The biochemical composition of Daphnia magna Straus, the dominant planktonic crustacean of the waste stabilisation pond of Differdange (Grand-Duchy of Luxembourg), was quantitatively determined from October 1993 to July 1994. Over the sampling period, the average composition (mean ± S.D.) was 271 ± 64 mg proteins.g-1 dry weight (DW), 100 ± 28 mg lipids.g-1 (DW), 96 ± 58 μg carotenoids.g-1 (DW), 49 ± 14 mg chitin.g-1 (DW) and 125 ± 78 mg ash.g-1 (DW). The seasonal variations of the biochemical composition were related to several ecological variables (water temperature, dissolved oxygen concentration, pH, water transparency, chlorophyll a concentration and D. magna biomass). The chitin content was positively correlated to the water temperature as a result of the strong influence of this later variable on the moulting rate of the daphnids and, subsequently, on the chitin synthesis by these organisms. The carotenoid content was positively correlated to the water transparency as a result of their photoprotective role in daphnids. The fluctuations of the lipid, protein and ash levels in D. magna depended to the food availability. Despite a seasonal variation in the biochemical composition, D. magna appeared to have adequate lipid and protein levels to be used in aquaculture. Its carotenoid content is similar to fish meals used to color salmonid flesh and these organisms could be used for this purpose. The prospect of using D. magna for chitin extraction is worth considering with respect to its significant chitin content, especially if highly valuable applications are aimed.

La réponse des communautés d'Oligochète aux fortes pollutions domestiques et industrielles d'un petit ruisseau, le Riou Mort, est examinée. L'installation d'une communauté caractéristique (Tubifex tubifex, Limnodrilus hoffmeisteri, L. udekemianus, L. claparedeanus, Nais elinguis) s'accompagne d'une réduction du nombre d'espèces, d'une très forte augmentation de la densité et d'une uniformisation des peuplements entre les faciès lotique et lénitique.La validité de certains indices structuraux (de diversité ou de dominance) appliqués aux seuls Oligochètes et de quelques paramètres spécifiques de ce taxon est discutée. Dans le cas du Riou Mort, il apparaît que des paramètres simples (densité, nombre d'espèces, proportion des diverses familles etc...) reflètent suffisamment bien les conditions de milieu et les Oligochètes sont utiles pour hiérarchiser les fortes pollutions.La tolérance de Lumbricillus rivalis, Pristina idrensis et Trichodrilus allobrogum est à souligner.

Madagascar has been isolated from other land for about 100 million years. Thus the hydra of the island have been evolving independently of the hydra on the continents during the Tertiary geological period. On the northern continents the species of hydra cluster into four groups. Three species were found in a search of about 100 sites across Madagascar. These species represent two, and perhaps three, of the four groups of species that are found on the northern continents. A green hydra found throughout the island is similar to the European Hydra viridissima. One type of brown hydra, H madagascarensis n.sp., has characters intermediate between those of the vulgaris and braueri groups of continental brown hydra. The third species, unnamed in this paper, belongs to the vulgaris group. One continental group of hydra, the oligactis group, is not represented on Madagascar. The hydra that occur in Madagascar are very similar to some on the continents, indicating that these animals evolve exceedingly slowly.

Complete inventories of the fauna at a given place, for a specific community or geographical area are often exceedingly hard to get. In recent years a number of estimation techniques have emerged that can be used to extrapolate from these samples to the true number of species in an area. These estimation models are based on different mathematical approaches and can be classified as either species accumulation curves or nonparametric estimators (Brose et al., 2003, Ecology, 84, 2364–2377). In this paper, we have tested the performance of some of the richness estimators on nineteen mountain ponds in Castilla y León (Spain) in order to provide guidance on their potential use in future researches. We collected benthic macroinvertebrate of these ponds from the littoral zone with a pond net by kicking and sweeping. Ten-second samples were collected in each pond up to a total time of 3 to 5 minutes per pond, depending on the pond size. In addition, two of the ponds, were sampled in 2004, 2006 and 2007 providing a three-year time series. The results of this study showed that Jackknife 2 was the best of the evaluated methods based on all chosen criteria and also performed well across all studied ponds. Jackknife 1, Chao 1 and Chao 2 also presented good results and they were inferior to Jackknife 2 mainly because of the requirement for larger sub-sample sizes.

