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The estuary at the mouth of the Columbia River in Wahkiakum County Washington) provides a natural laboratory for experiential learning. Wahkiakum High School students participate in interdisciplinary projects that have included habitat restoration, a salmon hatchery, stream restoration, tree planting, and recreating the final leg of the Lewis and Clark expedition, which followed the Columbia River to the Pacific Ocean. (TD)

Effective conservation of stream fishes and their habitats is complicated by the fact that human stressors alter the way in which natural factors such as stream size, catchment geology, and regional climate influence stream ecosystems. Consequently, efforts to assess the condition of stream fishes and their habitats must not only attempt to characterize the effects of human stressors but must account for the effects of natural influences as well. This study is an assessment of all stream fish habitats in the Mississippi River basin, USA. The basin supports over 400 stream fish species, drains a land area of 3.2 M km2, and includes a myriad of human stressors such as intensive agriculture, urbanization, nutrient loading, and habitat fragmentation by dams and road/stream crossings. To effectively characterize types and levels of human stressors specifically impacting the basin's stream fish species, our assessment approach first accounted for the influence of natural landscape conditions on species abundances with multiple steps, including stratifying our analyses by region and stream size and quantitatively modeling the influences of natural factors on stream fishes. We next quantified individual fish species responses to explicit human stressors for different measures of land use, fragmentation, and water quality, including summaries of measures in local vs. catchment extents. Results showed that many species had negative threshold responses to human stressors and that impacts varied by species, by region, and by the spatial extents in which stressors were summarized. Our spatially explicit results indicated the degree of stream reach impairment for specific stressor categories, for individual species, and for entire assemblages, all of which are types of information that can aid decision makers in achieving specific conservation goals in the region. [ABSTRACT FROM AUTHOR]

Pseudanomodon attenuatus, previously known as Anomodon attenuatus Hedw., is very rare in Britain. In this study, its population status and ecology in England were investigated. Located along the River Eden, Cumbria, the three previously known sites for the species in England were surveyed, plus three potential sites along the river. Abundance was evaluated in terms of 'individual-equivalents', each defined as an occupied 1 m grid cell, when the moss was growing on rock, or an occupied tree, when it was epiphytic. Geographical coordinates of each individual-equivalent were recorded with a GPS unit. Habitat and community composition were recorded by relevés. The species was found at each previously known site and a new site. A total of 127 individual-equivalents were found, and the actual total along the 10.4 km of riverbank surveyed was estimated to be 140–200 individual-equivalents. Along the whole River Eden may be as many as 250–1000 individual-equivalents, because significant amounts of potential habitat remain unsurveyed. The population is confined to the middle to upper inundation zone of the riverbank. About half of individual-equivalents occur on trees and about half on calcareous sandstone. Most trees are Alnus glutinosa; others include Acer pseudoplatanus, Betula pendula, Corylus avellana, Fraxinus excelsior, Quercus robur and Ulmus glabra. Common associates are Anomodon viticulosus, Didymodon insulanus, Homalia trichomanoides and Thamnobryum alopecurum. Reasons for the extreme rarity of P. attenuatus in Britain are uncertain and deserve investigation, as does its confinement to a narrow riparian niche, which appears untypical of P. attenuatus across most of its world range. [ABSTRACT FROM AUTHOR]

An increase in the demand for renewable energy is driving hydropower development and its integration with variable renewable energy sources. When hydropower is produced flexibly from hydropower plants, it causes rapid and frequent artificial flow fluctuations in rivers, a phenomenon known as hydropeaking. Hydropeaking and associated hydrological alterations cause multiple impacts on riverine habitats with cascading effects on ecosystem functioning and structure. Given the significance of its ecological and socio‐economic implications, mitigation of hydropeaking requires an inter‐ and transdisciplinary approach. An interdisciplinary network called HyPeak has been conceived to enrich international research initiatives and support hydropower planning and policy. HyPeak has been founded based on exchange and networking activities linking scientists from several countries where hydropeaking has been widespread for decades and numerous studies dedicated to the topic have been carried out. HyPeak aims to integrate members from other countries and continents in which hydropower production plays a relevant role, and grow to be a reference group that provides expert advice on the topic to policy‐makers, as well as researchers, stakeholders, and practitioners in the field of hydropeaking. [ABSTRACT FROM AUTHOR]

Species conservation often faces many challenges, such as addressing threats from multiple stressor sources, representing under-studied taxa, and understanding implications of spatial extent. To overcome these challenges, we assessed contemporary anthropogenic threats from stream fragmentation and landscape disturbance as well as future habitat suitability under climate change for traditionally well-studied (fishes) and under-studied (mussels) imperiled fluvial taxa in Michigan, USA. To understand how threats to species vary spatially, predicted habitat suitability was analyzed for three hierarchically nested spatial extents: statewide, within species' biogeographic ranges, and within river patches fragmented by barriers. Comparison of current and future habitat suitability for 27 fish and 23 mussel species indicates large potential statewide gains for many warmwater and/or large river fishes and several mussel species, however these gains are greatly diminished by biogeographic range limitations and habitat fragmentation among current and future habitats. One mussel species and several cold- and coolwater fishes are projected to have significant habitat losses under climate change irrespective of spatial extent. On average, 79% of habitats for mussels and 58% for fishes were considered moderately to severely disturbed from current human landscape activities. Habitat fragmentation was greater for fishes than mussels, with large dams playing a primary role in fragmenting habitats relative to small dams and waterfalls. Results indicate that threat assessments can vary substantially according to spatial extent and taxa, and consideration of both contemporary and future threats to habitats is needed to inform conservation of imperiled fluvial organisms. [ABSTRACT FROM AUTHOR]

Amazonia has a very high, although still incompletely known, species diversity distributed over a mosaic of heterogeneous habitats that are also poorly characterized. As a result of this multi‐faceted complexity, Amazonia poses a great challenge to geogenomic approaches that strive to find causal links between Earth's geological history and biotic diversification, including the use of genomic data to solve geologic problems. This challenge is even greater because of the need for interdisciplinary approaches despite the difficulties of working across disciplines, where misinterpretations of the literature in disparate research fields can produce unrealistic scenarios of biotic‐geologic linkages. The exchange of information and the joint work of geologists and biologists are essential for building stronger and more realistic hypotheses about how past climate may have affected the distribution and connectivity among populations, how the evolution of drainage networks influenced biotic diversification, and how ecological traits and species interactions currently define the spatial organization of biodiversity, and thus how this organization has changed in the past and may change in the future. The heterogeneity of Amazonia and the different effects of historical processes over its distinct regions and ecosystems have to be more completely recognized in biogeography, conservation; and policymaking. In this perspective, we provide examples of geological, climatological; and ecological information relevant to studies of biotic diversification in Amazonia, where recent advances (and their limitations) may not be apparent to researchers in other fields. The three examples, which include the limitations of climate model outputs, the complicated evolution of river drainages; and the complex link between species and their habitats modulated by ecological specialization, are a small subsample intended to illustrate the urgency for more integrated interdisciplinary approaches. [ABSTRACT FROM AUTHOR]

