Typically, lotic caddisflies attach their mineral pupal cases to cobbles in riffles, where rapid flows facilitate respiration but also decrease case-building material availability through erosion. Effects of local grain availability on grain quantities in and architecture of (per capita grain size use) pupal cases should be more important in Resident Construction Workers (RCWs, building immediately before pupation with minerals collected near the pupation location) than in Itinerant Construction Workers (ICWs, building months before pupation with minerals collected distantly from the pupation location). I tested these hypotheses analyzing mineral grain sizes in pupal cases and streambed sediments of cobble habitats in riffles of five running water types (headwater to large river in different regions) at baseflow or exceptional droughts. When pupae were abundant, the data supported both hypotheses at the local scale of samples, as grain size use by RCWs (as a group) but not by ICWs increased across all sites with local grain availability and abundant taxa among the former responded with four types of case-architecture modifications to grain size shortage. The data also supported the idea that at larger scales such as river or habitat types, mineral grains may be a limited resource for caddisflies building pupal cases with them. These findings suggest that water currents in streams or near shores of lakes and oceans that erode finer mineral grains can create conflicts in resource requirements for invertebrates that build with locally occurring finer mineral grains and simultaneously need high oxygen renewal rates and coarse grains for attachment.

Freshwater fish and mussel diversity is declining at an alarming rate across North America. Human land uses and disturbances within watersheds have been implicated as the primary cause of declines. In this paper, we demonstrate the utility of land use/land cover (LULC) variables in species distribution modeling and conservation planning using a straightforward multiscale approach for prioritizing freshwater fish and mussel conservation areas in the upper Green River catchment (Ohio River basin, USA). We developed distribution and species richness models for 10 uncommon fishes and 14 rare mussels using multiscale landscape data and boosted regression tree (BRT) analyses based on LULC composition and pattern, geology composition, and soil composition data. We then used probability of occurrence, endemicity, prevalence, trend and range of individual species to estimate the conservation value of each stream reach. Conservation areas were defined for three spatial scales nested within the catchment management zone (focal areas, riparian management buffer and subcatchment management zone) using a simple optimization technique. Priority conservation areas were located primarily in the eastern (upper Green River) and southern (upper Barren River) portions of the catchment. We found that focal species richness is explained most by soil composition in the subcatchment. However, nested within the subcatchment scale focal species richness responded positively to percent forest and negatively to patch density of developed/exposed land in the reach buffer. For both the reach and riparian buffers, retaining forested tracts of land and limiting the level of development and fragmentation would benefit the focal species.

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.

This paper provides an overview of the development and application of the National Aquatic Ecological Monitoring Program (NAEMP) in Korea, which uses biological and habitat–riparian criteria for river/stream and watershed management. Development of NAEMP began in 2003, with recognition by the Korean Ministry of Environment (MOE) of the limitations of applying chemical parameters (e.g., biochemical oxygen demand (BOD)) as the principal targets of water environment management. Ecosystem health criteria under NAEMP were developed from 2003 to 2006. Candidate sites for monitoring were also screened and established across the country. NAEMP was implemented in 2007, and since then a standard protocol of nationwide monitoring based on multi-criteria has been implemented to assess the ecological condition of rivers and streams. The monitoring results indicate that many Korean rivers and streams are severely degraded, with biological conditions that are much worse than their water chemistry suggests. In 2009, 24% of rivers and streams were in classes C (Fair) and D (Poor) for BOD, but more than 71, 53, and 27% were categorized as Fair to Poor according to fish, diatom, and benthic macroinvertebrate assemblages, respectively. NAEMP is promising in that the results have already had great impacts on policy making and scientific research relevant to lotic water environment and watershed management in Korea. In the future, NAEMP results will be used to develop more aggressive regulations for the preservation and restoration of rivers/streams, riparian buffer areas and watersheds. Another future aim of the NAEMP is to develop aquatic ecological modeling based on the monitoring results.