The 138 species and subspecies of Ephemeroptera now known to occur in Mexico, of which 35, approximately 25 %, areendemic, are listed along with distributional annotations. New Mexican records are included for Americabaetis lugoi Waltz &McCafferty, Baetodes velmae Cohen & Allen, Drunella coloradensis (Dodds), Farrodes otiesa Lugo-Ortiz & McCafferty,Plauditus virilis (McDunnough), Tricorythodes fictus Traver, T. texanus Traver, and Varipes lasiobrachius Lugo-Ortiz &McCafferty, the latter of which also constitutes a new continental record for the genus Varipes Lugo-Ortiz & McCafferty inNorth America. Traverella sallei (Navás), n. comb., is transferred from the genus Thraulus.

Collections of Chironomidae from aquatic habitats on the Azores islands of São Miguel and Flores during August 1997 and on São Miguel, Terceira and Graciosa in September-October 1998, yielded 33 species-level taxa. Representatives of 16 taxa in three subfamilies are new generic / species records for the Azores archipelago: Tanypodinae - Procladius (Holotanypus) choreus (Meigen), Paramerina sp. griechenland, Zavrelimyia sp.; Orthocladiinae - Metriocnemus (Inermipupa) carmencitabertarum Langton et Cobo, Orthocladius (Eudactylocladius) sp., Psectrocladius limbatellus (Holmgren), Psectrocladius sp., Pseudorthocladius sp., Smittia contingens (Walker); Chironominae - Chironomus cingulatus Meigen, Chironomus cf annularius (De Geer), Glyptotendipes barbipes (Staeger), Glyptotendipes pallens (Meigen), Polypedilum nubifer (Skuse), Micropsectra sp. (cf lindrothi Goetghebuer), Paratanytarsus grimmii (Schneider). A revised checklist is provided, incorporating and updating previous records.

The macroinvertebrate community was studied in 3 reaches along a north-Iberian stream that differ in the amount and nature of food resources. Regardless of shading and water quality, both invertebrate density and biomass were higher at the 2 downstream sites than at the headwater site. The taxonomic composition and functional organization of the faunal assemblages showed clear differences among sites: shredders and gatherers dominated the headwater site, and scrapers or gatherers, depending on the degree of shading and organic pollution, dominated the downtream sites. Macroinvertebrates responded roughly to intersite differences in food resources, but poor relationships between temporal dynamics of shredder or scraper abundance and that of their food were found. Likewise, no clear effect of floods on invertebrate density and biomass was observed.

The presence of different species of hydrophytes was investigated in relation to Secchi disk visibility, pH, dissolved oxygen,electrical conductivity, total Kjeldahl nitrogen, total phosphorus and chlorophyll-a concentration in two tropical ponds nearbyKolkata, India, during a three years period (June 1999 to May 2002). The dominant flora in the ponds namely, Alternantheraphiloxeroides, Nymphoides hydrophylla, Lemna aequinoctialis, and Vallisneria spiralis were found to subsist over a wide amplitudeof nutrient levels thereby showing their adaptability to highly eutrophic ecosystems, a common feature of the tropics.However, the presence of some minor species could be associated with a narrow range of specific limnological variables.

Cette étude porte sur les communautés d'Oligochètes aquatiques vivant dans une petite rivière atlantique, le Tambre, et ses milieux associés (lagune, lac de barrage, ria). Elle concerne la répartition spatiale des différentes populations et l'analyse des principaux facteurs qui la déterminent.Des données de l'évolution saisonnière des principales populations et des périodes de reproduction complètent l'inventaire faunistique des Oligochètes récoltés dans ces milieux.

Many freshwater algae are parasitized by aquatic fungi belonging to the Chytridiales Order. The top-down effects of parasitism result in individual losses within algal populations. We present data on the parasitism of the diatom Asterionella formosa Hassall by chytrids, occurring in response to hydrodynamic disturbances and the architecture of the algal host on the landscape scale. Among a series of nine reservoirs, the observed pattern of parasitism depends on the levels of hydrodynamic disturbance: the rate of parasitism is higher at intermediate disturbance levels. A. formosa cells are not randomly parasitized. Whatever the disturbance levels, fungi were found to mostly parasitize cell clusters forming non-stellate colonies.

