The rules governing the allocation of available resources to varying physiological processes are evaluated in three physiologically-based models of individual Daphnia. In laboratory experiments using a single clone, subjected to varying regimes of food deprivation, growth was found to vary inversely with food level, ceasing in the absence of food, implying that growth allocation is derived directly from food. Reproductive investment was reduced under food deprivation, ceasing at low food levels. By exposing juvenile and adult daphnia to varying food deprivation regimens during different periods within their intermoult interval, it was shown that instar durations vary as a function of body size and food availability independent of the age of the animal. For the first time, the role of variable instar duration, which critically influences physiological processes such as growth, moulting and reproduction in adult females, that has been neglected by existing Daphnia models, is explicitly incorporated in a physiological allocation model. The consequent model provides a simplified framework for modelling the consequences of food deprivation in cladocerans which has important application in population modelling and environmental risk assessment.

Aquatic microfungi play a fundamental role in organic matter decomposition in fluvial ecosystems. These micro-organisms degrade leaf recalcitrant compounds like lignin, thereby enhancing the utilization of organic material by the microbial community. The main input of allochthonous organic matter in Mediterranean streams occurs during the autumn. In-stream breakdown processes can be affected by high physical abrasion during flooding but changes in stream water chemistry may also affect decomposition enzymatic activities of stream microorganisms. We measured two ligninolytic activities (phenol oxidase and peroxidase) and a cellulolytic activity (cellobiohydrolase) in leaves, branches, sand and gravel substrata in a reach of a Mediterranean stream. Highest ligninolytic activities were measured in biofilm developed on inorganic substrata (sand and gravel) where also accumulated the highest fungal biomass (ranging from 3.3 x 10-4 to 7.22 mg Ergosterol gAFDM-1) especially in sand substrata. Conversely, cellulolytic activities were significantly higher in biofilm on organic substrata (leaves and branches). Physical and chemical factors, such as discharge and stream water nutrient concentration (Dissolved Inorganic Nitrogen) were affecting enzymatic activities, particularly enhancing the phenol oxidase. Moreover, the chemical composition of the available OM (high cellulose in leaves, high lignin in detritic material) strongly influenced the decomposition activity in each biofilm. A precise description and quantification of the benthic substrata was used to obtain enzymatic activity values in terms of stream reach. Those results showed a temporal pattern in the decomposition activities in the reach, beginning with the decomposition of cellulose (October) followed by lignin compounds (November and December).

The life cycle of Musculium lacustre populations in the Saône river at Lyon was studied over a three-years period. Following the growth period which occurs from March to June, adults released larvae, then disappeared during the summer. Only a few newborn of the new generation that appeared in May and June grow and give birth to a second generation at the end of summer or in autumn. Most of the juveniles of the first generation estivate, then hibernate with those of the second generation until the following spring. The individuals of each generation only reproduce once (semelparity). Longevity of M. lacustre is from 13 to 14 months. In 2001, the spring flood disturbed the progress of the life cycle and delayed the appearance of the new generation for one month. In 2003, a large accumulation of dead leaves at the beginning of winter and high spring temperatures led to considerable production of larvae. However, this was not followed by an increase in numbers: high mortality among the newborn occurred during May and June. These observations suggest that M. lacustre populations of the Saône are habitually food-limited. Nonetheless, the life cycle strategy adopted by this bivalve enabled it to withstand the high summer temperatures of 2003 as opposed to other Sphaeriidae (Pisidium) which disappeared in August.

