RECERCAT - Articles publicats en revistes (Ecologia)

Low Dynamics, High Longevity and Persistence of Sessile Structural Species Dwelling on Mediterranean Coralligenous Outcrops

Low Dynamics, High Longevity and Persistence of Sessile Structural Species Dwelling on Mediterranean Coralligenous Outcrops Teixidó, Núria; Garrabou i Vancells, Joaquim; Harmelin, Jean-Georges There is still limited understanding of the processes underlying benthic species dynamics in marine coastal habitats, which are of disproportionate importance in terms of productivity and biodiversity. The life-history traits of long-lived benthic species in these habitats are particularly poorly documented. In this study, we assessed decadal patterns of population dynamics for ten sponge and anthozoan species that play key structural roles in coralligenous outcrops (~25 m depth) in two areas of the NW Mediterranean Sea. This study was based on examination of a unique long-term photographic series, which allowed analysis of population dynamics over extensive spatial and time spans for the very first time. Specifically, 671 individuals were censused annually over periods of 25-, 15-, and 5-years. This long-term study quantitatively revealed a common life-history pattern among the ten studied species, despite the fact they present different growth forms. Low mortality rates (3.4% yr−1 for all species combined) and infrequent recruitment events (mean value of 3.1±0.5 SE recruits yr−1) provided only a very small fraction of the new colonies required to maintain population sizes. Overall, annual mortality and recruitment rates did not differ significantly among years; however, some species displayed important mortality events and recruitment pulses, indicating variability among species. Based on the growth rates of these 10 species, we projected their longevity and, obtained a mean estimated age of 25
200 years. Finally, the low to moderate turnover rates (mean value 0.80% yr−1) observed among the coralligenous species were in agreement with their low dynamics and persistence. These results offer solid baseline data and reveal that these habitats are among the most vulnerable to the current increases of anthropogenic disturbances.

Sea Urchins Predation Facilitates Coral Invasion in a Marine Reserve

Sea Urchins Predation Facilitates Coral Invasion in a Marine Reserve Coma Bau, Rafel; Serrano, Eduard; Linares Prats, Cristina; Ribes, M.; Díaz, D.; Ballesteros i Sagarra, Enric, 1958- Macroalgae is the dominant trophic group on Mediterranean infralittoral rocky bottoms, whereas zooxanthellate corals are extremely rare. However, in recent years, the invasive coral Oculina patagonica appears to be increasing its abundance through unknown means. Here we examine the pattern of variation of this species at a marine reserve between 2002 and 2010 and contribute to the understanding of the mechanisms that allow its current increase. Because indirect interactions between species can play a relevant role in the establishment of species, a parallel assessment of the sea urchin Paracentrotus lividus, the main herbivorous invertebrate in this habitat and thus a key species, was conducted. O. patagonica has shown a 3-fold increase in abundance over the last 8 years and has become the most abundant invertebrate in the shallow waters of the marine reserve, matching some dominant erect macroalgae in abundance. High recruitment played an important role in this increasing coral abundance. The results from this study provide compelling evidence that the increase in sea urchin abundance may be one of the main drivers of the observed increase in coral abundance. Sea urchins overgraze macroalgae and create barren patches in the space-limited macroalgal community that subsequently facilitate coral recruitment. This study indicates that trophic interactions contributed to the success of an invasive coral in the Mediterranean because sea urchins grazing activity indirectly facilitated expansion of the coral. Current coral abundance at the marine reserve has ended the monopolization of algae in rocky infralittoral assemblages, an event that could greatly modify both the underwater seascape and the sources of primary production in the ecosystem.

Rapid Biodiversity Assessment and Monitoring Method for Highly Diverse Benthic Communities: a Case Study of Mediterranean Coralligenous Outcrops

Rapid Biodiversity Assessment and Monitoring Method for Highly Diverse Benthic Communities: a Case Study of Mediterranean Coralligenous Outcrops Kipson, S.; Fourt, M.; Teixidó Ullod, Núria; Cebrian, E.; Casas, E.; Ballesteros i Sagarra, Enric, 1958-; Zabala i Limousin, Mikel; Garrabou, J. Increasing anthropogenic pressures urge enhanced knowledge and understanding of the current state of marine biodiversity. This baseline information is pivotal to explore present trends, detect future modifications and propose adequate management actions for marine ecosystems. Coralligenous outcrops are a highly diverse and structurally complex deep-water habitat faced with major threats in the Mediterranean Sea. Despite its ecological, aesthetic and economic value, coralligenous biodiversity patterns are still poorly understood. There is currently no single sampling method that has been demonstrated to be sufficiently representative to ensure adequate community assessment and monitoring in this habitat. Therefore, we propose a rapid non-destructive protocol for biodiversity assessment and monitoring of coralligenous outcrops providing good estimates of its structure and species composition, based on photographic sampling and the determination of presence/absence of macrobenthic species. We used an extensive photographic survey, covering several spatial scales (100s of m to 100s of km) within the NW Mediterranean and including 2 different coralligenous assemblages: Paramuricea clavata (PCA) and Corallium rubrum assemblage (CRA). This approach allowed us to determine the minimal sampling area for each assemblage (5000 cm2 for PCA and 2500 cm2 for CRA). In addition, we conclude that 3 replicates provide an optimal sampling effort in order to maximize the species number and to assess the main biodiversity patterns of studied assemblages in variability studies requiring replicates. We contend that the proposed sampling approach provides a valuable tool for management and conservation planning, monitoring and research programs focused on coralligenous outcrops, potentially also applicable in other benthic ecosystems.

Els boscos de Nothofagus de Terra de Foc com a paradigma de la dinàmica successional del no equilibri

Els boscos de Nothofagus de Terra de Foc com a paradigma de la dinàmica successional del no equilibri Gutiérrez Merino, Emilia Dues especies planifolies del genere Notllo/iigus, famili afagacies, integren els boscos de la Terra del Foc al llarg dels darrers contraforts dels Andes. Les grans valls en forma de <> i la morfologia de les muntanyes mostren dels efectes de les glaciations recents.

