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An introduction is presented in which the editor discusses various reports within the issue on topics including Cyprideis torosa which lives in both marine and limnic systems and evolutionary and biogeographical aspects of the endemic fauna from Lake Ohrid.

Within the EU LIFE‐Nature project 'River and floodplain revitalisation Emmericher Ward', three small temporary waters and a former gravel pit were connected by a side channel running parallel to the river Rhine through former groyne fields. The initial status of macrozoobenthos, fish, avifauna, flora, vegetation, and habitats before and their development after implementation of the project's measures were recorded and compared. The monitoring years 2018 and 2019 were exceptionally dry and accompanied by an extremely low runoff in the Rhine and the side channel. These conditions likely affected the development of habitats and species populations in the new side channel. The new side channel showed intensive morphodynamic development and differentiation of its structures. While the more complex vegetation and habitat types appeared as mostly species‐poor initial stages, short‐lived species‐rich pioneer habitats such as annual mud banks in the water exchange area were already established. Two years after the implementation, the benthic invertebrate fauna was still predominantly species‐poor and dominated by neozoans. Occasionally, representatives of the more sensitive EPT fauna (Ephemeroptera, Plecoptera, Trichoptera) were already detected but were, in general, strongly underrepresented in the main stream. Low colonisation potential, nonpermanent flow, and lack of river wood limit the development of the macrozoobenthos community. The relative abundance of rheophilic fish species increased in the project area and high juvenile fish densities proved the function as a nursery habitat. As pioneer species of riverine landscapes, sand martins and little ringed plovers colonised the new structures already in the first year. The initial state of the side channel represented a typical dynamic pioneer habitat pattern of a sandy lowland river, which was almost absent in the Lower Rhine area. The new habitats were quickly colonised by pioneer flora and fauna, but the potential for more demanding and complex communities was restricted by the poor structural and biological states of the Lower Rhine. [ABSTRACT FROM AUTHOR]

Re-meandering of degraded rivers is a frequently implemented measure in river restoration. A simple solution is reconnection of old meanders; however, its success likely depends on the reconnection method. We conducted a field study to analyze the benefits of a fully reconnected (fully opened meander, blocked main channel) and a partially reconnected meander (opened downstream, pipe bypass from main channel upstream, still open main channel) for macroinvertebrate communities in a German lowland river. Immediately upon reconnection of the two meanders, habitat diversity, and macroinvertebrates were recorded for three years with sampling in spring and in summer each year. The results of a principal response curve analysis show that the macroinvertebrate community in the fully reconnected meander reflected main channel reference conditions after 1.5 years. The macroinvertebrate community composition was not improved relative to in-stream reference conditions within the partially reconnected meander, which could be attributed to the almost complete lack of flow changes that resulted in missing improvements of substrate diversity. Our results show that the meander reconnection method must sufficiently affect the basic hydromorphological requirements to achieve reference macroinvertebrate community composition. Measures including hydromorphological conditions are therefore recommended for employment in environmental management. [ABSTRACT FROM AUTHOR]

The effects of damming, groyne building, and channelizing on habitats and ostracod assemblages in the Oder River, one of the six largest European river systems, were analyzed. Regulation works had been conducted on the river from the 18th to the beginning of the 20th century. Main objectives of the study were to detect the effect of river bed regulation on attributes of habitats and ostracod communities. The values of nitrogen were the highest in the dammed stretch and the lowest in the channelized one. As for conductivity, TDS (total dissolved solids) and salinity were the highest in the groyned stretch. Hardness had the highest values in the channelized and groyned stretches. The lowest visibility was noted in the dammed stretched. The stretch influenced by damming was dominated by habitats with a considerable proportion of detritus in sediments. In the stretch influenced by groynes, the proportions of habitats with mineral and organic substrates were similar and the proportion of habitats covered with vegetation was the highest. Habitats with rocky, sandy bottoms dominated in the channelized stretch and nearly half of the habitats were covered with vegetation. The highest ostracod density characterized the groyned stretch (658 ind · m−2), was moderate in the case of the dammed stretch (290 ind · m−2) and the lowest in the channelized one (107 ind · m−2). Bradleystrandesia reticulata, Candona neglecta, and Limnocythere inopinata dominated in the groyned and channelized stretches. Cypridopsis vidua, Darwinula stevensoni, and Pseudocandona compressa dominated in the dammed stretch. The type of river bed regulation significantly differentiated both habitats and ostracod assemblages. Differences among ostracod assemblages were related to particular species, but also regarding density and evenness. The degree of vegetation coverage and detritus content in the sediments were strong predictors for ostracod community composition. [ABSTRACT FROM AUTHOR]

