This paper presents a description of the hitherto unknown larva of Drusus muelleri McLachlan, 1868. Information on the morphologicaland genetic identification of this species is given, and the most important diagnostic features are illustrated. Its systematicposition within genus Drusus is affirmed and some zoogeographical and ecological notes are added.

L'utilisation des microhabitats par le vairon, Phoxinus phoxinus (L.), le goujon, Gobio gobio (L.) et la loche franche, Barbatula barbatula (L.) a été étudiée en conditions d'étiage d'hiver et d'été dans trois rivières du sud-ouest de la France : l'Ariège, la Nive et le Gave de Pau. Les poissons ont été échantillonnés par pêche électrique selon la méthode de l'Echantillonnage Ponctuel d'Abondance. Onze variables du milieu ont été prises en compte pour décrire l'environnement ponctuel des poissons. Pour chaque rivière, les associations interspécifiques et espèces-variables du milieu ont été calculées et comparées en fonction de la saison.Des variations saisonnières de l'utilisation du microhabitat et des associations interspécifiques ont été observées sur les trois rivières. La nature du substrat et la présence d'abris végétaux jouent un rôle important dans la microrépartition du vairon, du goujon et de la loche franche. Ces structures offrent aux poissons des habitats de refuge et de nutrition privilégiés.

Using several clonal lineages of Simocephalus vetulus (Cladocera, Daphniidae) as a random sample, we investigated the genetic component of the halotolerance of one brackish and two freshwater populations of this littoral filter feeder. We hypothesized that genotypes from the brackish population were more tolerant than freshwater ones, via adaptation to local environmental conditions. Clonal identity was established by a cost-effective molecular fingerprinting technique (microsatellite-primed polymerase chain reaction (MSP-PCR)). Two distinct methodologies were used to assess cladoceran sensitivity to synthetic-grade sodium chloride (NaCl): (i) standard 48-h acute assays and (ii) 12-h survival time (ST) trials. No correlation was found between acute EC50 and ST values. The sensitivity of brackish and freshwater clones was comparable in terms of acute EC50 (varied from 2.28 to 3.83 g.L−1). On the contrary, genetically determined differential tolerance to NaCl among populations was found for ST: all brackish genotypes, except one, were more resilient (ST>120 min) than freshwater clones (ST<120 min). Bearing in mind that these results were obtained with isolates from the extant population, it is surprising that the range of acute sensitivity of the freshwater and brackish genotypes was similar, and that the only difference between them was the ability of brackish clones to survive longer under high salinity stress (6 g.L−1, in ST trials). We must conclude that the effect of salinity (original environment context) on the selection of genotypes was weaker than we had expected and than other authors have shown for other stressors.

In running water, the main natural factor of disturbance is hydraulic. Investigation of its biological impact is currently complicated by the increase of anthropogenic disturbances which tend to mask the natural functioning of rivers. Monitoring of the impacts of the artificial alterations undergone by the Middle Rhone River for some decades took place in the mid-1980s. Discharge and temperature could constitute the major events controlling the biological dynamics in terms of variations in species richness, diversity, and abundance. The between-years changes of the structure and diversity of macroinvertebrate communities were connected with the amplitude of discharge fluctuations. This was in accordance with the disturbance-diversity concept and it seems to confirm the intermediate disturbance hypothesis. The fish community mainly depended on hydroclimatic factors that influenced breeding success. Variations in nutrient input played a secondary role in controlling changes in some communities (particularly the periphyton). Therefore it appears that the study of long-term changes in river systems, including the dynamics of their biological communities, requires continuous observations and data collection that only medium- to long-term studies can provide, implying the setting up of ecological monitoring centres for the natural environment such as the Long Term Ecological Research (LTER) sites in United.

