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.

Taxonomical efforts in freshwater zooplankton are continuously needed for the delineation of species. Even today, confusion exists in correct identification of several European Cladocera because of poor original descriptions and subtle differences in morphology. In this context, we discuss three of the rarest Alona-like Chydoridae in the Palaearctic and their validity. 1) Alona moniezi, only reported once from Vichy area, France, has a male indistinguishable from that of A. elegans Kurz, 1875 while females show characters of A. elegans and of Coronatella rectangula. We provide a description of this taxon, with intermediate morphology and discuss the possibilities of hybridization. 2) Alona karelica is unusual as one of the few eurythermic species of a predominantly stenothermic A. pulchella-group. We discuss Neotropical A. cf. karelica from Mexico as its closest relative. Both show similarities with the semi-terrestrial A. bromelicola from Nicaragua, forming a small A. karelica-section within the A. pulchella-group. 3) A. weltneri is redescribed based on type material and we confirm it as a member of the A. costata-group. We discuss the three taxa and expand their diagnosis. A. weltneri and A. karelica are both found sporadically, and little is known about their ecology. Their scarcity in the Palaearctic may be linked with specialisation to a peculiar habitat and the possibility that these are true relicts.

Benthic macroinvertebrates are considered as a representative taxon that indicates the ecological status of freshwater ecosystems. Numerous indices derived from community data have been proposed to estimate either biological water quality or ecosystem health. In this study, metrics based on benthic macroinvertebrates at the family level were screened using ecological informatics to provide a multi-metric measurement that would be suitable for presenting ecological integrity across different levels of environmental impact. Benthic macroinvertebrates were collected at a total of 720 sample sites from river basins and streams in Korea in 2009. Based on four categories of community status (i.e., diversity, richness, tolerance, and composition), 37 metrics were selected as initial candidates according to the literature. The candidate metrics were evaluated according to parameters including discriminatory power, redundancy, and responsiveness to stressors. Self-organizing map was utilized to assist the screening procedure by providing ordination, clustering, and visualization of metric and environmental data. Six metrics were finally selected as a multi-metric and were compared with conventional indicators for presenting the ecological integrity of streams.

Many species of Ephemeroptera have been described based on either nymphs or adults. Only 10% of Ephemeroptera species in South America are known in both life stages. The current research was carried out in order to molecularly associate nymphs and adults of Ephemeroptera, using the amplified fragment length polymorphism (AFLP) technique. We obtained molecular fingerprints by the AFLP of five species: Leptohyphes albipennis, Leptohyphes coconuco, Leptohyphes ecuador, Baetodes levis and Prebaetodes sitesi. The association between nymphs and adults of L. albipennis and L. coconuco by this analysis confirmed the effectiveness of the technique. The molecular fingerprints of B. levis and P. sitesi were generated with the hope that future collections of unknown adults would match the fingerprint and solve an identification problem. We describe here for the first time the adult of L. ecuador by matching an adult trapped in the field with the DNA fingerprint of nymphs obtained by means of AFLP.

A microcosm experiment was carried out in order to test the effect of the herbicide metolachlor on river periphytic diatoms and to find potential diatom bioindicators of contamination. Effects were investigated at different biological organization levels (biofilm, diatom community, population and individual levels). The colonization of glass substrates by natural biofilm in artificial streams did not vary quantitatively between control and contaminated conditions (5 and 30 μg.L−1). However, non-parametric multivariate analysis of variance revealed a significant difference between contaminated and control diatom communities with regard to species composition. The difference was due to the greater development of probably tolerant species in the presence of the herbicide (e.g., Planothidium frequentissimum, Planothidium lanceolatum, Amphora montana, Surirella brebissonii and Nitzschia gracilis). An increase in the occurrence of abnormal forms was observed in relation to metolachlor concentration. In particular, up to 8% of the frustules of the species Surirella angusta exhibited prominent deformities. Monospecific acute toxicity tests were then performed on two species to estimate toxicity parameters based on growth inhibition. These tests also confirmed the teratogenic effect of the herbicide on S. angusta. This study shows that low concentrations of metolachlor in natural streams may significantly alter diatom community structure and that abnormal diatom forms should be taken into account in water contamination assessment.