Cyanobacteria and their principal cyanotoxins were studied in the largest Italian lake (Lake Garda, 65 m a.s.l.) and in a near smaller reservoir (Lake Ledro, 652 m a.s.l.). The two lakes share a fraction of water due to a pipe pumping water from and into the lakes and the same dominant cyanobacterial species (Planktothrix rubescens). Despite the differences in the concentrations of cyanotoxins (mostly microcystins, MCs) and biovolumes of P. rubescens (BVPr) (over one order of magnitude), the Bayesian analyses linking these two variables showed striking similarities, suggesting the existence of similar toxic genotypes colonizing the two water bodies and a constitutive MC production. It was stressed that a greater sensitivity and reliability in the management strategies aimed at minimizing the risks due to cyanobacteria should also contemplate the use of specific lake-tailored models linking MCs and BVPr.

D. gonocephala se présente comme un animal relativement thermophile, doué d'une capacité reproductrice supérieure à celle de C. Alpina au-dessus de 10°, supérieure à celle de P. felina au-dessus de 15°. Une telle capacité explique l'élimination des deux dernières espèces par la première dans les zones les plus chaudes de nos ruisseaux.

Plusieurs populations des cinq espèces pyrénéennes de Micrasema sont étudiées dans des mousses d'eau courante.

Micrasema morosum présente la plus large amplitude altitudinale. Son cycle vital dure un an, deux ans ou trois ans selon l'altitude. Les quatre autres Micrasema ont un cycle d'un an, avec de simples décalages des périodes de vol selon l'altitude.

Au cours du développement larvaire, on ne constate pas d'arrêt saisonnier dans l'alimentation. Les larves de premier stade se nourrissent d'algues périphytiques ; aux autres stades, des fragments de mousses et des algues périphytiques sont indistinctement consommés. En présence d'une abondante couverture de mousses, les larves se développent presque exclusivement dans ce milieu. Dans le cas contraire, des déplacements peuvent être observés entre les pierres et les mousses.

Pour une même cohorte, le taux de croissance en poids sec moyen est relativement constant en basse altitude mais varie au cours du cycle vital en moyenne et en haute altitude. Ces variations se reproduisent d'une cohorte à la suivante. De même, les variations du taux de diminution des nombres se reproduisent, d'une manière semblable, d'une cohorte à la suivante.

Les trois méthodes utilisées pour calculer la production de deux espèces ont donné des résultats voisins. Des différences nettes apparaissent entre deux espèces de Micrasema en une même station de moyenne altitude. Pour une espèce donnée, la production varie également d'une cohorte à la suivante : l'origine de ces variations est à rechercher au niveau de la séquence nymphe -adulte - ponte. En revanche, le rapport Production/Biomasse maximale paraît constant et voisin de ceux mentionnés pour d'autres espèces des Pyrénées centrales.

En Suisse, les cours d'eau de types variés du Jura, des Préalpes et des Alpes ont encore une faune plécoptérique relativement intacte. Par contre, ceux des régions agricoles et industrielles du Plateau ont perdu la moitié de leur faune dansleur cours moyen et même parfois la totalité dans leur cours inférieur.L'atlas des Plécoptères donnera, par la méthode des quadrats, l'état actuel de nos connaissances sur la distribution géographique et sur l'écologie des espèces de Suisse.

Ce travail présente la répartition de 5 espèces de Gammaridae (Echinogammarus berilloni, E. spinulicornis, Gammarusfossarum, G. p. pulex, G. roeseli) dans la Région Centre qui correspond approximativement au bassin de la Loiremoyenne et au sud du bassin de la Seine moyenne. Environ 300 stations ont été échantillonnées entre 1980 et 1990.G. fossarum n'est présente que dans l'Allier. L'espèce la plus répandue est G. p. pulex ; elle apparaît souvent en sympatrieavec E. berilloni. E. spinulicornis et G. roeseli sont deux espèces en extension dans la région. E. spinulicornis estnettement dominante à l'ouest, mais uniquement dans le bassin de la Loire, tandis que G. roeseli est plus abondanteà l'est aussi bien dans le bassin de la Loire que dans celui de la Seine.

