Le cycle de développement de Capnioneura brachyptera dure deux ans dans un ruisseau des Pyrénées centrales, à 1 950 mètres d'altitude. Le premier hiver est passé à l'état d'oeuf ; la croissance, très faible la première année, devient très rapide au cours du deuxième été dès la fin de la fonte des neiges.

La production varie peu d'une cohorte à la suivante et correspond, pour 70 %, à la croissance de deuxième année. La mortalité larvaire paraît faible. Le rapport P/B max., compris entre 1,5 et 2 est voisin de ceux déjà mentionnés pour d'autres espèces des Pyrénées centrales.

Pupae and pupal exuviae were collected by drift and hand netting from 27 sites on 10 streams in the Sierra Nevadamountains in 1986 and 1987. The sites represented an altitudinal range from 340 m to 2100 m. The pupal exuviae collections revealed a composite fauna of 143 species. Eukiefferiella (12 spp.) and Tvetenia (3 spp.) were dominant both taxonomically and numerically along most of the altitudinal profile, followed by Cricotopus (11 spp.), Orthocladius (9 spp.) and Diamesa (7 spp.). The altitudinal distribution of the 99 most common species is shown and compared with those obtained in other Europeanstreams or rivers, especially in the Pyrenees. The general pattern of altitudinal zonation shows an increase in speciesrichness from the headwaters (< 2000 m : 58 spp.) toward the middle reaches (1000-1600 m : 121 spp.). The theoreticallyexpected highest species richness in the foothill reaches (> 1000 m : 113 spp.) was not obtained. The periods of reduced or intermittent flow, the domestic organic inputs and the narrowness of the channels in the foothill reaches appear responsible for the decrease of the species richness of the chironomid communities.

L'étude d'abondantes récoltes de larves d'Elmis aenea, E. maugetii et E. coiffaiti nous a permis de confirmer l'existence de six stades larvaires chez ces espèces. Le nombre des poils ramifiés latéraux portés par les lames paratergales des huit premiers segments abdominaux permet de différencier aisément ces six stades.

Les larves d'Elmis coiffaiti peuvent être identifiées dès le premier stade par leur ornementation tergale. Celles d'E. aenea et d'E. maugetii ne peuvent être distinguées l'une de l'autre qu'à partir du stade IV. Le plus ou moins grand développement de renflements parasagittaux sur les tergites abdominaux est le caractère spécifique le plus constant. Il existe également des différences dans la forme du neuvième segment abdominal, déjà indiquées par Bertrand [1939], pour E. coiffaiti (sub nom. Helmis fossulata), et dans la répartition des mamelons.

Toutes ces différences sont néanmoins assez réduites, ce qui confirme l'étroite parenté des trois formes. Adultes et larves vivent ensemble toute l'année dans le même habitat et, au point de vue pratique, il est préférable d'effectuer des récoltes suffisamment abondantes et de déterminer d'abord les mâles, par l'examen des édéages [Steffan 1958, 1961, Berthélemy 1962], puis les femelles, par comparaison de leur morphologie externe avec celle des mâles, et enfin les larves, en commençant par les stades les plus âgés. Il existe un certain parallélisme entre les variations que l'on observe dans la morphologie externe des images et celle des larves. La forme du pronotum, chez les premiers, et celle des renflements parasagittaux, chez les secondes, sont très constantes à l'intérieur de chaque population mais difficiles à décrire ou à schématiser. Le chagrin entre les points, sur le pronotum des imagos, ou la répartition des mamelons, sur les tergites des larves, sont des caractères qui paraissent au premier abord beaucoup plus tranchés mais les fluctuations intraspécifiques sont plus importantes (voir Steffan 1958 pour les différences entre E. aenea et E. maugetii, sub nom. megerlei).

Les trois espèces possèdent une période de reproduction largement étalée. Chez E. aenea, la ponte s'effectue de Juin à Octobre, les nymphoses présentent un maximum en Mai.

Nous avons enfin fourni quelques données préliminaires sur l'étude de la chétotaxie. Cette étude n'apportant pas d'éléments de diagnose spécifique, but principal de ce travail, n'a pas été poursuivie sur la totalité du corps. Des comparaisons sommaires avec des larves d'autres genres d'Elminthidae montrent cependant que la chétotaxie larvaire présente un intérêt certain pour l'interprétation des homologies et des relations phylogéniques.