Resposta dels arbres i dels boscos al canvi climàtic

Resposta dels arbres i dels boscos al canvi climàtic Gutiérrez Merino, Emilia; Ribas, M.; Octavi Planells,J.; Camarero, J.; Tardif, J. Durant el darrer segle, arbres, boscos i ecosistemes han estat responent a diversos efectes del canvi global, com són l"escalfament de la superfície terrestre, l"increment de la variabilitat climàtica o l"augment de la concentració de CO2. Les respostes dels arbres a aquests efectes han estat analitzades en diferents espècies de coníferes en diversos hàbitats i ambients de la península Ibèrica. Un compendi dels resultats obtinguts es mostra en el present treball. En tots els estudis presentats s"ha observat un augment de la variabilitat de les variables dendrocronològiques (gruix i composició isotòpica dels anells de creixement) en les darreres dècades del segle xx, fet que reﬂecteix un increment de la variabilitat climàtica i que, al seu torn, ha restringit el ventall de respostes dels organismes a causa de l"eixamplament dels períodes de creixement i de l"augment d"esdeveniments meteorològics extrems. Destaca, per tant, la sincronització del creixement dels arbres en detriment de les diferències explicades per causes cada cop més secundàries, com són les diferències de temperatura al llarg de gradients, altitudinals o latitudinals, o degudes a diferències d"hàbitat (orientació, substrat, etc.). Els efectes es manifesten en diferents nivells temporals i espacials. Així, s"ha trobat un increment de la variabilitat intraanual en el creixement en gruix d"espècies mediterrànies com el pi blanc (Pinus halepensis) associat a un eixamplament de l"època de creixement, o augments de la variabilitat interanual i entre dècades tant a escales locals com regionals en el gruix i composició isotòpica dels anells de creixement d"espècies subalpines. Les anàlisis de les relacions entre el creixement dels arbres i el clima, d"una banda, i la composició isotòpica i el clima, de l"altra, demostren que aquest augment de la variabilitat respon a un increment de les oscil.lacions climàtiques intraanuals, interanuals i entre dècades. La resposta sincrònica dels arbres a un menor nombre de variables ambientals s"entén com un augment de l"estrès d"aquests organismes enfront d"aquestes variables, que esdevenen factors limitants per al desenvolupament d"aquestes espècies. Els resultats presentats són contrastats amb resultats similars, tant locals com globals, obtinguts en altres indrets del planeta.

The subantartic Nothofagus forests of Tierra del Fuego: distribution, structure and production

The subantartic Nothofagus forests of Tierra del Fuego: distribution, structure and production Gutiérrez Merino, Emilia; Vallejo, V. Ramón (Victoriano Ramón); Romanyà i Socoró, Joan; Fons, J. Evergreen Nothofagus betuloides and decidoues N. pumilo form the main forest types in Tierra del Fuego. These forest were sampled along two altitudinal gradients to study their structure and dynamics and assess the causes of their distribution.

Estimating 750 years of temperature variations and uncertainties in the Pyrenees by tree-ring reconstructions and climate simulations.

Estimating 750 years of temperature variations and uncertainties in the Pyrenees by tree-ring reconstructions and climate simulations. Dorado Liñán, I.; Büntgen, U.; González Rouco, F.; Zorita, E.; Montávez, J.P.; Gómez Navarro, J.J.; Brunet, M.; Heinrich, I.; Helle, G.; Gutiérrez Merino, Emilia Past temperature variations are usually inferred from proxy data or estimated using general circulation models. Comparisons between climate estimations derived from proxy records and from model simulations help to better understand mechanisms driving climate variations, and also offer the possibility to identify deficiencies in both approaches. This paper presents regional temperature reconstructions based on tree-ring maximum density series in the Pyrenees, and compares them with the output of global simulations for this region and with regional climate model simulations conducted for the target region. An ensemble of 24 reconstructions of May-to-September regional mean temperature was derived from 22 maximum density tree-ring site chronologies distributed over the larger Pyrenees area. Four different tree-ring series standardization procedures were applied, combining two detrending methods: 300-yr spline and the regional curve standardization (RCS). Additionally, different methodological variants for the regional chronology were generated by using three different aggregation methods. Calibration verification trials were performed in split periods and using two methods: regression and a simple variance matching. The resulting set of temperature reconstructions was compared with climate simulations performed with global (ECHO-G) and regional (MM5) climate models. The 24 variants of May-to-September temperature reconstructions reveal a generally coherent pattern of inter-annual to multi-centennial temperature variations in the Pyrenees region for the last 750 yr. However, some reconstructions display a marked positive trend for the entire length of the reconstruction, pointing out that the application of the RCS method to a suboptimal set of samples may lead to unreliable results. Climate model simulations agree with the tree-ring based reconstructions at multi-decadal time scales, suggesting solar variability and volcanism as the main factors controlling preindustrial mean temperature variations in the Pyrenees. Nevertheless, the comparison also highlights differences with the reconstructions, mainly in the amplitude of past temperature variations and in the 20th century trends. Neither proxy-based reconstructions nor model simulations are able to perfectly track the temperature variations of the instrumental record, suggesting that both approximations still need further improvements.

Do mediterranean genera not included in Tachet et al. (2002) have mediterranean trait characteristics?

Do mediterranean genera not included in Tachet et al. (2002) have mediterranean trait characteristics? Bonada i Caparrós, Núria; Dolédec, S. Do mediterranean genera not included in Tachet et al. 2002 have mediterranean trait characteristics? Multiple-trait databases are increasingly used in community ecology in different regions of the world. In Europe, Tachet et al.(2002) compiled an aquatic macroinvertebrate database for 473 taxa using information on 11 biological traits described by 63 categories. However, less studied regions, at the time of the compilation of the database, such as the mediterranean Basin, can harbour exclusive genera, which were not included in Tachet"s database. In a large-scale study across the mediterranean Basin, we found 44 genera that were not included in Tachet"s database (NEW genera). Our main aim was to compile trait information for these NEW genera and assess whether these genera had speciﬁc traits that could explain their exclusivity to the Mediterranean region. We compared the trait characteristics of NEW genera to those of genera only found in Mediterranean or temperate regions that were included in the Tachet"s database (MED and TEM genera, respectively). We found that NEW genera had more mediterranean characteristics than TEM genera and that some trait categories of NEW genera were even more mediterranean-like than the traits of MED genera (e.g., diapause). Therefore, our results suggest that the speciﬁc biological traits of these NEW genera allow them to cope successfully and exclusively with the harsh environmental conditions of the mediterranean climate rivers, which could partially explain their absence in Tachet"s database. Other explanations, such as the limited dispersal ability of these NEW genera to reach and colonize temperate Europe or the rarity of these NEW genera, should also be considered. We provide biological traits of the NEW genera to be used in future studies on the mediterranean river ecology.

Sterol regulatory element binding protein-1a transactivates 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase gene promoter

Sterol regulatory element binding protein-1a transactivates 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase gene promoter Metón Teijeiro, Isidoro; Egea, Míriam; Anemaet, Ida Guurtje; Fernández González, Felipe Javier; Vázquez Baanante, Ma. Isabel 6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB)catalyzes the synthesis and degradation of fructose-2,6-bisphosphate, a key modulator of glycolysis-gluconeogenesis. To gain insight into the molecular mechanism behind hormonal and nutritional regulation of PFKFB expression, we have cloned and characterized the proximal promoter region of the liver isoform of PFKFB (PFKFB1) from gilthead sea bream (Sparus aurata). Transient transfection of HepG2 cells with deleted gene promoter constructs and electrophoretic mobility shift assays allowed us to identify a sterol regulatory element (SRE) to which SRE binding protein-1a (SREBP-1a)binds and transactivates PFKFB1 gene transcription. Mutating the SRE box abolished SREBP-1a binding and transactivation. The in vivo binding of SREBP-1a to the SRE box in the S. aurata PFKFB1 promoter was confirmed by chromatin immunoprecipitation assays. There is a great deal of evidence for a postprandial rise of PFKB1 mRNA levels in fish and rats. Consistently, starved-to-fed transition and treatment with glucose or insulin increased SREBP-1 immunodetectable levels, SREBP-1 association to PFKFB1 promoter, and PFKFB1 mRNA levels in the piscine liver. Our findings demonstrate involvement of SREBP-1a in the transcriptional activation of PFKFB1, and we conclude that SREBP-1a may exert a key role mediating postprandial activation of PFKFB1 transcription.