Blooms of Ceratium hirundinella (O. F. Müller) Bergh. have been detected in different water bodies in the Neotropical Regionsince 1990. The colonization began in southern lakes, and during the last decade the dinoflagellate arrived and bloomed in subtropicalreservoirs. In this context the colonization of C. hirundinella and its population development have been analyzed fromits first record in the Río Tercero Reservoir (February 1999 to February 2001). Phytoplankton and physicochemical sampleswere obtained from three sampling stations at the Reservoir, one in the outlet of the water cooling channel of the nuclear powerplant, and one in the nearest tributary (Quillinzo River). Two blooms of C. hirundinella were detected during the warm seasonswith temperatures higher than 18°C, and pH ranging between 8.5 and 8.9. Environmental conditions such as certain light intensityrange and percentage of dissolved oxygen mentioned as favorable for Ceratium development were always recorded in RíoTercero Reservoir. Cysts were observed in spring and summer months. Another dinoflagellate (Peridinium gatunense Nygaard)bloomed in previous summer in this water body but its population density decreased during the invasive phase of colonizationof C. hirundinella. Asplanchna girodi, became the dominant zooplankter after the first bloom of C. hirundinella. We believe thatthe presence of this dinoflagellate in the Neotropical Region could be a regional phenomenon associated with some dispersalmechanisms and favorable local conditions for its proliferation like those recorded in the Rio Tercero Reservoir.

Studies in tropical streams are relatively few, and one of the still-unresolved methodological issues is sample size. Adequate sample size for temperate streams cannot be extrapolated for tropical sites, because of the differences in species richness and the proportions of rare species. We evaluated reliable sample size for estimation of resemblance among samples of macroinvertebrate assemblages inhabiting riffles of tropical streams, using the autosimilarity approach. Sample sizes were much larger than those currently employed in tropical studies. Sampling units consisted of individuals associated with single stones (15–20 cm). Evaluations employed the Bray-Curtis index for abundance data and the equivalent Sorensen index for presence-absence data. Autosimilarity curves were constructed using both sampling units and individuals. The estimation of resemblance among samples was strongly dependent upon sample size at reduced sampling effort, particularly for the Bray-Curtis index. For the same sampling effort, fixed counts of individuals obtained randomly from sampling units gave better estimations of resemblance, and their similarity curves tended to stabilize earlier than those using sampling units. A minimum of 9–15 sampling units (stones) or 150–850 individuals is necessary for adequate estimations of resemblance using presence-absence data, and 13–18 sampling units or 750–1550 individuals are required for relative abundance data in tropical streams.

Des prélèvements par pompage manuel, faits depuis un an au voisinage du niveau piézométrique à partir de six stations d'étude, permettent d'intéressantes remarques sur le peuplement du « Rhône souterrain » en amont de Lyon :

- grande diversité zoologique (des Hydraires aux Insectes) et forte densité en individus (plusieurs centaines par 100 litres d'eau), variable selon les stations et selon les saisons.

- certaines formes phréatobies ont été récoltées, jusque là totalement inconnues dans la région (Potamodrilus, Salentinella, Niphargopsis, Siettitia, etc.).

- la structure biocénotique est complexe, avec la présence conjointe d'espèces phréatobies, troglobies et épigées aquatiques et terrestres ; cela souligne 1'"effet de lisière" de cet écosystème qui a des affinités autant avec l'eau libre voisine qu'avec l'eau souterraine plus profonde.

Despite numerous previous studies, relationships between watershed land use and adjacent streams and rivers at various scales in Korea remain unclear. This study investigated the relationships between land uses and the physical, chemical, and biological characteristics of 720 sites of streams and rivers across the country. The land uses at two spatial scales, including a 1-km buffer and the base watershed management region (BWMR), were computed in a geographical information system (GIS) with a digital land use/land cover map. Characteristics of land uses at two spatial scales were then correlated with the monitored multidimensional characteristics of the streams and rivers. The results of this study indicate that land use types have significant effects on stream and river characteristics. Specifically, most characteristics were negatively correlated with the proportions of urban, rice paddy, agricultural, and bare soil areas and positively correlated with the amount of forest. The site-scale and BWMR-scale analyses suggest that BWMR land use patterns were more strongly related to ecological integrity than they were to site land use patterns. Improving our understanding of land use effects will largely depend on relating the results of site-specific studies that use similar response techniques and measures to evaluate ecological integrity. In addition, our results clearly indicate that the characteristics of streams and rivers are closely linked and that land use types differentially affect those characteristics. Thus, effective restoration and management for ecological integrity of lotic system should consider the physical, chemical, and biological factors in combination.