Diel dissolved oxygen (DO) measurements can be used to estimate water metabolism of aquatic systems, in particular, lakes, lagoons and streams in terms of gross primary production (GPP), ecosystem respiration (Reco) and net ecosystem production (NEP). One of the main assumptions in the calculation of lake metabolism is that Reco is the same for daytime (Rdaytime) and nighttime (Rdarkhr). This study aimed at testing the equal Rdaytime and Rdarkhr assumption to estimate GPP, Reco and NEP in a littoral zone of a temperate shallow lake (Lake Yeniçağa) in northwestern Turkey with and without the assumption. Based on the equal Rdarkhr and Rdaytime assumption, values calculated for GPP and Rdaytime were different than those based on the different Rdarkhr and Rdaytime assumption (P<0.001). GPP was lower by 7.5% in July, 49.6% in September and 14.9% in October, while Reco was lower by 5.9% in July and 55.8% in September. GPP was higher by 8.9% in August and 55% in November, while Reco was higher by 7.8% in August and 23.9% in November.

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.

Water microbiological and physicochemical characterizations at various depths of aquatic ecosystems are basic requirements in several fields of research. A chief difficulty in hydrobiology, limnology, biological oceanography and water environmental microbiology is that of taking accurate field collections that are representative of the natural environment and population at various depths of aquatic ecosystems. Gathering water/plankton samples in a level just below the surface of the water body upon rising in columns from various depths due to hydrostatic pressure variations provided a simple approach for water and plankton sampling. Based on this approach, several forms of simple devices for water and plankton sampling were developed for water microbiological and physicochemical characterizations at various depths of aquatic ecosystems. The described approach showed less sampling errors in comparison to Van Dorn bottle and was comparable to water pumping but requires no external source of power. The described samplers are inexpensive and can be self constructed.

Stream development can generate environmental changes that impact fish communities. In temperate streams, the distribution of fish species is associated with environmental gradients. To analyze the relevant factors, large-scale exploration is required. Thus, to evaluate the distribution patterns of fish in Korea, sampling was conducted on a national scale at 720 sites over a 6-week period in 2009. A total of 124 fish species in 27 families were identified; Zacco platypus and Zacco koreanus of the Cyprinidae were the dominant and subdominant species, respectively. Of the species found, 46 (37.1%) were endemic and 4 (3.2%) exotic; of the latter, Micropterus salmoides and Lepomis macrochirus were widely distributed. Upon canonical correspondence analysis (CCA), both altitude and biological oxygen demand (BOD) were highly correlated with CCA axes 1 and 2, respectively. This explained 62.5% of the species–environment relationship. Altitude and stream order were longitudinally related to species distribution. The numbers of both total and endemic species gradually increased as streams grew in size to the fourth–fifth-order, and decreased in sixth-order, streams. Overall, fish communities were stable throughout the entire watershed, whereas some species showed site-specific occurrence patterns due to the paleogeomorphological characteristics of Korean peninsula. However, various anthropogenic activities may negatively affect fish communities. Therefore, both short- and long-term sustainable management strategies are required to conserve native fish fauna.

A literature survey and the identification of all available collection material resulted in a checklist and distribution maps for the mayflies occurring in Flanders. In addition, the relationship between the occurrence of mayflies and water characteristics was analysed. Of the 32 species that have been recorded, six are now extinct in Flanders (three of which are potamal species), while the majority of the remaining species are rare and their populations are often strongly isolated and therefore extremely vulnerable. Waters with relatively low oxygen levels and high conductivities were characterized by the most tolerant mayfly species Cloeon dipterum and Caenis robusta. However, most other species only occurred at higher oxygen concentrations and lower conductivities and could be separated into two groups. The first group mainly occurred in waters with a high pH and were often restricted to the loamy region or to stagnant waters, while the second group occurred in waters with a lower pH and mainly occurred in the Campine region. For most mayfly species, sustainable populations can only be achieved when their current habitats are adequately protected and, in addition, measures should be taken to connect and enlarge the remaining populations.

The objectives of this study were to evaluate fish guild compositions and national river health using a multi-metric model of the Korean index of biological integrity using fishes (K-IBIF) in four major Korean watersheds along with water chemistry and habitat quality. Tolerant and omnivore fish species dominated all the watersheds, and the proportions of tolerance guilds and trophic guilds reflected water chemistry and habitat quality. The number of sensitive species and insectivore species had negative correlations (r < −0.42, P < 0.01) with chemical water quality (biological oxygen demand (BOD)), while tolerant species and omnivore species had positive correlation (r > 0.27, P < 0.05) with BOD values. Physical habit conditions, based on qualitative habitat evaluation index (QHEI) model, indicated a “good” condition (mean = 68.9; range = 45–105) in three watersheds, except for the Yeongsan River watershed. Values of QHEI were significantly correlated (R2 > 0.4, P < 0.01) with nitrogen and phosphorus levels in all watersheds, suggesting that habitat degradation is associated with eutrophication. Model values of K-IBIF in the watersheds averaged 18.2, indicating a “fair” condition, and about 37% of all observations in K-IBIF model values were judged as a “poor” health condition, indicating severe health impairment. Overall, our data suggest that degradation of the river health was due to a combined effect of chemical pollution and physical habitat modifications. This research provides valuable information on Korean river conservation and restoration in the future.

