Stream development can generate environmental changes that impact fish communities. In temperate streams, the distribution of fish species is associated with environmental gradients. To analyze the relevant factors, large-scale exploration is required. Thus, to evaluate the distribution patterns of fish in Korea, sampling was conducted on a national scale at 720 sites over a 6-week period in 2009. A total of 124 fish species in 27 families were identified; Zacco platypus and Zacco koreanus of the Cyprinidae were the dominant and subdominant species, respectively. Of the species found, 46 (37.1%) were endemic and 4 (3.2%) exotic; of the latter, Micropterus salmoides and Lepomis macrochirus were widely distributed. Upon canonical correspondence analysis (CCA), both altitude and biological oxygen demand (BOD) were highly correlated with CCA axes 1 and 2, respectively. This explained 62.5% of the species–environment relationship. Altitude and stream order were longitudinally related to species distribution. The numbers of both total and endemic species gradually increased as streams grew in size to the fourth–fifth-order, and decreased in sixth-order, streams. Overall, fish communities were stable throughout the entire watershed, whereas some species showed site-specific occurrence patterns due to the paleogeomorphological characteristics of Korean peninsula. However, various anthropogenic activities may negatively affect fish communities. Therefore, both short- and long-term sustainable management strategies are required to conserve native fish fauna.

Phragmites australis is a stand forming emergent macrophyte that displays large phenotypic variation within Lake Balaton. The present study assesses morphological variations of P. australis within three transects of different reed stands of Lake Balaton which differ with respect to bathymetry, reed quality and geographic position in order to achieve a morphological typization. On average the southern stable stand produced the largest and thickest plants (295±9 cm and 7.5±0.2 mm), while plants of the northern die-back stand were approximately half this size (141±2 cm and 3.5±0.1 mm). The slow growth and development of Phragmites characterizing the northern die-back stand was the result of fewer and shorter internodes, which also resulted in the low number of green leaves. The most influential factor shaping the phenotypic properties of the plants was determined to be the reed quality (general condition), although site-specific differences, shore-specific differences, water depth and spatial position within reed stand transects were also found to be significant. Despite the differences in the studied stands and almost certain genetic dissimilarities, three morphological ecotypes of Phragmites were distinguished on the basis of stem height to basal diameter ratio, stem density and phenotypic plasticity of plants. These ecotypes were primarily correlated to water depth at their position within the reed stand. The similarity of the spatial distribution of stem heights to basal diameter ratios and phenotypic plasticity of plants along all studied reed stands suggests that morphological typization should be considered to provide additional information on ecological zonation of stands.

The diet composition and feeding strategy of native and exotic fish species were studied from May 2005 to February 2006 in three Patagonian low-order streams. A total of 464 fish were caught, which belonged to the exotic species Oncorhynchus mykiss (270), Salmo trutta (177) and the native species Hatcheria macraei (17). The analysis of 336 stomach contents indicated that at the individual level, the three species had a generalized feeding strategy based on benthic invertebrates (Plecoptera, Trichoptera, Coleoptera and Diptera). In the three streams, the widest population niches were observed in winter. There was, however, also a slight tendency toward an increased between-phenotype contribution to the niche width in same season, indicating that a small proportion of individuals within the fish populations specialized by predominantly feeding on a few specific prey species. Hence, the wide population niche widths observed throughout the year were partly a result of mixed individual feeding strategies within the populations. The higher diet overlaps were registered between exotics O. mykiss–S. trutta at Glyn and Carbón, and O. mykiss and the native H. macraei at Manguera, but it changed markedly through the year, perhaps depending on temporal changes in food availability suggesting a competitive coexistence of these species. This is mainly related to the fact that both species changed their food preferences in spring and foraged almost exclusively on Aubertoperla illiesi. This implies that in order to reduce the predation risk or the inter-specific competition for food, the fish species might partition the feeding habitats.

Seasonal samples of zooplankton were taken during 1997-1999 at fifteen stations in the Salado River basin, and analysed inorder to study the rotifer fauna. Spatio-temporal changes in the rotifer plankton composition were examined in the main channeland its tributaries. The majority of species found are tolerant of a wide range of pH, whereas others prefer neutral to alkalinevalues. The total rotifer plankton density increased downstream from the headwaters to the middle sector of the river. Theassociated shallow lakes and tributaries were an important source of species. Variations in density and number of species wereshown to be associated with conductivity, and species tolerant of high conductivity conditions were especially prevalent (upper7,000 µS cm-1). Rotifer density was influenced by hydrological conditions, which promoted maximum values during low waterperiods and in the high water condition promoted the incorporation of species from shallow lakes connected with the river duringflood events. The species associations found are related to such water parameters as conductivity and nutrient availability andto the presence of ponds and shallow, waterlogged depressions connected in varying extent to the main channel.