Ranunculus species grouped in the section Batrachium (water crowfoots) indicate the most valuable fluvial habitat in Europe under the EU Habitats Directive, and recognition of their environmental preferences plays a crucial role in efficient conservation. Moreover, water crowfoots are used in various monitoring systems throughout Europe. The aim of this study was to identify the distribution patterns of two common water crowfoot species (Ranunculus fluitans, R. circinatus) and their hybrid (R. circinatus × R. fluitans) in relation to environmental variables in rivers. Various chemical and hydromorphological parameters were estimated for 54 river sites where 58 different Batrachium populations were recorded. Our study revealed the most distinct positive reaction of R. fluitans to rhithral conditions characterized by rapid currents and coarse substrate. R. circinatus × R. fluitans preferred larger channels, although this taxon also flourished in rhithral rivers. The preferences of R. circinatus were not so evident confirming its occurrence under a wide range of habitat conditions. The ecological reaction of the hybrid was compared with its parental species, revealing their ecological specificity, which is useful in designing appropriate conservation programmes. [ABSTRACT FROM AUTHOR]

Food web analyses offer useful insights into understanding how species interactions, trophic relationships, and energy flow underpin important demographic parameters of fish populations such as survival, growth, and reproduction. However, the vast amount of food web literature and the diversity of approaches can be a deterrent to fisheries practitioners engaged in on‐the‐ground research, monitoring, or restoration. Incorporation of food web perspectives into contemporary fisheries management and conservation is especially rare in riverine systems, where approaches often focus more on the influence of physical habitat and water temperature on fish populations. In this review, we first discuss the importance of food webs in the context of several common fisheries management issues, including assessing carrying capacity, evaluating the effects of habitat change, examining species introductions or extinctions, considering bioaccumulation of toxins, and predicting the effects of climate change and other anthropogenic stressors on riverine fishes. We then examine several relevant perspectives: basic food web description, metabolic models, trophic basis of production, mass‐abundance network approaches, ecological stoichiometry, and mathematical modeling. Finally, we highlight several existing and emerging methodologies including diet and prey surveys, eDNA, stable isotopes, fatty acids, and community and network analysis. Although our emphasis and most examples are focused on salmonids in riverine environments, the concepts are easily generalizable to other freshwater fish taxa and ecosystems. This article is categorized under:Water and Life > Nature of Freshwater EcosystemsWater and Life > Conservation, Management, and AwarenessWater and Life > Methods [ABSTRACT FROM AUTHOR]

Invasive alien species are recognized as a significant anthropogenic threat to freshwater ecosystems, because they may bring about the local extinction of native species and the collapse of habitat types of special conservation concern.The Water Framework Directive (WFD) is an important legislative tool for the protection of water bodies in the European Union. It requires the assessment of the ecological status of water bodies and the enforcement of measures for water bodies that fail to achieve at least 'good' ecological status. However, the WFD does not explicitly mention alien species.This article presents a three‐tiered approach for the incorporation of data on alien species into WFD assessments of freshwater bodies in Norway. If relevant data on WFD parameters are available for the water body under consideration, its ecological status should be inferred from those data. Otherwise, ecological status should be assessed using evidence of the effects that the alien species have on biological quality elements in comparable water bodies. If neither of these options is feasible, the ecological status should be classified according to the ecological effect score of the alien species present, as obtained from the Generic Ecological Impact Assessment of Alien Species (GEIAA).It is further recommended that a water body cannot be assigned 'high ecological status' if at least one alien species is present. If more than one alien species is present, the status is determined by the species with the highest impact.Ecological, geographical, historical, and taxonomic delimitation criteria for this assessment method are presented, together with a list of the alien species that at present fulfil these delimitations in Norway.The management implications of the recommendations are that more Norwegian freshwater bodies are likely to require measures, and that further data must be collected. Most of the recommendations are transferable to other countries, although they may require adjustment. [ABSTRACT FROM AUTHOR]

Effective conservation of stream fishes and their habitats is complicated by the fact that human stressors alter the way in which natural factors such as stream size, catchment geology, and regional climate influence stream ecosystems. Consequently, efforts to assess the condition of stream fishes and their habitats must not only attempt to characterize the effects of human stressors but must account for the effects of natural influences as well. This study is an assessment of all stream fish habitats in the Mississippi River basin, USA. The basin supports over 400 stream fish species, drains a land area of 3.2 M km2, and includes a myriad of human stressors such as intensive agriculture, urbanization, nutrient loading, and habitat fragmentation by dams and road/stream crossings. To effectively characterize types and levels of human stressors specifically impacting the basin’s stream fish species, our assessment approach first accounted for the influence of natural landscape conditions on species abundances with multiple steps, including stratifying our analyses by region and stream size and quantitatively modeling the influences of natural factors on stream fishes. We next quantified individual fish species responses to explicit human stressors for different measures of land use, fragmentation, and water quality, including summaries of measures in local vs. catchment extents. Results showed that many species had negative threshold responses to human stressors and that impacts varied by species, by region, and by the spatial extents in which stressors were summarized. Our spatially explicit results indicated the degree of stream reach impairment for specific stressor categories, for individual species, and for entire assemblages, all of which are types of information that can aid decision makers in achieving specific conservation goals in the region.

Understanding movement patterns of anadromous fishes is critical to conservation and management of declining wild populations and preservation of habitats. Yet, the duration of observations for individual animals can constrain accurate descriptions of movements. In this study, we synthesized over a decade (2006–2018) of acoustic telemetry tracking observations of green sturgeon (Acipenser medirostris) in the Sacramento River system to describe major anadromous movement patterns. We observed that green sturgeon exhibited a unimodal in‐migration during the spring months but had a bimodal distribution of out‐migration timing, split between an "early" out‐migration (32%) group during May–June, or, alternatively, holding in the river until a "late" out‐migration (68%), November–January. Focusing on these out‐migration groups, we found that river discharge, but not water temperature, may cue the timing of migration and that fish showed a tendency to maintain out‐migration timing between subsequent spawning migration events. We recommend that life history descriptions of green sturgeon in this region reflect the distinct out‐migration periods described here. Furthermore, we encourage the continued use of biotelemetry to describe migration timing and life history variation, in not only this population but also other green sturgeon populations and other species. [ABSTRACT FROM AUTHOR]

Riparian zones are critical for functional integrity of riverscapes and conservation of riverscape biodiversity. The synergism of intermediate flood-induced disturbances, moist microclimates, constant nutrient influx, high productivity, and resource heterogeneity make riparian zones disproportionately rich in biodiversity. Riparian vegetation intercepts surface-runoff, filters pollutants, and supplies woody debris as well as coarse particulate organic matter (e.g., leaf litter) to the stream channel. Riparian zones provide critical habitat and climatic refugia for wildlife. Numerous conservation applications have been implemented for riparian-buffer conservation. Although fixed-width buffers have been widely applied as a conservation measure, the effectiveness of these fixed buffer widths is debatable. As an alternative to fixed-width buffers, we suggest adoption of variable buffer widths, which include multiple tiers that vary in habitat structure and ecological function, with each tier subjected to variable management interventions and land-use restrictions. The riparian-buffer design we proposed can be delineated throughout the watershed, harmonizes with the riverscape concept, thus, a prudent approach to preserve biodiversity and ecosystem functions at variable spatial extents. We posit remodeling existing conservation policies to include riparian buffers into a broader conservation framework as a keystone structure of the riverscape. Watershed-scale riparian conservation is compatible with landscape-scale conservation of fluvial systems, freshwater protected-area networks, and aligns with enhancing environmental resilience to global change. Sustainable multiple-use strategies can be retrofitted into watershed-scale buffer reservations and may harmonize socio-economic goals with those of biodiversity conservation. [ABSTRACT FROM AUTHOR]

