Seasonal dynamics of zooplankton were investigated in three different habitats of the shallow and temperate Kačležský pond (Czech Republic) during 2003–2004. The studied habitats included the limnetic zone and two littoral zones, each dominated by a different type of emergent macrophyte, reed grass (Glyceria maxima) and common reed (Phragmites australis). Species richness (calculated as number of taxa) was higher in both littoral zones than in the limnetic zone. The seasonal development of limnetic and littoral zooplankton communities differed. In contrast to the two littoral zones, close correlation with chlorophyll-a concentration was found for rotifers and cladocerans in the limnetic zone. Moreover, cladocerans inhabiting littoral areas (mainly Bosmina longirostris) reached annual maxima during spring when chlorophyll-a concentrations were low.

Temperate streams flowing through deciduous forests derive most of their energy and carbon from allochthonous organic matter supplied by the riparian vegetation mostly during the autumnal litter fall. The decomposition of this coarse particulate organic matter (CPOM) supports the aquatic foodwebs throughout the year. During the decomposition process, part of the CPOM is converted into fine particulate organic matter (FPOM). In this study, we assessed the relationships among decomposition rates of a dominant litter species, oak leaf litter (estimated by the litter bag approach in the presence and absence of macroinvertebrates), benthic CPOM stock and FPOM flux over 12 months in a temperate mountain oligotrophic stream. We also assessed the relationship between these organic matter variables and environmental variables over the same period. As expected from the seasonality in temperature, litter decomposition rates varied over the year and were positively correlated with water temperature and dissolved phosphorus concentration. However, benthic CPOM stock did not significantly change over the year; the higher rainfall in winter and the higher litter decomposition in spring might have compensated for each other in keeping the CPOM stock fairly constant year round. FPOM flux was positively correlated with litter decomposition rates as expected, and this relationship was primarily driven by the activities of detritivores and not of microbes. We can anticipate changes in the carbon cycle, both locally and downstream, if oligotrophic montane streams are subjected to temperature increases (e.g., due to removal of riparian vegetation or in a global warming scenario) and nutrient enrichment from effluents or agricultural activities.

Colonization of incubated wood samples by invertebrates and biofilm was compared between a lowland and an upland stream over a 15 month period. Invertebrate densities increased during the first weeks of incubation and then decreased to rather stable densities during the remaining investigation period in both streams. Within the first incubation weeks invertebrate numbers were significantly higher in the lowland stream. Higher dissolved nutrient concentrations and water temperatures accelerated initial epixylic biofilm development in the lowland stream. Lowest invertebrate numbers on incubated branches in the lowland stream coincided with increased discharge. Extreme low flows in the upland stream resulted in lowest invertebrate numbers on incubated wood during the study. Temporal patterns of biofilm and invertebrates indicated some interactions, but statistical significance was low, which might be caused by the variety of interacting effects. Additionally, invertebrate assemblages of in-stream wood samples were collected from four lowland and four upland streams to examine differences of epixylic invertebrate assemblages between the two stream types. Invertebrate densities were significantly higher on submerged wood from lowland streams than wood from upland streams. However, no clear differences in invertebrate assemblages found between the stream types. The study results show that introduced wood in lowland and upland streams is rapidly colonized by aquatic invertebrates and provided an attachment site for biofilms. Invertebrate numbers during the first two months of incubation significantly overestimate the invertebrate numbers found on resident in-stream wood in lowland and upland streams. Analyses of taxonomic composition of wood-inhabiting invertebrate assemblages from natural wood from lowland and upland streams revealed that each stream displayed a rather specific epixylic fauna.

Predator–prey interactions play major and direct roles in the structuring of zooplankton communities. Asplanchna usually predates ciliates, rotifers, cladocerans and sometimes even copepods, its predation may drive not only the ecological, but also the evolutionary dynamics of prey populations. In the present study, the life-table demography and the population growth of Asplanchna brightwelli were investigated at four temperatures (16, 20, 24 and 28°C) using Brachionus angularis as prey at four densities (10, 20, 30 and 40 ind.mL−1). The results showed that temperature affected significantly all the life-table demographic parameters (age-specific survivorship and fecundity, average lifespan, life expectancy at hatching, generation time, net reproductive rate and intrinsic rate of population increase) and the population growth rate obtained from the population growth studies, prey density affected the generation time, the net reproductive rate, the intrinsic rate of population increase and the population growth rate, and the interaction between temperature and prey density affected the generation time and the population growth rate. Both the average lifespan and the life expectancy at hatching were the longest at 16°C, the generation times were longer at lower temperatures (16 and 20°C) and higher prey densities (30 and 40 ind.mL−1), the net reproductive rates were higher at lower temperatures (16 and 20°C) and 20–40 ind.mL−1 of B. angularis, and the population growth rates were higher at 20°C under 20–40 ind.mL−1 of B. angularis.