Extirpation or even extinction of freshwater invertebrate species is a neglected conservation issue; declines in abundance and spatial distribution for freshwater invertebrates are far less documented than for vertebrate species. In the Minho River tidal freshwater wetlands (northwest of Iberian Peninsula), a rapid decline in density and biomass of the bivalve Pisidium amnicum was recorded at 16 different sites over seven years, from 2004 to 2010, without any sign of a potential recovery. Mean density values reached more than 80 ind.m−2 in 2004, but declined to less than 1 ind.m−2 in 2009 and 2010. An identical declining trend was observed for biomass. A significant reduction in the spatial distribution also occurred. The abiotic changes resulting from the 2005 heat wave and possibly the negative interactions imposed by the non-indigenous invasive bivalve Corbicula fluminea were the main factors responsible for the declining trends. Given the very low density, P. amnicum is facing a serious risk of extirpation in this ecosystem and conservational measures are urgently needed.

Typology schemes are useful in partitioning natural spatial variability and thus helping implementing bioassessment methods. They have become widely accepted in Europe after the publication of the Water Framework Directive (WFD). The major objective of this study was to test if six Portuguese pre-defined physical stream-types (using System-B of the WFD) are concordant with macroinvertebrate assemblages collected in 31 undisturbed sites in a Portuguese river basin. A top-down (stream types defined by physical attributes) and a bottom-up approach (river classes defined by biological communities) were used. No significant differences were found in the mean number of taxa and abundance of different physical stream types and few taxa are characteristic of specific stream types. Discriminant analysis (DA) considering family-level composition revealed that all stream-types were significantly different and the cross-validation process showed that all stream-types had more than 50% of their samples correctly assigned. On the other hand, the bottom-up approach based on a correspondence analysis (CA) showed some overlap of the  macroinvertebrate communities of pre-defined stream types, indicating that variations in the macroinvertebrate community structure was primarily related to altitude, mineralisation and a temporal gradient. DA cross-validation and CA results suggest that tested stream types do not account for natural temporal changes known to affect macroinvertebrate communities in this Mediterranean basin and that the WFD typology should account for these natural variations. The exclusion of natural variability could indicate impairment when it does not exist or no impairment when it does exist (type I and II statistical errors).

Although the data on phosphate obtained in surveys are used to assess the distribution of river biota, the approach is flawed when the organisms use P fractions not included in routine analysis. This is especially important where aquatic phototrophs are partially or largely dependent on aqueous organic phosphate. This paper reports a study where the data are sufficient to assess the quantitative importance of organic phosphate in rivers in eastern UK. Filterable hydrolyzable phosphate-P (FHP) is used as a surrogate for organic phosphate, although FHP sometimes includes other P forms. Eighteen sites were sampled weekly for at least one, but mostly three years (2033 samples). The data are compared for mid- and lower-reach sites. FHP formed at least 20% TFP (total filterable phosphate-P) at 14 sites, with the percentage values higher at the more upstream and more northern sites. FHP exceeded 1000 μg.L−1 P in 32 mid- and 53 lower-reach records. The lower the TFP concentration, the higher the % FHP at both types of site. Five sites had over 25% of their records where FHP is likely to be especially important for growth of algae and bryophytes, based on FHP being >50 μg.L−1 P when TFP ≤200 μg.L−1 P. These include the upper site on River Swale, and other literature for this river indicates that FHP becomes increasingly important further upstream and even more so in tributary streams. FHP should be included in monitoring programmes for upland rivers, especially where the catchment includes peat-rich soils.