Seasonal dynamics of zooplankton were investigated in three different habitats of the shallow and temperate Kačležský pond (Czech Republic) during 2003–2004. The studied habitats included the limnetic zone and two littoral zones, each dominated by a different type of emergent macrophyte, reed grass (Glyceria maxima) and common reed (Phragmites australis). Species richness (calculated as number of taxa) was higher in both littoral zones than in the limnetic zone. The seasonal development of limnetic and littoral zooplankton communities differed. In contrast to the two littoral zones, close correlation with chlorophyll-a concentration was found for rotifers and cladocerans in the limnetic zone. Moreover, cladocerans inhabiting littoral areas (mainly Bosmina longirostris) reached annual maxima during spring when chlorophyll-a concentrations were low.

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.

The effects of the North Atlantic Oscillation (NAO) on water temperature (WT) in Lakes Jamno, Gardno, and Łebsko were studied between 1961 and 2000. Both sets of data (NAO and WT) consisted of monthly and seasonal values. Correlation and regression analyses were used and the relationships were tested for statistical significance (Fisher-Snedecor test, coefficients of correlation and determination). Positive and statistically significant (even at α=0.01) relationships were demonstrated for the winter months (December, January, February and March) and in October. The strongest relationships were demonstrated for winter (December–February) in lakes Jamno and Gardno (correlation coefficients of 0.73 and 0.74). Extreme winters, particularly the very mild ones, tended to diminish the strength of the relationships. Very mild winters were characterised by relatively favourable solar (sunshine) conditions as well as high air and water temperatures, while the NAO Index values were relatively low. Relationships for spring (March–May) and summer (June–August) were not significant. In those seasons, the effects of atmospheric circulation (NAO) on WT were thus low, while the influences of solar factors were strong. Asynchronous relationships bear some predictive value, particularly when the predictive variable is the January NAO Index (NAOJan). These relationships were significant at α=0.01, out to April (NAOJan vs. WTApr). Attention is also drawn to local factors (air temperature, geostrophic wind, solar conditions, and sea water intrusions into lakes) which affected the strength of the relationships investigated.

The distribution of bloom-forming cyanobacteria in eutrophic to hypereutrophic ponds was studied in northern Taiwan in 2009. Eighty-four ponds were sampled in mid-summer, and the relationship between colony size and relative abundance of each cyanobacterial species was analyzed. Anabaena crassa and Cylindrospermopsis raciborskii were the dominant species in terms of frequency of appearance. The colony size of An. crassa increased significantly with its relative abundance. The relative abundance of C. raciborskii was usually below 10%, and its filament length was not correlated with its relative abundance. The colonies of Microcystis aeruginosa normally consisted of several tens of cells. However, when M. aeruginosa exclusively dominated the plankton community, the average number of cells in a colony reached several hundreds. The mean filament length of Planktothricoides raciborskii significantly increased with its relative abundance. The correlations between colony size and relative abundance of the ten cyanobacterial species were significantly positive for three species, insignificantly positive for five species and insignificantly negative for two species. Given the various ecological advantages of large colonies, the results of this study may suggest that the formation of large colonies of some cyanobacterial species is important to their dominance and/or bloom formation.

The dam reservoirs of the Upper Rhone were drained every three years until 2003, and the water level of the Villebois reservoir was lowered by 1.5 m. This resulted in considerable drying of its littoral habitats and the disappearance of the abundant macro-invertebrates that live in them. This study investigates the response to this drying disturbance of bivalve populations and especially of the life history traits of the two potamic species, Pisidium moitessierianum and Pisidium supinum. The low density of these bivalves observed during the months following the drying of May 2003 until spring 2004 shows that the contribution of drift in population recovery was very limited during this period. Due to the faster turnover of its cohorts and a higher increase in litter size in 2004, P. moitessierianum once again dominated bivalve communities from 2005 onwards. In the Villebois reservoir recovery of bivalve communities in terms of structure and density was total three years after the drying of 2003. Observations suggest an increase in litter size and continuous recruitment: the reproductive strategy adopted by these bivalves represent response to the fall in numbers on the one hand, and to considerable magnitudes of temperature and flow rates on the other hand, enabling the rapid adjustment of populations to drying disturbance and variations in environmental conditions. Taking into account the response of bivalve populations to this event, its effects are comparable to those of a supra-seasonal drought (Lake, 2003, Freshw. Biol., 48, 1161–1172).

