Spanish Lakes Research Articles

Presence of plastic particles in waterbirds faeces collected in Spanish lakes

Plastic intake by marine vertebrates has been widely reported, but information about its presence in continental waterfowl is scarce. Here we analyzed faeces of waterbirds species (European coot, Fulica atra, mallard, Anas platyrhynchos and shelduck, Tadorna tadorna) for plastic debris in five wetlands in Central Spain. We collected 89 faeces of shelduck distributed in four lakes, 43.8% of them presented plastic remnants. Sixty percent of 10 faeces of European coot and 45% of 40 faeces of mallard contained plastic debris. Plastic debris found was of two types, threads and fragments, and were identified as remnants of plastic objects used in agricultural fields surrounding the lakes. Differences in prevalence of plastic in faeces, number of plastic pieces per excrement and size of the plastic pieces were not statistically significant between waterfowl species. Thus, our results suggest that plastic may also be frequently ingested by waterfowl in continental waters, at least in our study area. Future studies should address this potential problem for waterbird conservation in other wetlands to evaluate the real impact of this pollutant on waterbirds living in inland water.

Modelling Primary Producers in Some Shallow Spanish Lakes

Increased nutrient loading is regarded as one of the major causes of a shift from macrophyte to phytoplankton dominance in shallow lakes. This work investigates the responses of phytoplankton and epiphyton biomass, macrophytes and algal species assemblages along a trophic gradient in some shallow Mediterranean lakes. A unimodal response of epiphyton biomass to increasing phosphorus levels was observed, while phytoplankton developed exponentially and submerged aquatic plant coverage decreased. At TP levels above 100 μg L−1 (~30 μg-P L−1 by element) phytoplankton began to dominate over the other primary producers and led the system to a turbid state, mainly dominated by cyanobacteria. This could be regarded as a critical threshold to avoid algal turbid states, especially for shallow Mediterranean lakes. Macrophyte typology was also important in modulating this response. On average, the unimodal maximum of epiphyton biomass was about 20 μg g−1 of macrophyte dry weight and hydrophytes had higher epiphytic biomass than helophytes. The coverage of submerged aquatic vegetation was not related to the epiphytic and phytoplanktonic biomass, but to the distribution of their species. Further studies on epiphyton-plant ecology are needed, especially for specific aquatic macrophyte conservation and lake management.

Empirical relationships for monitoring water quality of lakes and reservoirs through multispectral images

Remote sensing techniques can be used to estimate water quality variables such as chlorophyll\mbi a, total suspended particles, and water transparency. This paper describes empirical algorithms for the estimation of these variables using Landsat Thematic Mapper (TM) data. Ground data were taken from several Spanish lakes covering a variety of trophic statuses, ranging from oligotrophic to hypereutrophic. The studied lakes were the Albufera de Valencia and lakes and ponds of the Southeast Regional Park in Madrid. Empirical equations were obtained to estimate chlorophyll\mbi a from the ratio in reflectance values between bands 2 and 4 of TM ( R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> \mmb = 0.66, p\lt 0.001), transparency [Secchi disk (SD)] from reflectance in band 2 ( R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> \mmb = 0.80, pbf \lt 0.001), and total suspended particles from reflectance in band 4 ( R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> \mmb = 0.92, p\lt 0.001). The spectral equivalence between TM and the recent satellite Deimos-1 was also tested. By applying the proposed algorithms to this new sensor, the temporal resolution is improved by up to 3 days, which increases spatial resolution to 22 m. The algorithms were validated using three Deimos-1 scenes of the Albufera de Valencia together with ground measurements. Results of this validation showed root-mean-square errors (RMSEs) of 40\nbspmg·m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\mmb-3</sup> for Chl-\mbi a (data range: 32\mmb - 238\nbspmg·m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> ), 10\nbspmg·L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\mmb -1</sup> for total suspended solid (TSS) (data range: 25\mmb -89\nbspmg·L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\mmb -1</sup> ), and 0.10 m for SD (data range: 0.17-0.40 m). In any case, these results show the potential of Deimos-1 as a substitute of TM in water quality monitoring in small/medium water bodies, providing continuity to three decades of TM imagery.

