NOTICIAS VERANO

VERANO 2017

Récord de temperaturas en junio

Durante la primera quincena de junio de 2017 se han registrado en las orillas del lago de Sanabria temperaturas promedio 3ºC más elevadas que en los mismos días de junio de 2016.

LEER MÁS

Espumas

La formación de espumas endógenas es habitual en muchos lagos y ríos. Resulta de una compleja combinación de factores naturales y biogénicos; y no está basado en la presencia de vertidos urbanos sin depurar.

LEER MÁS

Sequía lagunas

Se muestra la situación de estiaje que muestran a lo largo del verano de 2017 los ecosistemas lacustres de la alta Sierra Segundera y Cabrera de la cuenca del lago de Sanabria.

LEER MÁS

Gambusias

Se recoge la presencia de Gambusia holbrooki, una especie exótica e invasora, que por primera vez se localiza en la cuenca del alto Tera, y se previene sobre el peligro de su aclimatación en la zona tras comprobarse la existencia de machos y hembras de varias cohortes, y también de alevines. 

LEER MÁS

OTOÑO 2017

TEMPERATURAS ALTAS JUN17

Récord de temperaturas en las primeras semanas de junio

Durante la primera quincena de junio de 2017, y dentro de las sucesivas olas de calor que se han adelantado en todo el territorio ibérico, se han registrado en la estación del Programa Bianual Intensivo situada en las orillas del lago de Sanabria temperaturas promedio 3ºC más elevadas que en los mismos días de junio de 2016.

En la siguiente gráfica se pueden observar la evolución de las temperaturas máximas y mínimas diarias de las tres primeras semanas (21 días, 3.018 mediciones de datos) en ambos años.

La subida ha afectado tanto a los promedios como a las máximas (34,66ºC el 18/06/2017 a las 17:00 h) y también a las mínimas nocturnas (5,84ºC el 05/06/2017 a las 5:20 h) en estos primeros quince días de junio. Aunque las mínimas nocturnas también se pueden considerar excepcionalmente elevadas al superarse valores de 11ºC como menor temperatura diaria en 19 de los 21 días de la serie de datos analizada aquí.

Las subidas de la temperatura ambiente repercuten en gran medida en toda la masa del agua, y ya no sólo en el calentamiento superficial de la misma que intensifica la estratificación de la columna. Sino también en las orillas y en las zonas someras, donde la energía de esta excepcional intensidad de radiación solar produce alteraciones etológicas sobre las comunidades de fauna; sobre todo para los más exigentes con los niveles de oxígeno disuelto y que necesitan aguas relativamente frías.

Además favorece en gran medida una mayor proliferación de los seres microscópicos bentónicos que se reproducen a una mayor velocidad de lo habitual para estas fechas. Se ha comprobado en otros lagos cómo el exceso de radiación solar puede producir en las células de los microorganismos planctónicos (fitoplancton) una gran excreción de sustancias al medio acuático, responsable en gran medida de la aparición del biofilm superficial y la posibilidad de que se formen espumas endógenas en la superficie de la masa de agua.

Leer más sobre esto

 

ESTUDIOS EN OTROS LAGOS


Los trabajos de este apartado están ordenados en estos contenidos temáticos:

A/ Cambio climático y sucesión en lagos

B/ Estado trófico producción primaria

 C/ Presiones antrópicas

D/ Redes tróficas y respuestas de las comunidades

E/ Composición química, geoquímica e hidrodinámica de lagos

 F/ Lagos como sensores ambientales en el Holoceno

Última actualización: 17/07/2017  19:11:11  


 A/ CAMBIO CLIMÁTICO Y SUCESIÓN EN LAGOS

• 2002/ Ignacio Granados; Manuel Toro

Recent warming in a high mountain lake (Laguna Cimera, Central Spain) inferred by means of fossil chironomids

Resumen

Lake Cimera (Lat. 40°15’50” N; Long. 05°18’15” W, Zmax = 9.4m, A = 4.5 ha, 2140 m a.s.l,) is one of the most remote and unpolluted high mountain lakes on the Sierra de Gredos (Central Spain). Intrannual and interannual variability in maximum water temperature and winter oxygen depletion can be related to climate variability (mainly air temperature), through controlling ice cover length. The extent of the oxygen depletion during ice cover period, which is related to this ice cover length, is a key factor controlling the relative abundance of chironomid (Diptera: Insecta) taxa, especially the low oxygen content adapted Chironomus sp. In this way, we have found a high negative correlation between the relative abundance of Chironomus head capsules in the sediment and the reconstructed air temperature in the last 200 years (n = 20, r = -0.75, p <0.001). The interpretation of such relationship throughout the fossil chironomid assemblage points to a recent warming (since ca mid 1980s) in Lake Cimera. The ecological interpretation of other taxa also supports this view. When applying to fossil chironomids of Lake Cimera the transfer functions developed to reconstruct summer past temperatures in the Alps, it is also well correlated with reconstructed air temperatures (n = 20, r = 0.45, p <0.01), especially when only the most accurate dating levels (top of the core, ca 75 years) are taken into account (n = 13, r = 0.75, p <0.01). However, 1) the linear regressions of both models show significantly different slopes, and 2) chironomid reconstruction underestimates in ca. 3 ºC air reconstruction. The later is probably because the fossil chironomid model has been developed for a different geographical region. Nevertheless, both models provide an independent line of evidence of a recent warming (since ca mid 1980s) in Lake Cimera. Our data also supports the use of chironomids head capsules as an effective tool to infer past temperatures.

