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A massive landslide occurred in May 2015 in the Mt. Hakusan Sennindani area, leading to the discharge of a substantial amount of sediment into the Tedori River. We conducted a cross‐sectional analysis of secondary data to assess the potential effects of discharged sediments on the downstream environment, including long‐term turbidity in rivers, alterations in fish habitats, and groundwater depletion. To analyse the spatio‐temporal changes in the river floodplain elevation and paddy fields, aerial photographs and airborne light detection and ranging data were assessed using the ArcGIS software. After the landslide, the turbidity of the Tedori River increased and continued flowing turbid for approximately 6 months. Turbid water spread in the alluvial fan through the irrigation canal network and sediment was deposited in the paddy fields, leading to a reduction in infiltration rates. The groundwater level in the alluvial fan area decreased by more than 2.0 m following the 2015 Sennindani landslide. The sediment deposition in the river floodplain increased by 0.58 m from 2013 to 2015 (pre‐ and post‐landslide). The sediment from upstream destroyed the spawning sites of the Ayu fish along the Tedori River, leading to a decrease in the number of eggs laid in 2015 and 2016 to the lowest levels. The Tomiyo fish disappeared in 2016 and 2017, downstream of the alluvial fan, which received water recharge from the Tedori River. Moreover, Chum salmon showed an exceptionally high anadromous movement towards the Tedori River from coastal areas during 2015 and 2016. In conclusion, discharged sediment from deep upstream landslides can have various adverse impacts on downstream ecosystems, and recovery to their original state may require a considerable amount of time. [ABSTRACT FROM AUTHOR]

The formation and development conditions of the Buzuluksky pine forest have been analyzed. The basis of the forest is isolated thin sandy deposits of an ancient sea on the elevation of the crystal bedrock with a sedimentary cover. Low water permeability has resulted in the retention of gravitational, capillary, and other water forms in sands with sporadic inclusions of clay layers at depths accessible for pine. The high filtration properties of sandy soils, in combination with forest litter, cause two to three times less snowmelt and storm-water runoff in comparison with steppe clay soils surrounding the forest. This increases the efficiency of the atmospheric precipitation use by vegetation under water-deficient conditions of the continental climate. The rise in atmospheric precipitation by 20–30% detected in the Buzuluksky pine forest as compared to the surrounding steppe is apparently related to the elevated topography and additional evaporation in the forest. The accumulation and preservation of meltwater in groundwater and in the perched water table of sandy deposits is an important habitat condition of the forest: this is an additional water source to atmospheric precipitation for pine trees in dry summer periods. The depth and fluctuations in the water level are determined by the thickness of sandy deposits, the location of clay layers, topography, and the transpiration of pine biocenoses. The groundwater depth is 2–3 m (with annual fluctuations to 1 m) in river floodplains and is 6–7 m (with fluctuation to 0.4 m) outside the floodplain. In depressions, the perched water table reaches 5 m in depth due to the groundwater flowing down from elevated areas. The differences in the groundwater depths and their fluctuations determine the predomination of pine stands of quality class II in river floodplains and depressions and of quality classes III and IV on elevations. [ABSTRACT FROM AUTHOR]

Floodplains play essential roles in the ecological functions of regional environments. The merging and coalescence of bacterial communities in aquatic environments results in periodic patterns driven by regular hydrological activities, which may, in turn, influence ecological activities. However, the degree of bacterial community coalescence in the lateral and vertical directions as well as the underlying hydrological mechanism of floodplain ecosystems is poorly understood. Therefore, we investigated the spatiotemporal patterns and coalescence processes of planktonic and sedimentary bacterial communities during normal and high-water periods in a floodplain ecosystem of the Yellow River source region. We classified bacterial operational taxonomic units (OTUs) based on 16S rRNA gene sequencing, and quantified community coalescence by calculating the proportions of overlapping OTUs, the contributions of upstream sources to downstream sinks, and positive/negative cohesion. The results revealed major differences in the composition and diversity of planktonic and sedimentary bacterial communities. Bacterial community diversity in the high-water period was higher than in the normal period. Laterally, hydrological connectivity promoted the immigration and coalescence of bacterial communities to oxbow lakes in both the mainstream and tributaries, with the coalescence degree of planktonic bacteria (2.9%) higher than that of sedimentary bacteria (1.7%). Vertically, the coalescence degree of mainstream planktonic and sedimentary bacterial communities was highest, reaching 2.9%. Co-occurrence network analysis revealed that hydrological connectivity increased the complexity of the bacterial network and enhanced the coalescence of keystone species to oxbow lakes. Furthermore, community coalescence improved the competitiveness and dispersal of bacterial communities. This study demonstrated that coalescence of bacterial communities is driven by hydrological connectivity in a floodplain ecosystem. Further studies should investigate the processes of bacterial community coalescence in floodplains in more detail, which could provide new approaches for environmental protection and ecological function preservation. [ABSTRACT FROM AUTHOR]