Patterns of parasite infestation by plerocercoid forms of the tapeworm Ligula intestinalis (Cestoda, Pseudophyllidea) in the second intermediate host, the roach Rutilus rutilus, were analysed in three fish populations of South-Western France during 1998. In all three studied sites, i.e. Pareloup Lake, Lavernose-Lacasse and Muret gravel pits, roach were commonly parasitized with plerocercoids. A strong increase in prevalence, mean number of parasites and parasitic load was observed in the youngest hosts with a maximum peak reached in the medium-age (2+, 3+)roach classes. Such trends as a function of host fish age would indicate the occurrence of parasite-induced host mortality, with the most heavily infected fish specimens being removed from the three roach populations. The three roach populations infected by L. intestinalis exhibit different patterns of parasite-induced mortality which could correspond to different possible ecological and evolutionary responses associated with local variation in host-parasite interactions. The parasite-induced host mortality observed, i.e. direct mortality caused by pathogenic effects and /or enhanced fish predation by piscivorous birds to increase parasitic transmission is discussed within the context of the adaptative parasite-induced manipulation hypothesis.

In a high mountain stream, Baetis alpinus at emergence is significantly smaller downstream than upstream. These size differences are used to demonstrate migration of adults upstream: downstream, the size of adult females caught after oviposition corresponds with the size of subimagines which have emerged there; upstream, the size of adult females corresponds with the size of subimagines which have emerged both up and downstream. The migration is clearly an upstream movement.

Aspects of the egg biology of the perlid stonefly, Dinocras cephalotes (Curtis), were studied experimentally. Development under constant laboratory conditions did not differ from development under variable field conditions. Exposure to 4°C, the lower threshold temperature for egg development, caused abrupt interruptions of embryonic development. Development was resumed after return to favourable temperatures, with an approximate two-week-delay. Up to six interruptions of egg development did not negatively affect hatching success, regardless of developmental stage at which disturbances occurred. However, the older embryos grew, the more rapidly development was resumed after a cold disturbance; embryos from fully developed eggs hatched even at 4°C, although this is too cold to support larval growth. While eggs at 4°C remain dormant and vital for long periods of time, eggs exposed to suboptimal temperatures (10°C) remain only temporarily dormant and eventually develop and hatch.D. cephalotes is assumed to satisfy its high thermal demand for egg development under harsh conditions, for example in arctic Scandinavia, by opportunistically using summer warmth and spreading embryogenesis over more than one year. I suggest that high cue temperatures required to initiate egg development in Scandinavian populations are adaptive and ensure that larvae in the Arctic hatch under favourable seasonal conditions.

Though much is known about freshwater snail ecology, their circadian rhythms remain poorly investigated. Well-fed, stress-free, mid-size adults of six species common in central Italian lakes were exposed to natural sunlight and photoperiod, and their activity status was recorded at 3-h intervals during a 9-d indoor experiment. All species exhibited evident diurnal habits despite high individual variability, with midday-to-early-afternoon activity peaks. Activity was correlated with diel light conditions but not with short-term changes in albedo. The prosobranch Bithynia (=Codiella) leachii and the pulmonates Physa (=Physella) acuta and Planorbis planorbis were the most active species and exhibited the longest-lasting response to daytime food addition. The prosobranch Valvata piscinalis exhibited long periods retracted in its shell with the operculum shut, and the remaining taxa (the pulmonates Galba (=Lymnaea) truncatula and Radix (=Lymnaea) auricularia) exhibited an intermediate degree of activity. P. acuta was the most active species at night and exhibited the quicker response to nighttime food addition. Alertedness to (diurnal) predators may be highest for the highly active P. acuta and P. planorbis, whose antipredator defenses are mainly behavioral. Diel activity patterns and other ecological characteristics suggest that P. acuta may be favored in food-rich habitats, while V. piscinalis may not be able to fully exploit food resources, especially if in limiting quantities. All snail species – and P. acuta in particular – may stimulate periphyton metabolism while keeping its biomass low by grazing mainly during the time of maximum photosynthesis.

