La liste de 93 espèces de Diatomées récoltées dans une source, un torrent froid et deux lacs du massif de Néouvielle est donnée. Le long du torrent et dans le lac de Port-Bielh, une zonation basée sur les Diatomées dominantes a pu être mise en évidence. L'influence des facteurs de milieu sur la répartition des espèces dominantes est discutée.

1) Le but de cette étude est de déterminer s'il existe, entre eurythermes et sténothermes, une différence de réaction métabolique à l'égard du réchauffement brusque, comme le laisse supposer une publication de SCHLIEPER [1950]. Une telle différence de réaction, traduisant une différence de sensibilité aux variations thermiques, serait susceptible d'intervenir dans la répartition de la faune entre les milieux à température stable et les milieux à température variable.

2) Des comparaisons intéressent chaque fois 2 ou 3 espèces voisines, à savoir les Turbellariés Crenobia alpina et Planaria gonocephala, les Crustacés Gammarus pulex, Asellus cavaticus et Asellus aquaticus, les larves d'Éphémères Baetis rhodani et Cloëon dipterum, enfin les Mollusques Ancylus fluviatilis et Acroloxus lacustris. L'un des termes de la comparaison provient d'un milieu stable (milieu généralement abrité, ou profond et agité), dans lequel la variation journalière est inférieure à 4° ; l'autre terme provient d'un milieu variable (milieu exposé et peu profond, zone superficielle des eaux stagnantes), dans lequel la variation journalière peut dépasser 9°.

3) Deux méthodes différentes servent, pour plus de sûreté, à déterminer la consommation d'oxygène des animaux : une méthode en milieu confiné, avec dosage de l'oxygène dissous selon WINKLER [1888] et Van DAM [1935], et la méthode manométrique de SCHOLANDER et EDWARDS [1942]. Les animaux disposent toujours d'un substrat rugueux.

Les deux méthodes font intervenir des conditions de milieu différant principalement par l'agitation de l'eau, le taux d'oxygène dissous et la fréquence du tranvasement des sujets. La consommation d'oxygène de Gammarus pulex et Crenobia alpina, par exemple, varie avec la méthode utilisée. Le réchauffement a davantage d'influence sur Asellus cavaticus en eau agitée et aérée. Chez Crenobia, l'aspect même de la réaction au réchauffement se modifie : la Planaire perd sa capacité de résistance lorsqu'elle se trouve en milieu stagnant.

Les conditions de vie au laboratoire et dans les appareils de mesure provoquent, chez plusieurs espèces, une modification graduelle du métabolisme dans un sens ou dans l'autre. Certaines espèces font preuve d'un rythme respiratoire. L'étude de la réaction au réchauffement exige donc l'intervention d'animaux-témoins, dont le comportement permet la correction des diverses réponses.

4) L'analyse de variance et le calcul des régressions interviennent pour déterminer le tracé des courbes-réponses au réchauffement et pour comparer les réactions des espèces entre elles.

5) Les résultats ne révèlent aucune différence systématique de comportement entre animaux de milieux stables et animaux de milieux variables, laissant donc à penser que les variations journalières de température ne jouent pas de rôle important dans la répartition de la faune aquatique. Les différences tendent plutôt à se manifester entre les représentants de groupes zoologiques distincts, car les graphiques mettent en évidence plusieurs traits communs aux deux Planaires, d'autres aux deux Crustacés épigés, d'autres encore aux deux Ephémères Baetidés.

Par ailleurs, l'étude fait apparaître ou confirme des particularités intéressantes de l'habitat et de la physiologie de plusieurs espèces, telles que la grande variabilité des milieux à Crenobia, la résistance temporaire dont cet animal et Planaria gonocephala sont capables de faire preuve à l'égard du réchauffement, la faible influence qu'exerce la température sur la respiration de Gammarus pulex et Asellus aquaticus, enfin la difficulté qu'éprouve Baetis rhodani à se procurer l'oxygène nécessaire, en dehors de son milieu naturel.