Chydorus sphaericus, a cladoceran characterized by a wide range of distribution, is often numerous in various water habitats. Its body size is a consequence of environmental characteristics and physiology. The aim of the study focused on the distribution of body size and densities of C. sphaericus in relation to environmental conditions represented by: (i) habitat types (elodeids, helophytes, and the open water); (ii) specific pond types (forest and field); (iii) pond size (surface area); (iv) the presence/lack of fish; and (v) physicochemical factors. Similar to large daphnids, in the case of the examined small water bodies, fish presence was responsible for a reduction of the body size of C. sphaericus in the zone of open water. More abundant crustacean communities and the presence of larger specimens were found among macrophytes, which indicated that aquatic vegetation offered optimal growth conditions as well as an effective refuge against fish predation. These facts reflect the necessity for maintaining a varied mosaic of habitats even in small water bodies such as the examined ponds. We found that not only the abundance of C. sphaericus but also its body size can be used as an bioindicator of environmental conditions as it preferred small and eutrophic ponds, particularly those with complex macrophyte cover (such as elodeids). Furthermore, the abundance pattern of zooplankton dominant species was affected by elodeids and fish presence as well as by the area of the ponds. [ABSTRACT FROM AUTHOR]

We analyzed the influence of a small dam on the temporal and spatial properties of zooplankton communities by comparing the zooplankton composition established prior to the dam's construction to that during 5 years after its construction. The dammed water of a small dam, even just by 1 m, induced spatial changes in the zooplankton communities similar to those induced by a large dam. Changes in the number of taxa and zooplankton densities were observed a few months after the construction of the dam. In particular, in the number of planktonic rotifers such as Keratella cochlearis, Filinia longiseta, Polyarthra longiremis, Trichocerca similis and the larval stages of copepods considerably increased, along with the density of the littoral taxa of rotifers and crustaceans. Cladocerans appeared in the impoundment after the construction of the dam and their abundance increased in the second year after the dam was built. The abundance of all systematic groups of zooplankton increased in subsequent years after the construction of the dam. The small dam had a great effect on the spatial and temporal composition of the zooplankton communities in the stream studied, related to an abrupt change in the physical conditions from those typical of flowing water to those typical of limnetic basins. [ABSTRACT FROM AUTHOR]

While ubiquitous, temporary waters vary greatly in geographic distribution, origin, size, connectivity, hydroperiod, and biological composition. However, all terminate as active habitats, transitioning into either dryness or ice, only to be restored when conditions improve. Hydroperiod in some temporary habitats is cyclical and predictable, while in others it is sporadic. Although the rotifer communities of temporary waters are subjected to unique selective pressures within their habitats, species share many of the same adaptive responses. Here, we review temporary waters and their rotiferan inhabitants, examining community composition, life history, and evolutionary strategies that allow rotifers to flourish in these fluctuating environments. [ABSTRACT FROM AUTHOR]