La concentration du milieu en carbonates alcalins, entre 1 et 18 g 1-1, n'affecte pas le taux intrinsèque d'accroissement naturel de B. dimidiatus qui dépend essentiellement de la température et de la qualité de la nourriture offerte. Les taux de croissance les plus élevés sont obtenus avec les Cyanophycées Chroococcales (Synechococcus cedrorum) ou des Chlorophycées Volvocales (Dunaliella salina) unicellulaires de petites tailles. La température agit peu sur le taux net de reproduction et le fort taux intrinsèque d'accroissement naturel à 30° est dû au raccourcissement des temps de développement embryonnaire et post-embryonnaire ainsi qu'à la rapidité du rythme de ponte.

We investigated benthic macroinvertebrate communities in three contrasting habitats of a large shallow lake from February to November 2009. The three habitats differed markedly in their environmental characteristics (e.g., trophic status, substrate type, wind exposure). A total of 36 species were collected from the three habitats. The calculated descriptors (abundance, biomass and Pielou evenness index) differed significantly among the habitats. Generally, Tubificidae, Bivalvia and Gastropoda dominated the benthic community in abundance and biomass, but they varied greatly in abundance among the habitats. Analysis of similarities (ANOSIM) and non-metric multidimensional scaling (NMDS) analyses revealed significantly different macroinvertebrate assemblages among the habitats. North Bays had the lowest biodiversity and were exclusively dominated by pollution-tolerant species (e.g., Limnodrilus hoffmeisteri and Rhyacodrilus sinicus). Communities in the open lake contained intermediate biodiversity and were characterized by five species belonging to several taxonomic groups (e.g., Corbicula fluminea, L. hoffmeisteri and Gammarus sp.). Macrophyte-dominated habitats (East Bays) presented the highest diversity and evenness and were mainly characterized by gastropods. A canonical correspondence analysis (CCA) demonstrated that habitat-specific differences in trophic status, pollution level, wind-induced disturbance and macrophyte distributions were highly correlated with macroinvertebrate community structure.

Mediterranean temporary ponds (MTPs) are highly distinctive habitats with intermittent and unstable environmental conditions,inhabited by several rare and endemic plant and animal species. Temporary pond ecosystems have been classified asendangered all over the world; nevertheless, they are disappearing at a high rate, especially in the Mediterranean region. MTPsare a priority habitat under the European Union Habitats Directive and thus appropriate management and conservation effortsshould be applied. Further research is needed in order to better understand the environmental characteristics and ecology of thishabitat which is not always the case in many countries. In this study a range of environmental data were collected from the GreekMTP habitat sites including the altitude, the geology, the representativity, the ecological status and other biological data aimingto assess the environmental status of all known Greek MTPs. Statistical analysis were performed and thematic maps were createdusing a Geographical Information System (GIS). Greek MTP’s were classified according to their characteristics and habitatpressures were identified and further analysed. A comparison between the present environmental status of the MTPs in Greecewith the MTPs in other Mediterranean countries was undertaken and relevant conservation and management measures were proposed.The outcome of this study was that a significant percentage of the MTP habitat sites in Greece are at risk mainly due tohuman activities, such as agricultural pollution, expansion of cropland and water resources over-exploitation. It was concludedthat immediate restoration and conservation actions should be taken so as to prevent further ecological degradation.

The testate amoebae communities living among different species of mosses in Sphagnum peatlands in eastern Poland were studied. Sampling was done on a monthly basis from April to November 2005-2007. To assess the importance of the vertical distribution of testate amoebae within the mosses, each sample was cut into two parts: the upper living part (1-5 cm) and the lower dead part (5-10 cm). The highest species richness occurred in hollows dominated by Sphagnum angustifolium, Sphagnum flexuosum and Sphagnum palustre. Lower numbers of taxa were observed in hummocks dominated by Sphagnum magellanicum, Polytrichum strictum and Polytrichum commune. There was a distinct horizontal micro-zonation of the abundance of testate amoebae occurring among Sphagnum mosses, but only a small difference ascertained among Polytrichum. The number of testate amoebae was significantly greater in the deeper samples. The results demonstrated that depth to water table, pH and total organic carbon can strongly regulate the abundance and taxonomic composition of testate amoebae.