Using Landsat image time series to study a small water body in Northern Spain

Ramsar Convention and EU Water Framework Directive are two international agreements focused on the conservation and achievement of good ecological and chemical status of wetlands. Wetlands are important ecosystems holding many plant and animal communities. Their environmental status can be characterised by the quality of their water bodies. Water quality can be assessed from biophysical parameters (such as Chlorophyll-a concentration ([Chla]), water surface temperature and transparency) in the deeper or lacustrine zone, or from bioindicators (as submerged aquatic vegetation) in the shallow or palustrine zone. This paper proves the use of Landsat time series to measure the evolution of water quality parameters and the environmental dynamics of a small water body (6.57 ha) in a Ramsar wetland (Arreo Lake in the North of Spain). Our results show that Landsat TM images can be used to describe periodic behaviours such as the water surface temperature or the phenologic state of the submerged vegetation (through normalized difference vegetation index, NDVI) and thus detect anomalous events. We also show how [Chla] and transparency can be measured in the lacustrine zone using Landsat TM images and an algorithm adjusted for mesotrophic Spanish lakes, and the resulting values vary in time in accordance with field measurements (although these were not synchronous with the images). The availability of this algorithm also highlights anomalies in the field data series that are found to be related with the concentration of suspended matter. All this potential of Landsat imagery to monitor small water bodies in wetlands can be used for hindcasting of past evolution of these wetlands (dating back to 1970s) and will be also useful in the future thanks to the Landsat continuity mission and the Operational Land Imager.

Diatom species composition and indices for determining the ecological status of coastal Mediterranean Spanish lakes

Diatom indices have been used and tested mainly for assessing the ecological status of rivers and deep lakes, but there are scarce studies that determine their effectiveness in shallow lakes and in coastal Mediterranean lakes. This study evaluates the validity of several common diatom indices (SPI, BDI, CEC and TDIL) for the determination of the ecological quality of three coastal lakes (Valencia, Spain) and presents descriptions and ecological data of the main diatom species recorded. Diatom samples were collected from phytobenthos, both from epiphyton of the dominant submerged macrophytes and the sediment. The ecological status of the systems was determined according to different physico-chemical variables and was compared with the results obtained from epiphytic diatom communities. The results showed discrepancies among diatom indices and also with the state determined by the environmental variables. The effectiveness of the indices depended on the number of species assessed for each index with respect to the total species recorded and the suitability of the weight assigned to each species. The results reveal the need to gather more information about the composition and ecology of the diatoms and microalgae characteristic of coastal Mediterranean standing waters. This work contributes to their better knowledge.

Effects of eutrophication and exotic crayfish on health status of two Spanish lakes: a joint application of ecological indicators

Lake Sentiz and Lake Chozas are two small water bodies in the Province of León (NW Spain). The former is mesotrophic and the latter went from oligotrophic to turbid in 1997, due to introduction of an invasive allochthonous crayfish Procambarus clarkii (Rodríguez et al., 2003, 2005; Marchi et al., 2011a,b). We set out to study health status of the two ecosystems by the joint use of different but correlated ecological indicators, supplementing the values obtained by monitoring campaigns. We examine three scenarios: (1) Lake Sentiz, (2) Lake Chozas before and (3) Lake Chozas after the biological invasion. We evaluate eco-exergy, emergy and eco-exergy–empower ratio, three holistic ecological indicators based on the thermodynamics of far-from-equilibrium systems. When structural changes take place in ecosystems it is recommended to apply holistic thermodynamic indicators as presented in Jørgensen et al. (2010a,b). We propose their joint application for a complete overview of the monetary value of natural capital, because they provide information added to statistical analysis and direct measurement. The aim is to determine which of these indicators best represents the effects of eutrophication and perturbations caused by alien species in the two freshwater systems. The eco-exergy–empower ratio gives the best results, since it clearly indicates lake efficiency in transforming direct and indirect solar energy inputs into organization. The eco-exergy (work capacity) results are used to estimate ecosystem services and quantify the economic value of lake natural capital. Calculation of ecosystem services on an eco-exergy basis provides good indications of monetary gains or losses possible in perturbed systems, including eutrophic or invaded ecosystems. This is not surprising, because work capacities include all possible services offered by ecosystems, not only the services actually used by humans. Eco-exergy and the eco-exergy–empower ratio can be guidelines for the calculation of ecosystem services, although they give only a partial indication of the environmental costs and benefits of a given level of information. The present results suggest political and economic considerations and solutions, and are a useful example for organisations involved in environmental management of pollution and biological invasions by exotic species.

