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Anthropogenic habitat fragmentation is often implicated as driving the current global extinction crisis, particularly in freshwater ecosystems. The genetic signal of recent population isolation can be confounded by the complex spatial arrangement of dendritic river systems. Consequently, many populations may presently be managed separately based on an incorrect assumption that they have evolved in isolation. Integrating landscape genomics data with models of connectivity that account for landscape structure, we show that the cumulative effects of multiple in‐stream barriers have contributed to the recent decline of a freshwater fish from the Murray–Darling Basin, Australia. In addition, individual‐based eco‐evolutionary simulations further demonstrate that contemporary inferences about population isolation are consistent with the 160‐year time frame since construction of in‐stream barriers began in the region. Our findings suggest that the impact of very recent fragmentation may be often underestimated for freshwater biodiversity. We argue that proactive conservation measures to reconnect many riverine populations are urgently needed.

Visiting urban green and blue spaces improves the quality of life in cities as it helps to preserve human-nature bonds. In this context, the role of urban parks and forests has been well-recognised; however, much less is known about the landscapes of inland water bodies. To fill this gap, the study aimed to identify spatiotemporal patterns of recreational activities in the urban riverscape in relation to the visitors’ residential proximity. Also, survey results were combined with spatial and remote sensing data to determine how the spatial characteristics of the riverscape affect its recreational use. The case of Warsaw, Poland, was used. The results indicated that the riverscape serves as a local park for the neighbouring communities, while it is rather a warm-weekend attraction for far-living ones. Visitors concentrate in the city centre, and spread out along the communication paths; however, spatial patterns of the magnitude of particular activities also show interbank differences. Spatial error models of drivers of riverscape recreation revealed (1) the multifaceted role of trees in densely visited areas and (2) the importance of physical availability for contact with the urban river. These findings expand knowledge on the recreational use of urban rivers by exploring its place-related motivations.

Moving beyond species count data is an essential step to better understand the effects of environmental perturbations on biodiversity and ecosystem functions, and to eventually better predict the strength and direction of those effects. Here, coupling an integrative path analysis approach with data from an extensive countrywide monitoring program, we tested the main spatial, environmental and anthropogenic drivers of change in the functional structure of aquatic macroinvertebrate communities along the entire Swiss Rhine river catchment. Functional structure was largely driven by inherent altitudinal variation influencing and cascading to regional scaled factors such as land use change and position in the riverine network, which, in turn, transformed local habitat structure variables. Those cascading effects across scales propagated through the biotic community, first affecting prey and, in turn, predators. Our results illustrate how seemingly less important local factors can act as essential transmission belts, propagating through direct and indirect pathways across scales to generate the specific context in which each functional group will strive or not, leading to characteristic landscape wide variations in functional community structure.

While factors influencing perceptions of drinking water have been well studied, those of aquatic ecosystems have been to lesser extent. We conducted a review to improve awareness of these factors. Environmental factors found to influence public perceptions of aquatic ecosystems were presence/absence of water plants and algae, presence/absence of floating debris, the odor, movement (for flowing waters) and clarity/turbidity of the water, and the type, condition, setting, naturalness, and overall aesthetic appeal of the ecosystem. Sociocultural factors found to influence public perceptions of aquatic ecosystems included age, education, gender, and place-based knowledge. We provide perspectives of how managers can better meet the diverse social demands placed on aquatic ecosystems. The importance and benefits of considering these perspectives may be especially beneficial where significant multi-generational and culturally relevant place-based knowledge exist.

Flooding in Kashmir results from a complex interplay of physical, sociopolitical, and economic factors, which presents a severe environmental challenge. The intricate interplay between the Jhelum’s riverscape, social interactions, and economic factors is profoundly shaped by the persistent problem of flooding and its associated vulnerabilities. In this study, we examine the vulnerability of Kashmir to flooding and provide a comprehensive assessment of the recent floods. The purpose of this vulnerability assessment is to delve into these intricacies and offer deeper understanding of flood vulnerability in Kashmir. We explore the concept of riverscape in the context of the Jhelum River to encompass a holistic view of the river, understanding its physical features and socio-economic aspects, and examining the spatial and temporal dynamics of river ecosystems. This study analyses the spatial distribution of the inundated population, rainfall and hydrological analysis, flood gauge analysis of the Jhelum River, hydrological trends, and annual peak discharge at key discharge stations from 2003 to 2023. We analyse the policy landscape, social capital, and responses to recent flooding and provide a historical analysis of these policies. Using a mixed methods approach of qualitative as well as remote sensing methods to analyse recent flooding in Kashmir, we assessed the impact of flooding on population and LULC. We analyse how marginalised communities, lacking essential services and resources, disproportionately bear the brunt of these floods.

Context Anthropogenic land use degrades matrix, habitat, and corridors and can disrupt dispersal rates or dispersal attempts, resulting in population connectivity patterns that reflect the cost (or resistance to dispersal) imposed from degraded conditions (isolation by resistance; IBR) rather than that of geographic distance alone (isolation by distance; IBD). Objectives As a small-bodied, benthic riverine species with relatively low dispersal capability, the imperiled Kentucky Arrow Darter (KAD), Etheostoma spilotum , is vulnerable to the negative effects of anthropogenic land use on population connectivity. To inform conservation efforts for KAD, we identified the primary drivers of population isolation (IBD vs. IBR) in the species using a riverscape genetics framework. Methods We created resistance surfaces from landscape variables that may influence KAD occurrence and dispersal success (elevation, presence of dams, stream order, and percent landcover type). Cumulative resistance was correlated with F ST values using a linear mixed effects model in R package corMLPE. Results Though we found significant, positive relationships between genetic and geographic distances, analyses of single and multi-surface resistance models demonstrated that isolation by resistance was the primary driver of genetic distances among KAD populations. In particular, decreased forest cover was linked to high genetic differentiation. Conclusions These results illustrate that population connectivity primarily degrades through resistance to dispersal rather than geographic distance between populations. Conservation efforts should focus on mitigating past and ongoing land use associated with deforestation, in addition to genetic rescue, as habitat restoration will not likely occur quick enough to prevent continued declines in KAD populations.

