference conditions across Ireland.

The Holocene history of Lagoa Grande (1360 m a.s.l; northwest Spain) has been investigated through the analyses of diatom remains found in a sediment core. Changes in the lake have been interpreted in terms both of climatic variability and major changes in the catchment area. The diatom record begins at about 9800 yr BP and exhibits three marked changes at 8200, 6000, 4200 and at 2600 yr BP, which are interpreted as responses to climatic changes detected by marine and other terrestrial palaeoclimatic records. The initial lake was shallow and Aulacoseira species characteristic of acidic and oligotrophic waters were dominant. The early Holocene is characterised by the presence of Aulacoseira ambigua , which suggests an increase in water depth and nutrient levels. Throughout the Holocene, diatom assemblages underwent several changes linked to fluctuating limnological conditions. These changes in lake characteristics coincide with the regional succession of vegetation, suggesting that climate forcing initiated these limnological changes. During the last 2000 years catchment processes appear to be the major factor controlling lake characteristics in Lagoa Grande site. Diatom responses reflected the progressive peatland development and growth of littoral vegetation in the lake, and not only a change in the regional environment.

Distribution patterns of epilithic diatom assemblages in streams in northeastern Spain and their relation to different environmental gradients are presented. Thirty-five sites were sampled covering a wide range of fluvial typologies. Gradient analysis was used to analyze the community structure and the major ecological gradients underlying variation in species composition. Two major gradients were evident; the first was a complex gradient from oligotrophic, pristine, fast-flowing highland rivers to mainly eutrophic rivers of low elevation; and the second related to altitudinal and seasonal variation of temperature. Two sets of factors were evident; one was associated with water chemistry, and the other to seasonal and physiographical variation. Variance partitioning allowed the separation of the effects of the different sets of environmental parameters. The contribution of physiography and water chemistry to diatom distribution was more unclear when the level of disturbance was intermediate. Considering the relatively high proportion of variation explained by physiographical variables alone, we suggest that when using diatoms to evaluate water quality, ecoregional characteristics of river stretches should also be considered.

Pollen and diatom analyses have been carried out in a 490-cm long core collected from Laguna Lucenza (1420 m a.s.l.; northwest Iberian Peninsula), spanning the last 10,000 yr. Pollen analyses show a decrease in deciduous Quercus pollen percentages and total pollen concentration after radiocarbon date 8350±80 yr BP. The estimated age by linear interpolation for the peak of this event is about 9200 cal yr BP. Diatom analyses have been carried out using the same samples in order to obtain complementary information about past environmental conditions within the water body. Pollen and diatom records show a response to changes in the palaeoenvironmental conditions. Diatom concentrations are relatively low, indicating low productivity within the lake. Fragilaria species are dominant and Fragilaria exigua is notably more abundant than during previous periods. These changes in the diatom community reflect a decrease in lake pH. This would be consistent with longer periods of ice cover and cold conditions in the lake at this time. We interpret this episode as a response to climatic change probably due to climatic deterioration. This interval coincides, at least in part, with an episode of abrupt and short widespread climate change lasting from 9000 to 8000 yr BP.

72 páginas, The multiproxy study (sedimentology, geochemistry and diatoms) of sediment cores from Sanabria Lake (42°07′30″ N, 06°43′00″ W, 1000 m a.s.l.) together with a robust 14C chronology provides the first high-resolution and continuous sedimentary record in the region, extending back the last 26 ka. The development of a proglacial lake before 26 cal ka BP demonstrates the onset of deglaciation before the global Last Glacial Maximum, similarly to other alpine glaciers in southern European mountains. Rapid deglaciation occurred at the beginning of the Greenland Interstadial GI-1e (Bølling, 14.6 cal ka BP). Following a short-lived episode of glacier re-advance (14.4–14.2 cal ka BP, GI-1d), a climatic improvement at 13.9 cal ka BP suggests the glaciers retreated from the lake basin during the GI-1c. Another glacier reactivation phase occurred between ca 13.0–12.4 ka, starting earlier than the onset of GS-1 (Younger Dryas). Rapid deglaciation during the Early Holocene (11.7–10.1 cal ka BP) was followed by a period of higher river discharge (10.1–8.2 cal ka BP). After 8.2 ka, the Holocene is characterized by a general decreasing trend in humidity, punctuated by the driest phase during the Mid Holocene (ca 6.8–4.8), a wetter interval between 4.8 and 3.3 cal ka BP, and a relatively decline of rainfall since then till present, with a minor increase in humidity during some phases (ca 1670–1760) of the Little Ice Age. Discrete silt layers intercalated in the organic-rich Holocene deposits reflect large flooding events of the Tera River (ca 10.1, 8.4, 7.5, 6.2, 5.7–5.6, 4.6, 4.2, 3.7, 3.3, 3.1, 2.7, 2.5 and 2.0 cal ka BP). Their synchronicity with a number of cold and humid events described in the Atlantic demonstrates a strong control of NW Iberian climate by North Atlantic dynamics at centennial–millennial scale. Comparison with Western Mediterranean records points to similar regional dynamics during the Holocene, although modulated in the NW Iberian Peninsula by the stronger Atlantic influence., Funding for this research has been provided by the Spanish Ministry of Economy and Competitiveness through the CALIBRE CGL2006-13327-C04-01/CLI and CONSOLIDER-GRACCIE CSD2007-00067 projects and by the Fundación Patrimonio Natural Castilla y León. M. Jambrina-Enríquez is supported by a PhD fellowship from Salamanca University (Spain). A. Moreno acknowledges the funding from the “Ramón y Cajal” postdoctoral program. We are grateful to Doug Schnurrenberger, Anders Noren and Mark Shapley (LRC, University of Minnesota) for the 2004 coring expedition.We thank Parque Natural Lago de Sanabria and Laboratorio Limnológico de Sanabria (Junta de Castilla y León) for logistic support. We are also grateful to the detailed criticisms and suggestions by two reviewers that greatly improved the manuscript.

Título del postprint: The last two centuries of environmental history in Picos de Europa National Park as assessed from sediments of a mountain lake (Lago Enol, N Iberia), We present a study of two short sediment cores recovered from Lago Enol, in the Picos de Europa National Park, Cantabrian Mountains, northern Iberia. We inferred past climate conditions and anthropogenic impacts using geochemical and biological (pollen and diatoms) variables in the dated sequences, in conjunction with temperature and precipitation data collected since 1871 at meteorological stations in the region. The record provides evidence of environmental changes during the last 200 years. At the end of the Little Ice Age (~1800-1875 AD) the region was characterized by an open landscape. Long-term use of the area for mixed livestock grazing in the mountains, and cultivation of rye during the nineteenth century, contributed to the expansion of grassland at the expense of forest. Warmer temperatures since the end of the nineteenth century are inferred from a change in diatom assemblages and development of the local forest. Socioeconomic transformation during the twentieth century, such as livestock changes related to dairy specialization, planting of non-native trees, mining activities, and management of the national park since its creation in 1918, caused profound changes in the catchment and in the lake ecology. The last several decades (~1970-2007 AD) of the Lago Enol sediment record are strikingly different from previous periods, indicating lower runoff and increasing lake productivity, particularly since AD 2000. Today, the large number of tourists who visit the area cause substantial impacts on this ecosystem. © 2011 Springer Science+Business Media B.V.