Oceanic islands freshwater systems are unique due to their volcanic origin, oceanic situation, catchment morphology and the presence of distinct freshwater communities when compared with continental systems. This study provides an update of Azorean chironomid fauna records, distribution data and includes biogeographical comments, based on collections covering a range of freshwater habitats on several islands over 2005 to 2008. Island species area-relationships or ISAR was performed as a descriptive model for species accumulation patterns in each island in relation to their area. Six new chironimid species records are given for the Azores archipelago: Orthocladiinae:Orthocladius (Eudactylocladius) fuscimanus (Kieffer, 1908), Pseudorthocladius (Pseudorthocladius) curtistylus (Goetghebuer, 1921), Synorthocladius semivirens (Kieffer, 1909), Parachaetocladius abnobaeus (Wülker, 1959); Chironominae:Chironomus (Chironomus) annularis (Meigen, 1818), Parachironomus tenuicaudatus (Malloch, 1915). As a result, the Azorean chironomid fauna has increased from 38 to 44 species, spread across 33 genera. Most recorded chironomids are primarily of western Palaearctic origin; Nearctic, Oriental and Neotropical regions are comparatively poorly represented. A checklist is provided, incorporating and updating previous records. Chirononidae distribution pattern among the islands is analyzed and island species area-relationship (ISAR) analyses, performed to provide a descriptive model for species accumulation patterns in each island, indicated a positive correlation between species richness (number of species) and the area of the Azorean islands, supporting MacArthur and Wilson’s equilibrium theory of island biogeography. Chironomidae could be promising for searching candidate bioindicators to answer the demand of Water Frame Directive.

The benthic community of a braided reach of a lowland river was studied with the aim to identify functional habitats through the assessment of potential habitats. Functional habitats were defined considering physical and biological characteristics. Three reaches of the Chocancharava River (Córdoba, Argentina) were selected and six potential habitats were sampled during high and low water periods. Hydraulic and environmental variables were also registered in each sampling occasion. Taxonomic composition, macroinvertebrate abundance, richness, diversity and evenness were estimated for each identified functional habitat. TWINSPAN analysis was applied separately for two data sets (high water and low water period). This analysis showed that samples of the low water period were mainly grouped in relation to three habitats units: vegetated habitats, unvegetated habitats and habitats related to bars. These three habitats were considered functional habitats. The whole biological and environmental data sets were ordinated by Canonical Correspondence Analysis (CCA) showing a significant relationship between benthic assemblages and environmental variables. This analysis grouped samples in relation to the functional habitats identified by TWINSPAN and indicated that the most influential environmental variables explaining the ordination were: current velocity, depth, substrate size and cover percent of rooted emergent macrophytes. Faunal composition determined by CCA for each functional habitat was in agreement with the results obtained by the Relative Preference Index (RPI). Factorial ANOVAs showed that abundance, taxonomic richness, diversity and evenness were different among the functional habitats and that the community attributes were influenced by the effect of the hydrological period and habitat. As the functional habitat approach provides useful tools in management and river rehabilitation the use of this methodology may allow to develop more appropriate restoration strategies to be applied in altered lowland reaches.

We studied the effect of point-source and non-point-source pollution on the retention capacity of the stream and its link with the metabolic state (primary production and respiration) and invertebrates assemblages in a third order Mediterranean stream. Two experimental sites were chosen: one in the upper part of the catchment (Montégut site) characterized by low concentrations in nitrate and phosphate and one in the lower part of the catchment (Lézat site) characterized by high nitrate and phosphorus concentrations. Both experimental sites were located on reaches that included a Waste Water Treatment Plant (WWTP) point nutrient source allowing discussion of the relative effects of point-source and non-point-source nutrients loads on ecosystem function (respiration and uptake rates) and aquatic organism assemblages. NH4 +-N, and PO4 3 −-P uptake rates were determined using solute additions conducted at constant rates (short-term nutrient addition procedure) and NO3 −-N uptake rates were determined using instantaneous solute addition (slug addition procedure). Rates of gross primary production (GPP) and ecosystem respiration were determined using the open system, two-stations diurnal oxygen change method. Benthic invertebrate communities were investigated for species and functional feeding groups diversities measurements. Results show that autotrophy in the river results from nutrients of two distinct origins: point sources for phosphorus (urban area and WWTP) and non-point sources for nitrogen (agricultural zones) with local additions from WWTP inputs. Comparison between the two sites shows that the WWTP did not affect uptake rates, respiration or primary production of the ecosystem in the low-nutrient Montégut reach despite increase of invertebrates communities biomass density. Inputs from the WWTP, in the high nitrate and phosphate Lézat reach, increased respiration, lower benthic biomass and led to changes in the species composition and did not affect uptake rates.