Nutritional regulation of glucose-6-phosphatase gene expression in liver of the gilthead sea bream (Sparus aurata)

Nutritional regulation of glucose-6-phosphatase gene expression in liver of the gilthead sea bream (Sparus aurata) Caseras Surribas, Anna; Metón Teijeiro, Isidoro; Vives, C.; Egea, Míriam; Fernández González, Felipe Javier; Vázquez Baanante, Ma. Isabel To examine the role of glucose-6-phosphatase (G6Pase) in glucose homeostasis in the diabeteslike experimental model of carnivorous fish, we analysed postprandial variations and the effect of starvation, ration size and diet composition on the regulation of G6Pase expression at the enzyme activity and mRNA level in the liver of gilthead sea bream (Sparus aurata ). G6Pase expression increased in long-term starved or energy-restricted fish. In contrast to data reported for other fish species, short-term regulation of G6Pase expression was found in regularly fed S. aurata. G6Pase mRNA levels were lowest between 4 and 15 h after food intake, whereas minimal enzyme activity was observed 10&br&15 h postprandially. Alterations of plasma glucose levels affect G6Pase in mammals. However, the carbohydrate content of the diet did not affect hepatic expression of G6Pase in S. aurata, suggesting that a different molecular mechanism is involved in the control of G6Pase expression in fish. Although G6Pase was unaffected, highcarbohydrate low-protein diets increased glucokinase (GK) expression and thus allowed a metabolic adaptation favouring glycolysis over gluconeogenesis. Interestingly, only the nutritional conditions that promoted variations in the blood glucose levels resulted in changes in the hepatic expression of G6Pase. These findings indicate a concerted regulation of G6Pase and GK expression and suggest that the direction and rate of the glucose&br&glucose-6-phosphate substrate cycle flux is finely regulated in the liver of S. aurata, challenging the role attributed to deficient regulation of G6Pase or GK expression in the low ability of carnivorous fish to metabolize glucose.

Effect of diet composition and ration size on key enzyme activities of glycolysis-gluconeogenesis, pentose phosphate pathway and amino acid metabolism in liver of Sparus aurata

Effect of diet composition and ration size on key enzyme activities of glycolysis-gluconeogenesis, pentose phosphate pathway and amino acid metabolism in liver of Sparus aurata Metón Teijeiro, Isidoro; Mediavilla Redondo, Dominica; Caseras Surribas, Anna; Cantó, E.; Fernández González, Felipe Javier; Vázquez Baanante, Ma. Isabel The effects of diet composition and ration size on the activities of key enzymes involved in intermediary metabolism were studied in the liver of gilthead sea bream (Sparus aurata). Highcarbohydrate, low-protein diets stimulated 6-phosphofructo 1-kinase (EC 2.7.1.11), pyruvate kinase (EC 2.7.1.40), glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44) enzyme activities, while they decreased alanine aminotransferase (EC 2.6.1.2) activity. A high degree of correlation was found between food ration size and the activity of the enzymes 6-phosphofructo 1-kinase, pyruvate kinase, glucose-6-phosphate dehydrogenase (positive correlations) and fructose-1,6-bisphosphatase (EC 3.1.3.11) (negative correlation). These correlations matched well with the high correlation also found between ration size and growth rate in starved fish refed for 22 d. Limited feeding (5 g/kg body weight) for 22 d decreased the activities of the key enzymes for glycolysis and lipogenesis, and alanine aminotransferase activity. The findings presented here indicate a high level of metabolic adaptation to both diet type and ration size. In particular, adaptation of enzyme activities to the consumption of a diet with a high carbohydrate level suggests that a carnivorous fish like Sparus aurata can tolerate partial replacement of protein by carbohydrate in the commercial diets supplied in culture. The relationship between enzyme activities, ration size and fish growth indicates that the enzymes quickly respond to dietary manipulations of cultured fish.

Cambios en el estado ecologico de tres rios producidos por el vertido de depuradoras

Cambios en el estado ecologico de tres rios producidos por el vertido de depuradoras Perreé, I.; Rieradevall i Sant, Maria; Prat i Fornells, Narcís; Martin, J.; Céspedes Sánchez, R. En el marco del proyecto Sostaqua se ha llevado a cabo la evaluación del efecto de las aguas residuales tratadas en tres depuradoras (dos en la provincia de Barcelona y una en Andorra), sobre la comunidad de macroinvertebrados bentónicos. En cada una de ellas se evaluó mensualmente el estado ecológico aguas arriba y aguas abajo del punto de vertido, utilizando varios índices biológicos. Mientras que en el río de andorra no se observó un efecto sobre los índices biológicos, en los ríos de la provincia de Barcelona (ríos ya perturbados y con una menor disolución del vertido) el efecto fue importante.

Comparación de tres protocolos de muestreo de macroinvertebrados para determinar la calidad del agua.

Comparación de tres protocolos de muestreo de macroinvertebrados para determinar la calidad del agua. Puértolas i Domènech, Laura; Rieradevall i Sant, Maria; Prat i Fornells, Narcís Para la implementación de la Directiva Marco del Agua (DMA, Directiva 2000/60/CE) es necesario establecer un protocolo estandarizado de muestreo y análisis que sirve para la evaluación de la calidad biológica mediante la fauna bentónica. En este trabajo se ha llevado a cabo un estudio comparativo de diversos protocolos de macroinvertebrados que se utilizan en España y en Europa (AQEM, EPA, Gudalmed). Valorando los tres protocolos con una lista de 12 criterios, el protocolo Guadalmed se adecuan mejor a la mayoría de ellos, por lo que aparece como una herramienta eficaz en la determinación del estado ecológico

Modelling nitrogen and phosphorus loads in a Mediterranean river catchment (La Tordera, NE Spain)