Zooplankton biomass was investigated monthly from September 1997 to August 1998 in a shallow eutrophic lake (San Miguel del Monte, Argentina). Duplicate samples of zooplankton were obtained from three stations with different limnological characteristics. The density of zooplankton community was dominated by rotifers and small cladocerans related to the trophic status of this shallow lake. The zooplankton biomass showed similar values to other eutrophic shallow lakes. The annual biomass distribution was bimodal (winter and summer peaks). The contribution of crustaceans, mainly copepods, determined the total biomass. The total zooplankton biomass was significantly correlated with chlorophyll «a» in the sampling station located at the deep part of this shallow lake. There were factors and processes promoting changes in the zooplankton biomass, such as food availability, grazing ability, fish predation, eutrophication process with alternation of turbid and clear water periods, and also the addition of organisms from the Salado River during floods.

1. The importance of microhabitat characteristics for macroinvertebrate microdistribution was studied within a reach of themain channel of the Upper Rhône River (France). 9 locations (3 on the left hand side, 3 across the middle, and 3 on the righthand side) were sampled twice on two dates (as duplicates in June and July 1982). From 19 variables, including substratum andhydraulic parameters, 14 were selected to describe the physical habitat of each location. 47 macroinvertebrate species were collectedby means of dredging with a modified Rallier du Baty dredge. The habitat-fauna co-structure was studied using co-inertiaanalysis.2. The river reach was transversally asymmetrical : shallow on one side (up to 2.80 m) with coarse sediments rich in periphyton,and much deeper on the other side (up to 4.80 m) with a gravel bottom rich in organic particles. In the middle of thechannel these conditions were intermediate, but the current was stronger. Velocity and the other hydraulic parameters variedindependently of the substratum characteristics. This independence is a consequence of old man-made impoundments (inheritedstructures) and perhaps of present paving of the substratum also.3. The macroinvertebrate fauna was closely linked to this transverse asymmetry of the reach, with the highest richness andabundance to the shallow side of the channel and the lowest species richness in the rapid central part. The most significant faunisticdifferences were linked i) to water depth, acting on both hydraulic parameters and periphyton (by light transmission), ii)to the inherited old bottom substratum, and iii) to a lesser extent, to the present current velocity.

We tested the individual and joint effects of stream order, riverbed morphology (i.e. pool-riffle sequence), and season on the structural (i.e. species composition, density and richness) and functional (i.e. percent ratio of shredders, collectors, scrapers, and predators) properties of caddisfly assemblages in a closely natural headwater system (Börzsöny Mts., North Hungary). Each factor, both individually and in interaction had a significant effect on caddisfly assemblages as shown by MANOVA analyses. To clarify the effects of stream order, riverbed morphology and season on caddisflies, assemblage properties were also separately studied by ANOVAs. Percent ratio of shredders and collectors were strongly affected by all factors, whereas other attributes were not always sensitive to stream order, season and riverbed morphology. In contrast, species compositions of the reaches differing in stream order and riverbed morphology were significantly different. Our findings on the contrasting differences in shredder composition between riffles and pools may suggest that not only riparian vegetation, but also instream habitat features could shape the accumulation and retention of particulate organic matter (in streams with pool-riffle heterogeneity).

Major pigment patterns of 18 chlorophyceae, 7 charales, 4 euglenophyta, and 2 dinophyta isolated from freshwater ecosystems, were investigated by means of HPLC. In this study, quantitative results are presented, too, which are capable for phytoplankton quantification techniques based on pigment patterns. Chlorophyceae revealed a pattern similar to that of higher plants, but in some strains, loroxanthin as well as α-carotene were present. In charophytes, except for vegetative specimens of Chara tomentosa, γ-carotene was detected in antheridia only. Among investigated freshwater euglenophytes diadinoxanthin was the major carotenoid, with neoxanthin and ß-carotene present in minor amounts. Besides chlorophylls-a and -c, dinophytes contained high quantities of peridinin, whereas fucoxanthin was absent. An unknown component eluting just before violaxanthin showed a spectrum reminding of peridinin.