Coastal pond systems can account for a rich aquatic faunal diversity and complex functioning due to interplay between freshwater wetlands and marine influences. Within the large Albufera wetland Natural Park, Racó de l'Olla is constituted by a set of permanent and temporary ponds with strict protection level for migrating bird conservation. Its terrestrial faunal diversity and dynamics has been partially characterized in previous studies, but nothing was known about its ostracod communities. Benthic samples collected monthly for 1 year in 11 points through the pond system, together with limnological information, allowed establishing a sound knowledge on its ostracod community and population ecology. The most common species found were the euryhaline Cyprideis torosa and Heterocypris salina. In addition, it was remarkable the finding of a well-established population of Candonocypris novaezelandiae, a new finding for Europe and considered a potential alien invader. We used multivariate ordination and classification (PCA, RDA and TWINSPAN) to characterize the ostracod biocoenoses and taphocoenoses and their relation to the environmental variables. Our results suggest that hydroperiod and salinity are the main factors structuring ostracod communities in this system. Finally, we discuss the distribution and morphological aspects of C. novaezelandiae and its relation with passive dispersal in such a wetland with a dense population of migrating birds.

Recent publications suggest that in large watersheds a large proportion (20 to 70%) of the net nitrogen input to the aquaticenvironment may be removed during water’s downstream path towards the outlet. In small watersheds there are few to no evaluationsof the importance of in-stream processes in the overall nitrogen budget due in part to the lack of simple and robustmethods for measuring in-stream nitrate uptake. We propose a comparative study for laboratory and field measurements on openmesocosms, 30 cm in diameter. Nitrate uptake was evaluated from the kinetics of disappearance of nitrate in water overlyingundisturbed sediment cores, both in the laboratory and in-situ. Using both laboratory and in-situ mesocosms was an effort todetermine whether the methods were comparable and applicable on a routine basis. Nitrate disappearance kinetics in the laboratoryyielded expected results, which are that nitrate uptake rates are linearly correlated to nitrate concentration in the watercolumn. In such conditions, our results show that the potential for nitrate uptake in streams can be calculated from the mass transfercoefficient. Our comparative study shows that incubations conducted in the laboratory intrinsically limit hyporheic exchanges,associated with small water level fluctuations, which may in fact prevail in the field as the in-situ incubations have shown.In-situ experiments yielded unexpected results, such as the succession of disappearance and gain of nitrate in the mesocosmsthrough time. This was attributed to hyporheic exchanges, both natural and artificially induced by the design of the mesocosms.Both methods should be considered for future nitrate uptake studies as they yield complementary results, provided that somesimple changes are made in the design of in-situ mesocosms.

Les prélèvements de dérive en période de décrue réalisés conjointement dans le chenal principal et un chenal secondaire de la Durance ont mis en évidence l'importance de la dérive dans le repeuplement du lit principal. Une partie de cette dérive provient du champ d'inondation temporairement colonisé par les organismes benthiques dispersés, l'autre vient des chenaux latéraux.

Since 1978 a sampling program is being conducted on various basins of Catalonia (NE-Spain), covering the whole ofthe basins of the rivers Tordera, Llobregat, Besòs, Ter, Foix and Segre (Andorran rivers included).A total of 51 species of Plecoptera has been collected in a range of altitudes from 100 m to 2 250 m. Among them, thereare stenothermal species of high altitude and a group of species that live in temporary water courses. Some species of Leuctridae, Capniidae and Chloroperlidae are members of the interstitial fauna in some instars of their life.