Modelling nitrogen and phosphorus loads in a Mediterranean river catchment (La Tordera, NE Spain) Caille, Frédérique; Riera, Joan Lluís; Rosell-Melé, Antoni Human activities have resulted in increased nutrient levels in many rivers all over Europe. Sustainable management of river basins demands an assessment of the causes and consequences of human alteration of nutrient flows, together with an evaluation of management options. In the context of an integrated and interdisciplinary environmental assessment (IEA) of nutrient flows, we present and discuss the application of the nutrient emission model MONERIS (MOdelling Nutrient Emissions into River Systems) to the Catalan river basin, La Tordera (north-east Spain), for the period 1996–2002. After a successful calibration and verification process (Nash-Sutcliffe efficiencies E=0.85 for phosphorus and E=0.86 for nitrogen), the application of the model MONERIS proved to be useful in estimating nutrient loads. Crucial for model calibration, in-stream retention was estimated to be about 50 % of nutrient emissions on an annual basis. Through this process, we identified the importance of point sources for phosphorus emissions (about 94% for 1996–2002), and diffuse sources, especially inputs via groundwater, for nitrogen emissions (about 31% for 1996–2002). Despite hurdles related to model structure, observed loads, and input data encountered during the modelling process, MONERIS provided a good representation of the major interannual and spatial patterns in nutrient emissions. An analysis of the model uncertainty and sensitivity to input data indicates that the model MONERIS, even in data-starved Mediterranean catchments, may be profitably used by water managers for evaluating quantitative nutrient emission scenarios for the purpose of managing river basins. As an example of scenario modelling, an analysis of the changes in nutrient emissions through two different future scenarios allowed the identification of a set of relevant measures to reduce nutrient loads.

Effects of alanine aminotransferase inhibition on the intermediary metabolism in Sparus aurata through dietary amino-oxyacetate supplementation

Effects of alanine aminotransferase inhibition on the intermediary metabolism in Sparus aurata through dietary amino-oxyacetate supplementation González, Juan D.; Caballero, Albert; Viegas, Iván; Metón Teijeiro, Isidoro; Jones, John G.; Barra, Joana; Fernández González, Felipe Javier; Vázquez Baanante, Ma. Isabel In liver, through the reaction catalysed by alanine aminotransferase (ALT), alanine becomes an effective precursor for gluconeogenesis. In the present study amino-oxyacetate (AOA) was used to evaluate its effect on liver ALT activity of the carnivorous ﬁsh Sparus aurata. Moreover, the derived metabolic effects on metabolites and other key enzymes of glycolysis, gluconeogenesis and the pentose phosphate pathway were also studied. A dose-effect-dependent inhibition of AOA on hepatic cytosolic and mitochondrial ALT activity was observed in vitro. In vivo, AOA behaved as an inhibitor of hepatic cytosolic ALT activity. A long-term exposure to AOA increased pyruvate kinase activity in the liver irrespective of the composition of the diet supplied to ﬁsh. 1H NMR studies showed that inclusion of AOA to the diet decreased the hepatic levels of alanine, glutamate and glycogen. Moreover, 2H NMR analysis indicated a higher renewal rate for alanine in the liver of ﬁsh fed with a high-carbohydrate/low-protein diet, while AOA decreased alanine 2H-enrichment irrespective of the diet. The present study indicates that AOA-dependent inhibition of the cytosolic ALT activity could help to increase the use of dietary carbohydrate nutrients.

Caracterización del estado ecológico de ríos mediterráneos ibéricos mediante el índice IBMWP (antes BMWP')

Caracterización del estado ecológico de ríos mediterráneos ibéricos mediante el índice IBMWP (antes BMWP') Alba-Tercedor, Javier; Jáimez-Cuéllar, P.; Álvarez, M.; Avilés, J.; Bonada i Caparrós, Núria; Casas, J.; Mellado, A.; Ortega, M.; Pardo, I.; Prat i Fornells, Narcís; Rieradevall i Sant, Maria; Robles, S.; Sáinz-Cantero, C.; Sánchez-Ortega, A.; Suárez, Ma. Luisa; Vidal-Abarca Gutiérrez, María Rosario; Vivas, S.; Zamora-Muñoz, C. En base a los datos obtenidos a lo largo de la primera fase del proyecto GUADALMED (1999-2001), se estudia la calidad biológica de las aguas de 65 ríos de 12 cuencas mediterráneas ibéricas y el comportamiento del índice IBMWP ("Iberian Biomonitoring Working Party"; antes BMWP"). Se proponen unas bases para el establecimiento de las clases de calidad para la evaluación de estado ecológico de los ríos, siguiendo las directrices de la Directiva Marco del Agua, basadas en los valores del índice obtenidos en las estaciones de referencia de cada una de las tipologías de ríos obtenidas en el estudio. Tras la comparación entre las cinco clases originales del índice y las posibles nuevas acotaciones obtenidas se observó una total coincidencia para todos los casos en que se contaba con un número de estaciones de referencia elevado (&50), observándose discrepancias respecto a aquellas tipologías de ríos en que el número de estaciones era escaso (&50). Por lo se propone seguir utilizando las mismas acotaciones del IBMWP hasta no contar con un mayor número de estaciones de referencia que permita evaluar si efectivamente las discrepancias observadas se deben a características diferenciales de las diferentes tipologías de ríos, o por el contrario son el resultado de no disponer de una representación suficiente de estaciones de referencia en algunas de las tipologías. ABSTRACT Using baseline data obtained during the first phase (1999-2001) of the project GUADALMED, we examined the applicability of the IBMWP (Iberian Bio-monitoring Working Party; former BMWP") to assess the quality of 65 rivers and streams within 12 Iberian Mediterranean basins. Moreover, criteria for the establishment of classes to assess the ecological status of the Iberian Mediterranean rivers are proposed. Criteria followed the European Water Framework Directive, and used the index values found in the reference stations of each river type in the study. By comparing the five original classes of the IBMWP index and the candidate new classes, similar values were obtained in all cases when the number of reference stations was high (&50), while discrepancies were observed within river types when the number of stations was low (&50). Therefore, we propose that the same IBMWP classes continue to be used, until a greater number of reference stations are available, which would be necessary to evaluate whether discrepancies observed are due to specific differences of river types, or are due to an insufficient representation of reference stations of some river types.

Criterios para la selección de condiciones de referencia en los ríos mediterráneos. Resultados del proyecto GUADALMED