1. Cinq espèces d'Elmidae typiques de ruisseaux furent étudiées et chacune se développe sur un substrat particulier : Stenelmis crenata aux endroits sablonneux, Optioservus ampliatus parmi les gravillons, Macronychus glabratus sur les bois pourris immergés, Promoresia tardella dans les mousses aquatiques et Oulimnius latiusculus sur les fonds de gravier mêlés avec du sable.

2. Ce sont des microphaghes qui se nourrissent de débris végétaux (30-90%) et de Diatomées (10-70 %).

3. Le nombre de stades larvaires varie d'une espèce à l'autre : 8 chez S. crenata, 7 chez O. ampliatus, 6 chez M. glabratus et P. tardella et 5 chez O. latiusculus.

4. Les stades larvaires se distinguent surtout par la longueur du prothorax ou du 9e segment abdominal et par l'ornementation tégumentaire.

5. La longueur minimale du cycle biologique de ces espèces semble être de trois années, peut-être quatre même chez S. crenata, dont deux à l'état larvaire (trois chez S. crenata) et une à l'état adulte.

6. Les oeufs sont pondus au cours de l'été et la majorité éclosent en août.

7. La première année, les larves se développent jusqu'au stade III et passent l'hiver à ce stade, car à 0 °C, la croissance est arrêtée ou du moins extrêmement ralentie.

8. Les larves atteignent leur plein développement du printemps à l'automne de la deuxième année et passent de nouveau l'hiver à l'état larvaire.

9. Ces larves de dernier stade quittent l'eau au printemps pour la nymphose qui a lieu de juin au début d'août, sous les débris végétaux du bord de l'eau.

10. Les imagos émergent surtout en août et doivent attendre jusqu'à l'été de la troisième année avant de se reproduire.

Ecotoxicological studies with cladocerans frequently assess the individual growth of the organisms. Measures upon living organisms should be avoided once they can lead to their death or affectation, therefore constraining the results. In this way, and considering that cladocerans species go through series of moults along their life cycle, measures upon the moult are preferred in almost all the studies. Thus, the establishment of allometric relations is required to enable feasible estimations of diverse growth parameters. Exopodite and total body length of two autochthonous (Daphnia longispina; Ceriodaphnia pulchella) and two standard (Daphnia magna; Ceriodaphnia dubia) living daphnids were registered. Regression analysis was applied in order to establish a relation between the two allometric measurements in each species. As high R-squared values were reached in all species, the obtained equations can be used as reference for estimations of body length in face of the «moult» exopodite length measure. Consequently, this work provides a support reference for ecotoxicological studies performed in lab with these species.

The growth and cell composition of C. meneghiniana in P-, N- or Si-limited continuous cultures under different dilutions are discussed. Carbon, nitrogen and phosphorus content per cell or per unit cell volume increased with growth rate in all chemostats. Maximum growth rate depends on the type of limiting nutrient. The maximum growth rates are. 1.65 ± 0.04, 0.73 ± 0.07 and 0.95 ± 0.08 d-1 for P-, N- and Si-limited cultures respectively. These values are close to those calculated by Droop, Caperon, Goldman and Monod models. The concentrations of N and P in the river Danube are much higher than the requirements for growth and uptake of C. meneghiniana. This indicates that neither P nor N are limiting to the growth of C. meneghiniana in natural habitat.

The distribution and overall fish abundance, and biomass of fish populations in the open water of meso-eutrophic Lake Balatonwere studied in 2003-2007 using hydroacoustics and gill nets. Gillnet catches revealed that bleak (53-76 %) common bream (8-42%), white bream and razor fish (2-18 %) dominated in the open water of the lake. Comparisons of target strength distribution fromhydroacoustics and length distribution from the gillnets showed that the fishing gear did not quantitatively catch the smallest andlargest size groups of fish. Mean acoustic fish abundance and biomass fluctuated significantly between both basins and years. Thebiomass of fish populations reflects the trophic gradient along the longitudinal axis of the lake (min-max.: 89-181 kg ha-1) showinga decreasing trend with years. The mean acoustic fish biomass was significantly higher in the eutrophic western basin, comparedwith mesotrophic eastern and middle ones.