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The present study aims to determine the spatial distribution of soils with lead (Pb) content above the quality thresholds in a section of the Ogosta River valley (NW Bulgaria). The study area was contaminated with mine waste from the extraction and flotation of iron, lead-silver, and gold-bearing ores in the second half of the XX century. Predictive modeling was performed with the software Maximum Entropy Species Distribution Modeling (MaxEnt), Version 3.4.4, which uses machine learning algorithms and applies the maximum entropy method. The choice of predictors of contaminated soil distribution is consistent with the main factor for Pb dispersal within the valley floor - flooding from the Ogosta River. The following six parameters explained the environmental settings related to the accumulation of contaminated floodplain sediment: vertical distance to the river channel, lateral distance to the Ogosta River, terrain slope, land cover (CORINE Land Cover, 2019), morphographic units of topography, and elevation. The results represent the average values of 10 replicates of the model. We evaluated the individual models by the value of the area under the relative operating characteristic curve (AUC) and the geographic logic of the obtained results. The AUC score for the test samples was 0.666 for the soil group 1 with Pb =120 mg/kg, 0.782 for group 2 with Pb (120-500] mg/kg, and 0.934 for group 3 with Pb>500 mg/kg. The most significant predictors for the models are the vertical and lateral distance to the river and the slope of the terrain. Lead concentrations tend to decrease with the distance from the main river and by increasing the elevation above the river channel due to lower inundation frequency and deposition rate of polluted river sediments. The soils with a Pb concentration below the permissible threshold of 120 mg/kg cover more than 58.42% of the valley floor of the studied section, and lands with Pb content above the intervention value of 500 mg/kg occupy nearly 10.82% of the investigated territory. The selected predictors describe the distribution of highly contaminated soils well and define the range of soils with lower Pb content worse. Combining clean and contaminated soil samples into one group is considered the main reason for the poor performance of MaxEnt for soils with Pb =120 mg/kg. However, the results prove the model's ability to predict the spatial distribution of not only biological species but also the dispersal of hazardous substances in soil. [ABSTRACT FROM AUTHOR]

The occurrence and characteristics of plastic debris in aquatic and terrestrial environments have been extensively studied. However, limited information exists on the properties and dynamic behavior of plastic-associated biofilms in the environment. In this study, we collected plastic samples from an inland river system in Mongolia and extracted biofilms to uncover their characteristics using spectroscopic, isotopic, and thermogravimetric techniques. Mixtures of organic and mineral particles were detected in the extracted biofilms, revealing plastic as a carrier for exogenous substances, including contaminants, in the river ecosystem. Thermogravimetric analysis (TGA) indicated the predominant contribution of minerals primarily comprising aluminosilicate and calcite, representing approximately 80 wt% of the biofilms. Differential thermal analysis (DTA) coupled with Fourier transform infrared (FTIR) spectrometry operated at 25°C–600 °C enabled the detection of gaseous decomposition products, such as CO 2 , H 2 O, CO, and functional groups (O–H, C–H, C–O, C O, C C, and C–C), released from biopolymers in the extracted biofilms. Dehydration, dehydroxylation, and decarboxylation reactions explain the thermal properties of biofilms. The stable carbon (δ13C) and nitrogen (δ15N) isotope ratios of the biofilms demonstrated variable signatures ranging from −24.1‰ to −27.0‰ and 3.1‰–12.3‰, respectively. A significant difference in the δ13C value (p < 0.05) among the upstream, middle, and downstream research sites could be characterized by available organic carbon sources in the river environment, depending on the research sites. This study provides insights into the characteristics and environmental behavior of biofilms which are useful to elucidate the impact of plastic-associated biofilms on organic matter and material cycling in aquatic ecosystems. [Display omitted] • Biofilm formation facilitated the accumulation of extraneous particles on plastics. • Plastics play a significant role as a metal (i.e., Mo) carrier in the environment. • Mineral-associated organics had a minor effect on pyrolytic behavior of biofilms. • Chemical heterogeneity in biofilms is reflected by inputs of organics into rivers. • The δ13C values were differentiated in the upstream, middle, and downstream sites. [ABSTRACT FROM AUTHOR]

The linkage between sediment physicochemical and microbial parameters within river terrace sedimentary ecosystems of semiarid regions is still in infancy. Here, we investigated microbial enzyme activities involved in C, N, P, and S cycling, and quantitative PCR (qPCR) based gene abundance of two laterally deposited sediment cores (28 and 25 m deep) comprising the Late Quaternary sediments of the Mahi River (Gujarat, India). Gene abundance indicates the presence of a sustainable bacterial population throughout both cores. The stratified subsurface sediments had notable microbial enzyme activities indicating an important role of both cores in biogeochemical cycling. Correlation between microbial and geological parameters revealed that various trace elements, rare earth elements, K2O, P2O5, EC, TDS, and salinity link significantly with microbial parameters. However, the direction and magnitude of the correlation differ in both cores under study. These results emphasize that sediment physicochemical properties influence microbial parameters differently in the laterally deposited subsurface sediments. [ABSTRACT FROM AUTHOR]