Criterios para la selección de condiciones de referencia en los ríos mediterráneos. Resultados del proyecto GUADALMED Bonada i Caparrós, Núria; Prat i Fornells, Narcís; Munné i Torras, Toni; Rieradevall i Sant, Maria; Alba Tercedor, Javier; Álvarez, M.; Avilés, J.; Casas, J.; Jáimez-Cuéllar, P.; Mellado, A.; Moyá, G.; Pardo, I.; Robles, S.; Ramon, G.; Suárez, Ma. Luisa; Toro, M.; Vidal-Abarca Gutiérrez, María Rosario; Vivas, S.; Zamora-Muñoz, C. La Directiva Marco del Agua (DMA) establece la necesidad de definir las condiciones de referencia, que sirvan de patrón del estado ecológico del resto de estaciones del mismo ecotipo. Varios son los criterios que pueden ser utilizados para la selección de las condiciones de referencia. En el proyecto GUADALMED cinco localidades por cuenca muestreada, fueron escogidas a priori según la experiencia de los expertos en cada zona, uno de los criterios contemplados en la DMA. Los resultados mostraron en muchas de las estaciones seleccionadas (un 72%) una calidad biológica alterada (IBMWP &100 en todas las campañas muestreadas) y un bosque de ribera perturbado (QBR &75). A partir de estos resultados se analizó si era posible el establecimiento de una serie de criterios que ayudaran a establecer condiciones de referencia. Para ello se seleccionaron diferentes criterios como la conservación del bosque de ribera, los usos naturales de la cuenca, la naturalidad del canal fluvial, la ausencia de embalses que regularan el caudal, un hábitat del lecho adecuado y concentraciones bajas de parámetros físico-químicos, en cada uno de los puntos estudiados. Algunas estaciones cumplían todos los criterios, mientras que otras podrían fácilmente cumplirlos reubicando el punto de muestreo aguas arriba o abajo del río o mediante técnicas de restauración. Los resultados fueron comparados con la tipología mediante el Sistema B establecida en otro trabajo de este volumen. En algunos ecotipos, la falta de estaciones de referencia y la imposibilidad de encontrarlas dadas las características de la cuenca y el tramo, implica la imposibilidad de establecer condiciones de referencia y la necesidad de establecer el Máximo Potencial Ecológico. Al comparar los criterios establecidos para cada estación con los valores de los índices biológicos hallados en todas las campañas, se observa que los criterios establecidos son adecuados, ya que las estaciones que los cumplen tienen un IBMWP y QBR superior. Este trabajo pretende establecer unos criterios generales que serán utilizados como base para la selección y validación de condiciones de referencia en la segunda fase del proyecto GUADALMED. ABSTRACT The water Frame Directive (WFD) establishes the need to define reference conditions in order to determine the ecological status of all the test sites from each ecotype. Several criteria may be used to select reference conditions. In the GUADALMED project, five localities per basin were selected a priori according to the experience of experts, which is one of the criteria considered in the WFD. Results showed that in 72% of selected reference conditions, water quality was poor (IBMWP&100 in all sampled seasons) and the riparian vegetation, altered (QBR&75). Consequently, we established a set of new criteria for appropriate selection of reference conditions for natural riparian vegetation status, natural basin uses, unaltered fluvial channel, absence of reservoirs, diverse river habitat conditions and low nutrient concentrations. A few sites conform to all these criteria, whereas others may comply when a site upstream or downstream is considered instead, or after restoration techniques are applied. Results obtained were compared with the previously established System B typologies. For some ecotypes, no reference sites were found occasionally because of the difficulty in finding given basin or river reach characteristics. In these cases, a"Maximum Ecological Potential" was used instead of the reference condition. When the criteria established were compared with the biological indices across seasons for each site, a positive and significant relationship was found between all criteria and the IBMWP and QBR indices. Here, we present a set of criteria for use as a general framework to select and validate reference condition during the second phase of the project GUADALMED.

Propuesta de un protocolo de evaluación de la calidad ecológica de ríos andinos (CERA) y su aplicación a dos cuencas de Ecuador y Perú

Propuesta de un protocolo de evaluación de la calidad ecológica de ríos andinos (CERA) y su aplicación a dos cuencas de Ecuador y Perú Acosta Rivas, Carlos Raúl; Ríos Touma, Blanca Patricia; Rieradevall i Sant, Maria; Prat i Fornells, Narcís ABSTRACT Proposal for an evaluation protocol of the ecological quality of Andean rivers (CERA) and its use in two basins in Ecuador and Peru A Rapid Protocol is presented for Evaluation of the Ecological Status of Andean Rivers (CERA) localized over 2000 m.a.s.l. from the Northern Andes (Venezuela) through the Altiplano in the Central Andes (Bolivia). This protocol was used in 45 sampling sites in the Guayllabamba River Basin in Ecuador and in 42 sampling sites in the Ca nete River Basin in Peru. Previously, and in order to test if the sampling stations may or not be considered reference stations, we constructed a method that assesses 24 basin attributes, hydrology, reach and riverbed and that uctuates from 24 to 120 points; sites with values higher than 100 were considered as potential reference sites. Besides the benthic macroinvertebrats" evaluation, the river habitat and riparian vegetation were also evaluated through of the application of the indices ABI (R´ os et al., submitted), IHF (Pardo et al., 2002) and QBR-And, respectively. The convenience of the initial allocation of the reference sites was evaluated as well. These indices have been properly adapted to the conditions and characteristics of the high Andes rivers. The results obtained for both basins were compared and discussed. Through the use of the CERA protocol, the particular perturbation gradients and the natural variability of the reference sites in both countries were recognized. RESUMEN Propuesta de un protocolo de evaluación de la calidad ecológica de ríos andinos (CERA) y su aplicaci´on a dos cuencas en Ecuador y Perú Se presenta un protocolo rápido de evaluación de la Calidad Ecológica de Ríos Andinos (CERA), situados sobre los 2000 m.s.n.m, desde los Andes del Norte (Venezuela) hasta el Altiplano de los Andes Centrales (Bolivia). Este protocolo ha sido aplicado en 45 estaciones de muestreo en la cuenca del río Guayllabamba en Ecuador y en 42 estaciones de muestreo en la cuenca del río Cañete en Perú. Previamente, para probar si las estaciones de muestreo pueden o no ser estaciones de referencia construimos un método que valora 24 atributos de cuenca, hidrología, tramo y lecho y que fluctúa de 24 a 120 puntos; valores superiores a 100 fueron considerados como sitios potencialmente de referencia. Además del estudio de los macroinvertebrados bentónicos, se evaluó el hábitat fluvial y la comunidad vegetal de ribera a través de la aplicación de los índices ABI (Ríos et al., sometido), IHF (Pardo et al., 2002) y QBR-And respectivamente; así como la conveniencia de la asignación inicial de las estaciones de referencia. Estos índices han sido adecuadamente adaptados a las condiciones y características propias de los ríos altoandinos. Los resultados obtenidos fueron comparados y discutidos entre ambas cuencas. Mediante la aplicación del protocolo CERA se han reconocido los respectivos gradientes de perturbación y la variabilidad natural de las estaciones de referencia en ambos países.

Redaccio col·laborativa de treballs en la docència de les ciències experimentals. Comparació entre mètodes tradicionals i wikis

Redaccio col·laborativa de treballs en la docència de les ciències experimentals. Comparació entre mètodes tradicionals i wikis Rieradevall i Sant, Maria; Pedro Puente, Xavier de; López Laseras, Ma. Pilar; Sant i Vilella, M. Dolors En aquest treball es presenta la recerca en docència que desenvolupen els autors, ique fa referència a l"ús de la redacció col·laborativa de documents i treballscooperatius en docència. Aquesta recerca es dedica principalment a l"anàlisi de l"ús de metodologies TIC, com és el wiki, per tal d"avaluar-ne els seus avantatges i inconvenients respecte als mètodes tradicionals de treball col·laboratiu. Entre d"altres aspectes, ens interessen la mesura de l"esforç en temps de dedicació de l"alumnat i també del professorat, i la possibilitat de fer una avaluació de cada alumne que inclogui la seva contribució individual al treball de grup. L"estudi s"està fent en diverses assignatures dels ensenyaments de Biologia, Ciències Ambientals i Infermeria. Es presenten algunes dades sobre els resultats obtinguts en aspectes com ara les dificultats tècniques, qüestions organitzatives i grau de satisfacció dels alumnes. S"aporten algunes dades preliminars sobre la valoració diferent de cada alumne segons el mètode.