El texto completo de este trabajo en Clic ¡


• 2002/ J. Catalan, M. Ventura, A. Brancelj, I. Granados, H. Thies, U. Nickus, A. Korhola, A. F. Lotter, A. Barbieri, E. Stuchlík, L. Lien, P. Bitušík, T. Buchaca, L. Camarero, G.H. Goudsmit, J. Kopáek, G. Lemcke, D.M. Livingstone, B. Müller, M. Rautio, M. Šiško, S. Sorvari, F. Šporka, O. Strunecký; M. Toro

Seasonal ecosystem variability in remote mountain lakes: implications for detecting climatic signals in sediment records

Resumen

Weather variation and climate fluctuations are the main sources of ecosystem variability in remote mountain lakes. Here we describe the main patterns of seasonal variability in the ecosystems of nine lakes in Europe, and discuss the implications for recording climatic features in their sediments. Despite the diversity in latitude and size, the lakes showed a number of common features. They were ice-covered between 5–9 months, and all but one were dimictic. This particular lake was long and shallow, and wind action episodically mixed the water column throughout the ice-free period. All lakes showed characteristic oxygen depletion during the ice-covered-period, which was greater in the most productive lakes. Two types of lakes were distinguished according to the number of production peaks during the ice-free season. Lakes with longer summer stratification tended to have two productive periods: one at the onset of stratification, and the other during the autumn overturn. Lakes with shorter stratification had a single peak during the ice-free period. All lakes presented deep chlorophyll maxima during summer stratification, and subsurface chlorophyll maxima beneath the ice. Phosphorus limitation was common to all lakes, since nitrogen compounds were significantly more abundant than the requirements for the primary production observed. The major chemical components present in the lakes showed a short but extreme dilution during thawing. Certain lake features may favour the recording of particular climatic fluctuations, for instance: lakes with two distinct productive periods, climatic fluctuations in spring or autumn (e.g., through chrysophycean cysts); lakes with higher oxygen consumption, climatic factors affecting the duration of the ice-cover (e.g., through low-oxygen tolerant chironomids); lakes with higher water retention time; changes in atmospheric deposition (e.g., through carbon or pigment burial); lakes with longer stratification, air temperature changes during summer and autumn (e.g., through all epilimnetic species).

El texto completo de este trabajo en Clic ¡


• 2002/ Manel Leira; Luisa Santos

An early Holocene short climatic event in the northwest Iberian Peninsula inferred from pollen and diatoms

Resumen

Pollen and diatom analyses have been carried out in a 490-cm long core collected from Laguna Lucenza (1420m 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 8350780 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.

El texto completo de este trabajo en Click ¡


• 2006/ Manuel Toro; Ignacio Granados; Santiago Robles; Carlos Montes

High mountain lakes of the Central Range (Iberian Peninsula): Regional limnology & environmental changes

Resumen

High mountain lake ecosystems in the Iberian Peninsula, being more than 1700 water bodies, are represented mainly by small or medium size lakes (75 % with a surface less than 0.5 Ha.). The knowledge of their regional limnology in Spain is yet uneven and insufficient, as well as their ecological status and sensitivity to human activity impacts. This work describes the major limnological characteristics and functioning of high mountain lakes in the Spanish Central Range, and their relationships with regional environmental variables and existing human pressures. Some hydrological processes (turnover rate), thermal properties (ice-cover dynamics) or hydrochemical parameters (conductivity) are discussed in more detail in those lakes with long term monitoring data. The composition of planktonic and benthic communities responds to both human pressures and biogeographical or environmental aspects. The effects produced by tourism, cattle, lake damming, wastewater inflow, watershed erosion, introduction of the brook trout, or environmental warming, are studied in some lakes. Implemented management and restoration measures to reduce environmental impacts are described and evaluated.

El texto completo de este trabajo en Clic ¡


• 2010/ Sven Björk

Chapter 2 The Evolution of Lakes and Wetlands

Resumen

When dealing with lake restoration, we should bear in mind that inland water ecosystems are not static units but subject to continuous evolution. Palaeolimnological studies have helped us to understand the development of lakes and their catchments. In particular, the development of northern European lakes has been studied very thoroughly. It has been revealed that the initially high productivity of lakes (shown by sediment growth rate) was due to the leaching of nutrients from the nutrient-rich moraine after the last deglaciation. With time, however, lake productivity dropped as the supply of nutrients from the catchment area diminished. This reduction depended partly on the decreased leaching and partly on the development of terrestrial vegetation as it accumulated and recycled nutrients. In southern Sweden, the current sediment growth rate is about 0.2 mm per year in more-orless- intact, shallow oligotrophic lakes, and about 0.5–1.0 mm per year in shallow eutrophic lakes. If a lake becomes polluted by the discharge of nutrient-rich sewage, the sediment growth rate can increase to about 10 mm per year. The ageing of lakes, and their potential terrestrialisation, depends on the balance between production and decomposition of organic matter. In northern latitudes, the break-down of organic matter in cold and oxygen-free sediment and peat is much slower than in warmer waters in the south where mineralisation processes take place at higher rates and over a longer period of the year. It is therefore much harder to prevent lakes in the north from being terrestrialised.

M. Eiseltová (ed.), Restoration of Lakes, Streams, Floodplains, and Bogs in Europe: Principles and Case Studies, Wetlands: Ecology, Conservation and Management 3, DOI 10.1007/978-90-481-9265-6_2, © Springer Science+Business Media B.V. 2010