Benthic macroinvertebrates are considered as a representative taxon that indicates the ecological status of freshwater ecosystems. Numerous indices derived from community data have been proposed to estimate either biological water quality or ecosystem health. In this study, metrics based on benthic macroinvertebrates at the family level were screened using ecological informatics to provide a multi-metric measurement that would be suitable for presenting ecological integrity across different levels of environmental impact. Benthic macroinvertebrates were collected at a total of 720 sample sites from river basins and streams in Korea in 2009. Based on four categories of community status (i.e., diversity, richness, tolerance, and composition), 37 metrics were selected as initial candidates according to the literature. The candidate metrics were evaluated according to parameters including discriminatory power, redundancy, and responsiveness to stressors. Self-organizing map was utilized to assist the screening procedure by providing ordination, clustering, and visualization of metric and environmental data. Six metrics were finally selected as a multi-metric and were compared with conventional indicators for presenting the ecological integrity of streams.

Escherichia coli is an indicator of fecal pollution used to mandate recreational and drinking water quality. Concentrations of culturable E. coli following contamination of surface water are determined by three factors: dilution; cell attachment to particulate material and settling or resuspension in the water column; and the net rate of change in viability. This study evaluated the variability in the latter parameter, and how predictive variation in death rate was of culturable population densities at the time of sampling. Water samples (N=232) with varying levels of E. coli contamination were collected from 46 discrete locations in four watersheds across Canada over a three-month period and enumerated for culturable E. coli by membrane filtration plate counting (T0EC). Water samples were again enumerated following a laboratory 24 h holding period at 30°C in the dark, and the difference considered the death rate (ΔEC). Relationships of T0EC and ΔEC with environmental and water chemistry factors were explored using step-wise multiple regression. The model predicting T0EC indicated that stream order, total rainfall seven days in advance of sampling day, total phosphorus, and ΔEC were the most significant contributors. The model predicting ΔEC indicated that turbidity and NH3+NH4 were the most important contributors. A model suggests that the persistence factor is less important than dilution (i.e. stream order) in describing E. coli densities, followed by factors that influence the loading of E. coli into watersheds.

Leaves of two species, alder (Alnus glutinosa) and holm-oak (Quercus ilex), were exposed in bags of two mesh sizes in two climatically contrasting sites of a Corsican softwater stream. Leaves were incubated both in winter and in summer for about 6 months. The field experiment was designed to determine the influence of both spatial (climate) and temporal (season) variations of temperature, as well as differences in the chemical and physical properties of sclerophyllous and malacophyllous leaves, on leaf decomposition rates. Comparisons were made between leaves colonized by macroinvertebrates and leaves protected by finemesh. In winter and summer, holm-oak leaves were colonized much less by macroinvertebrates than alder leaves. Spatial and temporal differences in leaf litter processing were mainly dependent on three factors (i) the chemical and physical properties of the leaves, (ii) the abundance of macroinvertebrates in the sediment and (iii) the temperature. The climatical pattern of temperature had a greater influence than its seasonal pattern. In contrast with many other studies, abiotic factors dominated over biotic factors in this study.

A limnological study was performed out, over 8 years from 1979 to 1986, in a shallow recently created sand-pit lake,Lake Créteil (Paris suburb, France). The lake is mainly supplied by phreatic waters. Typical of shallow waters, thermal stratification which occurred from May to October was intermittently broken by wind, leading to high seasonal fluctuations and allowing a reoxygenation of the total water column. The interannual development of the lake was characterized by a regular increase in transparency (from 1 m in 1979 to 2.7 m in 1985) which was partly due to not only stabilization of the bottom sediment and the banks, but also to a reduction of the biological component. A decrease in chlorophyll a concentrations resulted from nutrient diversion of domestic inputs collected through the rainwater pipe cominginto the lake. The rapid restoration of water quality shows that this small artificial lake is very sensitive to human interventions.