Las riberas de los rios mediterraneos y su calidad: el uso del indice QBR

Las riberas de los rios mediterraneos y su calidad: el uso del indice QBR Suárez, Ma. Luisa; Vidal-Abarca Gutiérrez, María Rosario; Sánchez-Montoya, María del Mar; Alba Tercedor, Javier; Álvarez, M.; Avilés, J.; Bonada i Caparrós, Núria; Casas, J.; Jáimez-Cuéllar, P.; Munné i Torras, Toni; Pardo, I.; Prat i Fornells, Narcís; Rieradevall i Sant, Maria; Salinas, M. J.; Toro Velasco, Manuel; Vivas, S. Se ha aplicado el QBR (índice de calidad del bosque de ribera) a 157 estaciones de muestreo localizadas en ríos pertenecientes a 12 cuencas diferentes del ámbito mediterráneo español. Los resultados indican que más del 34 % de las estaciones muestran valores de calidad buenos y muy buenos (QBR & 75), mientras que el 45 % presenta valores de mala y pésima calidad (QBR & 50). Según una tipología previa establecida para clasificar las estaciones de muestreo, los valores de mayor calidad de QBR se dan en estaciones de cabecera de cuencas calcáreas y en las zonas de karst. Los tipos denominados temporales y ramblas presentan los valores más bajos de calidad, o no tiene representantes de máxima calidad. La ausencia o escasez de bosques de riberas de máxima calidad en las cuencas del sur peninsular puede explicarse por el gradiente de aridez que se establece desde el norte hacia el sur. Además existe un evidente deterioro de las riberas desde las cabeceras a las desembocaduras de los ríos, de manera que ambos factores influyen en el estado actual de las riberas de los ríos mediterráneos ibéricos. Finalmente se discute la utilidad y limitaciones del QBR en ríos sometidos a situaciones de estrés hídrico o ambiental.

Benthos of Spanish lakes and reservoirs

Benthos of Spanish lakes and reservoirs Prat i Fornells, Narcís; Real i Ortí, Montserrat; Rieradevall i Sant, Maria A summary of the results from the study of benthos of lakes and reservoirs in Spain is provided, with a list of the species found to date. Spanish natural lakes are smaller than European lakes; the largest is Lake Sanabria, of glacial origin, which is 3 Km long and half a kilorneter wide. Many are very small and situated in the mountains; more than 200 hundred have been recorded in Spain, but only in Lake Sanabria and Lake Banyoles have the benthos been studied. Lake Sanabria is a cold oligotrophic, monomictic lake with oxygen always present in the deepest zones. Its fauna is similar to that of other central European lakes, with Mici.opsectra c.orztractu (a chironomid) as the dominan1 species. Lake Banyoles is a karstic, monomictic and multibasin lake; despite the low primary productivity, due to the abundante of sulphate in the water, the allochthonous inflow of organic matter and the inflow of water from bottom springs, the profunda1 environinent is very stressing for benthic fauna. Very low oxygen concentrations and high sulphide content in the water and sediments dueto meromixis mean that only the larva of the dipteran Chaohoi.lcs flai7icans was present in one of the 5 basins of the lake. In other basins, when oxygen is available (no meromixis), the fauna is similar to that of tlie inineralized lakes of the Aegean region and some lakes in central Italia. On the other hand, preliminary data from the Pyrenean lakes and from Sierra Nevada ponds reveal no differences with northern cold lakes. Tlie largest lakes in Spain are the reservoirs. There are nearly 1000 and data are available on 100 of them, including the kargest. In addition to oxygen and sulphide content in the bottom waters, water level fluctuation and high sedimentation rates are disturbance factors that prevented the organization of the community. Allochthonous inputs of organic matter are also an important factor both in the reservoirs and also in the small, oligotrophic lakes like Banyoles and Sanabria. As a result the meiofaunal loop is very important in many of the Spanish water bodies . For this reason the natural lakes and reservoirs of Spain are dominated by Oligochaeta, small crustaceans and the microcarnivore chironomids (such as Procladi~ls, Cladopelma and Mi(,rnc.hil-onnmus) that feed on these meoifaunal elements. The phytophagous chironomids, like Chironomus, are only abundan1 in the shallow areas of mesotrophic and eutrophic reservoirs. This situation makes it difficult to apply the typological system of SAETHER which predicts with some confidence only the benthic communities of Spanish natural lakes above 1500 m in the Pyrenees or the ponds above 2000 m in Sierra Nevada mountains. Higher temperatures (which originate a longer stratification period), the presence of sulphate in the waters of the eastern part of Spain and high inputs of sediments and allochthonous organic matter seem to be the factors that originated the differences between the benthic profunda1 faunas of Spanish lakes and reservoirs and those of the temperate lakes of north and central Europe.

Ensayo de una tipología de las cuencas mediterráneas del proyecto GUADALMED siguiendo las directrices de la Directiva Marco del Agua

Ensayo de una tipología de las cuencas mediterráneas del proyecto GUADALMED siguiendo las directrices de la Directiva Marco del Agua Bonada i Caparrós, Núria; Prat i Fornells, Narcís; Munné, A.; Rieradevall i Sant, Maria; Alba-Tercedor, J.; Álvarez, M.; Avilés, J.; Casas Grande, Jesús; Jáimez-Cuéllar, P.; Mellado, A.; Moyà, G.; Pardo, I.; Robles, S.; Ramon, G.; Suárez, Ma. Luisa; Toro, M.; Vidal-Abarca Gutiérrez, María Rosario; Vivas, S.; Zamora-Muñoz, C. RESUMEN Utilizando la propuesta de tipología de ríos de la Directiva Marco del Agua en su anexo 2 se realiza un ensayo tipológico de los puntos de muestreo del proyecto GUADALMED. Según el sistema A, se presentan 16 ecotipos, lo que se juzga poco adecuado para la gestión de los mismos y sin una base ecológica que lo justifique. De acuerdo con la selección previa hecha por los miembros del grupo GUADALMED para 5 de estos ecotipos no habría estaciones de referencia. Con algunas variables medidas en los puntos de muestreo y otras de tipo geológico e hidromorfológico, se realiza un ensayo tipológico usando el sistema B. El método implica un análisis de la correlación entre variables, un cluster de las estaciones utilizando el método K-means y un análisis discriminante de cuáles son las variables que distinguen estos grupos. El estudio da como resultado la caracterización de 6 ecotipos que sin embargo, a juicio de los miembros del proyecto GUADALMED, no recogen la variedad de tipos de ríos mediterráneos. Valorando cualitativamente parámetros no introducidos (por falta de datos) en el análisis K-means, se propone una tipología provisional en 9 grupos. Un análisis de las comunidades de macroinvertebrados (a nivel taxonómico de familia) revela un grado importante de coherencia entre las familias asociadas a cada tipo y sus preferencias ecológicas conocidas. ABSTRACT A preliminary analysis was conducted of the river types in the GUADALMED project using the river typology proposed in the Water Framework Directive (WFD) in its annex 2. Using System A, 16 different types were found, a number too high for water management purposes and such typology lacks a supportive ecological basis. For 5 of these 16 ecotypes, no reference stations exist. Reference stations were selected a priori in project GUADALMED for each of the 12 basins sampled. An ecotypological analysis was performed using System B of the WFD using several variables measured during the study, and other variables obtained from maps or data bases (e.g., geology). The method included the analysis of the calibration between variables, the clustering of stations by the K-means method and a discriminant analysis. The latter revealed which factors were distinctive of each group. Six ecotypes were established for the GUADALMED study sites. These, however, do not include all the mediterranean-type streams of the region. This is mainly due to the absence in the data base of some important features of streams in the data base such as temporality or the dependence of flow on the presence of karstic aquifers, attributes