El texto completo de este trabajo en Clic ¡


• 2011/ C. L. Faithfull; A. Wenzel, T. Vrede;  A.K. Bergström

Testing the light : nutrient hypothesis in an oligotrophic boreal lake

Resumen

Anthropogenic changes in the nitrogen (N), phosphorus (P), and carbon (C) cycles have altered nutrient concentrations and the light climate in freshwaters globally. These factors affect phytoplankton (PPr) and bacterial production (BP), which constitute the basal energy resource for higher trophic levels in the pelagic zone of lakes. The light : nutrient hypothesis (LNH) predicts that although basal production decreases at low light, seston C: nutrient ratios also decrease, thus increasing food quality for crustacean zooplankton and potentially offsetting the negative effects of reduced food availability. We tested the LNH in an oligotrophic boreal lake by manipulating N, P, C and reducing light, and measuring PPr, BP, seston C: nutrient ratios and zooplankton biomass in 32 mesocosms. Low light strongly reduced zooplankton biomass in contrast to LNH predictions. PPr did not decrease with low light as predicted by the LNH, however, the phytoplankton community shifted towards low light adapted, but potentially less edible phytoplankton species, such as colony forming Dinobryon (Chrysophyta) and gymnoid (Dinoflagellata) taxa, which were negatively correlated with zooplankton biomass. Seston C: nutrient ratios did not decrease with reduced light, possibly due to the high abundance of mixotrophic phytoplankton across treatments. BP decreased with low light and correlations between BP, bacterial biomass, ciliates and zooplankton suggest that bacteria may be coupled with zooplankton biomass. Thus, the LNH was inadequate when predicting changes in crustacean zooplankton biomass in this typical oligotrophic boreal system, where Daphnia is rare and mixotrophic phytoplankton are abundant. Instead, alternative explanations, such as changes in phytoplankton edibility and energy transferred through the microbial food chain may need investigation to explain reduced zooplankton biomass in low light treatments.

El texto completo de este trabajo en Clic ¡

 


• 2011/ Lourdes López-Merino; Ana Moreno; Manel Leira, Javier Sigró; Penélope González-Sampériz; Blas L. Valero-Garcés; José Antonio López-Sáenz; Manola Brunet; Enric Aguilar

Two hundred years of environmental change in Picos de Europa National Park inferred from sediments of Lago Enol, northern Iberia

Resumen

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. Longterm 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.

El texto completo de este trabajo en Clic ¡


• 2012/ Brian Moss

Cogs in the endless machine: Lakes, climate change and nutrient cycles: A review

Resumen

Lakes have, rather grandly, been described as sentinels, integrators and regulators of climate change (Williamson et al., Limnol. Oceanogr. 2009; 54: 2273–82). Lakes are also part of the continuum of the water cycle, cogs in a machine that processes water and elements dissolved and suspended in myriad forms. Assessing the changes in the functioning of the cogs and the machine with respect to these substances as climate changes is clearly important, but difficult. Many other human-induced influences, not least eutrophication, that impact on catchment areas and consequently on lakes, have generally complicated the recording of recent change in sediment records and modern sets of data. The least confounded evidence comes from remote lakes in mountain and polar regions and suggests effects of warming that include mobilisation of ions and increased amounts of phosphorus.
A cottage industry has arisen in deduction and prediction of the future effects of climate change on lakes, but the results are very general and precision is marred not only by confounding influences but by the complexity of the lake system and the infinite variety of possible future scenarios. A common conclusion, however, is that warming will increase the intensity of symptoms of eutrophication. Direct experimentation, though expensive and still unusual and confined to shallow lake and wetland systems is perhaps the most reliable approach. Results suggest increased symptoms of eutrophication, and changes in ecosystem structure, but in some respects are different from those deduced from comparisons along latitudinal gradients or by inference from knowledge of lake behaviour. Experiments have shown marked increases in community respiration compared with gross photosynthesis in mesocosm systems and it may be that the most significant churnings of these cogs in the earth–air–water machine will be in their influence on the carbon cycle, with possibly large positive feedback effects on warming.

El texto completo de este trabajo en Clic ¡


• 2015/ G. Sánchez-López, A. Hernández, S. Pla-Rabes, M. Toro, I. Granados, J. Sigró, R. M. Trigo, M. J. Rubio-Inglés, L. Camarero, B. Valero-Garcés; S. Giralt

Cogs in the endless machine: Lakes, climate change and nutrient cycles: A review

Resumen

Three Spanish alpine lakes located in the Central Range (Peñalara Lake and Cimera Lake) and the Pyrenees (Redon Lake) are selected to understand the effects of the North Atlantic Oscillation (NAO) on ice phenology. A conceptual lake model is formulated based on Pearson’s correlation coefficients obtained between season-scale time series of the NAO index, climatic data (i.e., precipitation, air temperature and snow data) and limnological variables (ice phenology records). The results suggest that the effects of the NAO are only reflected in the thawing process via the air temperature and the insulating effect of snow accumulation on the ice cover. An altitude component is evident in our survey because the effects of the NAO on Peñalara Lake (the lowest altitude studied lake) are restricted to winter, whereas for Redon Lake (the highest altitude studied lake), the effects extend into spring. A latitudinal component is also clear when comparing our data with northern European lakes. Snow accumulation primarily depends on the air temperature at high latitudes, and both precipitation and the air temperature control snow accumulation at lower latitudes. Consequently, in northern Europe, the NAO signal is primarily reflected in lake ice phenology via the air temperature, whereas our results confirm that in southern Europe, the strong dependence of precipitation on the NAO determines the importance of the NAO for lake ice cover.

El texto completo de este trabajo en Clic ¡


 B/ ESTADO TRÓFICO DE LOS LAGOS

• 1982/ OCDE

Eutrophication of waters monitoring. Assessment and control.

Resumen

Idiosyncrasies, erroneous assumptions and gaps are still hampering lake evaluations, despite several decades of defining the trophic state of lakes. I reevaluated nutrient and algal biomass limits that group lakes into oligo-, meso-, eu- and hyper eutrophic lakes at transition concentrations of 10, 30 and 100 μg · L−1 average total phosphorus concentration of the summer epilimnion. I investigated the direct and indirect effects of general lake characteristics like morphometry and geochemistry (water hardness and color) on lake trophic state and formulated models to deal with their significant influences. Nutrient and biomass concentrations as well as quantitative measures of anoxia were used to determine the trophic state. I demonstrated that the number of coldwater fish species may be used to classify the lower trophic levels in geographically constraint areas. Limits and models were established with data from well-studied lakes and verified with literature data from worldwide lakes. Trophic state limits were set for oligo-, meso-, eu- and hypereutrophic lakes at transition concentrations for average total nitrogen of 350, 650 and 1,200 μg·L−1, for summer chlorophyll of 3.5, 9 and 25 μg·L−1, for summer transparency (Secchi disk depth) of 4, 2 and 1 m, for die anoxic factor of 20, 40 and 60 d·summer−1, and for the areal oxygen depletion rate of 250, 400 and 550 mg·m−2·d−1.