Holocene environmental changes in the Gallocanta lacustrine basin, Iberian Range, NE Spain

The sedimentological and palynological study of the Gallocanta lake sediments, in the NE of Spain, has allowed the Holocene environmental evolution of this lacustrine basin to be established, and several changes in the hydrological balance to be interpreted. The chronology of the sequence is based on new radiocarbon datings and 210Pb radiometric techniques. Ten facies have been characterized, which have been grouped into five sedimentary units: two (Units A and B) are interpreted as deposited in alluvial areas, and three (Units C, D and E) in lacustrine environments. Moreover five pollen zones have been established for this succession. From the stratigraphic correlation of the cores extracted in this lake, three stages in the basin evolution have been interpreted. Stage 1 was characterized by a broad development of alluvial fans during the Fullglacial or Lateglacial times. The sediments of this stage are lacking in pollen as they were exposed for most of the time. Stage 2 started around 10 100 yr BP and is characterized by the establishment of a brackish lake linked to a decrease in alluvial supplies and a more positive water balance. The maximum lake level would have been reached around 8010 yr BP coinciding with the relatively moist period of the beginning of the Holocene recorded in some Spanish lakes, although this dating would not match that of other areas of the Iberian Peninsula, in which the maximum lake levels have been recorded around 6000 yr BP. A sharp decrease in the lacustrine level has been registered at 3405 yr BP, which may be correlated to a change to more arid conditions. Nevertheless, the lake level recovered later. Stage 3 was linked to the development of an ephemeral shallow lake. An age of AD 1840 yr has been calculated for this palaeogeographical change. The data obtained suggest that the main vegetation changes during stage 2 were more related to climate variability, whereas during stage 3 the anthropogenic impact became more significant.

Lipid geochemistry of lake sediments from semi-arid Spain: Relationships with source inputs and environmental factors

The lipid geochemistry of lake sediments can provide information on past environmental change. Detailed interpretation is, however, often hampered by a limited understanding of the provenance of many compounds and the multiple factors influencing their distributions in modern lake sediments. We have quantified the solvent extractable lipid compositions of modern surface sediments from fifty four Spanish lakes covering a range of hydrochemical (fresh to hypersaline) and hydrological (shallow ephemeral to deep permanent) conditions. Lipid compositions across the dataset are dominated by carboxylic acids (up to 86% total solvent extractable lipids), alkanols (up to 63%) and sterols (up to 58%), with smaller relative proportions of alkanes, alkenes, ketones (including long chain alkenones) and hopanols. Here we employ the distributions of these dominant compounds to explore relationships between lipid composition, source inputs and lake type. Source input is the major factor influencing the lipid composition, but there are also some indicators of early stages of lipid diagenesis in these surface sediments. Multivariate data analysis (non-metric multidimensional scaling ordination and cluster analysis) of normalised lipid concentrations shows a distinction between compounds originating primarily from algal, bacterial, macrophyte or terrestrial plant sources. This statistical technique enables sites to be grouped according to their dominant lipid compositional characteristics as well as enabling us to identify broad trends in groups of sites in terms of their environmental features (e.g. shallow or deep lakes). This modern training set study provides insight into patterns of contemporary lipid distributions and lipid source and site relationships across diverse lacustrine environments, which can then be useful in environmental monitoring and palaeoenvironmental studies using sediment cores.

On the occurrence and ecological features of deep chlorophyll maxima (DCM) in Spanish stratified lakes

Deep chlorophyll maxima (DCM) are absolute maxima of Chlorophyll-a concentration among the vertical profile that can be found in deep layers of stratified lakes. In this manuscript I review the principal mechanisms that have been argued to explain the formation of DCM, which include, among others, in situ growth of metalimnetic phototrophs, differential impact of grazing between the different lake strata, and passive sedimentation to the layers where water density and cell density are equalized. The occurrence of DCM in Spanish lakes, as well as the main ecology characteristics of the oxygenic phototrophs that form DCM in these lakes is also reported. Cyanobacteria, either filamentous or unicellular, and cryptophytes, are the main components of most DCM found in the reported Spanish lakes, although diatoms, chrysophytes, dinoflagellates, and chlorophytes also contribute to these chlorophyll maxima. These organisms cope with strong physical and chemical gradients, among which those of water density, light and inorganic nutrient availability, and sulphide concentrations appear to be the most determinant factors influencing planktonic community structure.

