bo ok of abstracts Oral Communications 3 Posters 59 Author index 116 Oral Communications EF.16 AE.8 SS4.4 Abelho, Manuela Abrantes, Nelson; Serpa, Dalila; Keizer, Jan J.; Cassidy, Joana; Abril, Meritxell1; Menéndez, Margarita1; Barceló, Milagros1; Ca- Cuco, Ana P.; Silva, Vera; Gonçalves, Fernando; Cerqueira, Mário sas, Joan P.2; Gómez, Lluís1; Muñoz, Isabel1 CFE · Centre for Functional Ecology & Escola Superior Agrária, Instituto Politécnico de Coimbra Department of Environment and CESAM, University of Aveiro, Campus de 1Department of Ecology, University of Barcelona; 2Catalan Institute for Water Santiago, Portugal Research (ICRA), Girona, Spain EFFECTS OF MIXTURES ON LEAF LITTER DECOMPOSITION: METHODOLOGICAL AND HABITAT INFLUENCES ASSESSMENT OF RIVER WATER QUALITY USING AN INTEGRATED CONSEQUENCES OF WATER FLOW REGULATION ON ECOSYSTEM PHYSICOCHEMICAL, BIOLOGICAL AND ECOTOXICOLOGICAL FUNCTIONING IN A MEDITERRANEAN WATERSHED The effect of mixing litter on decomposition and colonization APPROACH has been the focus of many studies carried independently in Mediterranean rivers are specially affected by flow regulation. terrestrial and aquatic ecosystems. Those studies are carried In order to maintain and improve water quality in European rivers, This drastically modifies the system morphology, creating a out in different regions, use different experimental protocols the Water Framework Directive (WFD) requires an integrated new structure based on an alternating series of lentic and lotic and methodologies for the assessment of additive or non- approach for assessing water quality in river basins. Despite aiming reaches that interrupt flow connectivity. The aim of this study additive effects and the conclusions on the effect of mixtures at a holistic understanding of ecosystem functioning, the WFD fails is to assess the variability caused by flow discontinuity on the vary accordingly. In this study I tested the hypothesis, via a to explicitly establish cause-effect relationships between stressors ecosystem functioning at a watershed scale, using the breakdown short-term decomposition experiment, that, when using the and changes in aquatic communities. To overcome this limitation, process as a functional indicator. We expect variability in the same experimental protocol, mixtures have similar additive the present study combines an ecotoxicological approach with process along the fluvial continuum, with higher breakdown rates effects on decomposition and associated biota in a stream and the typical WFD physicochemical and biological approaches. The in lotic reaches and as the stream order increases. To achieve at its riparian zone. The effect of mixing litter was assessed by main goal was to assess river water quality through an integrated this objective, we have studied the mass lost from wooden sticks comparing values in mixtures with the average of single-species, manner, while identifying potential risk situations for aquatic during 3 months in different lotic and lentic sites located along alder and poplar (method 1); comparing the value of a species in communities in the Cértima river basin (Portugal). To achieve this a Mediterranean watershed, both in winter and summer. The mixture with the value of that species alone (method 2); and by goal, surface water samples and macroinvertebrate specimens results show differences on the rates of wood mass loss between a graphical analysis of the average difference between observed were collected at contrasting hydrological conditions (autumn and sites, either summer or winter. On one hand, in winter, lotic and expected values and the 95% confidence intervals (method spring seasons) at three river sites exposed to distinct pollution reaches display an increment in the breakdown rates with the 3). Method 1 was the most conservative, detecting non-additive levels defined according to the WFD (low, moderate and highly river order. Lentic reaches, however, have more homogeneous effects on macroinvertebrate abundance only; method 2 detected polluted). Physicochemical water quality status was defined rates along the watershed, so the differences between adjacent non-additive effects on both dry mass remaining and ergosterol, according to the Portuguese classification for multipurpose lotic and lentic bodies are only found downstream. On the other, with differential responses of the leaf species and the habitat; surface waters, whereas biological water quality was assessed in in summer spatial variability is also found in lentic reaches and method 3 detected non-additive effects on all variables accordance with the South Invertebrate Portuguese Index (IPtIS). and there are not differences between adjacent lotic and lentic except macroinvertebrate biomass and also identified different