The role of predation in the regulation of freshwater communities is predicted to decrease along a habitat-duration gradient, from permanent to episodic waters. We tested the role of invertebrate predation in shaping the community structure in a fishless temperate intermittent pond with a three month long hydroperiod by comparing the community structure in two large field enclosures (4.2 m2) with added predators to two enclosures without added predators. The added predators reflected the density and composition of top predators in the pond and comprised weekly additions of dytiscid larvae (for three weeks) followed by weekly additions of odonate nymphs (for five weeks). Compared with the enclosure controls, the predator addition enclosures had fewer dipterans and crustaceans, higher concentrations of benthic ciliates and other protozoans, higher chlorophyll a and bacterial counts, and lower abundance of rotifers. Many treatment effects were temporally variable and this appeared to be linked to predator identity, predator size, and prey availability. Compared with the surrounding pondwater, the enclosed areas had lower abundance of molluscs, ostracods and cladocerans but higher abundance of cyclopoids and higher concentrations of phytoplankton and ciliates. Despite high productivity and seasonally variable predator and prey assemblages, which likely buffered against strong top-down control, we conclude that the top-predators regulate the dipterans and zooplankton in this intermittent pond and that the effects propagated down through the food web to lower trophic levels.

In the natural environment, microbial community structure of river biofilm is controlled by biotic and abiotic factors. This study explored the capacity to manipulate the structure of microbial communities by modifying environmental conditions during the course of biofilm development. River epilithic biofilm was cultivated in situ on artificial substrates placed parallel to river water flow. Substrates were incubated for 3 and 5.5 weeks in river to allow natural biofilm development, at two sites with contrasting physico-chemical characteristics. The first site (Auradé, Gers, France) was located in an agricultural watershed basin and the second site (Larroque, Haute-Garonne, France) was located in a forested watershed basin. After 3 weeks of biofilm development, a subset of substrates was collected from one site and transplanted to the second site where they remained for 2.5 further weeks. Epilithic bacterial community structure (at 3 weeks from each site and at 5.5 weeks from biofilms with and without transplantation) was assessed using PCR-DGGE of 16S rDNA fragment. Biofilm biomass was estimated using ash free dry mass (AFDM). After 3 weeks of development, biofilms from the two sites exhibited comparable AFDM values (average of 1.4±0.2 g.m-2). A difference between the two sites was observed after 5.5 weeks of development: AFDM decreased for biofilms from the agricultural watershed basin (from 1.4 to 0.18 g.m-2) as a consequence of grazing pressure (Bithynia), and increased for biofilms from the forested agricultural watershed (from 1.4 to 2.6 g.m-2). Microbial community analyses revealed a differentiated community structure between biofilms from the different sites and exhibited a change of microbial community structure after 5.5 weeks of biofilm development. These observations confirm a process of ecological succession in microbial communities. Changing the incubation site during biofilm development modified the trajectory of these ecological successions, suggesting that site characteristics mainly conditioned the structure of these microbial communities.

The population dynamics of the red swamp crayfish (Procambarus clarkii Girard, 1852) was studied from May 2005 to May 2006 in a pond (PCD) subjected to drought between June and December and in a continuously flooded rice field drainage channel (PMG) located in the Tejo river basin, Portugal. The proportion of females in the population was not independent from the season and was negatively correlated with both female and male maturation status. Male and female maturation was synchronous but males remained in a reproductive form after recruitment while females reverted quickly to lower maturation indexes. At PCD and PMG, respectively 2 and 5 cohorts were detected by modal analysis. Large crayfish were abundant in spring, summer and early autumn and juveniles were abundant in autumn, especially at PCD. Crayfish density at PCD was lower than at PMG and mortality rate (Z) was 3.99 at PCD and 2.43 at PMG. The average lifespan of the crayfish populations was 91 days at PCD and 150 days at PMG. Our study indicated faster growth and larger maximum sizes at the site with the more stressed environment and lowest relative crayfish densities (PCD), suggesting that any exploitation or control strategies for these two populations should consider management of the hydroperiod and of maximum crayfish densities.

La durée de vie et le taux net de reproduction (Ro) sont mesurés à 20 °C et avec une alimentation optimale chez 8 souches de Rotifères Monogonontes Pseudotroques, appartenant à 6 espèces différentes : Asplanchna brightwelli, Brachionus calyciflorus, Epiphanes brachionus, Notommata copeus, Polyarthra dolichoptera et Synchaeta pectinata. Les durées de vie et taux net de reproduction respectifs des femelles amictiques et des femelles mictiques fécondées et non fécondées sont comparés chez les quatre premières espèces. La durée de vie des femelles amictiques varie de 5 à 12 jours selon les espèces ou les souches d'une même espèce, de 5 à 8 jours pour les femelles mictiques non fécondées. A l'exception d'Asplanchna brightwelli, le nombre d'oeufs (femelles) pondus par une femelle amictique — soit de 13 oeufs ♀-1 chez Polyarthra dolichoptera à plus de 40 oeufs ♀-1 chez Epiphanes senta — est à peu près équivalent au nombre d'oeufs (mâles) pondus par une femelle mictique. Le taux net de reproduction dépend non seulement de la température mais aussi de l'alimentation qui n'a que peu d'influence sur la durée de vie.

