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Few studies have considered the effects of environmental variables at different spatial scales on Neotropical stream biodiversity. Furthermore, scale-related studies mostly include only one facet of biodiversity. To determine the contribution of local and landscape variables to the variation in the taxonomic, functional and phylogenetic α-diversity of stream fish assemblages, we sampled 85 streams in the Upper Paraná River basin, Brazil. Local variables explained a substantial fraction of the variance in almost all biodiversity facets. Landscape variables (i.e., land-use and spatial variables) contributed little to the variation in the α-component of biodiversity. Our results thus highlight the importance of local features for maintaining stream fish biodiversity in agroecosystems. Probably, land-use were not significant because the study area was in a relatively homogeneous landscape severely impacted by anthropogenic activities. It is possible that insignificant effects of spatial structuring occurred because the ichthyofauna has already gone through a homogenization process and/or due to the spatial scale of our study. We suggest that even though local-scale restoration actions would influence biodiversity, we should not neglect landscape restoration because substantial improvements in the ecological integrity of streams are more likely to be accomplished with large-scale actions (e.g., re-establishment of the native riparian forest). [ABSTRACT FROM AUTHOR]

Associating a deconstructive approach with metacommunity ecology brings insights into how biological communities are structured. We examined the effects of dispersal, habitat conditions, and grazing pressure on ecological guilds (i.e., deconstructed entire communities by guilds) of freshwater microalgae. The combination of focus on efficient passive dispersers, an extensive sampling survey, large numbers of abiotic explanatory variables, information on grazing pressure, and characteristics (i.e., high connectivity and areal extent) of the study area enabled us to model roles of various metacommunity processes for guild structure and diversity within guilds. We found that water chemistry, physical habitat, and spatial variables all accounted for rather small amounts of variation in the guild structures. Diversity within each guild generally showed clear spatial patterns independent of local environmental conditions. Wave action and slope of the study sites also affected diversity. Grazing had clear effects on some aspects of diversity. Importantly, the guilds showed significant spatial patterns, suggesting that mass effects occurred at different intensities in our highly-connected study system. The intensity of dispersal was partly related to different dispersal potentials among the guilds. Different traits associated with ecological guilds may hence be associated with dispersal processes detected in systems with high connectivity among sites. [ABSTRACT FROM AUTHOR]

Although several studies have examined the functional diversity of freshwater macroinvertebrates, the variety of methodologies combined with the absence of a synthetic review make our understanding of this field incomplete. Therefore, we reviewed the current methodology for assessing functional diversity in freshwater macroinvertebrate research. Our review showed that most papers quantified functional diversity using biological traits, among which feeding habits were the most common traits probably due to the assumed links between feeding and ecosystem functions. A large number of diversity measures have been applied for quantifying functional diversity of freshwater macroinvertebrate assemblages, among which Rao's quadratic entropy looks like the most frequent. In most papers, functional diversity was positively related to taxon richness, and functional redundancy was a key concept in explaining this correlation. Most studies detected strong influence of the environmental factors as well as human impact on functional diversity. Finally, our review revealed that functional diversity research is biased towards European running waters and is hindered by yet insufficient information on the autecology of macroinvertebrates. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Comparative effects of river-lake disconnection on taxonomic and functional composition of molluscan assemblages in floodplain lakes." The correction states that the affiliation of one of the authors, J. Heino, was incorrect and should be listed as the University of Oulu, Geography Research Unit, Oulu, Finland. The correct affiliations of all authors are provided in the document. The original article can be found online at the given link. [Extracted from the article]

Functional traits are promising features for biomonitoring in freshwater ecosystems. Here, we focused on 23 floodplain lakes to evaluate the responses of taxonomic and functional traits of freshwater mollusks to the loss of lateral hydrological connectivity (LHC). Our results revealed that the disconnected lakes (DLs) had significantly lower species richness of most functional trait categories of mollusks compared to the connected lakes (CLs). For percentages of species richness, only percentages of burrowers and thick-shelled species were significantly lower in DLs than CLs, while percentages of thin-shelled and small-sized species were higher in DLs. Therefore, there has been a shift toward assemblages with thin-shelled and small mollusks following LHC loss. We also found that key environmental variables affecting taxonomic and functional composition were connectivity, lake area, aquatic vegetable coverage, and water quality. Moreover, the functional composition of all Mollusca, Gastropoda, and Bivalvia were all better explained (explained variation ranged from 0.462 to 0.684) by environmental factors compacted with taxonomic composition (0.213–0.401). Connectivity was the most important factor affecting functional trait composition, whereas area was the most important variable for taxonomic composition. Thus, the trait-based approach based on mollusks was more sensitive in assessing the impacts of disconnection than the taxonomy-based approach. [ABSTRACT FROM AUTHOR]