We conducted a meta-analysis of the available literature to assess the effect of decapod crustacean macroconsumers on the processing and invertebrate colonization of leaf detritus in streams. Supplementary methodological (experimental set-up), geographical (i.e. latitude, climate) and biological (i.e. macroconsumers body size, detritus quality expressed as initial C:N ratio) data were collected, with the aim of assessing their influence on effect sizes variability. Overall, our results indicated some important effects of decapod crustacean macroconsumers on both detritus processing and colonization by invertebrates. Among the different factors examined, detritus quality and macroconsumer body size were important for predicting detritus processing and invertebrate colonization effects, respectively. This indicates that the pivotal role played by decapod crustacean macroconsumers on leaf decomposition, food webs, and wider stream ecosystem functioning, may be regulated by the interplay of both detritus chemistry and consumer's body size. The limitations and inadequacies of the analyzed literature are discussed. [ABSTRACT FROM AUTHOR]

ABSTRACT River impoundments and waste water discharge are a serious threat to the integrity and biodiversity of river ecosystems, especially in central Italy. Benthic macroinvertebrates were sampled in autumn and summer along the Aniene River to assess the cumulative biological effect of the numerous dams and sewage treatment plants that affect its middle and lower course. We hypothesized that (i) increasing habitat impairment would promote the formation of nestedness in species assemblage, where species poor locations support only a sub-set of organisms from richer sites; (ii) specific life-history traits would confer sensitivity to habitat degradation. Patterns of macroinvertebrate richness and diversity along the river tracked the distribution of dams and sewage treatment plants. Partial Mantel test showed that dissimilarity in assemblages increased with the number of dams and treatment plants between reaches after controlling for longitudinal distance. Assemblages were significantly nested, and nestedness appeared related to both water quality gradients (phosphorous, turbidity) that reflected anthropogenic inputs, and to natural gradient in altitude. Reaches with nested assemblages (supporting a sub-set of the species pool) were characterized by greater representations of taxa with shorter life cycles, while, in contrast, species rich sites supported taxa with longer life cycles and lower dispersal ability. These results suggest that the cumulative effect of dams and sewage treatment plants promoted the formation of nested subsets in species distribution. Moreover, it appeared that certain functional traits that conferred sensitivity also dictated the progressive non-random loss of taxa in face of multiple anthropogenic stressors. These findings have conservation implications in the regions, but need to be considered preliminary since anthropogenic and natural factors co-varied systematically along the study river precluding the identification of single factor effects. [ABSTRACT FROM AUTHOR]

Autecologic information of aquatic insects in the river systems under extreme continental climatic conditions is limited. Therefore, the objective of this study was to analyze life cycles, larval development, densities, microhabitat distribution, and secondary production of two sympatric burrowing mayfly species, Ephemera orientalis and Ephoron nigridorsum, in the Kharaa River, Northern Mongolia. Both species were typically distributed within the middle reaches of the focus river, displaying significant different larval densities across the three study sites. Four distinct microhabitats for E. orientalis and E. nigridorsum were identified. The preferred habitats of both species were substrates composed of rocks, cobbles, or coarse gravels with variable smaller mineral fractions of finer sandy, muddy, or organic substrates beside. Based on larval body size distribution and the emergence period, it was concluded that E. orientalis has a univoltine winter life cycle. The estimated annual production of larvae at two investigated sites in the middle stretch of the river in the year 2009 was 1.65 and 2.25 g DW m−2 year−1. Biomass was 294.8 and 490.3 mg DW m−2, and the annual production to biomass rate (P/B) was 4.5 and 5.6 year−1, respectively. In contrast, E. nigridorsum displayed a univoltine summer life cycle with a very likely egg diapause of approximately 8 months. Annual production estimates were 5.27 and 7.89 g DW m−2 year−1, biomass was 281.2 and 443.2 mg DW m−2; the annual P/B rates were 17.9 and 18.7 year−1 at the two sites reflecting the extremely shortened life cycle of this species. We conclude that the two sympatric species showed a difference in life cycles but no separation in habitat selection. [ABSTRACT FROM AUTHOR]