Des expérimentations de terrain en parcelles limitées ont permis, à partir de piégeages d'adultes, d'évaluer l'impactde huit insecticides sur des populations larvaires composées de 82 % de Chironomus salinarius, de 12 % de Chironomushalophilus et de Chironomus plumosus et 6 % d'autres espèces non identifées. Le diflubenzuron et les toxines de Bacillus thuringiensis H 14 et Bacillus sphaericus n'ont pas d'effet marqué aux doses détruisant les larves de moustiques. A ces mêmes doses, le fénitrothion, le téméphos et la deltaméthrine limitent fortement l'émergence. Le chlorpyrifos et le S 31183 (juvénoïde Sumitomo) sont très toxiques.

Perennial Oued Zegzel and temporary Oued Cherraa are parts of the same watercourse. Coinertia analysis showed the cleardistinction between these two parts and the close relationship of the faunal assemblages with the characteristics of the water. Theheadwater course of the Zegzel is covered with dense terrestrial vegetation whose debris were consumed by abundant shreddersdominated by the prosobranch Melanopsis praemorsa. The lower course of the Zegzel has sparse riparian vegetation and muchfine detritus, and collectors such as Ecdyonurus rothschildi, Caenis luctuosa, the Diptera Corynoneurinae and Tanytarsini,occurred. In contrast, dry, flowing-, and standing-water periods succeed each other in the Cherraa and terrestrial vegetation oftengrows in its bed. M. praemorsa was replaced by the air-breathing pulmonate Physa acuta, accompanied by the adults and larvaeof flying insects. However many shredders did not develop on the abundant plant litter. The short length of the submersionperiod was probably responsible for this lack of efficiency in the exploitation of such a non-limiting food resource.

Three males of Cryptocandona vavrai were discovered in geographically distant sites (UK, France, Romania), representingdifferent environments (surface and underground waters). The species may be considered a parthenogen with rare occurrence ofsingle males, the morphology of which was hitherto poorly known. The first complete description of males is given, which, togetherwith comparative descriptions of females from surface waters at the UK site and underground waters at an additional sitein eastern France, as well as consideration of the shape and size of the last juvenile stages, permits the presentation of a morecomplete description and an amended diagnosis of the species. Cryptocandona vavrai takes an intermediate position in thegenus, lodged between stygobitic species and the cluster of more primitive C. reducta and C. brehmi. Due to a number of traits(broad calcified inner lamella of the valves, 3rd ramus podomere of the antennule lacking the posterior seta, hook-like shortestterminal seta of the cleaning leg, specific morphology of the male prehensile palps and hemipenis lobes) C. vavrai is fairly easilyrecognised, although there seems to be considerable intraspecific variation. The comparison between females from surfaceand underground waters revealed substantial elongation of the apical antennal claws, aesthetascs and the distal claw of the walkingleg in the latter population. The major difference recorded among the compared males is the underdevelopment of the externalclaw z2 on the 3rd endopodial podomere of the antenna in the male from the underground waters in Romania. The revealedvariation could indicate that some populations may deserve a separate (sub-specific) taxonomic status. Finally, available data onthe distribution and ecology of this species are summarised.

Description de Parastenocaris nertensis n. sp. et Parastenocaris fontinalis meridionalis n. s. sp. récoltées dans le sous-écoulement d'un ruisseau des Pyrénées.

Une étude typologique est effectuée sur la Loue, grand cours d'eau à Salmonidés du massif du Jura, à l'aide de la méthode d'analyse factorielle des correspondances.

Cette méthode est appliquée à l'analyse des variations longitudinales de 18 composantes physico-chimiques et de la distribution de 135 espèces de Poissons (18 espèces), Plécoptères (27 espèces), Éphéméroptères (33 espèces) et Trichoptères (57 espèces) sur 18 stations jalonnant les 126 km du cours d'eau.

Les structures biologiques sont déterminées séparément pour chaque ordre puis pour l'ensemble de la faune étudiée ; 4 groupements et 12 noyaux d'affinités écologiques sont mis en évidence.

L'analyse mésologique fait apparaître une participation hiérarchisée des paramètres mais aussi l'absence d'une structure abiotique nette soulignant le caractère intégrateur des espèces et faisant appel à la notion de « complexes paramétriques équivalents ».

Les résultats obtenus au niveau des espèces, du cours d'eau lui-même et des paramètres physico-chimiques sont commentés puis confrontés ; l'intérêt de la recherche typologique est alors mis en évidence parallèlement au caractère essentiellement relatif du déterminisme des espèces et de leurs groupements.

