Research in the phytoplankton community has become an important part of the overall water-quality monitoring. However, to date studies in small rivers and streams were still scarce and sampling methods were also diverse and not as well developed as in lakes or large rivers. We investigated whether two sampling protocols collected different phytoplankton assemblages within a lowland catchment and, consequently, influenced the outcome of bio-assessment. Data collected from 77 sites by plankton net (PLNET) collection and sedimentation (SEDIM) protocols were analyzed. Median Bray–Curtis (BC) similarity between phytoplankton assemblages generated by the two protocols was 48.5% (range: 7.5–82.0%), and sites with the lowest BC similarities tended to have lower chlorophyll a (Chla), water temperature (WT), total suspended solid (TSS) and volatile suspended solid (VSS), but higher channel width and water depth, than other sites with higher BC similarities. Reduced total algal density and biomass, but higher species richness, were observed by the PLNET protocol. However, overall phytoplankton assemblages generated by the two protocols were similar, as indicated by dominant species (paired t-test, P>0.05) and non-metric multidimensional scaling (NMDS) ordination. Nevertheless, from the phytoplankton-based bio-assessment point of view, PLNET protocol was a better method compared with SEDIM protocol because algal data collected by PLNET protocol had higher relationship with environmental variables as indicated by ‘Correlation Index’ (CoI), Cumulative_R2 and canonical correspondence analysis (CCA).

Freshwater systems on volcanic oceanic islands have very particular characteristics as a result of their geological origins, relatively small size, distances from source areas for colonizers, and distinct catchment morphology. These factors result in freshwater communities that are clearly distinct from continental systems. Chironomid spatial and temporal distribution was investigated in chironomid assemblages at 21 sites across the Azores Archipelago. Results using PERMANOVA, a permutational multivariate analysis of variance, indicated significant longitudinal differences in assemblages but none between islands or over time.

Links between hydromorphological and physicochemical variables and the community assemblage were assessed using DISTLM, a linear model for distance-based multivariate analysis. The percentage of variation explained by hydromorphological factors (31%) was slightly higher than that explained by physicochemical (28%) factors. Descriptors of land use (forest area, scrub area, natural area of catchment) and stream slope were found to be the best environmental predictors of chironomid assemblages in Azores. Physicochemical variables such as temperature, pH, nitrite, iron and conductivity were the principal drivers of change in chironomid composition in stream locations. Headwater sites, characterized by lower temperature, acid to neutral pH values, low conductivity, nutrient and metal concentrations were dominated by Rheocricotopus atripes. Mid-section sites, located in agricultural areas were dominated by Thienemanniella clavicornis. Urbanized lower reaches were characterized by higher temperature, pH, conductivity and nutrient levels and were dominated by Cricotopus sp. These results give essential information that allows us to predict the response of different chironomid species to hydromorphological and physicochemical gradients across the archipelago's streams contributing providing the basis for the development of tools for the implementation of the Water Frame Directive.

The objective of the present study was to examine the colonization of oligochaetes during the decomposition of leaves of the macrophyte Eichhornia azurea in a lentic system in southeastern Brazil. The experiment was conducted between September and November 2007, with the use of 21 nylon bags measuring 15×15 cm with 2 mm mesh, each containing 10 g of dried leaves. The bags were removed from the lake after 2, 5, 8, 12, 25, 45 and 65 days. At the end of the experiment, 31.40% of the initial mass remained, and the decomposition rate was 0.018 d−1. The mean density of oligochaetes during the experiment was 32.81±9.58 ind.g−1 DM. The sub-families Naidinae and Pristininae accounted for 99.83% of the oligochaetes. The substrate quality influenced the colonization of E. azurea leaves, as observed from the cluster analysis by the formation of two groups based on increased density during the experiment, indicating a degradative ecological succession. During the decomposition there were changes in the community of oligochaetes, resulting from differences in the ability to exploit various food sources, with predominance of predators in the first decomposition phase and of collectors at the end of the experiment.

Vineyards are a dominant feature of many landscapes in Mediterranean-climate regions. We examined the effects of streamflow declines, associated with vineyard water-withdrawals for frost protection, on benthic-macroinvertebrate communities at three sites along three small streams in the Mediterranean-climate region of Northern California. One site was heavily affected by water withdrawals for frost protection, the other two were not. In addition, we examined relationships between vineyard coverage and benthic-macroinvertebrate community response using data from 59 sampling events at 39 sites along 35 small streams in Napa County, California. We tested three a priori hypotheses in terms of the response of biological traits of benthic macroinvertebrates to high vineyard coverage: (1) proportion of individuals with semi-voltine (i.e., one generation every 2 years) life cycles would be lower compared to those with uni- and multi-voltine cycles, (2) proportion of individuals able to undergo diapause would be higher, and (3) proportion of individuals with the ability to burrow into the substrate would be higher. In the three-site study, we found that vineyard water-withdrawals for frost protection coincided with consistently lower values in both the benthic-macroinvertebrate index of biotic integrity (B-IBI) developed for Northern California streams and the ratio of Ephemeroptera–Plecoptera–Trichoptera to Odonata–Coleoptera–Hemiptera individuals (EPT/OCH), a metric developed for European Mediterranean streams. In the broader-scale study, we observed that vineyard-coverage levels above about 20% coincided with lower values of the B-IBI. The semi-voltine life-cycle trait was lower above this level, whereas the diapause and burrowing traits were not affected.