El texto completo de este trabajo en Clic ¡


• 1996/ Gertud K. Nürnberg

Trophic state of clear and colored, soft-and hardwater lakes with special consideration of nutrients, anoxia, phytoplankton and fish

Resumen

Idiosyncrasies, erroneous assumptions and gaps are still hampering lake evaluations, despite several decades of defining the trophic state of lakes. I reevaluated nutrient and algal biomass limits that group lakes into oligo-, meso-, eu- and hyper eutrophic lakes at transition concentrations of 10, 30 and 100 μg · L−1 average total phosphorus concentration of the summer epilimnion. I investigated the direct and indirect effects of general lake characteristics like morphometry and geochemistry (water hardness and color) on lake trophic state and formulated models to deal with their significant influences. Nutrient and biomass concentrations as well as quantitative measures of anoxia were used to determine the trophic state. I demonstrated that the number of coldwater fish species may be used to classify the lower trophic levels in geographically constraint areas. Limits and models were established with data from well-studied lakes and verified with literature data from worldwide lakes. Trophic state limits were set for oligo-, meso-, eu- and hypereutrophic lakes at transition concentrations for average total nitrogen of 350, 650 and 1,200 μg·L−1, for summer chlorophyll of 3.5, 9 and 25 μg·L−1, for summer transparency (Secchi disk depth) of 4, 2 and 1 m, for die anoxic factor of 20, 40 and 60 d·summer−1, and for the areal oxygen depletion rate of 250, 400 and 550 mg·m−2·d−1.

El texto completo de este trabajo en Clic ¡


• 1997/ Howard P. Gross, Wayne A. Wurtsbaugh, Chris Luecke y Phaedra Budy

Fertilization of an oligotrophic lake with a deep chlorophyll maximum: predicting the effect on primary productivity

Resumen

We investigated how epilimnetic fertilization would affect chlorophyll levels and light penetration of oligotrophic sockeye salmon (Oncorhynchus nerka) lakes and how the resulting self-shading would affect primary production of the prominent deep chlorophyll maxima (DCM) of the lakes. Epilimnetic nutrient additions to large mesocosms (330 m3) in Redfish Lake, Idaho, increased levels of primary productivity and chlorophyll a but decreased Secchi depths and light available in the metalimnion and hypolimnion. Redfish Lake and other Sawtooth Valley (Idaho) lakes had DCM in which the mean chlorophyll a peaks were 240–-1000% of mean epilimnetic chlorophyll a concentrations. The DCM existed at low light levels and accounted for 36-–72% of the lakes’ primary production. Simulations using photosynthesis–irradiance (P–I) curves demonstrated that fertilization would increase predicted water column primary production by 75–-101%. Most of this increase occurred in the epilimnion, with only a slight decrease occurring in the DCM as the result of increased shading.


El texto completo de este trabajo en Clic ¡


• 2006/ Manel Leira, Phil Jordan, David Taylor, Catherine Dalton, Helen Bennion, Neil Rose y Kenneth Irvine

Assessing the ecological status of candidate reference lakes in Ireland using palaeolimnology

Resumen

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 μ g 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 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 (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.

El texto completo de este trabajo en Clic ¡


• 2009/ Manel Leira; G. Chen; C. Dalton; K. Irvine; D. Taylor

Patterns in freshwater diatom taxonomic distinctness along an eutrophication gradient

Resumen

Three sediment cores have been studied from the Morskie Oko (MOK), Przedni Staw Polski (PSP), and Czarny Staw Gąsienicowy (CSG) lakes to examine the recent environmental history of the alpine lakes located in the Polish part of the Tatra Mountains (Carpathians). Changes in the total phosphorus concentration in the water over the past centuries were reconstructed based on diatom data (DI-TP), assuming that diatoms are good indicators of productivity in lakes. The results of the analysis showed significant alterations in the trophic status of the studied lakes over the past 50 years. Clear changes from oligotrophy to mesotrophy occurred in the lakes located close to year-round mountain huts on the shores of MOK and PSP. In contrast, DI-TP decreased in CSG, and the only symptom of higher productivity in the lake was an increase in total organic carbon.

El texto completo de este trabajo en Clic ¡


• 2014/ Elwira Sienkiewicz y Michał Gąsiorowski

Changes in the Trophic Status of Three Mountain Lakes – Natural or Anthropogenic Process?

Resumen

Three sediment cores have been studied from the Morskie Oko (MOK), Przedni Staw Polski (PSP), and Czarny Staw Gąsienicowy (CSG) lakes to examine the recent environmental history of the alpine lakes located in the Polish part of the Tatra Mountains (Carpathians). Changes in the total phosphorus concentration in the water over the past centuries were reconstructed based on diatom data (DI-TP), assuming that diatoms are good indicators of productivity in lakes. The results of the analysis showed significant alterations in the trophic status of the studied lakes over the past 50 years. Clear changes from oligotrophy to mesotrophy occurred in the lakes located close to year-round mountain huts on the shores of MOK and PSP. In contrast, DI-TP decreased in CSG, and the only symptom of higher productivity in the lake was an increase in total organic carbon.