This paper reports data on a community of Trachelomonas species (Euglenophyta) occurring during Planktothrix agardhii bloom formation in a shallow, highly eutrophic dam reservoir. The results come from a long-term study of Siemianówka Dam Reservoir, located on the upper Narew River (NE Poland). From April to October 2007, 132 alga taxa were identified, including 32 Trachelomonas taxa, 23 of which are new for the reservoir; of those, three are first records for Poland: T. armata (Ehrenberg) Stein var. heterospina Swirenko, T. atomaria Skvortzov var. minor Hortobagi and T. minima Dreżepolski. One variety, T. curta var. pappilata Wołowski, is described as new for science. The ultrastructural details of Trachelomonas species are illustrated. The highest number of Trachelomonas taxa was recorded in August in the shore zone of the reservoir. At the end of summer 2007, the conspicuous development of P. agardhii (Gomont) Anagnostidis et Komarek, caused a rapid decrease of Trachelomonas biomass due to lower water transparency and the oxygen concentration. In addition, a decline in the Trachelomonas taxa and biomass was associated with a decrease of water temperature. The negative impact of extracellular microcystin on the Trachelomonas development requires further study.

Cross-transplantations of Omphiscola glabra between two French departments (Haute-Vienne and Indre) were carried out to study snail settlement in these new sites during six years and to determine if this snail species was well adapted to its local parasites (Fasciola hepatica and Paramphistomum daubneyi). Local snails placed in new sites for each department were used as controls. In Indre furrows, the number of adults per population and the area of each habitat peaked on the third year post-introduction. Similar findings were also noted in the Haute-Vienne furrows occupied by local snails but peaks were only observed on the fourth year. In contrast, in Haute-Vienne sites populated by introduced snails, there was a progressive decrease in snail abundance and habitat area from the second year. The local O. glabra transplanted in Haute-Vienne kept their same degree de susceptibility to F. hepatica and P. daubneyi, thus demonstrating a good adaptation of these snails to their parasites. In other groups of transplanted snails, the first natural infections were only noted from the second or third year post-introduction and their prevalence progressively increased over time. Local adaptation of these latter snails to parasites would be more progressive in time and would stretch over several snail generations.

Freshwater habitats of the Italian Alps are largely unexplored and further floristic-ecological surveys are needed to clarify the role of freshwater lichens in these environments. This applies especially to springs, since they seem to be suitable for a relatively high number of aquatic species due to their ecological stability. The present work is focused on springs in an alpine region, and is centered on: (a) floristics of freshwater lichens of the Italian Alps, (b) ecological and morphological information on potential indicator species for calcareous and siliceous springs. The study was carried out in the eastern Italian Alps on 36 perennial springs. Single springs proved to host a surprisingly low number of species, while at regional level the entire pool of investigated springs host a relevant lichen flora representing 45% of the freshwater lichens of the Italian Alps. One species is new to Italy and 3 are new to Trentino-Alto Adige. Biodiversity conservation measures should therefore be planned at regional level, including a whole network of sites in different altitudinal belts and with different substrates. Verrucaria elaeomelaena and V. funckii are the most frequent species on calcareous and siliceous springs respectively. They are suggested as potential indicator species, since they proved to be indicative of the main physical, ecological and hydrochemical features of their habitat. A detailed morphological description of these two species is also provided in order to enhance their identification by environmentalists.

Intraspecific variability in life-history traits was investigated comparing four geographically isolated populations of the shrimp Palaemonetes argentinus (Crustacea, Caridea, Palaemonidae) in the Province of Buenos Aires, Argentina. One population inhabits a creek (Vivoratá Creek, VC), which drains into the brackish coastal lagoon Mar Chiquita; three others live in inland lakes (Lakes Chascomús, LC; La Brava, LB; Los Padres, LP). Female size at the onset of sexual maturity, both realized and actual fecundity (i.e. number of eggs in an early stage of embryonic development and number of freshly hatched larvae per female, respectively), as well as the size of freshly hatched larvae were consistently largest at VC, intermediate at LC and LB, and lowest at LP. The opposite pattern was found in egg loss (estimated as difference between realized and actual fecundity), being lowest at VC, highest at LP, and intermediate in the other two populations. Initial embryonic dry weight (W) was higher at VC than in all other populations. However, the W of freshly hatched larvae was similarly high at VC, LC and LB, but significantly lower at LP. Intraspecific variation in life-history traits, in particular between shrimps from VC (lotic, slightly brackish; highly variable salinities) and those from inland lakes (lentic; low but stable ion concentrations) are discussed in relation to local variation in hydrological and other ecological conditions that may wield differential selection pressures in the life-history evolution of a species with a wide range of ecological and geographic distribution.