The structure and composition of the bacterial community associated with buoyant Microcystis colonies were monitored during the decline of a cyanobacterial bloom (from October 13, 2009 to January 27, 2010). When temperature decreased, the ratio between the colony-associated bacteria and the Microcystis gradually decreased as estimated by a quantitative real-time polymerase chain reaction (qRT-PCR)-based approach. Diversity of bacterial communities was determined through denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments. Cluster analysis of the DGGE profiles showed that most of the bacterial communities associated with Microcystis colonies collected on the nearby dates were clustered together. The bacterial clones from four clone libraries in different months were classified into 5, 12, 6 and 12 operational taxonomic units, most of which were affiliated with Gammaproteobacteria, Alphaproteobacteria and Bacteroidetes. Shift in dominance from pathogenic Aeromonas sp. to Shewanella sp. capable of remineralization of many organic materials was observed, and both species seemed to be associated with Microcystis colonies along with the bloom decline. These results indicated that the potential harmful effects of the Microcystis bloom on the safety of lake water during the decline period should be taken into account.

Eutrophication of freshwater lakes has led to blooms formed by cyanobacteria often associated with toxins harmful to livestock and humans. Environmental conditions that favor toxin production during cyanobacterial blooms are, however, not well understood. Moreover, the ability to use cyanobacteria quantity to assess the level of threat associated with toxin production is a topic of discussion. The purpose for this study was to examine Planktothrix agardhii dynamics in a shallow, temperate hypertrophic lake and to determine the factors that affect microcystin production. In addition, the relationship between P. agardhii morphology and microcystin production was examined. The study spanned 2 years, and we documented a perennial P. agardhii bloom that contributed up to 99% of the total biomass. Intracellular microcystins were primarily detected throughout the study, with the highest concentration in October. Microcystin concentrations ranged from 3.4 to 71.2 μg.L−1, and they had a strong, positive correlation with P. agardhii biomass. In contrast, the levels of weight-specific microcystin were relatively stable throughout the entire study, ranging from 0.23 to 1.18 μg.mg−1. We also found that environmental factors, such as water temperature, phosphate level, ammonium nitrogen and transparency, were the most related to microcystin production. Furthermore, a significant relationship between filament morphology and toxin concentration suggested that there were different morphotypes within the toxic and non-toxic populations of P. agardhii. Our study showed that P. agardhii biomass and filament morphology may be useful characteristics for the identification of threats associated with cyanotoxins.

In the present paper, adults of the family Gripopterygidae collected in Paranapiacaba mountains are analyzed, the new species are described and a key to species of this family from this area is presented. Twenty one species in four genera of Gripopterygidae are recorded in Paranapiacaba mountains, São Paulo State, Brazil. Gripopteryx comprises six species: Gripopteryx cancellata, Gripopteryx reticulata, Gripopteryx garbei, Gripopteryx coruja, Gripopteryx pinima and Gripopteryx flinti. Paragripopteryx is represented by eight species: Paragripopteryx klapaleki, Paragripopteryx anga, Paragripopteryx blanda, Paragripopteryx egena, Paragripopteryx hamata and three new species: Paragripopteryx intervalensis, Paragripopteryx kapilei and Paragripopteryx paranapiacabae. Tupiperla is represented by six species: Tupiperla gracilis, Tupiperla tessellata, Tupiperla eleonorae, Tupiperla umbya and two new species, Tupiperla amandae and Tupiperla froehlichi. Guaranyperla is represented by only one species: Guaranyperla guapiara.

Four new species of Thraulodes Ulmer (Ephemeroptera: Leptophlebiidae), Thraulodes amanda sp. n., Thraulodes pelicanus sp. n., Thraulodes xavantinensis sp. n. and Thraulodes sinuosus sp. n are described based on imagos. A new synonymy (Thraulodes lepidus [Ulmer]=Thraulodes cryptodrilus Nieto & Domínguez) is proposed and the distribution of Thraulodes schlingeri is expanded based on a new record from western Brazil.