Ecotoxicological assays included four standard species, a bacterial systems. Breakdown rates appear to be related to temperature, responses of the leaves exposed in the terrestrial and the aquatic species (Vibrio fischeri), a microalgae (Pseudokirchneriella concentrations of nitrogen oxides (NO2-, NO3-) and water habitats. These results show that (i) the methodology used subcapitata), a macrophyte (Lemna minor) and a crustacean residence time. Hydrological changes caused by flow regulation to detect the effects of mixtures deeply influences the results (Daphnia magna), which were exposed to different river water can interrupt temperature and nutrient gradients along the river, obtained, and may partially explain the diversity of responses concentrations. A clear and pronounced pollution gradient was affecting the natural ecosystem functioning at watershed level. available in literature; and (ii) the effect of mixtures may differ in identified between sites. Locations under moderate to high the stream and at the riparian area. However, the findings of the anthropogenic pressure presented clear signs of organic pollution, present work should be assessed in a larger-scale experiment in e.g. low dissolved oxygen, high nutrient levels and prevalence order to generalize the effects of mixing litter on terrestrial and of highly tolerant macroinvertebrate species, in contrast to the aquatic habitats. unpolluted reference site. Despite the evident signs of pollution, no clear evidence of toxicity was observed on test species, suggesting that ecotoxicological assays using standard laboratory species and methodologies might not be suitable for assessing the effects of organic pollution. Nonetheless, these results reinforce the importance of an integrated evaluation scheme combining standard WFD quality elements and an ecotoxicological approach for a realistic evaluation of river water quality. Thus, its wider use could contribute to a more comprehensive assessment of the effects of anthropogenic pollution on the status and functioning of aquatic ecosystems under the WFD, which is essential for risk assessment evaluations and for a sustainable management of freshwater resources. 4 RLWE.15 BB.10 SS5.2 Almeida, David1; Merino-Aguirre, Raquel1; Angeler, David G.2; Alonso, Miguel Alonso, Miguel1; Vega, José C.2 Serrano, José M.1 Departament d’Ecologia, Facultat de Biologia, UB 1Departament d’Ecologia, Facultat de Biologia, UB; 2Laboratorio de 1Department of Ecology, Complutense University of Madrid, Madrid 284, Limnología del Parque Natural del Lago de Sanabria Spain; 2Department of Aquatic Sciences and Assessment, Swedish University BRANCHIOPODS AND COPEPODS IN IBERIAN PENINSULA AND of Agricultural Sciences, Uppsala 757, Sweden MONGOLIA: SIMILARITIES AND POSSIBLE USE OF MONGOLIAN LONG TERM TROPHIC STATUS ASSESSMENT IN SANABRIA LAKE ONES AS REFERENCE CONDITIONS FOR ECOLOGICAL QUALITY SeASONAL AND SPATIAL PATTERNS OF BENTHIC INVERTEBRATE ASSESSMENT OF WATER BODIES IN SPAIN Sanabria lake is a middle mountain glacier lake located in COMMUNITIES BETWEEN REGULATED MEDITERRANEAN STREAMS north-west Spain, in Zamora province being the largest lake in AND THEIR NON-REGULATED TRIBUTARIES IN THE IBERIAN PENINSULA the Iberian peninsula. Since 1986 the lake has been object of A comparison of assemblages of Branchiopoda and Copepoda a detailed limnological monitoring, result of which a twenty six Flow regulation is perceived to negatively influence fluvial living in lakes and wetlands in two very distant territories in years monthly data series of trophic status indicators can be ecosystems through alterations of natural habitat conditions, the Palaearctic Region: Iberian Peninsula and Mongolia is presented. None of the mentioned indicators shows significant particularly in highly variable Mediterranean streams. However, presented. Both territories have significant similarities in the variations or tendencies along the whole temporal series. The the detection of adverse effects may depend on chosen metrics, hydromorphological and physicochemical characteristics of analyzed information allows to conclude that the lake has requiring a multiple-lines-of-evidence approach for ecologically their water bodies, and also in the structure and composition maintained its oligo-mesotrophic character since the beginning relevant impact assessment. Thus, the aim of this study was of their fauna of branchiopods and copepods. Some species of the monitoring. to compare the community structure, the trophic function, are coincident, others are taxonomically closely related the microhabitat influence and the body condition of benthic and others behave as ecological vicariants. Most of these invertebrates between a regulated Mediterranean stream, crustaceans