El texto completo de este trabajo en Clic ¡


• 2016/ Carmen López Rodríguez; Manel Leira; Ramón Valle; Gabriel Moyá Niell

El fitoplancton como indicador de calidad de masas de agua muy modificadas en la DMA. El lago artificial de As Pontes (A Coruña. España)

Resumen

Se recogen los primeros resultados del estudio de la composición y abundancia del fitoplancton del lago artificial de As Pontes, desde 2009 hasta 2014, destinados a la evaluación del potencial ecológico de las masas de aguas continentales en el marco de la implantación de la Directiva Marco Europea del Agua (DMA) en Galicia.

Se han identificado un total de 125 taxa: 22 Cyanophyta, 47 Heterokontophyta de las cuales 42 son Bacillariophyceae, 4 Chrysophyceae y 1 Xantophyceae, 6 Dinophyta, 2 Cryptophyta, 4 Euglenophyta y 44 Chlorophyta. Ninguna de ellas se reconoce como tóxica, aunque se ha detectado una gran concentración de cistes que asociamos a la crisofícea Mallomonas sp. a finales de agosto de 2013.

El estado trófico actual del lago se corresponde con una situación de oligotrofía, produciéndose una disminución de la biomasa del fitoplancton y de los factores de producción a medida que se avanzaba en los muestreos.

A partir de la composición cualitativa y cuantitativa del fitoplancton y de las variables que definen su estado trófico, podemos concluir que el lago se encuentra en buenas condiciones ecológicas, de acuerdo a los criterios de la DMA.

El texto completo de este trabajo en Clic ¡


• 2016/ Eglantine Chappuis; Enric Ballesteros; Esperança Gracia

Temporary emersion enhances amphibious Isoetes production

Resumen

La emersión temporal aumenta la producción de los Isoetes anfibios.

En este trabajo se ha medido la producción primaria anual de dos isoetes anfibios en dos sistemas temporales diferentes en el NE de España: Isoetes echinospora, en una charca semipermanente de alta montaña y Isoetes delilei, en una charca temporal mediterránea. La producción primaria de las hojas mostró una distribución unimodal con un máximo en julio para I. echinospora y en abril para I. delilei. La población de I. echinospora produjo 38.7 g PS m–2y–1 (15.5 g C m–2y–1) en hojas el año de completa inmersión, pero la producción aumentó a 49.3 g PS m–2y–1 (19.7 g C m–2y–1) el año en el que las plantas estuvieron emergidas durante dos meses (incremento del 27.4%). La producción de hojas de I. delilei también aumentó significativamente después de la emersión (la charca se seca anualmente) y alcanzó una producción anual de 676.7 g PS m–2y–1 (265.3 g C m–2y–1). La producción primaria de hojas de I. delilei fue 15 veces mayor que la de I. echinospora y muy superior a los rangos descritos para los isoétidos submergidos. El incremento de producción de I. echinospora en condiciones de emersión temporal junto con la inusual y elevada producción de I. delilei en una charca temporal, sugieren que la emersión temporal aumenta la producción primaria en los isoetes anfibios.

El texto completo de este trabajo en Clic ¡


• 2016/ Sandra Poikane , Martyn Kelly , Marco Cantonati

Benthic algal assessment of ecological status in European lakes and rivers: Challenges and opportunities

Resumen

This opinion paper introduces a special series of articles dedicated to freshwater benthic algae and their use in assessment and monitoring. This special series was inspired by talks presented at the 9th International Congress on the Use of Algae for Monitoring Rivers and Comparable Habitats (Trento, Italy, 2015), the latest of a series of meetings started in 1991. In this paper, we will first provide a brief overview of phytobenthos methods in Europe. Then, we will turn towards the ‘dark side’ of phytobenthos and describe four particular problems for phytobenthos assessment in the European Union: (1) over-reliance on a single group of algae (mostly diatoms) to the exclusion of other groups; (2) relatively low adoption of benthic algae for ecological assessments in lakes; (3) absence of measures of phytobenthos abundance; (4) approaches used to define boundaries between ecological classes. Following this, we evaluate the strengths and limitations of current phytobenthos assessment methods against 12 criteria for method evaluation addressing four areas: ecological rationale, performance, feasibility of implementation, and use in communication and management. Using these criteria, we identify and discuss three general challenges for those developing new methods for phytobenthos-based assessment: a weak ecological rationale and insufficient consideration of the role of phytobenthos as a diagnostic tool and for communicating ecosystem health beyond a narrow group of specialists. The papers in the special series allow a comparison with the situation and approaches in the USA, present new methods for the assessment of ecological status and acidification, provide tools for an improved management of headwaters and petrifying springs, discuss the utility of phytobenthos for lake assessments, and test the utility of functional measures (such as biofilm phosphorus uptake capacity, PUC).


El texto completo de este trabajo en Clic ¡


 C/ PRESIONES ANTRÓPICAS

• 2007/ Christian Bigler, Lucien von Gunten, André F. Lotter, Sonja Hausmann, Alex Blass, Christian Ohlendorf; Michael Sturm

Quantifying human-induced eutrophication in Swiss mountain lakes since AD 1800 using diatoms

Resumen

Sedimentary diatom assemblages from three lakes in the southeastern Swiss Alps were analysed at high temporal resolution since AD 1800. Altered land-use patterns, increasing population and exploitation through tourism are clearly reflected in annually laminated sediments of Lej da San Murezzan (Lake St Moritz) and Lej da Silvaplauna (Lake Silvaplana). Diatom assemblages originally dominated by Cyclotella taxa are replaced by taxa indicating higher total phosphorus (TP) concentrations, such as Asterionella formosa, Fragilaria crotonensis and Stephanodiscus parvus. In Lej da la Tscheppa, located well above the treeline in a catchment that was hardly exposed to human impact, Cyclotella comensis prevails throughout the entire sediment sequence. Quantitative estimates of past TP concentrations were inferred using a newly developed regional diatom-TP inference model based on 119 modern samples. In Lej da la Tscheppa diatoms imply stable, low TP concentrations (~10 μg/l), which can be considered as natural background concentration. Elevated TP levels are inferred for Lej da San Murezzan (max. 60 μg/l) since AD 1910 and for Lej da Silvaplauna (max. 40 μg/l) since AD 1950, corroborated by changes in sedimentary biogenic silica concentration and organic carbon content. Since ~AD 1970 improved waste water management led to a considerable reduction in TP loading in Lej da Silvaplauna and Lej da San Murezzan.