Riverscape genetics, which applies concepts in landscape genetics to riverine ecosystems, lack appropriate quantitative methods that address the spatial autocorrelation structure of linear stream networks and account for bidirectional geneflow. To address these challenges, we present a general framework for the design and analysis of riverscape genetic studies. Our framework starts with the estimation of pairwise genetic distance at sample sites and the development of a spatially structured ecological network (SSEN) on which riverscape covariates are measured. We then introduce the novel bidirectional geneflow in riverscapes (BGR) model that uses principles of isolation-by-resistance to quantify the effects of environmental covariates on genetic connectivity, with spatial covariance defined using simultaneous autoregressive models on the SSEN and the generalized Wishart distribution to model pairwise distance matrices arising through a random walk model of geneflow. We highlight the utility of this framework in an analysis of riverscape genetics for brook trout (Salvelinus fontinalis) in north central Pennsylvania, USA. Using the fixation index (F ST) as the measure of genetic distance, we estimated the effects of 12 riverscape covariates on geneflow by evaluating the relative support of eight competing BGR models. We then compared the performance of the top-ranked BGR model to results obtained from comparable analyses using multiple regression on distance matrices (MRM) and the program STRUCTURE. We found that the BGR model had more power to detect covariate effects, particularly for variables that were only partial barriers to geneflow and/or uncommon in the riverscape, making it more informative for assessing patterns of population connectivity and identifying threats to species conservation. This case study highlights the utility of our modeling framework over other quantitative methods in riverscape genetics, particularly the ability to rigorously test hypotheses about factors that influence geneflow and probabilistically estimate the effect of riverscape covariates, including stream flow direction. This framework is flexible across taxa and riverine networks, is easily executable, and provides intuitive results that can be used to investigate the likely outcomes of current and future management scenarios.

In this paper, we present a new, semi-automated methodology for mapping hydromorphological indicators of rivers at a regional scale using multisource remote sensing (RS) data. This novel approach is based on the integration of spectral and topographic information within a multilevel, geographic, object-based image analysis (GEOBIA). Different segmentation levels were generated based on the two sources of Remote Sensing (RS) data, namely very-high spatial resolution, near-infrared imagery (VHR) and high-resolution LiDAR topography. At each level, different input object features were tested with Machine Learning classifiers for mapping riverscape units and in-stream mesohabitats. The GEOBIA approach proved to be a powerful tool for analyzing the river system at different levels of detail and for coupling spectral and topographic datasets, allowing for the delineation of the natural fluvial corridor with its primary riverscape units (e.g., water channel, unvegetated sediment bars, riparian densely-vegetated units, etc.) and in-stream mesohabitats with a high level of accuracy, respectively of K = 0.91 and K = 0.83. This method is flexible and can be adapted to different sources of data, with the potential to be implemented at regional scales in the future. The analyzed dataset, composed of VHR imagery and LiDAR data, is nowadays increasingly available at larger scales, notably through European Member States. At the same time, this methodology provides a tool for monitoring and characterizing the hydromorphological status of river systems continuously along the entire channel network and coherently through time, opening novel and significant perspectives to river science and management, notably for planning and targeting actions.

ContextGlobal climate change poses a significant threat to the habitat connectivity of cold-water-adapted organisms, leading to species extinctions. If gene flow can be modeled by landscape variables, changes in connectivity among populations could be predicted. However, in dendritic and heterogeneous stream ecosystems, few studies have estimated the changes in gene flow from genetic data, in part due to the difficulty in applying landscape genetics methods and accessing water temperature information.ObjectivesInferring the determinants and future changes of the gene flow in the cold-water adapted fluvial sculpin Cottus nozawae using a recently developed model-based riverscape genetics technique and a hydrological model for estimating water temperature.MethodsThe strength of gene flow on each stream section was modeled by watershed-wide riverscape variables and genome-wide SNP data for C. nozawae in the upper reaches of the Sorachi River, Hokkaido, Japan. Future changes in gene flow were inferred by this model and hydrologically estimated water temperatures under the high greenhouse gas concentration scenario (IPCC RCP8.5).ResultsStream order, water temperature, slope, and distance were selected as riverscape variables affecting the strength of gene flow in each stream section. In particular, the trend of greater gene flow in sections with higher stream order and lower temperature fluctuations or summer water temperatures was pronounced. The map from the model showed that gene flow is overall prevented in small tributaries in the southern area, where spring-fed environments are less prevalent. Estimating future changes, gene flow was predicted to decrease dramatically at the end of the twenty-first century.ConclusionsOur results demonstrated that the connectivity of cold-water sculpin populations is expected to decline dramatically in a changing climate. Riverscape genetic modeling is useful for gaining information on population connectivity that does not fully coincide with habitat suitability.

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.