The data presented here cover ∼4 decades of electrofishing surveys in mainland France rivers. Despite some changes in field protocols and sampling site locations over time, the ASPE database offers a unique set of 47,869 georeferenced and standardised sampling surveys. Fish individuals are identified to species, measured and weighted. Additional information encompasses habitat features as well as "river health" assessment by two fish-based indices. Though preferentially focused on fishes, the surveys also report crayfish data. Numerous studies have been already published using these data, mainly on the fields of macroecology, community and/or population ecology and bioassessment. However, we believe much more knowledge can be gained from the database in fields such as population dynamics or conservation practices in the context of global change. [ABSTRACT FROM AUTHOR]

The study aimed to analyse the representativeness of the monitoring sites for the ecological status assessment of running water bodies through an example of a model systems: Chetirka (Logodashka) River and its tributaries Gabrovska and Leshtinska River as well as the section of the Struma River after the Chetirka inflow. Hydrobiological (benthological and physical-chemical) studies were conducted in the summer of 2016 at six selected representative sites affected by different types of anthropogenic pressures (habitat change, over-exploitation, contamination with nutrients, etc.). The data were compared to the ecological status assessment performed by the Bulgarian West-Aegean Basin Directorate during 2011-2018. The analysis of the associated physical-chemical parameters showed good-high status for all studied rivers and stretches. According to the Biotic Index, the Gabrovska River was determined in a high-good status whereas the Leshtinska, Chetirka and the section of the Struma River after the Chetirka inflow were characterised by moderate ecological status. The results obtained for the polluted sites demonstrate the need for more frequent monitoring observations at vulnerable sites exposed to adverse influences and droughts in order to prevent potential negative impacts on the main river basin. [ABSTRACT FROM AUTHOR]

The Sickle Darter Percina williamsi (Page and Near, 2007) is a species of fish endemic to the upper Tennessee River basin in eastern Tennessee, southwestern Virginia, and western North Carolina. Because of its narrow range and presumed decline in occupied sites over the last half century, it is being proposed for federal listing under the Endangered Species Act. We analyzed the current distribution of the Sickle Darter and temporal trends in its distribution in relation to temporal trends in environmental and habitat covariates for each of the historically occupied sub‐basins (upper Clinch, Emory, upper French Broad, Little, Little Pigeon, Middle Fork Holston, North Fork Holston, Powell, South Fork Holston, and Watauga) with multiple linear regression modelling. A total of 154 Sickle Darters were observed at 15 sites throughout the upper Tennessee River Basin. Sickle Darters were observed in the Little River, Emory River, and Middle Fork Holston River sub‐basins. A total of 133 unique historical occurrences were used for the spatiotemporal analyses. Sickle Darters have declined in 8 out of 10 historically occupied sub‐basins. Our best model for the whole distribution scale (Mallow's Cp = −0.87; Adjusted R2 =.92) suggests that habitat fragmentation due to damming has had adverse effects on Sickle Darter populations across its distribution. Models were very similar for the sub‐basin specific models as well. The results from this study highlight the drivers of decline in Sickle Darter distribution and outline the future research needs for this species that should be used to inform future conservation decisions regarding this species. [ABSTRACT FROM AUTHOR]

The diversity of species inhabiting freshwater relative to marine habitats is striking, given that freshwater habitats encompass <1% of Earth's water. The most commonly proposed explanation for this pattern is that freshwater habitats are more fragmented than marine habitats, allowing more opportunities for allopatric speciation and thus increased diversification rates in freshwater. However, speciation may be generally faster in sympatry than in allopatry, as illustrated by lacustrine radiations such as African cichlids. Such differences between rivers and lakes may be important to consider when comparing diversification broadly among freshwater and marine groups. Here I compared diversification rates of teleost fishes in marine, riverine and lacustrine habitats. I found that lakes had faster speciation and net diversification rates than other aquatic habitats. However, most freshwater diversity arose in rivers. Surprisingly, riverine and marine habitats had similar rates of net diversification on average. Biogeographic models suggest that lacustrine habitats are evolutionarily unstable, explaining the dearth of lacustrine species in spite of their rapid diversification. Collectively, these results suggest that strong diversification rate differences are unlikely to explain the freshwater paradox. Instead, this pattern may be attributable to the comparable amount of time spent in riverine and marine habitats over the 200‐million‐year history of teleosts. [ABSTRACT FROM AUTHOR]

Large wood (LW) is used for river restoration, aquatic habitat conservation, and flood control; however, it can pose a threat to human life and the built environment. The formation of LW jams, river management strategies, and design of mitigation measures crucially all depend on how the large wood is transported along a river. This paper experimentally analyses at laboratory scale the motion of natural sticks in a long stretch of a straight channel (>16 m), when LW is released at different locations and with different flow conditions. Results show that instream large wood, following a transient motion shortly after being released at the water surface, tends to follow preferential patterns along the channel. Froude number and location of large wood input may provide an estimation of the LW location in downstream reaches. Several mechanisms of motion were observed, some of which were very common, including a frequent tendency to assume a tilted position with respect to the direction parallel to the flow. The experiments also suggest that theories on secondary cells responsible for channeling LW in preferential directions are incomplete. A new model, based on acceleration induced by hydrodynamic actions, has been established and proposed in this work, showing promising results and paving the way for the development of a comprehensive model for transport of large wood at the river surface in full‐scale applications. Key Points: Transport of large wood (LW) at the river surface after an initial transient motion is observed in narrow areas of the channelOther theories on secondary cells prove inconclusive since only limited effects were observed at convergence points of flow velocityA novel approach and system of equations on acceleration induced by hydrodynamic forces is proposed and tested on experimental observations [ABSTRACT FROM AUTHOR]

To adequately protect habitat for economically important fishes, the habitats used must first be identified and described. Coastal geomorphology is often overlooked as an influential parameter of fish habitat use in favor of readily available data taken at the time of sampling. We hypothesized that river dynamics (e.g., length, watershed, floodplain connectivity) and mesohabitat categories based on geomorphology (e.g., backwater, river bend) were at least as important as fine-scale microhabitat (e.g., depth, shore type) for describing the distribution and habitat affinities of Common Snook Centropomus undecimalis (hereafter referred to as snook) in coastal rivers of the Atlantic coast and Tampa Bay, Florida. Contrary to previously studied rivers where adult snook abundance increased during a seasonal prey pulse, adult snook abundance in the study rivers differed little between seasons and the rivers were used as nurseries by juveniles. Mesohabitat categories were important for describing snook distribution. For example, the smallest snook (≤ 250 mm total length, TL) strongly selected for backwater habitats while the largest (≥ 851 mm TL) selected river bends. Detailed microhabitat data collected at individual capture locations were helpful in describing the habitat associations of the smallest size group of snook (shallow depths and aquatic macrophytes with various shore types) and for characterizing river bends (high flow, deep water, and lower salinities) but were not strongly associated with other snook sizes or mesohabitat categories. Thus, broader scale habitat features were found to be equally as important as detailed microhabitat and should be considered when informing conservation efforts. [ABSTRACT FROM AUTHOR]

