Sediment-water interactions play an important role in influencing the water quality of aquatic systems. Water quality managementof freshwater systems needs to take into account this behaviour, which depends largely on early diagenetic processes thatcondition the physical and biogeochemical properties of the sediment. Among these processes, the redox transformations resultingfrom the oxidation of organic matter by the microbial activity have a major influence on the biogeochemical properties of sediments.In particular, these reactions condition the vertical profiles of nutrient concentrations, pH and metals along the sedimentarycolumn. This paper presents a method which couples both experimental and modelling approaches in order to characterise andanalyse the biogeochemistry of freshwater sediments. The modelling approach is based on a coupling between biogeochemicalprocesses and interstitial diffusion. As pore water pH influences the behaviour of the biogeochemical species, we have extendedthese models to allow for the calculation of pH by taking into account the inventory of protons consumed or produced by differentbiogeochemical reactions. In parallel, an analytical protocol has been developed to obtain vertical distributions of the main physicochemicalparameters in natural sediments cores. To illustrate this approach, we apply our method to sediments cores sampled inthe Durance, a river in the south-east of France.

L'analyse des sédiments de quinze stations de l'Ill et de ses affluents a révélé l'existence de contaminations par les métaux lourds qui sont associées, dans la majorité des sites prospectés, à une forte charge en matières organiques. Les peuplements d'oligochètes inféodés aux sédiments fins sont dominés par des espèces résistantes à la pollution (Limnodrilus hoffmeisteri, Tubifex tubifex, Pristinella jenkinae...) ou ubiquistes (Aulodrilus pluriseta). Les fortes contaminations métalliques des sédiments sont généralement associées à des valeurs de l'indice oligochètes IOBS ≤ 1 et à des effectifs ≤ 1000.0,1 m-2. Elles sont corrélées négativement avec le pourcentage de Tubificidae avec soies capillaires et positivement avec le pourcentage de Tubificidae sans soies capillaires. Les métaux semblent perturber la reproduction in situ des oligochètes. Les adultes de Tubificidae sont en général moins résistants que les immatures et la stratégie de reproduction par voie asexuée pourrait constituer un facteur de résistance aux contaminations métalliques.

L'imago male de Rhithrogena ourika n. sp., récoltée dans le Haut Atlas (Maroc) est décrite et figurée. Il s'agit de la première espèce de Rhithrogena identifiée en Afrique du Nord.

Two greenhouses were operated as emergence traps in a stream in southwestern Lower Austria from 1984 to 1989 at a distanceof 28 m from each other. The stream bed under the traps was covered by a metal sheet alternately for one year, thus preventingemergence under the trap with covered bottom so that insects caught in this trap must have come from outside. Theresults have shown that insects from outside constitute a high but un quantifiable proportion of the total catch. In many instancesthere were more insects in the trap with a covered stream bed than in the open one. Therefore the emergence trap method is notadequate for quantitative surface-related studies, including secondary production.

Bosminopsis brandorffi, nouveau Bosminidae, se différencie de toutes les autres espèces du genre par l'importance de la région céphalique, l'absence de rostre, le grand développement de l'œil et des antennules, la présence d'un fort talon abdominal. Mâles et femelles ephippiales sont inconnus.

Lumbriculus illex sp.n. is described from the Komarovka Stream, north of Vladivostok. It differs from all other congeners in having single-pointed setae and very long spermathecal ampullae. L. sachalinicus Sokolskaya, 1967 is regarded as its closest relative.

Les larves de Drusus rectus et d'Anomalopterygella chauviniana sont décrites et figurées. Une clé de détermination est donnée pour distinguer les larves des quatre espèces pyrénéennes de Drusinae : Drusus discolor, D. rectus, Ecclisopteryx guttulata, Anomalopterygella chauviniana. Ces espèces présentent un comportement semblable d'oviposition, d'éclosion, de construction du fourreau, de mues larvaires et de nymphose.

An account is given of the chemistry and phytobenthos of streams in the vicinity of two old lead mines in the Hautes-Pyrénées south of Lourdes. All of the nine sites studied had elevated levels of aqueous Zn, and also in most cases of Cd and Pb. There was some evidence that increasing levels of heavy metals led to a decreased flora, but 30 species were recorded at sites with > 10 mg l-1 Zn. The most restricted flora occurred at a site with a conspicuous white precipitate, consisting largely of anglesite; here only three species were present: Schizothrix sp., Pohlia cruda, Solenostoma crenulatum.