The macrobenthic fauna of the Rhône River below Lake Geneva was studied between 1983 and 1993 to describe patterns of longitudinal and temporal community changes. Sampling was based upon the use of artificial substrates in 11 stations. The confluence with the Arve (an alpine tributary) is the first source of faunal discontinuity, both in terms of species and feeding group composition. The Verbois hydropower plant is the second longitudinal disruption. From a temporal point of view, the construction of the Seujet hydropower plant was a major source of faunal fluctuation. After this event, and until the end of the study, lenitophilous taxa increased to the detriment of rheophilous taxa.

The tropical Matutinao River was investigated to study factors determining the distribution of the extant gastropods. Since ecological zonation and life-cycles are somewhat correlated, we followed both research avenues and in particular focused on early ontogenetic strategies, discriminated by detailed studies of corresponding shell features. Twenty-six gastropod species, almost all of which are distributed over whole Cebu Island, occurred in the small Matutinao River. The specific associations of river sections, and ecological demands and life-cycles of gastropods are characterized. Of special interest are planktotrophic neritoidean larvae, which are usually carried to the sea and develop in the marine environment, but in rare cases remain and successfullymetamorphose in freshwater. The biogeographic background and evolutionary consequences of the results are discussed.

The objective of the present study was to examine the colonization of oligochaetes during the decomposition of leaves of the macrophyte Eichhornia azurea in a lentic system in southeastern Brazil. The experiment was conducted between September and November 2007, with the use of 21 nylon bags measuring 15×15 cm with 2 mm mesh, each containing 10 g of dried leaves. The bags were removed from the lake after 2, 5, 8, 12, 25, 45 and 65 days. At the end of the experiment, 31.40% of the initial mass remained, and the decomposition rate was 0.018 d−1. The mean density of oligochaetes during the experiment was 32.81±9.58 ind.g−1 DM. The sub-families Naidinae and Pristininae accounted for 99.83% of the oligochaetes. The substrate quality influenced the colonization of E. azurea leaves, as observed from the cluster analysis by the formation of two groups based on increased density during the experiment, indicating a degradative ecological succession. During the decomposition there were changes in the community of oligochaetes, resulting from differences in the ability to exploit various food sources, with predominance of predators in the first decomposition phase and of collectors at the end of the experiment.

Morphology of both the valves and limbs of several parthenogenetic populations of the widespread non-marine ostracodCryptocandona vavrai Kaufmann (sensu lato) living in groundwater habitats of western (France) and south-eastern Europe(Romania) was examined for the extent of intra- and interpopulational variation. Geometric morphometrics and multivariatestatistics were employed for the description of the valve morphological disparity whereas the discriminant analysis wasperformed for the comparative analysis of the limb chaetotaxy. The ranges of the most studied limb traits principally overlappedamong the populations, however considerable differences in the carapace shape and size, reflecting microevolutionary changes ata macro-scale (inter-population) level, allowed distinguishing quantitatively some Romanian populations which deserve aseparate specific status. Hence, a new species Cryptocandona racovitzai sp. nov. is described which differs from C. vavrai sensustricto mainly in larger size, in more triangular valve shape as seen laterally and in less developed inner lamella of the valves.Finally, after examination of more material from Romanian groundwaters, we hypothesised the presence of more new specieswithin the studied lineage and concluded that Cryptocandona vavrai sensu lato is a polymorphic lineage consisting of severalgeographically differentiated species rather than just only one widely dispersed species.

Rangabradya n. gen. and Rangabradya indica n. sp. from the subterranean freshwaters of India axe described. The new genusbelongs to a group of genera in the family Ectinosomatidae Sars, 1904 possessing fusiform body shape and it is very similar tothe genus Halectinosoma Lang, 1944. The new genus has the exopodite and basiendopodite of the fifth leg completely fused,without surface seta, as well as a characteristic appearance of the antennula, antenna and maxilla. The position of the genusRangabradya n.gen. within the family Ectinosomatidae is discussed.