El texto completo de este trabajo en Clic ¡


 D/ REDES TRÓFICA Y RESPUESTAS DE LAS COMUNIDADES

• 2009/ Iwona Jasser, Iwona Kostrzewksa-Slakowska, Jolanta Ejsmont-Karabin, Krystyna Kalinowska; Teresa Eeglenska

Autotrophic versus heterotrophic production and components of trophic chain in humic lakes: the role of microbial communities

Resumen

The ratio and rates of autotrophic and heterotrophic pathways of organic matter cycles constitute the basic functions of aquatic ecosystem and humic lakes are unique in this respect. The autotrophic and heterotrophic production, the food web structure and the role of microbial communities in three humic lakes (area 1.3–9.2 ha) were studied. The abundance of bacteria, autotrophic picoplankton (APP), nanoflagellates (NF), ciliates, phytoplankton, rotifer and crustacean zooplankton as well as chlorophyll a and primary (14C method) and bacterial production (3H–thymidine method) were measured. The lakes differed in humic matter content, water colour, pH and hydrology. Two lakes were acidic (pH 5.2–4.9) with different dissolved organic carbon (DOC) content: oligo/mesohumic – 7.1 mg C L–1 , and polyhumic lake – 21 mg C L–1. Due to draining of surrounding meadows, the third lake – formerly humic – experienced changes in the hydrological regime together with liming and fertilisation. Despite low DOC, the oligohumic lake resembled a low productive, typically humic, acidic lake with dominating bacterial production. The lake was characterised by the highest crustaceans biomass and very variable chlorophyll a concentration (between 1.5 and 71 mg Chl a m–3). The polyhumic lake had the highest mean and maximal chlorophyll a content but the lowest crustacean biomass, and functioned more like a eutrophic lake. The formerly humic lake had lost probably most of its humic features and experienced a eutrophication process that resulted in a food web structure typical of a shallow eutrophic pond-like environment. The mean chlorophyll a concentration there was at the same level as in an oligohumic lake, but the variability was much lower. This lake can be considered as an example of the posthumic lakes abundant in the managed wetland regions.

Microbial communities were numerous in both humic lakes, with bacteria prevailing in microbial biomass in the oligo-humic and APP in the polyhumic lake. In the former humic lake the microbial communities, especially APP, seemed to play a lesser role, while the whole planktonic food web was more balanced. The results demonstrated that uncontrolled drainage and reclamation of wetland can be detrimental to biodiversity of small, mid-forest lakes. Although biodiversity in almost all plankton groups was the highest in the posthumic lake but this lake lacked rare species typical of humic acidic lakes like: Gonyostomum semen, Dictyosphaerium sphagnale from phytoplankton or Holopedium gibberum from crustacean zooplankton. Instead eurytopic species, common in eutrophic waters, were present.

El texto completo de este trabajo en Clic ¡


• 2015/ K. Sparber, C. Dalton, E. de Eyto, E. Jennings, D. Lenihan; F. Cassina

Contrasting pelagic plankton in temperate Irish lakes: the relative contribution of heterotrophic, mixotrophic, and autotrophic components, and the effects of extreme rainfall events

Resumen

The mobilisation of energy from allocthonous carbon by heterotrophic bacterioplankton can be proportionally more important than autotrophic production in humic lakes. Moreover, increasing levels of dissolved organic carbon (DOC) in many aquatic systems linked to increases in precipitation, which in turn may be related to changing climate, mean that this heterotrophic component of the food web may play an increasing role in the overall transfer and production of energy, particularly within peatland catchments. While such catchments are common in the temperate northwest Atlantic regions of Europe, studies describing the seasonal dynamics of the heterotrophic, mixotrophic, and autotrophic components of their aquatic food webs are rare. In this study, the biomass of these pelagic components was enumerated
over 1 year in 2 oligotrophic lakes, both situated in peatland catchments in the west of Ireland but with contrasting DOC concentrations. Bacterial biomass dominated the pelagic food web of the more humic lake, Lough Feeagh, while autotrophic phytoplankton biomass was greatest in the clearwater lake, Lough Guitane. The biomass of potentially mixotrophic flagellates was also slightly larger in the Lough Guitane, while phagotrophic ciliate biomass was comparable between the 2 lakes. An extreme precipitation event led to a significant increase in bacterial biomass while simultaneously depressing autotrophic production for several months in the humic lake. Extreme precipitation in the clearwater lake also depressed autotrophic production but did not give rise to significant increases in bacterial biomass.
This quantification of autotrophic, mixotrophic, and heterotrophic components provides a vital first step in understanding how pelagic communities contribute to net ecosystem productivity, and thus how Irish peatland lakes may be affected by projected climate changes.