The habitat use by stream fish can provide an understanding of this important component of species niches, and the changes in the availability of certain structures of instream habitats have a strong influence on the occurrence and abundance of fish species. In this study, we identified the interaction networks between fish and microhabitats in 19 streams of three watersheds from the Brazilian savanna, known as the 'Cerrado'. We also investigated whether the connectance between fish species and microhabitats depends on either the species abundance or availability of microhabitats and verified whether the use of stream microhabitats vary among watersheds. The data for the fish were obtained using standardized fish collections and underwater (snorkeling) observations to record the association of fish species with 11 stream microhabitats. We used the incidence data to calculate the connectance of species with different microhabitats, a Spearman correlation analysis to test the dependence of the connectance to the species abundance and microhabitat availability, and an Analysis of Similarity to test whether the use of stream microhabitats by fish can vary among watersheds. In all of the watersheds, the tetras of the family Characidae used the largest number of microhabitats. The most-used microhabitats by the fish watersheds were the lateral surface, column surface, and unconsolidated substrate, which were differentially used by the fish in each watershed, indicating the variable importance of microhabitats. Despite this observation, the fish occurred more frequently in the lateral microhabitats. When the data for all of the streams were combined, the species connectance was correlated with the species abundance. We also discuss the consequences of the elimination of certain bottom structures in the context of siltation, which is the main issue in the studied region. The results of our study allowed the detection of key microhabitat structures and can be used for the aquatic ecosystems restoration. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The caddisfly community composition in different microhabitats at tufa barriers was studied in the Plitvice Lakes NP, Croatia. Three tufa barriers were investigated and six emergence traps were installed at each site covering various microhabitats. Sampling was conducted monthly during the year 2008. Tufa barriers are lake outlet habitats, but they feature a variety of microhabitats similar to streams, which is reflected in the composition of caddisfly communities regarding longitudinal distribution preferences. The caddisfly communities at all three sites were dominated by species typical for the rhithral zone, but there was a shift in species composition along a longitudinal gradient, from the epirhithral to the metarhithral zone. Analysis of functional feeding guilds showed considerable differences between the caddisfly community at the Labudovac barrier and both downstream barriers, shifting from one with a quite diverse composition, to one completely dominated by passive filter-feeders. Passive filter feeders were not represented by the same taxa at up- and downstream barriers ( i.e., by Hydropsyche species and Wormaldia species, at the Labudovac barrier and at both downstream barriers, respectively). Due to high complexity and habitat diversity, the highest diversity and equitability of caddisfly communities were recorded at microhabitats with particulate tufa and medium current velocity (10-20 cm/s). The lowest diversity and species richness were recorded for silt with low current velocity (0-10 cm/s). Abundance of caddisflies was positively correlated with current velocity due to a very high proportion of rheophilic passive filter feeders in the communities. However, community composition and structure is only to some degree influenced by microhabitat characteristics, but rather by their general position within the barrage-lake system, i.e., longitudinal distribution and thereby availability of different food resources. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We assessed the impacts of damming on the biological quality of Estonian streams. A total of 24 dammed sites on 22 streams were sampled. Standard samples were taken during two consecutive springs, 2009 and 2010 in three habitat locations: above dam (reservoir), immediately below dam, and at an undisturbed (reference) site nearby. To estimate biological quality, the national multimetric index (based on five pollution-sensitive and/or general quality metrics) was used. To estimate direct hydromorphological effects on macroinvertebrates, the locally adapted index, Macroinvertebrates in Estonia: Score of Hydromorphology (MESH) was employed. We found a significant decrease in the biological quality of the above-dam sites compared to the undisturbed sites (probably due to accumulation of fine sediments and lower flow velocity). Of the five ordinary quality indicators tested, only one (ASPT index) was significantly different between the below-dam sites and the undisturbed sites. However, the MESH indicated significant stress of macroinvertebrates both at the above-dam and below-dam sites, even when flow velocity and bottom type at the below-dam sites was similar to that at the undisturbed sites. At the same time, hydrochemical parameters were constant among the three habitats. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Cyprideis torosa ( Jones, 1850) (Ostracoda, Crustacea) is one of the most common marginal marine ostracod species in the Northern hemisphere. We investigate the relationship between variable noding of its valves and salinity as well as Ca2+ concentration in the ambient water, analysing populations from an in vitro experiment and field data from the southern Baltic Sea coast. There is a clear negative linear correlation between the proportion of noded individuals from our microcosms and salinity. Deficiency of Ca2+ causes heavier noding in laboratory cultures. The same effect can be seen in the field, however, the increase of noded individuals with falling salinity appears to be stepped, not linear. This pattern probably reflects the ability of the animals to wait some time until better salinity conditions occur within the highly variable conditions of estuaries and lagoons. At the southern Baltic Sea coast, proportions of more than 20% noded valves within a C. torosa population indicates salinities of up to 2 psu, up to 10% noded valves indicate salinities between 2 and 7 psu, and the lack of noded valves salinities > 7 psu. Stable salinity conditions as in the studied microcosms cause a shift of these salinity limits to 5 and 14 psu approximately but in a linear relationship between salinity and proportion of noded individuals. Hence, athalassic populations from more stable water bodies should be used for continuous and more detailed salinity trend reconstructions. Deficiency of Ca2+ (approximately < 120 mg/l) effects up to about 20% more noded individuals than in water with same salinity but with higher Ca2+ concentrations. The reproduction rates within the microcosms indicate a salinity optimum of C. torosa eggs of 8 psu whereas the optimum of the adults seems to be at least 14 psu (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

