Glaciers cover ∼10% of the Earth's land surface, but they are shrinking rapidly across most parts of the world, leading to cascading impacts on downstream systems. Glaciers impart unique footprints on river flow at times when other water sources are low. Changes in river hydrology and morphology caused by climate-induced glacier loss are projected to be the greatest of any hydrological system, with major implications for riverine and near-shore marine environments. Here, we synthesize current evidence of how glacier shrinkage will alter hydrological regimes, sediment transport, and biogeochemical and contaminant fluxes from rivers to oceans. This will profoundly influence the natural environment, including many facets of biodiversity, and the ecosystem services that glacier-fed rivers provide to humans, particularly provision of water for agriculture, hydropower, and consumption. We conclude that human society must plan adaptation and mitigation measures for the full breadth of impacts in all affected regions caused by glacier shrinkage.

The species concept is the cornerstone of biodiversity science, and any paradigm shift in the delimitation of species affects many research fields. Many biologists now are embracing a new "species" paradigm as separately evolving populations using different delimitation criteria. Individual criteria can emerge during different periods of speciation; some may never evolve. As such, a paradigm shift in the species concept relates to this inherent heterogeneity in the speciation process and species category-which is fundamentally overlooked in biodiversity research. Cryptic species fall within this paradigm shift: they are continuously being reported from diverse animal phyla but are poorly considered in current tests of ecological and evolutionary theory. The aim of this review is to integrate cryptic species in biodiversity science. In the first section, we address that the absence of morphological diversification is an evolutionary phenomenon, a "process" counterpart to the long-studied mechanisms of morphological diversification. In the next section regarding taxonomy, we show that molecular delimitation of cryptic species is heavily biased towards distance-based methods. We also stress the importance of formally naming of cryptic species for better integration into research fields that use species as units of analysis. Finally, we show that incorporating cryptic species leads to novel insights regarding biodiversity patterns and processes, including large-scale biodiversity assessments, geographic variation in species distribution and species coexistence. It is time for incorporating multicriteria species approaches aiming to understand speciation across space and taxa, thus allowing integration into biodiversity conservation while accommodating for species uncertainty.

1.  Riverine landscapes are heterogeneous in space (complex mosaic of habitat types) and time (expansion and contraction cycles, landscape legacies). They are inhabited by a diverse and abundant fauna of aquatic, terrestrial and amphibious species. 2.  Faunal distribution patterns are determined by interactive processes that reflect the landscape mosaic and complex environmental gradients. The life cycles of many riverine species rely upon a shifting landscape mosaic and other species have become adapted to exploit the characteristically high turn‐over of habitats. 3.  The complex landscape structure provides a diversity of habitats that sustains various successional stages of faunal assemblages. A dynamic riverine landscape sustains biodiversity by providing a variety of refugia and through ecological feedbacks from the organisms themselves (ecosystem engineering). 4.  The migration of many species, aquatic and terrestrial, is tightly coupled with the temporal and spatial dynamics of the shifting landscape mosaic. Alternation of landscape use by terrestrial and aquatic fauna corresponds to the rise and fall of the flood. Complex ecological processes inherent to intact riverine landscapes are reflected in their biodiversity, with important implications for the restoration and management of river corridors.

An experiment in >1000 river and riparian sites found spatial patterns and controls of carbon processing at the global scale.

With 10 figures and 5 tables in the text Abstract: Val Roseg in the Swiss Alps is a complex alluvial valley formed in glacial outwash. The braided flood plain, 2.6 km long and 130-510 m wide, begins 1.2 km downstream of the glacier terminus and extends to a "knickpoint" at 1990 m a.s.!. where water upwells before entering a constrained reach. A long-term study has been initiated to investigate habitat heterogeneity and how such heterogeneity (I) contribu tes to the biodiversity of benthos, groundwater fauna, and periphyton in a harsh envi ronment and (2) influences ecosystem processes such as productivity and decomposi tion dynamics. As a first step we have distinguished different channel types based on the correspondence between hydrological connectivity and physico-chemical attrib utes. This functional characterization will serve as a habitat template to structure future ecological research in the Val Roseg flood plain. Six distinct channel types have been identified within the fl oodplain ecosystem: (i) Main channel. (ii) Side channels, (iii) Intermittently-connected channels. (iv) Mixed channels, (v) Ground water channels, and (vi) Tributaries. Distinct seasonal and daily runoff patterns, caused by ice melt, change the hydrological connectivity between individual channel types. Results clearly demonstrate that the whole flood plain shifts from dominance by surface water at high summer discharge to a groundwater-controlled system in winter. Temporal variability, rather than the means of environmental values, has been used to differentiate between individual floodplain channel types. Groundwater chan nels exhibit the highest spatial but the lowest temporal variability. In contrast, inter mittently-connected channels are characterized by a low spatial but an extraordinary temporal variability. High spatio-temporal heterogeneity resulting from a diversity of channel types is believed to play a major role in maintaining what appears to be re markably high biodiversity in this glacial flood plain.

Greater scientific knowledge, changing societal values, and legislative mandates have emphasized the importance of implementing large‐scale flow experiments (FEs) downstream of dams. We provide the first global assessment of FEs to evaluate their success in advancing science and informing management decisions. Systematic review of 113 FEs across 20 countries revealed that clear articulation of experimental objectives, while not universally practiced, was crucial for achieving management outcomes and changing dam‐operating policies. Furthermore, changes to dam operations were three times less likely when FEs were conducted primarily for scientific purposes. Despite the recognized importance of riverine flow regimes, four‐fifths of FEs involved only discrete flow events. Over three‐quarters of FEs documented both abiotic and biotic outcomes, but only one‐third examined multiple taxonomic responses, thus limiting how FE results can inform holistic dam management. Future FEs will present new opportunities to advance scientifically credible water policies.

1. Determined by landscape structure as well as dispersal-related traits of species, connectivity influences various key aspects of population biology, ranging from population persistence to genetic structure and diversity. Here, we investigated differences in small-scale connectivity in terms of gene flow between populations of two ecologically important invertebrates with contrasting dispersal-related traits: an amphipod (Gammarus fossarum) with a purely aquatic life cycle and a mayfly (Baetis rhodani) with a terrestrial adult stage. 2. We used highly polymorphic markers to estimate genetic differentiation between populations of both species within a Swiss pre-alpine catchment and compared these results to the broader-scale genetic structure within the Rhine drainage. Landscape genetic approaches were used to test for correlations of genetic and geographical structures and in-stream barrier effects. 3. We found overall very weak genetic structure in populations of B. rhodani. In contrast, G. fossarum showed strong genetic differentiation, even at spatial scales of a few kilometres, and a clear pattern of isolation by distance. Genetic diversity decreased from downstream towards upstream populations of G. fossarum, suggesting asymmetric gene flow. Correlation of genetic structure with landscape topography was more pronounced in the amphipod. Our study also indicates that G. fossarum might be capable of dispersing overland in headwater regions and of crossing small in-stream barriers. 4. We speculate that differences in dispersal capacity but also habitat specialisation and potentially the extent of local adaptation could be responsible for the differences in genetic differentiation found between the two species. These results highlight the importance of taking into account dispersal-related traits when planning management and conservation strategies.

Perennial rivers and streams make a disproportionate contribution to global carbon (C)cycling. However, the contribution of intermittent rivers and ephemeral streams, which