El texto completo de este trabajo en Clic ¡


• 2012/ Jan Karlsson, Martin Berggren, Jenny Ask, Pär Byström, Anders Jonsson, Hjalmar Laudon; Mats Jansson

Terrestrial organic matter support of lake food webs: Evidence from lake metabolism and stable hydrogen isotopes of consumers

Resumen

We quantified the utilization of terrestrial organic matter (OM) in the food web of a humic lake by analyzing the metabolism and the consumers’ stable isotopic (C, H, N) composition in benthic and pelagic habitats. Terrestrial OM inputs (3 g C m22 d21) to the lake greatly exceeded autochthonous OM production (3 mg C m22 d21) in the lake. Heterotrophic bacterial growth (19 mg C m22 d21) and community respiration (115 mg C m22 d21) were high relative to algal photosynthesis and were predominantly (. 85%) supported by terrestrial OM in both habitats. Consequently, terrestrial OM fueled most (85%) of the total production at the base of the lake’s food web (i.e., the sum of primary and bacterial production). Despite the uncertainties of quantitatively estimating resource use based on stable isotopes, terrestrial OM clearly also supported around half the zooplankton (47%), macrozoobenthos (63%), and fish (57%) biomass. These results indicate that, although rates of terrestrial OM inputs were around three orders of magnitude greater than that of autochthonous OM production, the use of the two resources by higher trophic levels was roughly equal. The disproportionally low reliance on terrestrial OM at higher trophic levels, compared with its high rates of input and high support of basic biomass production in the lake, suggests that autochthonous resources could not be completely replaced by terrestrial resources and indicates an upper limit to terrestrial support of lake food webs.

El texto completo de este trabajo en Clic ¡


 E/ COMPOSICIÓN QUÍMICA Y DINÁMICA GEOQUÍMICA

• 1994/ Pessner R.; Jordi Catalan

Chemical composition of lakes in crystalline basins: a combination of atmospheric deposition, geologic background, biological activity and human action

Resumen

Non-sedimentary basins are characterized by the lack of easily soluble minerals and, as a consequence, by holding soft-waters. Regional limnology has shown that, besides biogeographical reasons, alkalinity is one of the main factors determining the distribution of organisms. In soft-water areas, slight changes in mineral content strongly affect the composition of aquatic communities. Anthropogenic impacts are predominant in eutrophied marine and freshwater environments and the chemical composition of many soft-water lakes in the northern hemisphere is largely influenced by acids emitted from the burning of fossil fuels. Eutrophication and acidification have some effects in common, such as changes in species composition and the extinction of sensitive organisms. Nitrogen compounds have become an issue of research in the eutrophication of marine environments, and nitric acid in combination with NH4+ at present exceeds the importance of sulphuric acid in deposition chemistry.

El texto completo de este trabajo en Clic ¡


• 1951/ Stommel H.

Streaks on natural water surfaces

Resumen

I was very much interested to see Mr. A. K. Totton’s photographs of markings on the water because recently I have been trying to collect as much information about such phenomena as possible. I enclose two photographs which may interest the readers of Weather; one, showing venous streaks on the surface of the Great Salt Lake of Utah, was kindly given to me by Prof. A. J. Eardley of the University of Utah; the other, a picture of the Banana River in Florida, shows a remarkable development of “parallel streaks”. Most natural bodies of water have a streaky appearance which results from a natural process, although artificial streaks are also frequently observed. There has been quite a difference of opinion in the literature as to the nature of the process which produces streaks. I am personally inclined to admit that under certain circumstances any one of the processes suggested may account for them ; to attribute all streaks to the same mechanism would be a great mistake. I should like, therefore, to review briefly what little material there is in the literature about these streaks on the surface of natural bodies of water.

El texto completo de este trabajo en Clic ¡


• 2016/ F. Stefani, F. Salerno, D. Copetti, D. Rabuffetti, L. Guidetti, G. Torri, A. Naggi, M. Iacomini, G. Morabito & L. Guzzella

Endogenous origin of foams in lakes: a long-term analysis for Lake Maggiore (northern Italy)

Resumen

The formation of foams on lakes is a complex phenomenon whose origin is often hardly identifiable. Recently (2007, 2008, and 2010) foam episodes started to occur in Lake Maggiore, northern Italy. The present work aimed to verify the hypothesis of an endogenous-natural origin of these foams, driven by trophic or climatic changes. To this purpose, a long-term (2000–2013) analysis of phytoplankton biovolumes, meteorological, and hydrological data has been performed together with the chemical characterization of foams. Foams resulted of endogenous origin and likely related to phytoplankton biomass degradation. Data analysis highlighted atypical warm temperature and residual lake stratification in winter in two of the three years of foam events, coupled with exceptional Bacyllariophyceae blooms in spring. Tabellaria flocculosa mostly contributed in terms of biomass in 2007 and 2008, but not in 2010; thus overall algal biomass seemed a better predictor of the risk of foam formation. Foam events occurred from July to December, driven by atypically windy conditions, and congruently with the time needed to degrade biomass into surface-active compounds. A co-occurrence of different factors resulted essential to generate foams, and climate changes likely contribute to enhance their occurrence in Lake Maggiore.

El texto completo de este trabajo en Clic ¡


• 2011/ K. Schilling & M. Zessner

Foam in the aquatic environment

Resumen

Foams are ubiquitous in the environment, commonly seen as discoloured patches on streams, rivers, lakes and sea water. They often are assumed to be anthropogenic in origin as they are aesthetically unpleasant, yet they frequently appear in pristine environments indicating a natural origin. In contrast to “hidden” chemical pollution, e.g. heavy metals, pesticides etc. the visibility of foam alarms the public. To derive more information on foam in freshwaters and marine ecosystems, a literature review was performed. Alongside with some basic considerations on the formation of foam, on methods to measure foam formation and on the legal aspects of foam on surface waters, the ecological importance of foam in the aquatic environment is discussed in this paper.

El texto completo de este trabajo en Clic ¡

 


 F/ LAGOS COMO SENSORES AMBIENTALES EN EL HOLOCENO

• 1993/ Toro M.; Flower. R.J.; Rose N.L.; Stevenson A.C.