We studied the effects of a waste water treatment plant on organic matter dynamics in Fosso Bagnatore, a Mediterraneanstream near Rome (Italy). Concentrations of dissolved organic carbon and seston, along with the standing crops of coarse benthicorganic matter and fine benthic organic matter, were monitored monthly during 2002 in two reaches situated upstream anddownstream of a waste water treatment plant effluent. Additionally, we examined two stream functional characteristics: wholestream metabolism, which was measured from diel changes in oxygen concentrations, and nutrient removal, which was studiedby experimental additions of NH4-N, NO3-N and PO4-P. The possible influence of WWTP organic matter alterations on ecosystemfunctioning was addressed by measuring epilithon characteristics (standing crop, C:N:P ratios and chlorophyll a content).The WWTP effluent caused an increase (several-fold) of DOC and seston concentrations, and FBOM standing crop, moreoverit modified their temporal variation. Downstream of the wastewater treatment plant we detected an higher heterotrophic microbialbiomass and a correspondent higher community respiration. The uptake of NH4-N, NO3-N and PO4-P was highly variableprobably as consequence of the high variability of the compartments involved (e.g. DOC, FBOM, community respiration). Weshowed that WWTP effluent altered the organic matter dynamics of this Mediterranean-type headwater stream and that theseeffects were reflected in its ecosystem functioning. Because of the linkage of headwaters to downstream ecosystems and due totheir significant role in landscape and catchment processes, the alterations of organic matter dynamics that we detected at a localscale may have important consequences on a broader scale.

The epikarstic waters of a restricted sector of the Ojo Guareña cave (north Iberian Peninsula) were investigated to characterizethe physico-chemical variation in an annual cycle, to improve the scarce knowledge of the aquatic cave fauna on the IberianPeninsula, to look for distribution patterns of species per habitat along the annual cycle, and to search for the environmentalbasis (either physico- or hydro-geochemical) that could explain species distribution in the epikarst. The habitats studied includedall puddles and gours present in the sector selected making a total of 51 chemical and 42 biological samples for the entirecycle. The waters show no appreciable contaminationand exhibit small chemical variations throughout the year which arepatently affected by external weather conditions. The 53 taxa found belong to ten higher taxonomic groups (Oligochaeta,Turbellaria, Mollusca, Copepoda, Ostracoda, Isopoda, Bathynellacea, Tardigrada, Acarina and Cnidaria), and consist mainly ofcrustacea with a total of 27 species. Fourteen species were stygobionts (belonging to ten genera), nine of which are new to scienceand ten of which are endemic. Cave pools that appeared to be more stable in terms of water volume and mineralization, hada lower pCO2 and were carbonate oversaturated, harboured the greatest number of taxa. It is these pools that can maintain strictlycave dwelling species. Pools with lower levels of mineralization and greater water volume fluctuations had a lower diversityof fauna and in general lacked stygobiotic species.

Nine biological indices based on the macroinvertebrate community inhabiting rivers have been calculated in order to find out which of them is more appropriate to evaluate the qualitative status of the running water for public environmental authorities. The BMWP' score (Alba-Tercedor & Sánchez-Ortega 1988) has been chosen because it is both accurate and precise, and easy to calculate. Some problems derived from sampling strategies are discussed.

Landscape is important in determining the composition of aquatic assemblage, and benthic invertebrates, particularly Chironomidae, are often used as bioindicators of environmental quality because their occurrence and distribution are influenced by different land uses. The objective of this study was to evaluate the influence of different land uses, considering three landscape scales (drainage basins, riparian buffer and streams), on chironomid assemblage. We sampled streams located in an agricultural matrix by collecting chironomid larvae and water samples and performed a landscape analysis using Geographical Information System techniques. The drainage basins had a high percentage of agricultural land use; in all of the drainage basins studied, 79% of the riparian buffer was not in accordance with Brazilian law. Cricotopus proved to be a good indicator of the agricultural conditions, whereas Thienemanniella and Rheotanytarsus proved to be indicators of exposed soil. Lopescladius was more sensitive to disturbance and was positively correlated with the presence of riparian vegetation. Although the variables at the local scale (stream) were responsible for a major change in the assemblage, the landscape attributes at large scales (drainage basin and riparian buffer) generated significant effects on Chironomidae fauna. Our results suggest the importance of the conservation of two larger landscape scales to support the equilibrium and maintenance of aquatic assemblage.