A second species of the genus Macrogynoplax, hitherto known only from northern South America, is described fromthe State of São Paulo, in southeastern Brazil.

L'influence des variations de la quantité de nourriture (de 5.103 à 1.107 cell.mL-1 de chlorelles) sur la dynamique de populations est étudiée à deux températures (16 et 24°C) chez trois espèces, Brachionus angularis, B. calyciflorus (représentée par deux clones) et B. plicatilis. En observant isolément une quinzaine de femelles, on évalue le taux net de reproduction, R0, le taux intrinsèque de croissance, rm, la quantité minimale de nourriture pour une croissance nulle, S0, et la concentration algale, Ks, nécessaire pour atteindre un taux de croissance maximale (ou la moitié). Les valeurs obtenues pour ces variables sont comparées entre elles et à celles de la littérature. La souche de B. plicatilis se singularise par des valeurs particulièrement basses. Les auteurs relient cette particularité au métabolisme propre à cette espèce adaptée à de fortes variations de salinité et de nourriture.

Headwater woodland streams are primarily heterotrophic: they receive substantial inputs of organic matter from the riparian vegetation, while autochthonous primary production is generally low. A substantial part of leaf litter entering running waters may be buried in the streambed because of flooding and sediment movement. Although the general significance of the hyporheic zone for stream metabolism has been reported early, organic matter storage within the sediment of streams has received less attention, with most studies only quantifying accumulations at the streambed surface and ignoring other stream compartments. In the present study, the amounts of three fractions of coarse particulate organic matter (CPOM; >16, 4–16 and 1–4 mm) were determined in late autumn and early spring in the interstitial and benthic zones of three headwater streams of the Montagne Noire (South-Western France) differing in their substratum grain size. Our findings demonstrated that the total CPOM content in the interstitial zone can be much (up to one order of magnitude) higher than at the sediment surface. The sandy bottomed stream exhibited a higher amount of CPOM (whatever the size fraction) than the two other streams, suggesting that the sediment particle size may be a major determinant of CPOM storage. Given the large amount of organic matter stored in the interstitial zone, this compartment may play an important role for the carbon turnover and associated trophic dynamics in the stream ecosystem.

White-clawed crayfish, bullhead, and freshwater pearl mussel are different model organisms in terms of biological traits.Analysing their distribution patterns, habitat demands, and causes of decline may thus help to derive broader frameworks forconservation projects. This paper includes a wide-ranging literature review for these three threatened freshwater animals, thenuses general patterns to make suggestions about broader protection measures for freshwater species. Each species has a patchydistribution, from local to broad spatial scales. However, we point out the difficulty to summarise such knowledge, because manyvariables were not consistently and/or accurately recorded by workers, and because the range of colonised habitats depends onthe environmental heterogeneity within study areas. Causes of decline are chiefly related to human activities which modify thebiological, chemical, and physical features of the aquatic environment, and can be classified into four types: physical habitatalterations, interspecific interactions, overfishing and poaching, and natural disturbance. By analysing causes of decline andpossible actions, we develop seven general trends that could be adopted for a wider array of species. However, protection planscannot be effective without actual collaborations between river managers, local inhabitants, and authorities. Finally, there-introduction procedure itself (if needed) depends on the biology of the species under survey, and remains specific. At the sametime, further fundamental research is needed to generalise relationships between population and habitat dynamics at differentspatial and temporal scales.

A new genus (Callibaetoides) and species (Callibaetoides caaigua) of Baetidae (Ephemeroptera) is described based on nymphs and adults of both genders collected in forested areas of Amazonia and Mata Atlântica biomes. The nymphs were collected from leaf packs accumulated in the backwaters of small streams. The genus and species can be easily distinguished from other members of the family in South America by the following combination of characteristics: male and female imagos with costal process of hind wing centrally located and strongly projected; marginal intercalary veins long and paired in male imago; nymphs with deep medial emargination of labrum, maxillary palp three segmented and third segment of labial palp quadrangular.