Tropical island streams worldwide are being threatened by existing or proposed dams and diversions. Numerous streams of the Hawaiian Islands have diversions that remove freshwater for human use; however, little research has addressed diversion effects on aquatic insect communities in tropical streams. We studied the effect of water removal by a stream diversion on density and biomass of two introduced Trichoptera, Cheumatopsyche analis (Banks) (Hydropsychidae) and Hydroptila potosina (Buenoa-Soria) (Hydroptilidae), in Iao Stream, Maui, Hawaii, from April-August 2000. Both species seem to have multivoltine life cycles. Pooled Trichoptera (both species) biomass was significantly greater above the diversion (178.3 mg.m-2 and 112.9 mg.m-2 for upstream and downstream, respectively). For each individual species the mean total instar biomass was significantly reduced below the diversion (38 % and 54 % reduction for C. analis and H. potosina, respectively). Both species had greater densities above the diversion; however, individual larval mass of H. potosina instars, but not C. analis instars, was significantly lower below the diversion. Our results suggest that reduced habitat quality, due to lowered stream flow, limits density of both species below the diversion, whereas lowered food quantity and quality may differentially affect H. potosina biomass through reduced body sizes. These data suggest that water removal not only reduces habitat quality, but significantly lowers the community biomass of these introduced Trichoptera species, affecting the trophic energetics of stream reaches downstream of a diversion in Hawaii. Similar changes to macroinvertebrate communities would be expected below dams and diversions of streams in other tropical regions.

In this study, we investigated variation in offspring size (OS) of Daphnia magna in relation to multiple maternal traits and environmental variables. Data originated from laboratory experiments conducted at different feeding scenarios. The mother daphnids had different life-history traits and were reared under various feeding and density conditions. OS showed linear relationships with maternal traits, varying positively with maternal body size, age and brood number, and negatively with brood size and with the amount of ingested carbon. OS increased exponentially with crowding. Using stepwise multiple regression analysis, we developed an empirical model for the OS variation with the relevant maternal and environmental variables. Density dependence was considered by multiplying the resulting model by a density-effect function. We found that the ingested carbon and the maternal body size were the strongest determinants of the observed variation in the OS, whereas the brood size had the least impact on OS. Additionally, the brood number had no significant effect in determining the variability in the OS. The validity of the multivariate model was tested against an independent dataset. The model accurately predicted the OS despite several genetic and environmental differences compared with the data used for parameterization.

La part prise par les aliments végétaux décroît dans la série Arcynopteryx -Isoperla - Périodes - Perla et Dinocras. Des différences morphologiques sont liées à cette évolution. Les régimes alimentaires des Isoperla, Perla et Dinocras varient au cours de la vie larvaire. Les relations entre la taille du prédateur et celle des proies sont plus nettes pour les Baetis que pour les Chironomides. Pour les Chironomides, elles sont de plus en plus marquées dans la série Arcynopteryx - Isoperla - Perlidae.

To test whether leaf litter from eucalyptus plantations affects stream macroinvertebrate communities, we manipulated litterinputs into a small headwater tributary of the Agüera stream (northern Spain) running under mixed deciduous forests. Threecontiguous 50 m long reaches were used: the upstream reach was left as a control (site C), whereas the two downstream siteswere covered by 1 mm mesh nets to avoid natural litter inputs, and twice a month received litter collected at a deciduous forest(site D, mid) or a eucalyptus plantation (site E, downstream). Benthic Surber samples were taken from the three sites before andafter the treatment and density, biomass and structure of the community were compared. Density and biomass of macroinvertebratesdid not differ among sites before the treatment. Total density and biomass of macroinvertebrates increased in all the sitesduring the experimental period but most considerably at the site were deciduous forest inputs were simulated (station D). At theend of the experiment shredders were significantly less abundant at site E (eucalyptus) than at site D (deciduous). In addition,shredder density and biomass per total organic matter amount and per total leaf amount became higher at site D. In conclusion,these results suggest a subtle negative impact of eucalyptus litter on stream macroinvertebrate communities, especially on shredders.