The diatoms are an ecologically important group of algae that have been extensively studied by ecologists and taxonomists. However, the large-scale patterns of diatom distribution and the factors underlying this distribution are largely unknown. The aims of this study were to identify the large-scale spatial patterns of benthic diatom assemblages in Korean streams and rivers, and to assess the importance of numerous environmental factors on diatom distribution. We classified 720 study sites based on diatom flora. Benthic diatoms, water chemistry, altitude, and riparian land cover and use were characterized by multivariate analyses, Monte Carlo permutation tests, and indicator species analysis. In total, we identified 531 diatom taxa. Diatom assemblages were mostly dominated by species of the genera Achnanthes, Navicula, Nitzschia, Cocconeis, Fragilaria (Synedra included), Cymbella, Gomphonema, and Melosira. Cluster analysis partitioned all 720 sites into eight groups based on diatom species composition. Canonical correspondence analysis indicated that altitude, land cover and use, current velocity, electrical conductivity, and nutrient levels explained a significant amount of the variation in the composition of assemblages of benthic diatoms. At the national scale, a downstream ecological gradient was apparent, from fast-flowing, mostly oligotrophic highland streams to slow-flowing, mostly eutrophic lowland rivers. Our data suggest that spatial factors explain some of the variation in diatom distribution. The present investigation of the spatial patterns of benthic diatoms, the ecological determinants of diatom occurrence, and the identification of diatom indicator species contributes to development of a program for assessing the biological integrity of lotic ecosystems in Korea.

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.

Rainbow trout is one of the most popular introduced game species around the world. Similar patterns of use for lake and inlet streams have been described for both native and introduced populations. However, for many introduced rainbow trout populations, there is a lack of information about how and when those habitats have been used. Here, we hypothesized that the majority of adult and sexually mature individuals inhabit inlet streams during the reproductive period most likely to spawn whereas juvenile trout occupy these same streams as nursery areas most of the year before emigrating to the lake. We studied rainbow trout age distribution and sexual maturity in a lake and its main inlet streams in southern Chile. We found that stream-dwelling individuals inhabited inlet streams up to age 2+ whereas lake-dwelling trout were older (most of them from ages 4+ to 6+). During the reproductive period (May to September) older and sexually mature individuals were in both habitats probably indicating movement to upstream locations to spawn. Rainbow trout of the same ages were larger in the lake than in streams, which may imply better growth in the lenthic environment. Our study offers further evidence of the highly adaptable nature of rainbow trout. Future regulations should consider rainbow trout populations in lakes and streams separately because trout life histories suggest that both environments are important to different ontogenic stages. This study provides key information that may be useful in the management of ad-fluvial populations of rainbow trout in Patagonia.

The golden mussel Limnoperna fortunei was introduced into Argentina in 1991 and has since been spreading through the Plata and Guaíba basins at a rate of 240 km.year−1. To assess their ability to invade the Andean tributaries of the Plata Basin (Pilcomayo, Bermejo and Salado del Norte rivers), their current range was assessed and related to the abiotic parameters of sites where they were present and absent. These data were then compared with their known tolerances to identify possible barriers to invasion. Outputs suggested that three environmental parameters are barriers to invasion: salinity and river flow intermittence in different sectors of the rivers Pilcomayo and Salado del Norte, and concentration of suspended sediments in the Bermejo River and in the upper reaches of the Salado del Norte and Pilcomayo rivers. The importance of these findings is discussed in relation to using environmental data to infer the invasion possibilities and the utility of environmental data to better understand invasion patterns and processes.

Escherichia coli is an indicator of fecal pollution used to mandate recreational and drinking water quality. Concentrations of culturable E. coli following contamination of surface water are determined by three factors: dilution; cell attachment to particulate material and settling or resuspension in the water column; and the net rate of change in viability. This study evaluated the variability in the latter parameter, and how predictive variation in death rate was of culturable population densities at the time of sampling. Water samples (N=232) with varying levels of E. coli contamination were collected from 46 discrete locations in four watersheds across Canada over a three-month period and enumerated for culturable E. coli by membrane filtration plate counting (T0EC). Water samples were again enumerated following a laboratory 24 h holding period at 30°C in the dark, and the difference considered the death rate (ΔEC). Relationships of T0EC and ΔEC with environmental and water chemistry factors were explored using step-wise multiple regression. The model predicting T0EC indicated that stream order, total rainfall seven days in advance of sampling day, total phosphorus, and ΔEC were the most significant contributors. The model predicting ΔEC indicated that turbidity and NH3+NH4 were the most important contributors. A model suggests that the persistence factor is less important than dilution (i.e. stream order) in describing E. coli densities, followed by factors that influence the loading of E. coli into watersheds.