Cyclotella hispanica a new dimorphic centric diatom species (Bacillariophyceae)

Cyclotella hispanica Kiss, HEGEWALD et Acs is described as a new taxon from three Spanish lakes. It is characterized by two unusual morphotypes. One morphotype has a plain valve face and a fine striation seems to be close to C. gracilis NIKITEEVA et LIKHOSH-WAY. The other morphotype has three remarkable depressions and elevations on the valve face and a well-developed striation, therefore resembling C. tripartita HAKANSSON. The existence of two morphotypes on one and the same cell affirms, that these are different features of one species only.

Benthos of Spanish lakes and reservoirs

Benthos of Spanish lakes and reservoirs

Phototrophic sulfur bacteria in two Spanish lakes: Vertical distribution and limiting factors1

The anaerobic zones of Lakes Cisó and Vilar (Banyoles karstic area, NE Spain) had mass developments of purple sulfur bacteria during summer 1982. In Lake Vilar, Chromatium spp. was dominant (up to 92% of the microbial biovolume). In Lake Cisó, the predominant microorganisms were Chromatium spp. (up to 71%) and another purple sulfur bacterium forming aggregates (20%).The bacterial layer could be divided according to the physiological state of the cells into a top part of maximal specific activity, a peak of maximal abundance, and a bottom part of inactive cells. The bacteria in the peak were predominantly limited by light; sulfide, phosphate, and acetate were not limiting in the middle of the day. The light limitation started at the depth having the maximal concentration of cells; the top of the layer appeared to be sulfide‐limited. Specific contents of photopigments, elemental sulfur, and reserve polymers decreased from the top to the bottom of the bacterial layer. These phenomena point to the crucial role of light in the development of layers of phototrophic bacteria in stratified lakes.

Ecology and Physiology of the Competition for Light Between Chlorobium limicola and Chlorobium phaeobacteroides in Natural Habitats

Accurate studies of the pigment composition and isolation in pure cultures of Chlorobiaceae from samples of eight Spanish lakes show that there are two main coexisting groups of green and brown Chlorobium spp. represented respectively by Chlorobium limicola and Chlorobium phaeobacteroides. Laboratory experiments with pure and mixed cultures of the isolated strains show that light quality plays a selective role on the species composition among Chlorobiaceae. This selection depends on the pigment composition which determines the in vivo absorption spectrum of the cells as well as on their ability to adjust the intracellular concentration of light-harvesting pigments to the spectral distribution and energy of light. Correlation analysis performed with field data resulted in significant, but low, correlation coefficients. Nevertheless, they were consistent with laboratory data showing that brown Chlorobiaceae were dominant in deep layers in meromictic lakes, whereas green Chlorobiaceae dominated in layers nearer the surface or underneath plates of Chromatiaceae. The combination of laboratory and field observations stress the role of biological light filtering in determining the species composition among Chlorobiaceae in lakes.

Electron microscope study of the interaction of epibiontic bacteria withChromatium minus in natural habitats

Epibiontic cells on the surface of the photosynthetic purple sulfur bacteriumChromatium minus, collected several times during the year from 3 different Spanish lakes, were examined using scanning and transmission electron microscopy. The cells attached to theC. minus cell wall by an electron-dense pad, but did not enter the cell. They were ovoidal (about 0.6Μm wide) when free, and slightly curved rods (0.3×0.6Μm) when undergoing division. Division only occurred when cells remained attached toChromatium. A septum was formed, resulting in 2 or 3 curved rods surrounded by a common capsule. Detached daughter cells became ovoidal.The host ultrastructure changed as a result of epibiontic attachment, showing symptoms of cellular degradation. Simultaneously, plaques could be detected on cell lawns formed spontaneously upon cell sedimentation from field samples.