Keywords: History; Infrastructure; Federal Legislation; Federal Funding; Lakes; Rivers; Estuaries; Wetlands; Habitats; Wildlife; Pipes; Lead; Service Lines; Emerging Contaminants EN History Infrastructure Federal Legislation Federal Funding Lakes Rivers Estuaries Wetlands Habitats Wildlife Pipes Lead Service Lines Emerging Contaminants 6 8 3 04/07/22 20220401 NES 220401 The bipartisan Infrastructure Investment and Jobs Act (P.L. 117-58) provides a historic opportunity to deliver on the promise of clean water, now and for future generations. Congress established the SRFs as subsidized loan programs that would be capitalized with a federal grant, plus state funding equivalent to 20% of federal funding. [Extracted from the article]

Both terrestrial and aquatic food webs are characterized by similar key parameters: connectance, robustness, and linkage. Ecosystems vary in basic structures and by processes that govern their dynamics and complexity. A study of complexity, connectance and link density in terrestrial and aquatic food webs, was conducted. We used 49 food webs apportioned in 23 terrestrials, 15 lacustrine and 11 rivers. The results revealed that aquatic food webs presented a difference in superiority of average connectance and link density, (p ~ 0.05), depicting an absence of differences in means. A regression test revealed that connectance and link density are inversely correlated in terrestrial food webs and contrary in other habitats, which was the same case for connectance and the average length of chain. We assume that connectance should be positively correlated with other parameters (fluxes and interaction strengths) in terrestrial habitat as its variations were not explained by link density or the average length of chain. This study revealed a higher estimate of connectance in aquatic habitats compared to their terrestrial counterparts. Aquatic habitats are potentially characterized by high values of parameters related to the connection (interactions quality, organisms’ growth, and food web size) while terrestrial ones are more branded by features depicting constancy (productivity, complexity, and diversity). [ABSTRACT FROM AUTHOR]

The importance of flow‐related factors to benthic organisms, as well as the role of habitat conditions in shaping aquatic communities during low‐flow periods, have been recognised. Despite this, the preferences of macroinvertebrates to the ratio of lentic to lotic habitats at the reach scale have not been accurately quantified in most instances.Aquatic invertebrates and habitat features in a range of temporary rivers in Sardinia were investigated. The investigation focused on the flow‐related characteristics that contribute to defining the lentic–lotic condition of the river reaches. The relation of habitat features to benthic taxa distributions was assessed using multidimensional scaling. The main aim of the paper was to quantify the responses of taxa to the different lentic and lotic habitat conditions by applying hierarchical logistic regressions. Finally, taxon optima were aligned along the lentic–lotic gradient and the responses of different taxonomic groups compared.Unbroken waves and imperceptible flow were correlated with benthic taxa variability, suggesting local hydraulics and turbulence have a major role in regulating community composition. The overall lentic–lotic character of the river reaches was also clearly related to the benthic taxa distribution. More than 80% of taxa were significantly related to the lentic–lotic gradient, and an asymmetrical response curve was the predominant model.Benthic groups showed taxon optima clustered in different ranges of the lentic–lotic gradient. Odonata, Coleoptera, Hemiptera, and Mollusca preferred clearly lentic conditions. Diptera mainly ranged on the lotic side of the gradient, while Trichoptera were relatively uniformly distributed across the gradient. Ephemeroptera taxa clustered in intermediate lentic–lotic conditions, with two species preferring extremely lentic habitats. In general, optima converged at intermediate and extremely lentic conditions, presumably due, respectively, to the coexistence of different lentic and lotic features and to the highly diverse environmental characteristics under extremely lentic situations.These results support the conclusion that dissimilar ecological factors act on benthic taxa along the lentic–lotic range and species favouring different lentic–lotic conditions are subjected to pressures of different nature. This should not be ignored when defining species preferences and studying community structure or relationships between species in Mediterranean rivers, which cyclically vary their habitat composition. In addition, the uneven distribution of optima of different groups along the lentic–lotic gradient might affect macroinvertebrate metrics when assessing ecological status or establishing reference conditions under variable climatic conditions. [ABSTRACT FROM AUTHOR]

Ecological information on the rivers of eastern Himalaya, specifically the state of Arunachal Pradesh is not studied well. The present study describes fish assemblage patterns and deriving relationships between local habitat variables in the upper reaches of Subansiri River, Arunachal Pradesh. This study was carried out during October to November 2014 and February to March 2015. A total of 26 fish species belonging to eight families were recorded, in which eight species are endemic to the eastern Himalayan region. Fish species richness varied from two to 18 species in the upper reaches of Subansiri River and high species diversity was recorded in Sigin Stream (H'=2.76). Based on the seven habitat variables (water velocity, depth, channel width, percentage of substrate composition, percentage of riparian vegetation, altitude, and water temperature) then streams were categorized into lower-order and higher-order streams using principal component analysis (PCA). The site-wise fish abundance data along with habitat variable information was then subjected to the canonical correspondence analysis (CCA) for testing the association of habitat variables on fish abundance. The CCA results revealed that the abundance of large-size barbs, Neolissochilus hexagonolepis, N. nigrovittatus, Schizothorax progastus, and S. richardsonii were strongly associated with high altitude, water velocity, rich dissolved oxygen, and good riparian vegetation. On the other hand, Channa gachua, Botia rostrata, Danio rerio, Devario aequipinnatus, and Garra nasuta showed strong association with warm water streams with more conductivity. [ABSTRACT FROM AUTHOR]

Understanding juvenile salmonid habitat requirements is critical for their effective management, but little is known about these requirements in lowland rivers, which include important but unique salmonid habitats. We compared the relative influence of in‐stream Ranunculus cover, water depth, prey abundance, distance upstream and two previously unexplored factors (water velocity heterogeneity and site colonisation potential) on summer densities of juvenile Atlantic salmon and brown trout. We applied electrofishing, habitat surveys and macroinvertebrate kick sampling, and calculated the site colonisation potential from salmon redd surveys across 18–22 sites in a lowland river in 2015–2017. Due to a recruitment crash in 2016, models including and excluding this unusual year were explored. Excluding 2016 data, juvenile salmon densities showed a positive association with Ranunculus cover and numbers of nearby upstream redds, and a negative association with distance upstream from the tidal limit. Trout densities were positively associated with velocity heterogeneity, indicating a potential indirect influence of Ranunculus mediated by water velocity. When including 2016, year had the largest effect on densities of both species, highlighting the impact of the recruitment failure. These findings uncover interspecific differences in the habitat requirements of juvenile salmonids in lowland rivers. Velocity heterogeneity and site colonisation potential had high explanatory power, highlighting that they should be considered in future studies of habitat use. These findings demonstrate that temporal replication and recruitment dynamics are important considerations when exploring species–habitat associations. We discuss potential management implications and argue that Ranunculus cover could be an important management tool in conservation of lowland salmonids. [ABSTRACT FROM AUTHOR]