This study investigated the relationships of three major aquatic assemblages (diatom, macroinvertebrate, and fish) and environmental variables, including sub-basin, hydrology, land cover, and water quality variables on multiple scales. Samples were collected at 720 sampling sites on the Korean nationwide scale. Geological variables, including altitude and slope, showed a strong positive correlation with proportions of forest in land cover types and cobbles in substrates, while they were negatively correlated with water quality variables, including conductivity and total phosphorus. Considering the concordance of the different assemblages, species richness of fish and macroinvertebrates displayed significant correlation, and diatoms were significantly correlated with fish. However, diatoms did not show significant correlation with macroinvertebrates. Altitude and slope showed significant correlation with all biological variables of the three assemblages. Macroinvertebrates and fish showed positive relations with large substrate sizes. Indices of diatoms and macroinvertebrates well reflected the perturbation of water quality variables. However, fish indices showed a relatively low association with water quality variables, compared with those of diatoms and macroinvertebrates. These patterns were also confirmed by the ordination and prediction of biological indices with environmental variables through the learning process of a self-organizing map as well as random forest. Overall, our study supports the concept of multi-scale habitat filters and functional organization in streams, and is consistent with the recommended use of multiple biological indices with more than one assemblage for the assessment of the biotic integrity of aquatic ecosystems.

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.

Similar to other Mediterranean lakes, Lake Vela displays a marked dominance of alien species, but the impact of such an assemblage on the lower trophic levels of shallow eutrophic lakes has been overlooked. In this study, zooplanktivory in the omnivorous fish assemblage of Lake Vela was examined from April to October 2003 (and also in January 2004). During this period, ichthyocenosis was characterized by abundance of juvenile fish, which strongly depended on zooplankton. Adult mosquitofish (Gambusia holbrooki) and pumpkinseed (Lepomis gibbosus) foraged on the same zooplanktonic prey than juveniles, although planktivory was less important in larger fish. Using multivariate analysis, it was possible to attribute most of the variability in planktivory to resource availability, as both fish foraged on the most abundant prey in each month. Albeit this opportunistic behaviour, mosquitofish was found to be positively selective towards small-sized littoral cladocerans, while pumpkinseed displayed positive selection towards Alona and Daphnia. In the absence of more efficient planktivores, pumpkinseed is now the main planktivore in Lake Vela and the main predator of Daphnia. However, due to low densities of Daphnia during most of the study period, Daphnia was virtually absent from the diet of pumpkinseed from June to October, a period during which this benthi–planktivore foraged chiefly on less-rewarding planktonic prey (small-sized cladocerans and cyclopoid copepods). Mosquitofish was an important planktivore in littoral and structured habitats. Flexible foraging behaviour partly explains the success of these two species in Lake Vela.

We investigated benthic macroinvertebrate communities in three contrasting habitats of a large shallow lake from February to November 2009. The three habitats differed markedly in their environmental characteristics (e.g., trophic status, substrate type, wind exposure). A total of 36 species were collected from the three habitats. The calculated descriptors (abundance, biomass and Pielou evenness index) differed significantly among the habitats. Generally, Tubificidae, Bivalvia and Gastropoda dominated the benthic community in abundance and biomass, but they varied greatly in abundance among the habitats. Analysis of similarities (ANOSIM) and non-metric multidimensional scaling (NMDS) analyses revealed significantly different macroinvertebrate assemblages among the habitats. North Bays had the lowest biodiversity and were exclusively dominated by pollution-tolerant species (e.g., Limnodrilus hoffmeisteri and Rhyacodrilus sinicus). Communities in the open lake contained intermediate biodiversity and were characterized by five species belonging to several taxonomic groups (e.g., Corbicula fluminea, L. hoffmeisteri and Gammarus sp.). Macrophyte-dominated habitats (East Bays) presented the highest diversity and evenness and were mainly characterized by gastropods. A canonical correspondence analysis (CCA) demonstrated that habitat-specific differences in trophic status, pollution level, wind-induced disturbance and macrophyte distributions were highly correlated with macroinvertebrate community structure.