The sedimentary record of the recent history in a high mountain lake in central Spain 

El texto completo de este trabajo en Clic ¡


• 2009/ Jordi Catalan; Sergi Pla; Joan García; Lluís Camarero

Climate and CO2 saturation in an alpine lake throughout the Holocene

Resumen

This study shows that diatom sediment records can be used to investigate the long-term inorganic carbon dynamics in oligotrophic and poorly acid-buffered lakes. Using a training set of 115 high-mountain lakes in the Pyrenees, we found that both alkalinity and potential hydrogen (pH) independently explained some of the variability in diatom assemblages. Transfer functions for both variables were developed and applied to a Holocene record from Lake Redon and CO2 changes calculated. CO2 saturation broadly followed alkalinity, which in turn was related to summer and autumn air-temperature fluctuations. In general, warmer climate during the ice-free period led to higher supersaturation, due to increased alkalinity, which facilitated retention of CO2 from respiration, and decreased primary production (assessed by diatom fluxes). Only during the early Holocene, there were periods of extreme undersaturation, corresponding to cold periods of low alkalinity (<20 microequivalents per liter [µeq L−1]), and suggesting carbon limitation of primary production. The winter and spring climate, which determines the ice cover duration, appears to be relevant for CO2 saturation only during periods when the organic-matter content of the sediments was low (<22%). Longer periods of ice cover led to lower lake CO2 saturation, suggesting that the ice cover influence on internal nutrient loading may regulate lake productivity fluctuations under low allocthonous nutrient and organic-matter inputs. Alkalinity ~20 µeq L−1 and sediment organic matter ~22% appear as critical thresholds in the way lake CO2 levels respond to climate fluctuations.

El texto completo de este trabajo en Clic ¡


• 2009/ Craig E. Williamson; Jasmine E. Saros; Warwick F. Vincent; John P. Smol

Lakes and reservoirs as sentinels, integrators, and regulators of climate change

Resumen

Climate change is generating complex responses in both natural and human ecosystems that vary in their geographic distribution, magnitude, and timing across the global landscape. One of the major issues that scientists and policy makers now confront is how to assess such massive changes over multiple scales of space and time.
Lakes and reservoirs comprise a geographically distributed network of the lowest points in the surrounding landscape that make them important sentinels of climate change. Their physical, chemical, and biological responses to climate provide a variety of information-rich signals. Their sediments archive and integrate these signals, enabling paleolimnologists to document changes over years to millennia. Lakes are also hot spots of carbon cycling in the landscape and as such are important regulators of climate change, processing terrestrial and atmospheric as well as aquatic carbon. We provide an overview of this concept of lakes and reservoirs as sentinels, integrators, and regulators of climate change, as well as of the need for scaling and modeling these responses in the context of global climate change. We conclude by providing a brief look to the future and the creation of globally networked sensors in lakes and reservoirs around the world.

El texto completo de este trabajo en Clic ¡


• 2007/P. Rosén; D. Hammarlund

Effects of climate, fire and vegetation development on Holocene changes in total organic carbon concentration in three boreal forest lakes in northern Sweden

Resumen

Near infrared spectroscopy (NIRS), diatoms, pollen, charcoal, loss-on-ignition (LOI), and nutrient elements in lake sediments were used to assess important factors controlling Holocene hanges in the total organic carbon (TOC) concentration, pCO2, color and pH of lake water in three boreal forest lakes in northern Sweden. The results suggest that mire formation, fire frequency and humidity are the most important forcing factors on millennial timescales. Mires produce humic acids that become available to the lakes, whereas fires may reduce the pool of carbon in the catchments, and humidity controls the transportation of allochthonous carbon into the lakes. Vegetation development and temperature as sole factors are of minor importance
for the TOC concentrations in these lakes on a millennial timescale. Two of the sites indicate that liming and possibly fish introduction and rotenone treatment in recent time has led to increased TOC, color and pH in the lake water, and changed the diatom community composition to an assemblage that has never been present before. Given the predicted climate change scenario that suggests a more humid climate, expanding mires and less frequent fires, our paleolimnological data suggest that TOC concentrations can be expected to increase in boreal forest lakes in the future. Since supersaturation and emission of CO2 from lakes is correlated to the TOC concentration of lake water, higher TOC concentrations may lead to increased emission of CO2 from lakes to the atmosphere.

El texto completo de este trabajo en Clic ¡


• 2008 / Manuel Toro; Antonio Camacho; Eugenio Rico; Carlos Rochera; David Velázquez; José Antonio Domínguez; Antonio Quesada

Implicaciones del cambio climático en el funcionamiento de los ecosistemas antárticos: los lagos como centinelas de la variación ambiental

Resumen

Entre las Islas Shetland del Sur, en la Antártida marítima, se encuentra la Isla Livingston, en cuyo extremo oeste se localiza una de las zonas con mayor biodiversidad no marina de la Antártida, y una de las concentraciones más importantes de cuerpos de agua continentales en toda la Antártida: la Península de Byers. En la región de la Península Antártica se están detectando los mayores incrementos de temperatura del Planeta en las últimas décadas como consecuencia del calentamiento global (Sun y Hansen, 2003). Por estos motivos, el proyecto LIMNOPOLAR, con un marcado carácter multidisciplinar, estudia el funcionamiento de estos ecosistemas acuáticos y su posible papel como sensores del cambio climático. La investigación llevada a cabo en esta Zona de Especial Protección de la Antártida (ASPA nº 126) cubre aspectos relacionados con la limnología básica, la hidrología, los ciclos biogeoquímicos, la biodiversidad y sus redes tróficas, la meteorología, la paleoecología y la teledetección, entre otros. Los resultados previos que van obteniéndose en el estudio apuntan a una gran dependencia de todos los procesos ecológicos e interrelaciones entre la biota y el medio abiótico, respecto a variables climáticas como la temperatura y la precipitación. El objetivo final del proyecto es elaborar un modelo predictivo basado en los estudios actuales y en las reconstrucciones paleoecológicas del clima pasado, que permitiría estimar los posibles efectos del cambio climático y la respuesta de estos ecosistemas únicos en el Planeta.

El texto completo de este trabajo en Clic ¡