Algas de una laguna salobre mediterranea (Lago di Patria, Napoles)

Algas de una laguna salobre mediterranea (Lago di Patria, Napoles) Margalef, Ramon, 1919-2004 Lista de especies de algas identificadas en los ambientes salobres constituidos por el Lago di Patria, una laguna salobre próxima a Nápoles y diversas zanjas y charcas próximas. El conjunto de la flora y las comunidades son comparables a las que se encuentran en lagunas análogas de las costas francesa y española.

Community structure and water quality in Mediterranean streams of a Natural Park (Sant Llorenç del Munt, NE Spain)

Community structure and water quality in Mediterranean streams of a Natural Park (Sant Llorenç del Munt, NE Spain) Rieradevall i Sant, Maria; Bonada i Caparrós, Núria; Prat i Fornells, Narcís Se estudian las comunidades de macroinvertebrados de los ríos del Parque Natural de Sant Llorenç del Munt i la Serra de l'Obac (Barcelona, NE España) y su relación con las condiciones de flujo de los ríos. Hasta 78 localidades se visitaron en dos ocasiones (invierno y verano de 1996) y en 26 de ellas se tomaron muestras de macroinvertebrados. Mientras en invierno el 63 % de los kilÛmetros investigados tenía flujo continuo y menos del 1% estaba seco, en verano solo el 26% tenía flujo continuo, un 20% estaba totalmente seco y el resto presentaba pozas en su lecho. A pesar de ello el número de familias de macroinvertebrados fue de 54 en invierno y 94 en verano, siendo dominantes en este último caso los heterópteros, coleópteros, odonatos y dípteros, mientras que en invierno los tricópteros y plecópteros eran más diversos. En general, la comunidad presentó una estrategia trófica recolectora aunque la proporción de los ramoneadores y depredadores aumentó en verano. El estudio de las comunidades mediante el análisis de su abundancia en los dos perÌodos, mostró que las variables temporales (flujo, temperatura) o las relacionadas con el incremento de la producciÛn primaria (oxÌgeno, pH) explicaban la mayor parte de la variabilidad con los elementos mas reófilos propios de invierno y los leníticos de verano, mientras que otros factores fisicoquímicos no eran relevantes. Calculado el índice biológico BMWP' se demostró que los valores en verano eran superiores o similares a los de invierno lo que se explica por la mayor diversidad aunque la calificaciÛn individual de cada una de las familias encontradas en verano fuera menor que las halladas en invierno.

Evaluacion del estado trofico de tres cuencas interiores de Cataluña (Foix, Besos y Llobregat) mediante la vegetacion acuatica: Aplicacion de un indice trofico de resolucion generica (IVAM)

Evaluacion del estado trofico de tres cuencas interiores de Cataluña (Foix, Besos y Llobregat) mediante la vegetacion acuatica: Aplicacion de un indice trofico de resolucion generica (IVAM) Moreno Alcázar, José Luis; Heras, Jorge de las,; Prat i Fornells, Narcís; Rieradevall i Sant, Maria Durante abril de 2005 se realizó una campaña de muestreo de la vegetación acuática macroscópica en las cuencas de los ríos Foix, Besòs y Llobregat, sumando un total de 68 estaciones de muestreo. El objetivo principal fue evaluar el estado trófico de dichas cuencas mediante el índice trófico generado en España denominado IVAM (Índice de Vegetación Acuática Macroscópica). Se identificaron un total de 44 táxones, 8 géneros de Cyanophyta, 5 de Rodophyta, 2 de Xantophyceae, 3 de Bacillariophyceae, 15 de Clorophyta, 8 de Spermatophyta, 1 liquen y 2 briófitos (musgos y hepáticas). La cuenca del Llobregat fue la más diversa (37 t´axones), seguida del Besós (33) y el Foix (25). Los táxones más frecuentes fueron Cladophora, Vaucheria, Oedogonium, Apium, Rorippa y Oscillatoria, además de los musgos. Las fanerógamas fueron escasas, destacando los g´eneros Ranunculus, Zannichellia y Potamogeton. Los táxones que alcanzaron una mayor puntuación del IVAM (valor de tolerancia, vt = 8), aunque poco frecuentes, fueron Ranunculus, Cymbella, Rivularia, Nostoc, Tolypothrix, Chroococcus y Lemanea, todos indicadores de aguas oligotr´oficas. En aguas de buena calidad pero algo eutrofizadas (aguas mesotróficas, vt = 6), los táxones más frecuentes fueron Chara, Monostroma y Hildenbrandia, además de las hepáticas y un liquen. Según la calificación de los tramos en clases de estado trófico realizada por el IVAM, el 38.2% de los tramos presentaron una buena calidad (clases I y II) mientras que el 61.8% presentaron un estado trófico alterado (clases III, IV y V). La respuesta del IVAM a la concentración de nutrientes (fosfato, amonio, nitrito y nitrato) fue siempre significativa, destacando la alta correlación alcanzada con el ión fosfato (r = 0.71, p & 0.001), superior a la alcanzada por otros índices de diatomeas y macrófitos de resolución taxonómica específica. Este hecho confirma la ventaja de utilizar el IVAM en la evaluación del estado trófico de los ríos, ya que sin necesidad de alcanzar un nivel taxonómico de especie se obtiene una respuesta adecuada a dicha perturbación.