To trace environmental changes in water hydrology and salinity in the Late Glacial to Holocene of the Gulf of Gdańsk, a south-eastern bay of the Baltic Sea within the maritime zone of Poland, the distribution of ostracod valves was studied in 20 sediment cores collected from both the shallow- and deep-water zones (depth 10.9-67.5 m). The studied sediment sequences yielded ca. 3000 valves of 21 ostracod species, of which only five are known to live today in the Gulf, which has a present maximum depth of 118 m and water salinity up to 7-8‰. The majority of the studied sediment layers that contained ostracod valves corresponded to the period of the Late Glacial to Mid-Holocene and was dominated by non-marine species, of which the most common were Candona neglecta (present in 17 cores), Cytherissa lacustris (15 cores) and Candona candida (14 cores). By clustering classification five major ostracod assemblage types were recognised in the studied cores. Initial assemblage types dominated mostly by inhabitants of the profundal/sub-littoral zones of modern oligo-mesotrophic lakes ( C. lacustris and C. neglecta) in some sediment sequences were replaced in stratigraphical order by the assemblages dominated by brackish-water species ( Cyprideis torosa or Cytheromorpha fuscata). The structure and species composition of the distinguished ostracod assemblage types as well as their successional transitions indicate that the studied sediments were deposited initially in the Late Glacial in freshwater lacustrine conditions, and subsequently, during the Holocene marine transgression, covered by marine sands. The present results confirm and consolidate inferences based on previously published data on ostracods from the western part of the Gulf of Gdańsk as well as on other biotic (molluscs, diatoms) and abiotic (seismoacoustic) indices from this area (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