We characterized phytoplankton community succession at different depths of a shallow hypertrophic reservoir in relation to physical and chemical environmental variables. The phytoplankton community was sampled biweekly at three different water depths (surface, middle and bottom) in the reservoir from November 2002 to February 2004. A range of 18 environmental variables including temperature, electrical conductivity (EC), total phosphorus (TP) and total nitrogen (TN) were measured to assess their influence on phytoplankton community succession. As well, combined multivariate analyses with a cluster analysis and a nonmetric multidimensional scale (NMDS) were conducted. Microcystis aeruginosa was the dominant species in all seasons except spring. Thus, Cyanophyceae was a dominant taxonomic group. In spring, Bacillariophyceae dominated, followed by Cryptophyceae and Chlorophyceae. The succession was relatively delayed at the middle and bottom layers compared with at the surface layer. Abundance and species richness of phytoplankton were also higher in the surface layer than in the bottom layer. Cluster analysis classified the phytoplankton community into four clusters at each depth, and the changes were also well reflected in the NMDS ordination. Each cluster showed seasonal patterns characterized by indicator species, as well as environmental variables such as temperature, conductivity, and nutrients including N and P. Seasonal dynamics of the phytoplankton community was the strongest at the surface layer and weakest at the bottom layer. These depth-variable environmental variables are likely to be the key factors driving changes in the phytoplankton community composition.

The spatial and temporal distribution of zooplankton and environmental parameters in Kasseb, Mornaguia and Ghdir El Goulla reservoirs (North of Tunisia) were studied monthly from July to December 2002 in order to establish seasonal patterns, biotic and abiotic relationships for these reservoirs. In Kasseb reservoir, the zooplankton community was dominated by Acanthocyclops sp. (37.3% of total zooplankton density) and Bosmina longirostris (32.6% of total zooplankton density). In Mornaguia and Ghdir El Goulla, Copidodiaptomus numidicus was the most abundant species with 62.1% and 97.5% of total zooplankton density respectively. Our study indicated that the zooplankton community of Ghdir El Goulla reservoir was influenced by the impact of internal environmental factors and artificially introduced water from the two Kasseb and Mornaguia reservoirs. Highest density of zooplankton species was recorded in Kasseb reservoir, which indicated an increased tendency for eutrophication. Mornaguia and Ghdir El Goulla are oligo-mesotrophic reservoirs. Understanding the relationship between the zooplankton community and temporal distribution is important for the understanding of trophic interactions within these reservoirs.

We analysed the responses of Anabaena doliolum to elevated levels of copper and zinc in batch and semi-continuous cultures. Approximately 10, 4 and 8 and 5-times greater inhibition in final yield of A. doliolum occurred at 1, 2 μM Cu and 2.5 and 5 μM of Zn, respectively, in semi-continuous culture in comparison to batch culture. Protein, chlorophyl a and carotenoid contents of A. doliolum showed significantly (P < 0.05) higher inhibition by test metals in semi-continuous culture than in batch culture. The greater sensitivity of different parameters of the test organism was related to the high metal content of the cells grown in semi-continuous system. Moreover, enhancement of pH of the culture suspension in batch culture showed a negative relationship with metal accumulation, and therefore with toxicity. This was due to decrease in free ionic concentrations of test metals. Carotenoids acted as a metal detoxifying agent by minimizing metal-induced inhibition in batch culture as was evident from its negative relationship with metal toxicity.

A new species of Tricorythodes Ulmer (Ephemeroptera: Leptohyphidae) is described based on nymphs from the Northern Region of Brazil. Tricorythodes rondoniensis sp. n. can be distinguished from other species in the genus by the following characters: wide femora, nearly circular, with the margins covered with very long setae; tarsal claws with 5–6 marginal denticles; terga III–VII with an acute median tubercle; operculate gill ovoid and abdominal colour pattern.