Field investigations on 12 populations of Omphiscola glabra were carried out in central France over a 5-year period to determine the ability of the species to aestivate in its habitats when summer drying occurred. In the department of Haute-Vienne, spring-born snails aestivated with their apertures applied to the surface of a substratum and most of them were located on the banks of ditches. With the return of wet conditions, the survival of these snails was low. In the department of Indre, most springborn snails aestivated by burrowing into the marl and were distributed over the whole surface area of their habitats. Higher survivals were noted for these O. glabra after aestivation. Despite a significant difference in the frequencies of buried lymnaeids, the position of snails with a natural infection with F. hepatica in their dried habitats was similar to that found for uninfected ones. The variations found in the aestivation of O. glabra might be explained by the dominant substratum (granite gravel and scarce mud in Haute-Vienne, or a thick layer of marl in Indre) and the plant cover on ditch bottoms.

The alien and potentially invasive species Elodea nuttallii was observed for the first time in Slovenia's Drava River in 2007, when its huge biomasses were observed at some locations. Changes in biomass of submerged macrophyte communities and abiotic factors such as water temperature, discharge and level were monitored at two impoundments of the Drava River (2009, 2010 and 2011). The correlations between abiotic factors and developed final biomass were assessed to determine if the level of abiotic factors has an impact on the final biomass and invasive behaviour of E. nuttallii. The results obtained showed that biomass of E. nuttallii was not excessive in 2009 and 2010, while in the year 2011 it developed huge biomass at locations, which were not directly exposed to the main water current. The biomass of Myriophyllum spicatum was also higher in 2011 in comparison with 2009 and 2010 but not in such high degree. The key factor for the development of the final biomass of E. nuttallii was the water temperatures in winter and spring and also the point at which water temperatures in spring surpassed 10°C. The invasive behaviour of E. nuttallii is expected in the years with higher temperatures in January and March and at the locations which are not directly exposed to the main water current. We assume that continuation of the deposition of silt in the impoundments of the Drava River could contribute to invasive behaviour of species E. nuttallii in the years with mild winters and warmer springs.

The species diversity of Clitellata (a group of annelid worms) is described for three river systems in different parts of southernSweden. The water of one river (Säveån) discharges into the harbour of Göteborg on the Swedish west coast, that of theother two rivers (Svartån and Kilaån) into the Baltic Sea. A total of 143 species, representing the taxa Enchytraeidae (61),Propappidae (1), Lumbricidae (15), Lumbriculidae (6), Tubificidae (4 Rhyacodrilinae, 33 Naidinae, 13 Tubificinae), andHirudinida (10), are reported. Of these, 24 enchytraeids and six lumbricids were found only in the riparian zone, i.e., in the semiaquatichabitats of the river banks. Six species of Enchytraeidae could not be assigned to any known species and are likely tobe new to science. In addition, the following species are recorded from Sweden for the first time : Achaeta brevivasa, Fridericiabenti, F. healyae, F. lenta, F. sylvatica, Oconnorella tubifera (all Enchytraeidae), Aporrectodea limicola (Lumbricidae),Stylodrilus brachystylus (Lumbriculidae), Dero dorsalis, Nais behningi, Haber speciosus, and Peipsidrilus ?saamicus (allTubificidae). Overall, the species composition is typical of today’s fauna of the once glaciated Northern Europe, but for the familyEnchytraeidae, the biogeographical affinity of Sweden is stronger with Denmark and Germany than with, e.g., the British Islesand the eastern parts of Central Europe.

Dans 2 ruisseaux artificiels similaires, 500 alevins vésiculés de Truite commune Salmo trutta L. sont introduits et les alevins "dévalants" de ces ruisseaux sont recueillis et déversés dans un troisième ruisseau identique aux 2 premiers. Le comportement et l'activité des alevins "dévalants" et sédentaires sont observés : une liaison apparaît entre l'activité de dévalaison nocturne des très jeunes alevins et le comportement d'immobilité sur le substrat le jour. Les alevins "dévalants" sont moins actifs globalement que les alevins sédentaires. L'hypothèse du retard de développement des alevins "dévalants" se trouve renforcée.