The Asian clam Corbicula fluminea is one of the most invasive species in freshwater aquatic ecosystems. The rapid growth, earlier sexual maturity, short life span, high fecundity and its association with human activities makes C. fluminea a non-indigenous invasive species likely to colonize new environments. This species, originally distributed in Asiatic ecosystems, is now a common inhabitant of American and European freshwater habitats. The present paper reviews the information related to the life cycle, ecology and potential ecological and economic impacts caused by C. fluminea in the invaded habitats. Furthermore, this paper also proposed future works that may be implemented in order to increase our general knowledge about the ecology of this bivalve.

White-clawed crayfish, bullhead, and freshwater pearl mussel are different model organisms in terms of biological traits. Analysing their distribution patterns, habitat demands, and causes of decline may thus help to derive broader frameworks for conservation projects. This paper includes a wide-ranging literature review for these three threatened freshwater animals, then uses general patterns to make suggestions about broader protection measures for freshwater species. Each species has a patchy distribution, from local to broad spatial scales. However, we point out the difficulty to summarise such knowledge, because many variables were not consistently and/or accurately recorded by workers, and because the range of colonised habitats depends on the environmental heterogeneity within study areas. Causes of decline are chiefly related to human activities which modify the biological, chemical, and physical features of the aquatic environment, and can be classified into four types: physical habitat alterations, interspecific interactions, overfishing and poaching, and natural disturbance. By analysing causes of decline and possible actions, we develop seven general trends that could be adopted for a wider array of species. However, protection plans cannot be effective without actual collaborations between river managers, local inhabitants, and authorities. Finally, the re-introduction procedure itself (if needed) depends on the biology of the species under survey, and remains specific. At the same time, further fundamental research is needed to generalise relationships between population and habitat dynamics at different spatial and temporal scales.

The Guadiana estuary (Iberian Peninsula, Europe) has low agriculture, industry and urban pressure, unlike other major Iberian estuaries; however, this situation is about to change. The Alqueva dam was constructed at 150 km from the river mouth, creating one of the biggest artificial lakes in Europe, which will support 110 000 ha of irrigation areas. Moreover, the estuarine margins are suffering increased human pressure. The risks that the Alqueva dam will pose to the downstream ecosystems, mainly to the estuary and adjacent coastal area, will be reviewed in this paper. Other issues are also analysed, as increased human desertification in the Portuguese basin, real estate pressure and the impact of the construction of a public infrastructure in the Portuguese lower estuary. Increased problems of sediment load reduction, water quality deterioration and shifts in the downstream fish populations are expected due to higher river flow reduction. Irreversible changes to estuarine margins and increased risk of pollution in the estuary will result from the multiple urban pressures. Lack of forest management and increased risk of wildfires, leading to water quality degradation and increased soil erosion, are a result of human desertification in the upper Portuguese basin. Multiple solutions to tackle these problems have to be considered. Creating the International Natural Park of the Lower Guadiana would not be enough and tourism should not be regarded as the only way to develop such a poor region. An ecohydrological approach of the basin should be implemented, to establish scientific based solutions to help solving conflicts and testing scenarios. Ultimately, the creation of a Portuguese-Spanish Basin Management Council for the lower Guadiana, involving those that are interested in the sustainable development of the Guadiana (local populations and associations, private stakeholders (dam managers, tourism entrepreneurs, farmers), local and national authorities, ENGO’s and scientists) is essential to produce ecological and sustainable management decisions.

Benthic macroinvertebrates collected at seven different streams displaying different pollution levels were used to investigate species abundance patterns in polluted streams. Community response to disturbances in streams was analysed using species abundance distribution (SAD) for benthic macroinvertebrates across different levels of pollution. The slopes of rank abundance were characteristically steeper with decreasing species richness at the polluted sample sites, while the slopes were less steep with higher species richness at the clean or slightly disturbed sample sites. The SADs were broadly fitted to the log normal distribution in benthic macroinvertebrate communities across different levels of pollution. A geometric series was partly accepted for the communities at the severely polluted sites where new species could not be readily introduced. A power law was applied to the SADs, and the parameters reflected the states pertaining to the sample sites. The SADs were also efficient in revealing ecological state of communities where physico-chemical indicators could not be easily differentiated for stressful conditions in streams.