Une série de dragages effectués dans la Saône au niveau de 13 stations réparties sur 377 km de rivière montre que le macrobenthos du chenal de cette rivière est, dans les stations les moins dégradées, largement dominé par les Ephéméroptères fouisseurs (Ephoron virgo et Ephemera lineata). La comparaison avec le macrobenthos du Haut-Rhône indique que ce dernier, qui présente des caractéristiques mésologiques et hydrologiques similaires, se situe typologiquement plus à l'amont que la Saône. La durée et l'importance de l'étiage combinées avec les différences de pente, cette dernière influençant la vitesse du courant et la granulométrie, sont probablement les facteurs essentiels qui structurent les peuplements macrobenthiques de ces deux cours d'eau.

La production annuelle nette de Ch. commutatus est évaluée, en 1971-72 à 6,29 kg/PS/ha, plaçant cette espèce au deuxième rang d'importance dans la production de la communauté benthique littori-profonde du lac. Le rapport P/Bmax = 1,49 confirme la stabilité de sa valeur, précédemment montrée chez plusieurs représentants du benthos, et, plus récemment, chez deux crustacés monocycliques du zooplancton de ce même lac.

Plus du tiers (36 %) de la production est perdu pour l'écosystème lors de la nymphose (30 %) et de l'émergence des adultes (6 %).

Les truites (Salmo trutta fario L.) utilisent 10,5 % de la production de Ch. commutatus par l'ingestion de nymphes au cours de leur ascension ; cela représente 49 kg/PF consommés pour les 10,5 ha de la zone 7-19 m.

The current status of the stream-living insects and gastropods of the island of Gran Canaria in the Atlantic Canary Islands is documented. Data from semiquantitative kick samples taken in 11 streams are supplemented by non-standardized collecting in the same and ten additional streams. The kick samples included some 9,000 specimens of 98 taxa, and in total 123 taxa were recorded from the studied streams in 1994 and 1995. The stream fauna was dominated by Diptera with some 80 taxa, followed by Coleoptera with 37 species known from the island. The kick samples yielded 11-36 species per stream and visit, whereas up to 48 species were scored when all collecting methods were included. Local diversity given as Fisher's α ranged from 3.2 to 10.3. Clustering showed only weak spatial patterns and resulted in much higher similarities among localities when based on the semiquantitative samples than when based on presence/absence including records from all collecting methods. Species distributions among localities were not significantly nested. The faunal similarity with the adjacent island of Tenerife is striking. Six of the Tenerife species are seemingly absent from Gran Canaria, whereas Gran Canaria has 13 species not found in Tenerife. Most of the 22 aquatic insect species in Gran Canaria only known from older records, prefer lentic habitats not included in our study. All except one of the five species endemic to Gran Canaria are considered extinct or on the edge of extinction. Increased future extinction rates are predicted as a response of the extreme habitat loss, with only three permanent streams known on the island today.

The within-site patchy distribution of organisms represents a natural source of variability that can bias the precision of biotic indices. This study aims to evaluate the spatial distribution of benthic macroinvertebrates and its effects on the biotic index used in Italy for assessing the ecological status of rivers. Two main issues were considered: the sampling design and the minimum number of replicates which are necessary to achieve a given precision level. To this purpose, 30 surber replicates were taken, instead of the ten required for the application of the index, in a homogeneous reach of a mid-sized perennial river (Trebbia River, Northern Italy). The percentile confidence interval (p.c.i.) of the index was calculated from 1000 possible communities with the resampling method and the bootstrap procedure. The 95% p.c.i. varied from 0.195 to 0.227, which is great considering that the index ranges from 0 to 1. The metrics based on abundance data were especially affected by the heterogeneous distribution of organisms. The resulting precision of the index increased only partially when doubling the sampling effort.

Spatial-temporal changes in the physico-chemical characteristics of the Agura river (Basque Country and Cantabrian region, Spain) were studied over six months, a period that included a long period of unusual drought and the return to more normal hydrological conditions. The chemical composition of the water was affected by water flow. It wasinfluenced either directly through the drainage characteristics at the level of different parts of the surrounding basin,or indirectly through the action of biotic communities on their environment. From these results, some spatial and/ortemporal models have been developed for the dynamics of the different variables in this study.