Fish assemblages in large rivers are governed by spatio‐temporal changes in habitat conditions, which must be accounted for when designing effective monitoring programmes. Using boat electrofishing surveys, this study contrasts species richness, catch per unit effort (CPUE), total biomass, and spatial distribution of fish species in the Saint John River, New Brunswick, Canada, sampled during different diel periods (day and night) and macrohabitats (hydropower regulated river and its reservoir) in the vicinity of the Mactaquac (hydropower) Generating Station. Taxa richness, total CPUE, and total biomass were significantly higher during night surveys, resulting in marked differences in community composition between the two diel periods. Furthermore, the magnitude of diel differences in catch rate was more pronounced in lentic than in lotic macrohabitats. The required sampling effort (i.e., number of sites) to increase accuracy and precision of CPUE estimates varied widely between fish species, diel periods, and macrohabitats and ranged from 15 to 185 electrofishing sites. Determining a correction factor to contrast accuracy and precision of day‐ with night‐time surveys provide useful insights to improve the design of long‐term monitoring programmes for fish communities in large rivers. The study also shows the importance of multihabitat surveys to detect differences in the magnitude of diel changes in fish community metrics. [ABSTRACT FROM AUTHOR]

River gravel-bar habitats are highly endangered. They are still well-preserved in the Caucasus, but developing conservation strategies is burdened by the lack of data from this region. We studied vegetation and habitat types on gravel bars of 22 rivers in Georgia, including successional stages from open early-successional herbaceous vegetation to scrub. We distinguished five vegetation types based on vegetation physiognomy and β-flexible clustering of species composition, and described them as phytosociological vegetation units: Early-successional herbaceous vegetation at higher elevations was described as the new association Epilobietum colchici and that at lower elevations as the Petrorhagia saxifraga–Crepis foetida community. The grassland dominated by Calamagrostis pseudophragmites and scrub vegetation were assigned to the associations previously described from Central Europe (Tussilagini farfarae-Calamagrostietum pseudophragmitae, Salici purpureae-Myricarietum germanicae and Salici incanae-Hippophaëtum rhamnoidis). We established diagnostic plant species for each type using the fidelity calculation and related these types to environmental variables. We further compared them with the previously published data on gravel-bar vegetation from the Russian part of the Caucasus and with European systems of habitat classification. This study demonstrates that vegetation and habitat types occurring in Georgia correspond to those recognized earlier in Europe, and can be easily linked to the European systems of habitat classification. Unlike in other parts of Europe, these habitats are still well-preserved on rivers with natural hydrological dynamics, but they are threatened by plans of dam building and other river regulations. Our study provides baseline data for developing conservation strategies for the Caucasian gravel-bar habitats. [ABSTRACT FROM AUTHOR]

Introduction: Describing biodiversity patterns and the underlying drivers is relevant for tackling the rampant pressures on tropical freshwaters. This is particularly relevant in scarcely studied regions, such as in the Colombian Guiana shield. Objective: To describe the taxonomic and functional structure of macroinvertebrate communities and assess their variability across spatial and temporal scales. Methods: We sampled the invertebrate communities in four streams during the dry seasons of 2017 and 2018. Additionally, we assessed diversity patterns within and among streams and between different sampling months in one stream. To assess diversity patterns, we compared alpha (differences in taxon richness and abundance within communities) and beta (differences in taxon composition among communities) diversity patterns among and within rivers. Alpha diversity was estimated using the numbers of Hill, while beta diversity was estimated using the Sørensen and Morisita-Horn indices and compared using a similarities analysis (ANOSIM). Results: The taxon composition of the communities was different within (mesohabitat scale) and among streams (regional scale). However, the composition of FFGs changed among but not within streams. The comparison of the numbers of Hill and the taxon composition suggested that the mesohabitat type is a determining factor of the taxonomic but not FFG diversity across scales. At the temporal scale, alpha diversity was low for months with high precipitation (February-April) and high for the dry season (January). The temporal beta diversity was high among sampling periods, being nestedness processes driving beta diversity among years and turnover processes driving beta diversity within years. Conclusion: Streams from Serranía de la Lindosa host a high diversity of freshwater macroinvertebrates. Seasonality and differences in the in-stream habitat heterogeneity seem to determine the diversity patterns observed at different temporal and spatial scales. A deeper study is needed to understand the functioning of these ecosystems and improve the ability to generate management and conservation strategies. [ABSTRACT FROM AUTHOR]

Predicting how stream fishes may respond to habitat restoration efforts is difficult, in part because of an incomplete understanding of how basic biological parameters such as growth and ontogenetic habitat shifts interact with flow regime and riverscape ecology. We assessed age-specific Guadalupe Bass Micropterus treculii habitat associations at three different spatial scales in the South Llano River, a spring-fed stream on the Edwards Plateau of central Texas, and the influence of habitat and flow regime on growth. We classified substrates using a low-cost side-scan sonar system. We used scale microstructure to determine age and to back-calculate size at age. Over 65% of captured Guadalupe Bass were age 2 or age 3, but individuals ranged from 0 to 7 y of age. Habitat associations overlapped considerably among age classes 1–3+, but age-0 Guadalupe Bass tended to associate with greater proportions of pool and run mesohabitats with submerged aquatic vegetation. Although habitat metrics across multiple scales did not have a large effect on growth, river discharge was negatively correlated with growth rates. Understanding age-specific Guadalupe Bass habitat associations at multiple scales will increase the effectiveness of restoration efforts directed at the species by assisting in determining appropriate ecological requirements of each life-history stage and spatial scales for conservation actions. [ABSTRACT FROM AUTHOR]

Dam removals allow fish to access habitats that may provide ecological benefits and risks, but the extent of fish movements through former dam sites has not been thoroughly evaluated for many species. We installed stationary PIT antennas in 2016 and 2017 to evaluate movements and survival of brook trout Salvelinus fontinalis in the West Branch of the Wolf River (WBWR) in central Wisconsin following removal of two dams and channel modifications designed to promote fish movement. These changes provided access to lacustrine habitats that might provide suitable winter habitat or act as ecological sinks. We used multistate models to estimate transition probabilities between river sections, to determine whether brook trout: (a) moved between multiple river sections and (b) entered lacustrine habitats as seasonal refuges, but eventually returned to lotic habitat. We also used a Cormack‐Jolly‐Seber model to evaluate whether apparent survival of brook trout in the WBWR was comparable to other populations. Few fish moved among river sections or used lacustrine habitat (<5% of tagged fish); most brook trout remained in sections where they were initially tagged, potentially due to quality habitat located throughout the river. Like other studies, brook trout in the WBWR appear to experience high mortality based on low number of detections, few physical recaptures and an estimated eight‐month apparent survival rate of 0.27. In scenarios where fish can already access suitable habitat, removal of dams may not result in substantial increases in fish movement and colonisation of newly accessible habitat may not occur immediately. [ABSTRACT FROM AUTHOR]