The short-term stimulation of production, due to marine-derived nutrients (MDN) from spawning salmon, is well documented for certain trophic levels in stream communities (e.g., algae and insect biomass). The effect of these nutrients on the stream ecosystem as a whole, however, remains unclear especially later in the year. Trichopterans have been shown to feed on salmon and other fish carcasses and there is evidence for greater growth rates in the presence of salmon tissue. To address the question of long-term MDN subsidy on trichopterans, we investigated the growth of three limnephilid caddisflies in the spring in the Harris River on Prince of Wales Island, Southeast Alaska. The Harris River has a natural waterfall barrier to salmon and receives large runs of pink (O. gorbuscha) and chum (O. keta) salmon each fall. We selected two shredding caddisflies (Onocosmoecus unicolor) and (Psychoglypha spp.) and one facultative scraper, (Dicosmoecus atripes) for our study. We had two objectives : 1) compare the spring growth of larval caddisflies in a stream section that receives a large autumn run of salmon with their growth in a stream section that is blocked from receiving salmon (due to an impassable waterfall), and 2) compare the growth of shredders with that of a facultative scraper when provided either leaves or biofilm on rocks as food.

Insects were placed in growth boxes in May 2001 with either conditioned alder leaves or stream rocks as food sources. The boxes were placed along with temperature loggers in both the salmon (below the waterfall) and non-salmon (above the waterfall) reaches. The boxes were removed 40 days later. In-stream samples were taken of each caddisfly initially and at the end of the experiment to establish in-stream growth versus growth in the boxes. All larvae were coaxed from their cases, measured for total wet length, dried and weighed. Only D. atripes and Psychoglypha spp. were growing during our experiment and both showed very high relative growth rates in the Harris River. Psychoglypha spp. and O. unicolor were both significantly larger in the leaf boxes and D. atripes was significantly larger in the rock boxes. Both D. atripes and Psychoglypha spp. had significantly greater relative growth rates between food types (on biofilm on rocks and leaves respectively). These results support the notion that D. atripes are most likely facultative scrapers at least in their first year of growth. None of these caddisflies showed differences in their final mean weights or relative growth rates between stream sections, suggesting no effect of MDN on their spring growth in the Harris River. Further research on caddisfly communities in the fall and winter will help clarify if MDN has an influence on the abundance and life history of these species closer to the salmon run. This study questions the long-term influence of MDN on stream communities, particularly those populations that do most of their production in the spring, months after salmon carcasses are no longer visible.

Collections of ostracods from various habitats in and around Lake Inari, Finnish Lapland, provide the first record of these crustaceans from Finland north of the Arctic Circle. From a total of 35 sites visited, 14 species were collected, out of which four appeared to be new to Finland: Fabaeformiscandona lapponica, Pseudocandona pratensis, Eucypris pigra and Paralimnocythere relicta. Two major assemblage groups were recognised by clustering classification and multi-dimensional scaling ordination, one dominated by Cyclocypris ovum, the second by Candona candida. Taxonomic diversity of the most assemblages was of expected range based on the inventory of 53 freshwater species of Finland.

During the summers 1992 and 1993, 15 species of Clinocerinae (Empididae) were collected on Corsica. The illustrated descriptions of six new species are given: Roederiodes wagneri sp. n., Clinocera (Kowarzia) cataractae sp. n., Wiedemannia (Chamaedipsia) ariolae sp. n., Wiedemannia (Chamaedipsia) bravonae sp. n., Wiedemannia (Philolutra) kallistes sp. n. andWiedemannia (Wiedemannia) martini sp. n.. Their systematic relations with other species are discussed. Informations is given about their geographic distribution and their habitats.

The distribution and ecological data base of Vaucheria bursata, V. frigida, V. geminata, V. racemosa, V. erytrospora, V. canalicularis,and V. debaryana occurring in streams of the Kraków-Czestochowa Upland (Poland) are provided.

The distribution of 37 species of Plecoptera in the Spanish area of the Duero basin is studied. A factorial analysis ofthe data indicates that current and substrate are the major factors controlling the distribution of the stonefly nymphsin the area. Water temperature and periodical drought have also a marked influence on such distributions.