The temporal dynamics in density, life histories, and emergence patterns were described for the first time for five Plecoptera species in tributaries of the Futaleufú River in Patagonia, Argentina. Benthic samples and adult collections were made in five low order Nothofagus forested streams. Four species of Gripopterygidae; Aubertoperla illiesi, Notoperlopsis femina, Antarctoperla michaelseni and Senzilloides panguipulli had simple, highly synchronized univoltine life histories. The austroperlid Klapopteryx kuscheli takes more than two years to develop. Emergence periods of most of the species were concentrated in late spring and summer (October to February), which suggests seasonal and synchronized life histories. Most N. femina adults were collected in mid spring indicating this species emerged first, whereas S. panguipulli emerged last from January to April. Aubertoperla illiesi showed a slightly delayed emergence at the high elevation site (La Hoya Stream) when compared to a piedmont stream, suggesting that temperature was an important control. Although we were unable to describe the life history of Limnoperla jaffueli (Gripopterygidae) its adult emergence period was November to January. Life histories of Plecoptera species in the studied streams seem to have a high degree of seasonality at least at this latitude, and are possibly determined by predictable temperature patterns and discharge regimes. This first contribution on the life histories of Plecoptera species helps us to better understand the dynamics and functioning of pristine but fragile aquatic environments in Patagonia.

Temporal and spatial variation in the concentrations of intra- and extra-cellular microcystins were studied in a hypertrophic lake with bloom of Planktothrix agardhii (Gomont) Anagnostidis et Komarek. Concomitantly with increase in water temperature (from 2 to 20 °C) abundance of P. agardhii increased from 1.9 x 105 to 4.3 x 107 trichomes L-1. In autumn, in spite of temperature lower (14°C) than in summer it was still very high. Mass development of P. agardhii (to 6 x 106 L-1 and higher) caused a severe decrease in water transparency (to 0.5 - 0.2 m in summer/autumn). The cyanobacterium density was relatively uniform within water column; only in summer (July) it was significantly higher (by about 30%) in surface than in bottom layer. From spring to autumn microcystins (MCs) were mainly biomass-bound (up to 90 μg MC-LR equiv. L-1), whereas the level of extra-cellular toxins was much lower (up to 2 μg L-1) and relatively stable. Only in winter, high amounts of MCs (11.3 μg L-1) were released from decaying biomass into water. The increasing concentrations of biomass-bound microcystins in the lake water positively correlated (R2 = 0.9863; y = -0.1285x2 + 7.14x ) with the abundance of P. agardhii and the highest concentrations of the intracellular MC fraction were found during the exponential phase of P. agardhii growth. In addition, the surface-sampled biomass of P. agardhii contained in autumn 2-fold more MCs (2.75 μg MC-LR equiv. per 106 P. agardhii trichomes) than the bottom-sampled one (1.41 μg MC-LR equiv. per 106 trichomes). This is the first report showing that despite the homogenous distribution of P. agardhii in water column of a shallow lake, various seasonal and spatial distributions of both extra-cellular and intracellular fractions of microcystins occur.

Morphology of both the valves and limbs of several parthenogenetic populations of the widespread non-marine ostracod Cryptocandona vavrai Kaufmann (sensu lato) living in groundwater habitats of western (France) and south-eastern Europe (Romania) was examined for the extent of intra- and interpopulational variation. Geometric morphometrics and multivariate statistics were employed for the description of the valve morphological disparity whereas the discriminant analysis was performed for the comparative analysis of the limb chaetotaxy. The ranges of the most studied limb traits principally overlapped among the populations, however considerable differences in the carapace shape and size, reflecting microevolutionary changes at a macro-scale (inter-population) level, allowed distinguishing quantitatively some Romanian populations which deserve a separate specific status. Hence, a new species Cryptocandona racovitzai sp. nov. is described which differs from C. vavrai sensu stricto mainly in larger size, in more triangular valve shape as seen laterally and in less developed inner lamella of the valves. Finally, after examination of more material from Romanian groundwaters, we hypothesised the presence of more new species within the studied lineage and concluded that Cryptocandona vavrai sensu lato is a polymorphic lineage consisting of several geographically differentiated species rather than just only one widely dispersed species.