25-years of biomonitoring in two mediterranean streams (Llobregat and Besos basins, NE Spain)

25-years of biomonitoring in two mediterranean streams (Llobregat and Besos basins, NE Spain) Prat i Fornells, Narcís; Rieradevall i Sant, Maria Biological water quality changes in two Mediterranean river basins from a network of 42 sampling sites assessed since 1979 are presented. In order to characterize the biological quality, the index FBILL, designed to characterize these rivers" quality using aquatic macroinvertebrates, is used. When comparing the data from recent years to older ones, only two headwater sites from the 42 had improved their water quality to good or very good conditions. In the middle or low river basin sites or even in headwater localities were river flow is reduced, the important investment to build up sewage water treatment systems and plants (more than 70 in 15 years) allowed for a small recovery from poor or very poor conditions to moderate water quality. Nevertheless still a significant number (25 %) of the localities remain in poor conditions. The evolution of the quality in several points of both basins shows how the main problems for the recovery of the biological quality is due to the water diverted for small hydraulic plants, the presence of saline pollution in the Llobregat River, and the insufficient water depuration. In the smaller rivers, and specially the Besòs the lack of dilution flows from the treatment plants is the main problem for water quality recovery.

Substrate and depth preferences of macroinvertebrates along a transect in a Pyrenean high mountain lake (Estanh Redo, NE Spain)

Substrate and depth preferences of macroinvertebrates along a transect in a Pyrenean high mountain lake (Estanh Redo, NE Spain) Rieradevall i Sant, Maria; Bonada i Caparrós, Núria; Prat i Fornells, Narcís Se estudia la composiciÛn y estructura de la comunidad de macroinvertebrados a lo largo de un transecto en profundidad en el lago Redó (Pirineos). Este estudio se enmarca dentro del proyecto de ámbito europeo MOLAR (Mountain Lake Research). Un equipo de buceadores muestreo dos tipos de substrato, piedras y fondos blandos, cada 2 m desde los 2 a los 20 m de profundidad. En la parte m·s profunda del lago las muestras se tomaron con draga Ekman (tres rÈplicas). Todas las muestras se tomaron el mismo día, el 15 de Julio de 1997. Los resultados, mediante un análisis de autocorrelación de Mantel, muestran que no existe un gradiente continuo en la sustituciÛn de unas especies por otras en la comunidad sobre substrato rocoso, sino que se distinguen dos discontinuidades claras, una a los 4 metros y otra a los 14 metros. La primera separa las especies propias de la zona litoral respecto a las de la zona sublitoral, mientras que la segunda coincide con la parte inferior de la termoclina, una zona siempre mas frÌa, con menos luz y con mayor acumulación de material fino sobre los sustratos duros a la vez que desaparece la cobertura algal que cubrÌa las piedras hasta esta profundidad. Respecto al sustrato existen especies que claramente prefieren el sustrato blando (oligoquetos, o los quironÛmidos Micropsectra radialis y Pseudodiamesa nivosa), mientras que otras eran más abundantes o exclusivas de los sustratos duros (Radix peregra, Plectrocnemia laetabilis, Psectrocladius octomaculatus). Estos resultados seran muy útiles para la interpretaciÛn de los datos paleolimnolÛgicos de los cores que actualmente se est·n estudiando en el lago.

Bryozoans of Banyoles lake

Bryozoans of Banyoles lake Rieradevall i Sant, Maria; Busquets, Josep M. Data for bryozoan species from Banyoles lake (NE Spain) are presented. Three species have been recorded: Fredericella sultana, Lophopus crystallinus and Plurnatella repens, the first two for the first time in the Iberian peninsula. An examination of the F. sultana colony and the statoblast observations of L. crystallinus and P. repens with the scanning electron rnicroswpe made possible the identification. Details of the floatoblast structure are given.

Deriva nictemeral de macroinvertebrados en el rio Llobregat (Barcelona)

Deriva nictemeral de macroinvertebrados en el rio Llobregat (Barcelona) Rieradevall i Sant, Maria; Prat i Fornells, Narcís A study on the qualitative and quantitative coniposition of macroinvertebrate drift in the Llobregat river ( N E Spain) is put fonvard. Samples were taken hourly during a 24 hour period in august 1982. The samples were taken with a net of 625 cm. of filtering surface and an opening mesh size of 500 microns, which íiltered 72,1 m3 /h. and collected 75.719 individuals during the sampling period. That means a drift rate of 1.224 indiv./h. and a drift density of 17 indi/m3 . 8 I0/o of the organismes collected were exuviae, mainly pupal chironomid skins (54%) and nimphal ephemeroptera moults (27(Ynj. The remainder percentage of living organisms represents a drift rate of 227 indiv./h. and a drift density of 3.14 indiv./m3. These are intermediate values ifwe compare them with the data published. Sixty per cent of the living drift were chiroiiomids. 17.5 '1 ephemeroptera and 10 (%1 trichoptera; these being the niost iniportant groups. Ofthe 87 species identified in those groups 23 were common in al1 the (7 1 ) samples (Table 1)

Temporalidad y contaminacion como claves para interpretar la biodiversidad de macroinvertebrados en un arroyo mediterraneo (Riera de Sant Cugat, Barcelona)

Temporalidad y contaminacion como claves para interpretar la biodiversidad de macroinvertebrados en un arroyo mediterraneo (Riera de Sant Cugat, Barcelona) Bonada i Caparrós, Núria; Rieradevall i Sant, Maria; Prat i Fornells, Narcís En Octubre de 1995 se estudiaron 10s macroinvertebrados acuaticos en varias localidades de la cuenca de la Riera de Sant Cugat (Barcelona) situadas dentro y fuera del Parque Metropolitan0 de Collserola y, se relacionaron con la calidad y la temporalidad de las aguas. Gran parte del recorrido de 10s cauces estaba sec0 en el moment0 de estudio. Algunas localidades, situadas en 10s limites del Parque, poseian flujo permanente per0 con elevados signos de contaminacibn. Dentro del Parque se encontraron algunas zonas con caudal permanente, aunque reducido (desde menos de 1 V s hasta 32 Us), y zonas con flujo intermitente, ademas de 10s que estaban secos. En las quince localidades muestreadas se encontraron un total de 65 taxones distintos; la mayor riqueza en una sola estacidn fue de 33 y se encontraron tanto especies de zonas redfilas (simlilidos o algunos efemerdpteros) como aquellas m8s propias de aguas 16nticas como hemipteros, odonatos o algunos cole6pteros. Mediante un anhlisis de ordenacidn en el espacio se agruparon las estaciones y se ordenaron en funcibn de su flujo y del grado de polucibn, diferenciindose claramente las estaciones externas al parque (con flujo moderado y cierta contaminacidn) de aquellas situadas en el interior del parque y, entre Cstas, las de flujo permanente respecto a las encharcadas. Se analizaron las diferencias entre estos cuatro grupos segun 10s tipos de organismos existentes y su estrategia trófica. A pesar de que muchos puntos de muestreo presentaban poca agua, se refuerza la idea de la importancia de mantener 1os flujos minimos de estos rios para conservar la biodiversidad.