Répartition géographique comparée des trois espèces de Rhithrogena du groupe germanica sensu stricto de l'Ouest del'Europe et de l'Afrique du Nord. Redescription de l'holotype de Rh. soteria Navás, 1917 (imago male, terra typica : l'Espagne) et description de Rh. ryszardi n. sp. (imago male) provenant du Moyen Atlas. Cette dernière est nettement moins orophile que les trois autres espèces de ce genre déjà signalées du Maroc.

Pour D. gonocephala, les limites de survie indéfinie à température constante et en eau agitée sont voisines de 20-21° C. Par sa résistance thermique comme par sa répartition dans la nature, cette espèce se montre remarquablement intermédiaire entre Polycelis felina et Polycelis nigra.

Le taux de croissance de Scenedesmus crassus est décrit en fonction de l'intensité lumineuse. Différentes expressions de cette fonction sont testées. Les paramètres de l'équation résultante sont alors exprimés en fonction de la température. La comparaison des taux de croissance observés et simulés met en évidence la valeur prédictive du système élaboré.

Dans un marais saumâtre temporaire de la Crau, les seuls insectes adaptés à l'assèchement estival sont les Coléoptères Hydrophilidae et notamment l'espèce Berosus guttalis. Son cycle biologique est décrit et montre que l'assèchement qui survient lorsque près de 80 % des larves se trouvent au Stade III s'avère déterminant pour la nymphose. Le synchronisme du développement larvaire et de l'assèchement estival assure les plus grandes chances de survie à l'espèce.

Papuanatula, n. gen. (Ephemeroptera : Baetidae), is described from New Guinea and New Britain and based on both larvae and adults. Larvae of Papuanatula are distinguished by having basally narrow and distally broad antennal scapes ; glossae shorter than paraglossae ; segment 3 of labial palps more convex laterally than medially ; ventral long, somewhat robust, simple seta subdistally on tarsi ; gills on abdominal segments 2-7 ; reduced medial caudal filament ; and absence of hindwingpads. Adults have double marginal intercalaries in the forewings, lack hindwings, and males possess a sclerotized process between the genital forceps. Five new species are described from New Guinea [P. bessa n. sp., P. copis n. sp., P. lenos n. sp., P. plana n. sp., and P. tuber, n. sp. (type species)] and one new species named from New Britain (P. vaisisi n. sp.). An identification key to the larvae of the six new species is included.

En dépit de l'importance des micro-organismes dans le processus de décomposition de la matière organique dans le milieu aquatique, les études sur leur dynamique et leur mode d'action restent restreintes.Dans cette étude nous essayons de quantifier l'activité des micro-organismes en suivant la dynamique des cellulases, des hydrolases et des déshydrogénases, groupes d'enzymes intervenant dans la transformation de la matière organique de structure complexe en substances simples. Les résultats montrent une liaison entre la vitesse de décomposition des feuilles du saule et l'activitéenzymatique des micro-organismes associés. Les fortes valeurs de l'activité des micro-organismes s'observent sur les feuilles incubées dans le site amont du Zeghzel où le processus de décomposition est plus rapide.Le séchage des feuilles, avant leur immersion dans l'eau, influence profondément l'activité hydrolytique et cellulolytique, alors que l'activité des oxydo-réductases reste indifférente à l'état du matériel en décomposition. L'activité déshydrogénasique est importante au printemps, s'accentue en été et s'atténue en automne et en hiver. L'activité cellulolytique est très prononcée pendant la saison automnale. Elle est plus élevée dans la Branche Sud-Ouest que dans les deux autres stations étudiées. Malgrél'existence de variations spatiale (entre les trois sites) et temporelle (entre les saisons) les dynamiques des trois groupes enzymatiques semblent très dépendantes les unes des autres.

Après 55 ans d'immersion continue dans un réservoir en forêt boréale, les troncs de conifères (Abies balsamea. Picea mariana et Pinus banksiana) sont peu modifiés. En effet, leur bois ne présente qu'une faible dégradation périphérique. Leur pourcentage en matériel soluble dans NaOH (1%) et leur pourcentage en pentosans ont quelque peu diminué ; par contre, leur teneur en lignine acido-insoluble et leur densité de bois n'ont guère changé, ce qui montre que leur réseau ligneux dense reste quasiment inaltéré. Au niveau histologique, celui-ci présente plusieurs hyphes de champignons et des ponctuations aérolées agrandies. Ces faibles modifications résultent vraisemblablement d'une action microbiologique synergique des champignons de la carie molle et de certaines bactéries. Les conditions physico-chimiques du réservoir ne s'avèrent pas incompatibles pour les décomposeurs bien que les basses températures qui y règnent favorisent peu leur action.