The Brook Trout Salvelinus fontinalis is a native salmonid that provides a valued and productive sport fishery in northeastern Minnesota. Revival of North American beaver Castor canadensis (hereafter, "beaver") populations since their near extermination and concern over their impacts on Brook Trout habitat prompted a reexamination of the complex ecological relationship where the two taxa interact. Suitable Brook Trout habitat is characterized by cold, spring‐fed water with silt‐free rocky substrate and abundant cover, all of which beaver may directly or indirectly affect. Data collection occurred on 79 stream sections (200 m each) and 21 beaver ponds spanning the North Shore of Lake Superior during the summer in 2017 and 2018. Habitat suitability index (HSI) models determined the average HSI and quantity of suitable Brook Trout habitat (m2/100 m2) at stream and beaver pond sites, and a bioenergetics model calculated Brook Trout growth availability (m2/100 m2) and mean growth (g/d) at stream sites. Classification regression trees identified significant thresholds at which beaver activity (e.g., number of dams upstream of sampled sites and beaver pond age) influenced the quantity or quality of Brook Trout habitat and growth. No significant variables were identified as affecting Brook Trout habitat or growth rates in stream sites. Alternatively, the quantity and quality of Brook Trout habitat in this region appeared to be influenced by microhabitat variables (depth, velocity, and temperature) that are eminent at individual stream sites. Brook Trout growth was strongly influenced by velocity (m/s) and mean prey concentration (mg dry mass/m3). Results indicated that 12 of the 21 sampled beaver ponds contained suitable Brook Trout habitat, with dissolved oxygen (mg/L) identified as a threshold. This study recommends focusing on individual stream characteristics and beaver pond dissolved oxygen concentrations to achieve desired Brook Trout habitat and aid in the development of management strategies pertaining to these two taxa in Lake Superior's North Shore streams. [ABSTRACT FROM AUTHOR]

Crayfishes (Decapoda) are common inhabitants of agricultural headwater streams in the Midwestern USA that have been impacted by physical habitat degradation and contamination by agricultural pollutants. The frequency and severity of injuries within crayfish communities are indicators of crayfish aggression, which is influenced by physical, chemical, and biotic factors. Previous studies have not evaluated the relationships of the frequency and severity of crayfish injuries with physical habitat quality, water quality, and biotic factors within agricultural headwater streams. Understanding these relationships will assist with determining if crayfish injury variables can serve as an indicator of physical habitat quality or water quality in these small degraded streams. We sampled crayfishes, documented the frequency and type of injuries, and measured instream habitat and water chemistry in 2014 and 2015 within 12 agricultural headwater streams in Indiana, Michigan, and Ohio. We documented five native crayfish species from 1641 adult captures. The most abundant species were Faxonius rusticus, Faxonius immunis, and Faxonius propinquus. Linear mixed effect model analyses indicated that four crayfish injury response variables were positively correlated (p < 0.05) with crayfish density, physical habitat quality, and water velocity diversity and that crayfish injury response variables were more strongly correlated with crayfish density than physical habitat quality or water quality. Our results indicate that response variables describing the severity and frequency of crayfish injuries can be effective indicators of physical habitat quality in agricultural headwater streams. [ABSTRACT FROM AUTHOR]

Stream metabolism is an important metric of ecosystem function. Accurate estimates of gross primary production (GPP) and respiration (ER) are based on metabolism models that require estimates of gas transfer rates at the surface–water interface. When the gas exchange rate K (d−1) is measured directly from the environment, it can be used with dissolved O2 data to estimate GPP and ER. However, inverse modeling methods can also be used to solve for GPP, ER, and K simultaneously. Estimates of K from inverse models have rarely been compared to direct estimates of K. Additionally, the effects of the method used to estimate K on estimates of ecosystem metabolism are unknown. We compared these methods in shallow, low-gradient, open-canopy experimental streams under a range of hydrologic conditions with (vegetated) and without (unvegetated) instream vegetation. The different methods gave similar results for K estimates in vegetated streams. In unvegetated streams, however, inverse modeling methods that simultaneously estimated K with GPP and ER gave higher K estimates than did our direct measurements. When K was modeled rather than measured, metabolism estimates were higher in unvegetated streams, and model fits struggled to replicate dissolved O2 data. The different methods of estimating K resulted in similar metabolism estimates within vegetated streams. However, the linear relationships between ER and GPP were not significantly different among methods of estimating K for vegetated or unvegetated streams. This study demonstrates that in shallow, low-gradient, open-canopy streams, particularly those with high GPP and low K , practitioners can use inverse modeling approaches to estimate K. Estimates in unvegetated systems, which have lower GPP, may be hindered by uncertainty in measured K in low gas transfer environments or by process errors within existing models. [ABSTRACT FROM AUTHOR]

In this study, we analysed the diet of two populations of Perlodes intricatus (Pictet, 1841) inhabiting river sections characterised by different environmental quality. Macrobenthic communities and nymphal gut content data were acquired in a nearby pristine environment and in a station compromised by sewage discharges. No differences in size were detected between these populations. Both populations select positively Chironomidae as prey, but marked differences are evident between their diet. Nymphs from pristine station feed on a wide range of prey, but also include algae and organic detritus. By contrast, nymphs from polluted station show a different and restricted trophic spectrum, likely because of the reduced prey availability. Interestingly, the occurrence of fine organic detritus in these latter nymphs is much higher, evidencing a shift to a more collector-gatherer feeding. This study shows that some Perlodidae can survive and develop in contaminated environments, also due to their trophic plasticity. [ABSTRACT FROM AUTHOR]

Copyright of Stratum Plus Journal is the property of P.P. Stratum plus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Habitat homogenization has been a major impact in stream ecosystems, and it is considered one of the main drivers of biotic homogenization as well, leading to the loss of water quality and fish diversity. In this study, we added artificial woody structures and leaf packs in physically impacted streams to test if the additions can improve habitat complexity and change the taxonomic and functional structure of fish communities. The experiment was done in eight streams impacted by siltation, deforestation, and habitat homogenization, inserted in an agricultural landscape from the Upper Paraná River Basin, and lasted 112 days. The provision of artificial microhabitats increased instream habitat diversity by creating patches of organic matter deposits, changing flow, and providing substrate for grass colonization of the instream habitat. The experimental manipulation also changed fish species abundance. Nine species contributed to these changes, five decreased and four increased in abundance, indicating species responded differently to the experimental manipulation. However, overall species richness, diversity, and community functional traits remained unaltered. These results indicate that short-term habitat restoration on a local scale may not be enough to promote changes in fish community attributes of streams that are heavily impacted. [ABSTRACT FROM AUTHOR]