Fish assemblages inhabiting the mountain streams of the Guiana shield have scarcely been studied. Here we investigated fish assemblages in eight headwater mountain streams of the Mount Itoupé (French Guiana), and tested how local freshwater fish assemblages are shaped by environmental characteristics. We show that Mount Itoupé streams host uneven species assemblages, characterized by low species richness (less than ten species per site) and a high proportion of small Siluriform species. Differences in fish assemblage composition between the sites were mainly due to basin identity, but regional climate and position of the site in the river gradient also had a significant effect, although of lower magnitude. In contrast, local habitat hardly affected fish richness, abundances or assemblage composition. Species richness increased along the upstream–downstream gradient, whereas fish abundance depended mainly on the slope orientation of Mount Itoupé. Although these results need confirmation on a larger amount of sampling sites, located on other Guianese mountains, this preliminary study shows that the mountain streams of the Guiana Shield, although rarely investigated, host not only uneven species assemblages, but also present an original combination of environmental determinants shaping fish assemblage structure. Those rare and original ecosystems hence deserve more attention and should be preserved from human disturbances.

We studied the genus Pleuroxus (including Picripleuroxus) of the rainforests of Cameroon, making extensive use of trunk limb morphology. Six species were found. Pleuroxus aduncus, P. toumodensis, P. unispinus, Pleuroxus cf similis, P. laevis and P. denticulatus show differences in postabdomen, but also in the inner distal lobes (IDL) and endites (E1-E3) of the first trunk limb (P1), endopodites (EN) of the second limb (P2), exopodites (EX) and outer spines of the endopodite of the third limb (P3), and epipodites (EP)/ endopodites (EN) of the fourth and fifth limbs (P4 & P5). These limbs, previously believed to be structurally similar, are thus seen to be built according to a strongly conserved plan, yet with specific differences. The differences found do not coincide with Frey’s subdivisions of the genus based on external characters. Consequently, we cannot confirm the existence of a (sub)genus Picripleuroxus. Four species are shared with temperate to continental and subarctic Eurasia. Pleuroxus cf. similis is closest to a species originally described from Chile, and subsequently reported from Central Asia and Australia. It remains insufficiently characterized. Pleuroxus toumodensis is an African endemic, typical of gallery forests along rivers (from the Niger to the Nile). It is now also found in true rainforest waters. Pleuroxus unispinus was previously known only from Australia.

Lithoglyphus naticoides was observed for the first time in the north of France at the beginning of the 19th century, but sincethen this gastropod has only succeeded in colonising the eastern half of this country. A map showing its distribution in Franceis proposed. In the Saône river, L. naticoides is an annual species: spawning occurs from March to June and the juveniles thatgenerally appear in May grow rapidly during the summer then spawn and disappear in the spring of the following year. Differentobservations suggest that increased water temperatures occurring in the context of global warming and potential/possible interspecificcompetition are the main reasons for the disappearance of L. naticoides in the Saône river at Lyon since November 2004.

The diversity of chironomid larvae in relation to flooding and drought phases in a marginal fluvial wetland of the Middle ParanáRiver floodplain was analyzed. Four sampling stations in the right bank of the Tiradero Viejo River towards the interior of themarginal wetland were established: one at the riverside, and three more at 10, 30 and 40 m from the river. Bottom sedimentsamples were extracted during the hydrosedimentological cycle of 2001. A total of 25 taxa of Chironomidae were recorded. Thevalues of taxonomic richness, density and diversity were higher in the marginal fluvial wetland than in the riverside, increasingwhen the wetland is disconnecting from the river. Polypedilum (Tripodura) spp., Polypedilum (Polypedilum) spp., Ablabesmyia(Karelia) spp., Coelotanypus sp., Monopelopia cf. boliekae, Goeldichironomus holoprasinus and Chironomus gr. decorus spp.were dominant in marginal wetlands. The results indicate that the variations in the hydrosedimentological regime, the degree ofdisconnection with the river and the progressive desiccation at each one of the stations of the marginal fluvial wetland arelimitant factors in the distribution and abundance of aquatic chironomids. The different assemblages of Chironomidae werestrongly conditioned by temporal changes related to the gradient of inundation-drought and to the hydroperiod dynamics.