A complete assessment of effects of pollutants in the environment requires the use of a wide assemblage of test organisms. Crustaceans have been widely used in aquatic environments, but within this group, ostracods have been overlooked, even though they are one of the commonest groups of animals in temporary waters. Within this framework, static acute toxicity bioassays were conducted with heavy metals Cd and Pb, the surfactant SDS and spores of the bacteria Bacillus thuringiensis var. israeliensis using adult parthenogenetic females of the temporary pond ostracod Heterocypris bosniaca. Experiments were run at 20 °C and in a 12 by 12 h photoperiod. The toxicity tests results are expressed as LC50 and EC50 at 48 h and 96 h using probit analysis. The sensitivity of H. bosniaca at 48 h decreased in the following order Cd > Pb > SDS > Bti, while Pb and SDS exchanged their positions at 96 h. Comparison of the LC50 values for this species with information available in the literature reveals that it is generally more resistant than other crustaceans. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The aims of this study included: specifying values of ecological parameters and Ostracoda species characteristic for different types of plant habitats occurring in lake systems, determining the impact of mud presence on the taxonomic structure and density of the ostracods, tracing seasonal changes in the structures of Ostracoda assemblages identifying the species typical of particular seasons. Various types of rushes and underwater meadows were taken into consideration as lake microhabitats. The research was conducted in the shallow Lake Œwidwie (NW Poland). Multivariate (constrained) ordination methods were used to analyse the relationships between species composition and environmental variables. In the lake and its margins 31 species of the Ostracoda were identified. The development of water vegetation during the vegetation season was conducive to growth in ostracod density. The accessibility of mud in plant habitats had a favourable effect on the general density of ostracods. Species which preferred a high mud content in their habitats included: Cypria ophtalmica, C. exsculpta and Physocypria kraepelini. Species typically encountered in underwater meadow habitats were: Cyclocypris ovum and Cypridopsis vidua. Underwater meadows of charophyte were characterized by the highest ostracod density in the whole lake system, with the average of 7860 ind. m-2 and the maximum of 17 470 ind. m-2. Species typically encountered in rush habitats included Notodromas monacha, Dolerocypris fasciata and Metacypris cordata. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Cyprideis torosa ( Jones, 1850) is a very common brackish water ostracod of the German coasts, but, despite empty valves are found occasionally in surface sediments of some modern inland waters, C. torosa could not be found living in modern athalassic waters of Germany so far. During interglacial periods, including the Holocene, however, fossils of this species are quite common in Central Germany, at a distance of more than 300 km away from the coasts of the Baltic and North Seas. All 31 Quaternary localities with C. torosa known so far from Germany are documented. C. torosa is an indicator for brackish waters and widely used as index-fossil in palaeosalinity reconstructions relying on water chemistry bound morphological changes (nodes, sieve-pores). The comparisons imply a general underestimation of palaeosalinity in oligo- to mesohaline athalassic waters if using nodes and sieve-pores of C. torosa as proxy. A water chemistry (ionic composition) driven morphological response is assumed instead one by salinity only. Palaeosalinity estimations for athalassic waters, relying on morphological variability alone, should therefore be used with caution. Palaeosalinity trends, however, can be detected. Distinguishing thalassic and athalassic sediments with C. torosa is possible by using the associated ostracod fauna as a discriminator. Regarding the ecology and distribution of C. torosa, permanent, brackish, and shallow water bodies under relatively warm conditions are required for its settlement. The source of the salt are brines originating from Zechsteinian or Triassic underground evaporites. Warm and relatively dry climates could enhance the process for such water bodies of becoming salty, a situation present in Holocene Central Germany. The occurrence of C. torosa can therefore be used for palaeoclimatological studies. The most probable migration path of this ostracod species to athalassic waters is by avian transport. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Leptocythere karamani Klie, one of few non-marine species of the family Leptocytheridae (Ostracoda), is redescribed from specimens recently collected from the long-lived Lake Ohrid on the Albanian-Macedonian border. Detailed morphologies of valves and limbs of this species were compared with those of other Ohrid-Prespa leptocytherids, of some recent marine representatives of the genera Leptocythere Sars and Callistocythere Ruggieri from the Mediterranean, Irish and Baltic seas as well as with that of fossil non-marine species from the Miocene palaeo-Lake Pannon belonging to the genera Amnicythere Devoto and Euxinocythere Stancheva. Comparison with other species of Leptocytheridae inhabiting fresh to brackish waters of the Black-Azov, Caspian and Aral seas were also carried out using descriptions provided in the literature. Based on the comparative morphological studies it is shown that L. karamani and other Ohrid leptocytherids have a number of characters distinguishing them from other members of the genus Leptocythere but demonstrating a relationship with species of the genus Amnicythere. The most reliable of these characters are: a) anterior valve vestibulum from where mostly uni-ramified pore canals start, b) the entomodont hinge type with a strong anterior anti-slip tooth, a smooth posterior anti-slip bar on the left valve, and c) the hemipenis with underdeveloped lateral lobe and reduced clasping organ. From this strong evidence, the Ohrid leptocytherid species are allocated to the genus Amnicythere. Finally, a biogeographic scenario on the origin of the Ohrid leptocytherids is proposed which matches the 'Lake Pannon derivate hypothesis'. Close relationship of the Ohrid Amnicythere species with the non-marine leptocytherid taxa from the Neogene lakes of Central and Eastern Europe and with extant taxa from the Black and Caspian seas may indicate that the Ohrid Amnicythere derived from Lake Pannon species which were able to colonise lakes in Southern Europe through a stepping-stone process and subsequently to adapt to freshwater environment. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We quantified how sample size influences the variation of the diversity of caddisfly assemblages among different levels of a stream habitat hierarchy. Caddisflies were collected using a Surber sampler and these Surber units were used in a computer algorithm to generate samples in a variety of sample sizes. Our results show that the sample size has a primary role on how the variation of diversity among the levels of the habitat hierarchy is distributed. Thus, a practical implication of this study is that projects using different number of replicate samples cannot be directly compared. This finding calls the attention to the careful consideration of sampling issues in biodiversity assessment and monitoring (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The species diversity and distribution of rotifers between different habitats (elodeids, helophytes and open water) of 34 field and 31 forest ponds, differing in regard to origin, size, depth, macrophyte cover, overshading and the presence of fish were examined ( N = 381). 197 taxa were found in both types of ponds with 32 species being rare, endangered or new to Polish fauna. The species composition and Shannon-Wiener index distribution reflected heterogeinity of the habitats, while rotifer mean densities revealed a reverse pattern in both types of water bodies. The great variability of limnological features contributed to a lack of significant differences in rotifer abundance between both types of water bodies. Although some rotifers preferred one specific type of water body (forest vs. field), the type of habitat was a much stronger predictor of their distribution, which reflects a necessity to examine ponds in relation to their microhabitats created by various macrophytes. Rotifers revealed a strict division into two groups - of pelagic origin ( e.g., Polyarthra vulgaris), which were attributed to the open water and helophytes, and of littoral origin ( e.g., Lepadella patella), which were associated with elodeids, biomass of a plant habitat and a lack of fish. The selective choice of the most complex habitat (elodeids) by only littoral species suggests the weak impact of fish in the studied ponds and the most advantageous conditions for littoral rotifers among such a habitat. The first group comprised species characteristic of field ponds, while the second was characteristic of forest ponds. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