Recognition that beavers are integral components of stream ecosystems has resulted in an increase in beaver‐mediated habitat restoration projects. Beaver restoration projects are frequently implemented in degraded stream systems with little or no beaver activity. However, selection of restoration sites is often based on habitat suitability research comparing well‐established beaver colonies to unoccupied stream sections or abandoned colonies. Because beavers dramatically alter areas they occupy, assessing habitat conditions at active colonies may over‐emphasize habitat characteristics that are modified by beaver activity. During 2015–2017, we conducted beaver activity surveys on streams in the upper Missouri River watershed in southwest Montana, United States, to investigate habitat selection by beavers starting new colonies in novel areas. We compared new colony locations in unmodified stream segments to unsettled segments to evaluate conditions that promoted colonization. Newly settled stream segments had relatively low gradients (β ± SE = −0.72 ± 0.27), narrow channels (β = −1.31 ± 0.46), high channel complexity (β = 0.76 ± 0.42), high canopy cover of woody riparian vegetation (β = 0.56 ± 0.21), and low‐lying areas directly adjacent to the stream (β = 0.36 ± 0.24), where β denotes covariate effect sizes. Habitat selection patterns differed between our new settlement site analysis and an analysis of occupied versus unoccupied stream segments, suggesting that assessing habitat suitability based on active colonies may result in misidentification of suitable site conditions for beaver restoration. Our research provides recommendations for beaver restoration practitioners to select restoration sites that will have the highest probability of successful colony establishment. [ABSTRACT FROM AUTHOR]

Acipenseriformes (sturgeons and paddlefish) globally have declined throughout their range due to river fragmentation, habitat loss, overfishing, and degradation of water quality. In North America, pallid sturgeon (Scaphirhynchus albus) populations have experienced poor to no recruitment, or substantial levels of hybridization with the closely related shovelnose sturgeon (S. platorynchus). The Lower Missouri River is the only portion of the species' range where successful reproduction and recruitment of genetically pure pallid sturgeon have been documented. This paper documents spawning habitat and behavior on the Lower Missouri River, which comprises over 1,300 km of unfragmented river habitat. The objective of this study was to determine spawning locations and describe habitat characteristics and environmental conditions (depth, water velocity, substrate, discharge, temperature, and turbidity) on the Lower Missouri River. We measured habitat characteristics for spawning events of ten telemetry‐tagged female pallid sturgeon from 2008–2013 that occurred in discrete reaches distributed over hundreds of kilometers. These results show pallid sturgeon select deep and fast areas in or near the navigation channel along outside revetted banks for spawning. These habitats are deeper and faster than nearby river habitats within the surrounding river reach. Spawning patches have a mean depth of 6.6 m and a mean depth‐averaged water‐column velocity of 1.4 m per second. Substrates in spawning patches consist of coarse bank revetment, gravel, sand, and bedrock. Results indicate habitat used by pallid sturgeon for spawning is more common and widespread in the present‐day channelized Lower Missouri River relative to the sparse and disperse coarse substrates available prior to channelization. Understanding the spawning habitats currently utilized on the Lower Missouri River and if they are functioning properly is important for improving habitat remediation measures aimed at increasing reproductive success. Recovery efforts for pallid sturgeon on the Missouri River, if successful, can provide guidance to sturgeon recovery on other river systems; particularly large, regulated, and channelized rivers. [ABSTRACT FROM AUTHOR]

Spawning season and habitat of invasive smallmouth bass were studied for two seasons in the Chikuma River, Nagano, Japan. Smallmouth bass spawning started in early May, when required water temperatures were met, and continued as long as spawning was not disrupted by high water levels. Spawning sites were found in patches throughout the study area that had significantly different physical characteristics than typical stream habitat features. Utilized spawning sites had low current velocity, were relatively shallow, and had pebble-sized substrate. Individual nest variables showed correlation with nesting male size as larger males constructed larger and deeper nests in faster flowing and deeper areas of the river. Nest guarding rates were low while egg presence rates were high compared to the native range, which may indicate that factors such as favorable water levels and water temperature and prevalence of spawning habitat facilitate spawning and the spread of smallmouth bass in the Chikuma River. [ABSTRACT FROM AUTHOR]

Copyright of Caldasia is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We used mitochondrial DNA to assess the genetic structure of endangered lake chubsucker Erimyzon sucetta across its Canadian range. We found unique mitochondrial haplotypes in Lyons Creek, a tributary of the Niagara River that faces a strong potential for habitat deterioration. Lyons Creek may therefore serve as a reservoir of unique genetic diversity. The sensitivity of Lyons Creek, combined with the genetic uniqueness of its E. sucetta population, call for further investigation into whether this population should be considered a separate designatable unit for conservation purposes. [ABSTRACT FROM AUTHOR]

Ecology of the Sierra Nevada Yellow-Legged Frog (Rana sierrae) is well understood in high elevation lakes, but data on habitat preferences in stream-dwelling populations are lacking. We sought to expand understanding of stream habitat use by R. sierrae by investigating habitat suitability at the microhabitat and reach scales. We collected habitat availability and use data during 2016–2017 at five stream sites representative of geomorphic diversity in the northern Sierra Nevada mountains of California. At each frog use and availability location, we collected data on geomorphic unit type (e.g., riffles, pools), water depth, water velocity, substrate (e.g., gravel, cobble), and percent cover, including herbaceous, canopy, and total cover. Bootstrapped logistic regression models for all study sites combined indicated water depth and velocity were the strongest predictors of post-metamorphic (adult and subadult) use by R. sierrae, while substrate and total cover provided moderate improvement in microhabitat use predictions. Specifically, adults had the highest probability of use in microhabitats with <0.3 m depth and <0.1 m s–1 velocity. For tadpoles, we found velocity was the strongest microhabitat predictor for all study sites combined, with the highest probability of use in habitats with <0.01 m s–1. Site-level models highlighted the relative importance of non-hydraulic habitat variables, such as cover, when suitable depth and velocity conditions occurred. At the reach scale, we found hydraulic conditions varied widely in geomorphic units over time, but suitable microhabitat conditions emerged in differing geomorphic units as flows changed over the season. These data indicate that R. sierrae, like other ranid species, may be limited by hydraulically suitable habitat availability, but habitat preferences can be met in a variety of stream reaches when variations in flow conditions over time and space are considered. [ABSTRACT FROM AUTHOR]

The Sierra Nevada Yellow-Legged Frog (Rana sierrae) has generally been viewed as a lake species, but it has increasingly been found in streams, including in the northern part of its range where it is particularly at risk. Developing effective conservation strategies has been hindered by a lack of knowledge of its basic ecological requirements in stream habitats. To address this information gap, we investigated the demography, habitat use, and movements of stream populations of this federally endangered species. We conducted capture–mark–recapture of adults, quantitatively described stream channel and riparian vegetation characteristics, and collected habitat use data at four northern Sierra Nevada mountain streams, counted egg masses at three central Sierra Nevada streams, and radio-tracked individuals at three central and southern Sierra Nevada streams. Stream populations in the northern range were very small with maximum abundances of <15 individuals, and apparent survival probability ranged from 0.57–0.81. In contrast, one southern Sierra Nevada stream had a large count of 547 adults. Egg mass counts ranged from 22–104 per stream. We found frogs in diverse headwater streams ranging from perennial to intermittent flow regimes, pool versus riffle dominated, and low to high channel gradient, and they used diverse microhabitats within these streams. In these stream habitats, frogs moved little over four-day survey periods but were capable of moving longer distances of up to 1248 m over the summer. Conservation and management of the at-risk R. sierrae are most likely to be effective when built on comprehensive quantitative information on basic ecological requirements in all habitats used by the species. [ABSTRACT FROM AUTHOR]