The responses of 32 Hydraenidae and Elmidae species to six chemical parameters - alkalinity, Cl-, SO4 --, COD, NO3 - and total P have been analysed in the Orbigo river basin. The study of the distribution in relation to these factors by means of elaborating their ecological profiles pointed out the indicator species for each one of these parameters, according to their reciprocal species-factor information.

Species composition, distribution and biomass of benthic macrophyte communities have been studied in a high mountain, oligotrophic, softwater lake from the Central Pyrenees. Isoetids (Isoetes lacustris L., Isoetes setacea Lam., Subularia aquatica L. and Eleocharis acicularis (L.) Roemer & Schultes) are the dominant macrophytes in areas over 2-3 meters in depth. Natopotamids (Sparganium angustifolium Michx.) are restricted to shallow waters. Algae (Nitella gracilis (Smith) Agardh) only predominate in deep waters. Three main communities have been distinguished : the Sparganium angustifolium community (160 g dwt m-2), the Isoetes lacustris community (120-460 g dwt m-2) and the Nitella gracilis community (11 g dwt m-2). Biomass differences between shallow and deep water Isoetes populations have been attributed to ice-scour stress. Neither irradiance nor slope can explain the lower boundaries observed in the distribution of vascular plants ; sediment features may be responsible for them. Mean lake macrophyte biomass amounts to 140 g dwt m-2 (20 g C -2), a very high value if compared with boreal lakes with similar limnological characteristics.

The epiphytic diatom communities living on two macroalgae, Chara vulgaris L. and Cladophora glomerata Kütz.) and oneangiosperm Potamogeton densus L., were collected in the Mediterranean river Durance. Each macrophyte species was studied on the basis of three plant replicates, each of which cut into three segments. Although considerable heterogeneity was observed in density of the epiphytic populations between the plant species studied as regards, the composition of these algal populations showed a conspicuous degree of homogeneity within each macrophytic species. These observations were corroborated by the coefficients of variation calculated on the main diatoms and by the non parametric Friedman tests.The qualitative homogeneity of epiphyton on Potamogeton densus foliage made it possible to map the spatial repartition of the main groups of diatoms growing on the upper side of leaves.These data support the hypothesis that the epiphytic algae occupy specific microhabitat niches on their host plants according to a non stochastic pattern of distribution.

The chub, Leuciscus cephalus, colonizes the Durance river from its confluence with the Rhône river (alt. 13 m) up to the Serre Ponçon dam (alt. 780 m.). The Durance has been exposed to strong human pressure, notably dam construction, reduction of flow rate and perturbation of the natural zonation patterns. The linear growth of chub was studied by scale measurement at six stations in the Durance catchment area : two of which are located in its main tributaries, the Buech river and the Verdon. An analysis (ANOVA) of the mean size of fish from one to five years of age shows significant differences between the stations. Principal Component Analysis, in which the stations are characterized by eight mesological variables associated with the density of invertebratesand the number of degree-days above 12° and 22°C established a correlation between chub growth and species habitat, defined in terms of current flow rate, depth and substrate type and temperature. This correlation could be explained in two ways : 1- in slow-flowing homogenous riffle zone, the low water depth and absence of shelters limit the diversity of habitats and the biological richness; nevertheless the abundance of invertebrates does not seem to play an important role ; 2 - in zone of slow flowing riffles subjected to large daily and seasonal variations in water temperature, as in this mediterranean river, temperature might be quite high. Fish older than two years, therefore prefer zones of deep water, where the thermic inertia is stronger.