Des investigations malacologiques ont été réalisées en 1974 et en 1994-1995 dans trois prairies de la Haute-Vienne afin depréciser les caractéristiques des gîtes à limnées lorsque les parcelles sont abandonnées ou modifiées par l'application de mesures agronomiques. L'abandon d'une prairie et l'invasion de ragondins se sont traduits par des modifications dans la distribution des limnées. Lymnaea cf. fuscus a déserté le fossé principal de drainage pour coloniser les rigoles et les couloirs créés par ces rongeurs,ce qui s'est traduit par un accroissement important de la superficie du nouveau gîte. Les effectifs moyens de L. cf. fuscus et de L. truncatula ont augmenté aux dépens de ceux de L. glabra. Un autre mollusque aquatique, Physa acuta, a envahi le fossé laissé libre. Le curage des rigoles dans les deux autres prairies et leur invasion par une ou deux espèces aquatiques (L. ovata, Potamopyrgus antipodarum ou Physa acuta) se sont traduits par une extension dans la superficie du gîte aussi bien pour les mollusques colonisateurs que pour L. glabra et L. truncatula. Les effectifs des trois premières espèces sont assez importants dans ces deux rigoles ; par contre, on note une réduction du nombre des deux limnées.

La larve au dernier stade d'Ecdyonurus rothschildi Navás est figurée et décrite comparativement à celles d'E. aurantiacus (Burmeister) et d'E. dispar (Curtis).

Les cinétiques de traçage isotopique des échanges entre les ions phosphates en solution et les sédiments en suspensionpermettent de définir des indices caractérisant les potentialités de transfert du P entre les sédiments et l'eau. L'utilisation de cette méthode nous a permis de déterminer une quantité de phosphore isotopiquement échangeable dans différents types de sédiments ; cette valeur est fonction de la durée d'échange, fixée ici à 24 heures (E24).La dilution du sédiment provoque le passage en solution d'une fraction croissante de ce pool d'ions échangeables selon une loi Q = a.E24.Sb qui permet de calculer la concentration (Q) de phosphore dans l'eau connaissant la masse(S) de sédiments en suspension. L'épuisement du P le plus mobile et l'allongement de la phase d'adsorption qui résultent de la dilution du sédiment entraînent une modification des cinétiques d'échange.

Les effets des rejets de matières organiques sur les Oligochètes du Bief Rouge se traduisent par le développement de trois espèces qui prolifèrent au détriment des autres Oligochètes : T. tubifex, N. elinguis, S. heringianus (et, dans une certaine mesure, N. communis). Par contre, ni L. hoffmeisteri ni L. udeke-mianus n'atteignent de densités élevées. Tout en soulignant l'utilité des Oligochètes en tant qu'indicateurs de la qualité des eaux, l'auteur montre que les associations d'espèces polluorésistantes peuvent varier suivant le type de cours d'eau envisagé et son degré de contamination.

The larvae of three species of the Rhyacophila tristis group: Rhyacophila aquitanica, Rhyacophila pubescens and Rhyacophila tristis are described. A key is given. Revised data on their distribution in France are presented.

A strictly phylogenetic classification of the supergeneric taxa within the subfamily Timpanoginae includes the Attenellini, n.tribe, consisting of Attenella Edmunds ; the Eurylophellini, n. tribe, consisting of Dentatella Allen, n. stat., and EurylophellaTiensuu ; and the Timpanogini, n. tribe, consisting of Timpanoga Needham and Dannella Edmunds, n. stat. Dentatella danutae McCafferty, n. sp., is described from larvae taken from a stream in southern Québec, Canada. The new species differs from the obviously closely related D. bartoni (Allen) by possibly striking coloration differences as well as numerous slight structural differences.

Changes in body shape of the rotifer Keratella quadrata in a pond were recorded over the course of half a year (endof November 1981 to beginning of June 1982). Body and caudal spine lengths increased from November until the endof February, and then decreased until June. Such changes were not significantly correlated consistently positively ornegatively to water temperature, pH, hardness, food levels or copepod numbers. The individuals present during the firsthalf of the study period corresponded most closely to the literature descriptions of the group or subspecies quadrata,while those present during the second half resembled the form, group or variety dispersa. The first half of the studyperiod was characterized by water of relatively low temperature, low pH and high hardness, while, for the second half, temperature and pH increased and hardness decreased.