Turtle populations are imperiled worldwide, but limited ecological information from unaltered systems hampers science‐based management and conservation of some species, especially riverine turtles such as the spiny softshell (Apalone spinifera). We therefore investigated movements and spatial habitat selection of 54 A. spinifera in 633 river kilometres (rkm) of the least‐altered river in the conterminous United States—the Yellowstone River in Montana—from 2005 to 2009. Movement rates and home ranges were smaller than in fragmented, altered river systems because nesting and overwintering habitats were common and in close proximity. Habitat selection also differed. A. spinifera in the Yellowstone River overwintered in unaltered bluff pools and summered in complex reaches with side channels, islands, and diverse habitats. However, those in the highly altered Missouri River used deep alluvial pools for overwintering and flooded, inundated, or backwatered tributary mouths in spring and summer. Importantly, selected habitats in both rivers were functionally similar, including complex river reaches (with multiple channels, islands, and diverse habitats) and natural pool types. Unfortunately, these are the very habitats that are limited in rivers affected by dams, bank stabilization, and channelization. Therefore, preservation of natural and diverse riverine habitats—and the fluvial dynamics that maintain them—may enhance conservation of A. spinifera in large rivers. [ABSTRACT FROM AUTHOR]

River restoration offers the potential to enhance biological integrity, often measured as fish population changes. We used a meta-analytical approach to synthesize density responses to in-stream habitat restoration by young-of-the year (YOY) brown trout and Atlantic salmon in 28 rivers (overall 32 restoration projects) in Finland. We also examined which local and watershed-scale factors most influenced restoration success. Finally, we conducted an expert survey to obtain an independent estimate of a sufficient density enhancement for restoration to be considered successful. Despite strong context-dependency, habitat restoration had an overall positive effect on YOY salmonid density. When compared to target levels derived from the expert survey, density responses mainly reached the minimum expected success rate, but remained short of the level considered to reflect distinct success. Variability in restoration responses of trout was linked mainly to river size, predominant geology, water quality and potential interspecific competition (trout vs. European bullhead). Fishing mortality tended to obscure positive effects of restoration and stocking by YOY fish affected negatively trout's response to restoration, supporting a shift towards self-sustainable schemes in fisheries management. These results imply that habitat restoration is a useful approach for improving the ecological and conservational status of salmonid populations in boreal rivers. To further improve the success rate, and thereby public acceptance, of restorations they need to be complemented by other management measures that enhance the potential for the recovery of threatened salmonid populations. [ABSTRACT FROM AUTHOR]

The physical characteristics of river habitats constitute the setting in which fluvial biota dwell and thrive. Determining the spatial and temporal patterns of physical habitat characteristics and the main factors that control them is extremely important to increase the efficiency of river management, conservation, and restoration. This study determined spatial patterns of physical habitat characteristics for Atlantic and Mediterranean rivers in northern Spain and developed a river classification based on hydromorphological characteristics. Data gathered from almost 600 sites following a modified version of the River Habitat Survey methodology were used. In addition to the usual River Habitat Survey variables, the sequence of hydromorphologic units (i.e., areas exhibiting similar hydraulic characteristics, in terms of water velocity and depth), water depths, and widths were recorded. Unmodified reaches were selected computing the Habitat Modification Score. Multiple Linear Regression models were employed to test relationships between Principal Component Analyses that summarized physical river habitat characteristics with ecological relevance and environmental variables (i.e., climate, topography, land cover, and geology) at different spatial scales and used to predict physical habitat attributes for all river reaches. The density of hydromorphologic units, flow turbulence, substrate size, and channel dimensions were able to discriminate river classes within the river network, with topography being the main environmental driver of habitat characteristics (although climate, geology, and land cover were also relevant). This classification scheme could constitute a useful tool to restore physical habitat conditions in modified river reaches. [ABSTRACT FROM AUTHOR]

Amphibians are one of the most vulnerable groups of tetrapods with 41% of species considered threatened with extinction. In amphibians, an increase in stress level is an early physiological response to factors associated with habitat degradation. In vertebrates, stress increases the susceptibility to parasite infections and is associated with changes in the number of blood cells, and therefore the proportion of the leukocytes, neutrophils to lymphocytes (N/L ratio) is used as a proxy measure of stress hormones. In this study, we used such leukocyte profiles to analyze stress levels and evaluate parasite load to elucidate the health condition of the endangered Mexican stream salamander, Ambystoma ordinarium. The habitat quality of streams inhabited by A. ordinarium was evaluated by Rapid Bioassessment Protocols (RBPs). We selected three streams with the highest RBPs scores as the undisturbed streams and three with the lowest scores as the disturbed streams. In each stream, we determined leukocyte profile and searched for ecto/endoparasites on sampled individuals. We report for the first time the leukocyte profile of A. ordinarium. A significantly higher N/L ratio was found in salamanders from disturbed vs. undisturbed streams. We also found a higher parasitic infection in salamanders from disturbed streams. Our results suggest that low habitat quality can increase stress levels and susceptibility to parasitic infections, thereby compromising the long-term persistence of populations of this species in disturbed habitats. [ABSTRACT FROM AUTHOR]

Tropical forests are declining at unprecedented rates in favour of agriculture, and streams can be severely impacted due to effects of multiple stressors that have rarely been considered together in tropical studies. We studied the effects of multiple stressors associated with agricultural practices (pesticide toxicity, nutrient enrichment and habitat alteration–quantified as TUmax, soluble reactive phosphorus concentration and sedimentation, respectively) on macroinvertebrate communities in a tropical catchment in Panama (13 stream sites sampled in 20 occasions from 2015 to 2017, with 260 samples in total). We examined how macroinvertebrate abundance, taxonomic richness, community composition and biotic indices (SPEAR and BMWP/PAN, which were specifically designed to detect pesticide toxicity and nutrient enrichment, respectively) varied depending on the studied stressors, considering their single and combined effects. Our analyses revealed significant effects of the studied stressors on macroinvertebrate communities, with two particular results that merit further attention: (1) the fact that pesticide toxicity affected BMWP/PAN, but not SPEAR, possibly because the former had been adapted for local fauna; and (2) that most stressors showed antagonistic interactions (i.e., lower combined effects than expected from their individual effects). These results highlight the need for toxicity bioassays with tropical species that allow adaptations of biotic indices, and of observational and manipulative studies exploring the combined effects of multiple stressors on tropical macroinvertebrate communities and ecosystems, in order to predict and manage future anthropogenic impacts on tropical streams. [ABSTRACT FROM AUTHOR]