Aquatic insects are widely distributed, and are especially diverse and abundant in tropical streams, where they play an important role in the food chain due to their diversity of feeding strategies, and the potential for the transfer of energy between aquatic and terrestrial environments. The intimate relationship found between these insects and environmental variables means that they are often used as bioindicatorss in environmental studies. We tested the hypothesis that the loss of environmental integrity in tropical streams will lead to a loss of species and a decline in the abundance of mayflies (Leptophlebiidae), in addition to a change in species composition, and the dynamics of population. Collect immature leptophlebiids in 18 streams representing different degrees of conservation, in the Brazilian Cerrado. The environmental integrity of the sites was assessed using a Habitat Integrity Index (HII), which generates values of zero (degraded) to one (preserved), based on soil use, the extension and conservation of riparian forest, as well as morphological features of the stream. A total of 4945 immature leptophlebiids were collected and identified as belonging to 16 species or morphospecies. On an average, a reduction of 0.1 in the value of the HII led to the loss of five specimens and one species. The composition of the communities varied systematically along the environmental gradient, with more sensitive species being found only when the index was above a threshold of 0.6. The importance of the riparian vegetation for the aquatic biota, especially its role in the mitigation of impacts from the surrounding matrix, supports the universal conservation of this type of habitat.

During 2001 - 2002, we studied periphytic biomass at 5 sites along the Agüera stream (Northern Iberian Peninsula), and comparedthe results to those from two previous researches (1990 - 1991 and 1992 - 1993). Sampling sites showed large differencesin cover, conductivity and nutrient contents, as well as some inter-annual differences, resulting from changes in discharge andin human activities. Most environmental variables showed low seasonality, main variations being produced by floods. Solarradiation changed little during 2001 - 2002, because of the coincidence of a sunny winter followed by a cloudy summer, andseasonal differences in riparian cover resulted in more sunlight reaching the streambed of closed sites during winter, and smalldifferences at the open ones. The growth and abscission of riparian leaves results in a strong light regime at the closed sites, withmore sunlight during winter, but this pattern changes from year to year, depending on the weather. Spatial differences and highestvalues of periphytic biomass were much lower than those measured in 1990 - 91, because of contrasting weather patterns.Variables controlling periphytic biomass in the Agüera change from reach to reach. At open sites flow is the main temporalcontroller, whereas at closed sites the effects of light availability prevail, thus giving more similar seasonal patterns from yearto year. Nutrients seem to play a minor role in temporal variations.

Weight loss of leaves of Populus nigra and Quercus ilex was observed in coarse-mesh bags exposed in three watercourses and their sediment (-30 and -50 cm) near the city of Fes. The watercourses were: Oued Sebou (a river), Oued Sidi-Harazem (issuing from a warm spring), and Ain Chkef (a cold spring). Weight loss was faster at the surface than within the sediment. Weight loss was faster in poplar than in the tough holm oak leaves. At all levels, weight loss was fastest in Oued Sebou where the water flowed faster both at the surface and within the coarser sediment. It was slowest in the cold spring. Thus the influence of leaf texture, current velocity, and temperature were stressed.

Présentation, sous forme de catalogue, des principaux renseignements tirés de l'étude des 204 espèces et sous-espèces de Trichoptères récoltés sur le versant nord des Pyrénées. Ce travail est basé sur des captures d'adultes effectuées ces dernières années, ainsi que sur l'étude des collections de Trichoptères pyrénéens du Muséum d'Histoire Naturelle de Paris et du British Museum.

Les principaux travaux de faunistique sont indiqués, avec les dates et lieux de capture.

Pour chaque espèce sont signalés :

1) les citations antérieures,

2) la classe d'abondance,

3) la répartition dans les vallées nord-pyrénéennes,

4) les mois de capture des adultes,

5) l'habitat et l'amplitude altitudinale,

6) des remarques d'ordre systématique.

35 espèces — citations douteuses ou inexactes, synonymes — ont été écartées de la liste des Trichoptères pyrénéens.

Les mois de capture des adultes sont indiqués dans un tableau concernant l'ensemble des espèces. Les formes à longue période de vol sont relativement nombreuses.

L'étude des captures d'adultes dans trois stations différentes montre une contraction des périodes de vol en montagne, avec un seul maximum, en juillet-août, au-dessus de 1 400 m.

Les modifications subies par les périodes de vol en fonction de l'altitude sont différentes pour les espèces des faunes précoce, intermédiaire et tardive.

La faune précoce de haute montagne paraît très appauvrie dans les Pyrénées; la faune automnale survit jusqu'en décembre à des altitudes élevées.