Abiotic heterogeneity of the littoral zone of Lake Balaton influences both horizontal and vertical distribution of macrophytes, but biotic differences could shape the nature of a community. Vertical and temporal (small timescale) biomass distributions of Potamogeton perfoliatus and Myriophyllum spicatum were analysed in relation to their photosynthetic capacities to understand their coexistence, general presence over the northern shore of the lake seasonal shift of dominance within the community.

Our results indicated the adaptation of these macrophytes to the rapidly changing and mostly low irradiance of the Lake Balaton originated from its high turbidity: both P. perfoliatus and M. spicatum had high photosynthetic activity (20 to 50 mg O2.g drw−1.h−1), low dark respiration (around 12–14% of maximal photosynthetic capacity) and high shade tolerance (Ic of plants were 29±18 and 26±18 μmol.m−2.s−1, respectively). The majority of photosynthetic parameters had no (or little) seasonal changes. On the other hand, in Lake Balaton P. perfoliatus and M. spicatum differed in vertical distribution of biomass: Myriophyllum concentrated its biomass in the upper, well-lit region of the water more strongly than the Potamogeton.

Results suggest that the autogenic shift of dominance from Potamogeton to Myriophyllum in Lake Balaton can't be explained only by seasonal patterns of photophysiological changes, but supported by constitutive differences in plants architecture could led to the described phenomena.

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.

In the present work, based on material from several localities in Brazil, the genus Aturbina is reviewed. Two new species, A. maculata, sp. nov. and A. nigra, sp. nov. are described based on nymphs and adults; the type-species, A. georgei, is redescribed based on nymphs and reared adults; the nymphs and adults of A. beatrixae are respectively described and redescribed, as well as recorded from Brazil for the first time. Based on these findings, an updated key to nymphs and adults of the genus is provided.

River floodplains and riparian areas are often considered efficient traps for sediment and sediment-associated nutrients such as nitrogen (N) and phosphorus (P). However, few studies have focused on the fate of sediment-bound N and P after deposition on floodplains. In this study, the leaching of N and P from sediment deposited on a Danish-restored floodplain was quantified by placing trapped sediment samples under a rainfall simulator and exposing them to in situ temperatures and precipitation for two months. The nitrate release was 2.72–1600 μg NO3-N.g−1 DW which corresponded to 0.06–6.42% of the total nitrogen contained in the sediment. Total dissolved phosphorus (TDP) release was 0.44–3.17 μg P.g−1 DW, corresponding to 0.021–0.065% of the TP content of the sediment. Our results indicate that N and P release from floodplain sediment subjected to rainfall events is very low, which should be considered when applying floodplain restoration to mitigate the load of N and P to rivers.

Anthropogenic land use within watersheds has substantial effects on aquatic habitats and biological communities. From September 2006 to December 2008, we investigated the effects of land use on benthic macroinvertebrate communities by comparing Song Stream and Odae Stream, two adjacent mountain streams in Korea whose watersheds have different land use patterns. Song Stream is significantly disturbed by agricultural activities in the watershed, whereas Odae Stream is relatively undisturbed and is surrounded by a well-conserved forest area. Song Stream had significantly higher levels of all nutrients and sediment-related factors due to the adjacent agricultural area. As a result, Song Stream had markedly lower species community indices, such as taxa richness and abundance. In Song Stream, macroinvertebrate scrapers and predators were most adversely affected, whereas collector-gatherers became a dominant group. Based on correlation and multivariate analyses, total dissolved solids had the strongest negative relationship with macroinvertebrate assemblages, followed by electrical conductivity, total nitrogen, and pH. The proportion of cobble in stream substrate was positively related to the richness and abundance of macroinvertebrates. Our results indicate that disturbances caused by agricultural land use, particularly sand deposition, had significant adverse effects on macroinvertebrate habitats and on the biotic integrity of benthic macroinvertebrate communities.