A fish-based Index of Biotic Integrity (IBI) was adapted for use in a stream of the heavily impacted Piracicaba River basin in southeastern Brazil. The influences of land use (mainly sugar-cane crops) and an urban area on the fish community were investigated at ten sites along a 17 km-long stream during the dry and rainy season. The IBI varied with the season and location along the stream, reflecting differences between the agricultural and urban sites, which were more pronounced during the dry season. The final index was positively correlated with a Habitat Quality Index (dry season) but not with a Water Quality Index. The results can be viewed as a tool for assessing and monitoring the ecological health of streams in this watershed. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We examined responses of macroinvertebrate assemblages to environmental and temporal variations along spring source-spring brook transects in two fen habitats, sharply differing in groundwater chemistry, and compared the patterns among individual taxonomical groups. We hypothesised a different importance of environmental heterogeneity and seasonal changes primarily linked to strong tufa precipitation, which causes stronger environmental filtering in the calcareous fen. In concordance, we observed that assemblages of the more homogenous calcareous fen primarily changed over time, due to seasonal shifts in source availability and favourable conditions. Their spatial distribution was determined by the amount of CPOM, tufa crusts and temperature variation, but a substantial part of the assemblage exhibited spatial uniformity (Plecoptera, Clitellata, and especially Trichoptera and Diptera). The assemblages of the more heterogeneous Sphagnum -fen were primarily driven by water pH and substrate and the season was a notably weaker predictor. We found that different macroinvertebrate groups can display various responses to the measured variables shaping the overall pattern obtained based on the whole community. Further, greater environmental heterogeneity can result in temporally stable species distribution patterns even at very small spatial scales within a single site. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]