Tanypus complanatus sp. n., Pseudosmittia remigula sp. n, and Polypedilum (Tripodura) silhoettarium sp. n. are described as male imagines and Clunio gerlachi sp. n. as male and female imago. The male imagines of Larsia pallidissima (Kieffer), Gymnometriocnemus (Gymnometriocnemus) mahensis (Kieffer), Pseudosmittia xanthostola (Kieffer) and Polypedilum (Polypedilum) glabripenne (Kieffer) are described for the first time. The male imagines of Paramerina minima (Kieffer), Smittia megalochirus (Kieffer) n. comb., Smittia mahensis (Kieffer) and Pseudosmittia melanostola (Kieffer); and the female imago of Pseudosmittia xanthostola (Kieffer) are redescribed. A key to the known chironomids of the Seychelles is given. Twenty-eight chironomid species are known from the Seychelles, 23 from the island of Mahé, 12 from Silhouette, 3 from Curieuse, 2 from Anonyme and 1 from each of Fregate, North and the coralline Alphonse. The likely marine intertidal species appears to have their closest relatives in Micronesia and the Pacific, while the freshwater chironomid fauna appear to have more Afrotropical relatives.

The Chironomidae fauna of ten large European rivers (Rhine, Elbe, Oder, Danube, Loire, Pripjat, Po, Maas, Garonne and Rhône) were investigated by analysing their ecological traits (longitudinal zonation pattern, saprobiological affinities, feeding types) using one-dimensional and multivariate methods. The results confirm the geomorphological differentiation of these rivers in two main types, i.e. gravel-type and sand-type rivers. The analyses of the Chironomidae traits also showed that transition zones separate the two main types of rivers.

The spatial and temporal distribution patterns of benthic macroinvertebrates were studied in an intermittent river in Algeria (Chelif wadi, North Africa), by using the self-organizing map (SOM), an unsupervised artificial neural network. The samples were collected monthly at 8 sampling sites (630 to 20 m above sea level) and community variation was analysed in space and time. Overall, the study sites showed a very poor macroinvertebrate fauna: more than 60% of samples contained less than 11 species, and 99% had less than 30 species. Furthermore, most species displayed very low abundance: 66% of the species were represented by less than 20 individuals (abundance). Among the identified taxa, Chironomidae was the dominant taxon at all sampling sites except at the most upstream site (630 m a.s.l.) where it was replaced by Coleoptera. Concerning monthly changes, the species richness was very low in August and October. Through the learning process of the SOM, samples were classified into four clusters by the SOM, and the classification was mainly related to the location of the sampling sites. Benthic macroinvertebrates were divided into four classes, which revealed the influence of pollution on their longitudinal distribution in this stream. According to the distribution gradients of the environmental variables on the SOM map, their influence on the classification of the sampling sites could be assessed effectively.

We report the results of a study carried out in 2002 on the main limnological characteristics and on the ostracod communities of 16 wetlands of the Parco Oglio Sud (Northern Italy). Physical and hydrochemical variables were measured and ostracod samples were collected in different seasons (April, June, August, and October). Most of the considered sites were characterised by high concentrations of nitrogenous compounds due to washing out from cultivated areas, intermittent river flooding and internal recycling. Observed differences in macrophyte communities were consistent with trophic status of waters, with pleustonic forms dominating most degraded areas. Both morphology of valves (by scanning electron microscopy) and anatomy of soft parts were analysed for ostracod species identification. Nineteen ostracod species in five families were found. Two species, Candona weltneri and Pseudocandona compressa, are new records for Italy. Cypria ophthalmica was collected from all sampling sites; other relatively common species were Cypridopsis vidua, Cyclocypris ovum, and Candona weltneri. No clear seasonality was observed in community structure; highest species diversity occurred in June in most of the studied wetlands. The maximum number of species per site was seven, and a maximum of six species was found in a single sample. Ostracod occurrence in relation to environmental factors was examined using Canonical correspondence analysis (CCA). Total alkalinity and pH were the most important variables structuring the species assemblages. The ostracod fauna found in this area was compared to the known distribution of recent non-marine ostracods in Italy, and the validity of published checklists is discussed.

The larvae of Allogamus gibraltaricus González & Ruiz, 2001 and A. mortoni (Navás, 1907), two endemic species of the Iberian Peninsula, are described for the first time and compared with other known Iberian species. A key to the larvae of genus Allogamus including all Iberian species is given.