Reed canarygrass (Phalaris arundinacea) is invasive in temperate freshwater wetlands throughout the United States and Canada and presents challenges to restoring tidal freshwater wetlands. Methods for the prevention or elimination of reed canarygrass in palustrine wetlands are generally well established, typically involving herbicide application, mechanical treatments, prolonged inundation, or establishment of competitive plant species. These methods are often not suitable for the unique conditions in tidal wetlands and alternative strategies remain poorly understood. Prolonging inundation of tidal wetlands requires a loss of habitat forming processes, connectivity, and other functions. Treatments such as mowing, discing, or fire are not feasible in the perpetually wet conditions of tidal wetlands. Restoration practitioners aiming to design self-sustaining wetlands in the lower Columbia River estuary and the U.S. Pacific Coast have found that reed canarygrass is widespread and quick to establish post-restoration creating a management burden and impacting restoration goals. Here we report the results of a comprehensive effort to develop methods for control in tidal wetlands through systematic review of the scientific literature, interviews with experienced practitioners, and field observations at nine Pacific Northwest sites. The review framework evaluated key environmental conditions affecting reed canarygrass, control methods, and practical considerations. Findings support an integrated long-term control strategy at the largest possible scale to establish effective and self-sustaining control. Appropriate and practical strategies for tidal freshwater wetlands include implementing control pre-restoration to suppress existing populations; topographic modification such as scrape-downs and mounds to support competitiveness of desired vegetation communities; seeding or planting strong native competitors; limiting nutrient availability; and periodic, targeted control to limit reinvasion. These strategies are supported by the study, but long-term results are generally not available. Formal field experiments are recommended by the authors to better evaluate factors that influence reed canarygrass control in tidal freshwater wetlands. [ABSTRACT FROM AUTHOR]

Although experiences with ecological restoration continue to accumulate, the effectiveness of restoration for biota remains debated. We complemented a traditional taxonomic analysis approach with information on 56 species traits to uncover the responses of 3 aquatic (fish, macroinvertebrates, macrophytes) and 2 terrestrial (carabid beetles, floodplain vegetation) biotic groups to 43 hydromorphological river restoration projects in Germany. All taxonomic groups responded positively to restoration, as shown by increased taxonomic richness (10–164%) and trait diversity (habitat, dispersal and mobility, size, form, life history, and feeding groups) (15–120%). Responses, however, were stronger for terrestrial than aquatic biota, and, contrary to our expectation, taxonomic responses were stronger than those of traits. Nevertheless, trait analysis provided mechanistic insights into the drivers of community change following restoration. Trait analysis for terrestrial biota indicated restoration success was likely enhanced by lateral connectivity and reestablishment of dynamic processes in the floodplain. The weaker response of aquatic biota suggests recovery was hindered by the persistence of stressors in the aquatic environment, such as degraded water quality, dispersal constraints, and insufficient hydromorphological change. Therefore, river restoration requires combined local‐ and regional‐scale approaches to maximize the response of both aquatic and terrestrial organisms. Due to the contrasting responses of aquatic and terrestrial biota, the planning and assessment of river restoration outcomes should consider effects on both components of riverine landscapes. Article impact statement: River restoration increases taxonomic richness and trait diversity of terrestrial biotic groups and to a lesser extent aquatic groups [ABSTRACT FROM AUTHOR]

River floodplains of Czech rivers serve as refugia to woodland or hydrophilous gastropods, in current intensively agriculturally utilised, urbanised and largely fragmented landscape. This habitat often form one of the last refuge and replace the natural habitat of these species. River floodplains also represent linear bio-corridors in landscape and allow gastropods to spread through the landscape in both directions, up and down the stream. We showed based on available fossil mollusc successions that development of the floodplain mollusc fauna took place quite different way in various river floodplains, depending on their specifics and geographical location, because especially the ones situated in the chernozem area of the Czech Republic had very different history in comparison with those in higher altitudes. The species richness and composition of recent floodplain malacofauna arises from historical development of particular area/site and depends also on environmental factors such as an elevation, humidity gradient, vegetation type and its biomass, light conditions of the site and soil reaction. Recently, the invasive plants represent a serious problem for current floodplain ecosystems; species richness and abundances of terrestrial mollusc floodplain assemblages are changing due to their effect. The impact on gastropods is species-specific and was described for the following species: Impatiens glandulifera, Fallopia japonica subsp. japonica, F. sachalinensis, F. ×bohemica.

The article presents the main results of a field research carried out between 2012 and 2014. It is a comparison case study of vegetation diversity of pools and dead-end branches of the Orlice River in Eastern Bohemia, Czech Republic. The actual state of wetland vegetation is being compared to data from literature that is several decades old. Botanical survey was conducted in the study area located between the town of Hradec Králové and parishes of Malšovice, Malšova Lhota a Svinary. The research confirmed that dead-end river branches and oxbow lakes form potential refugia of biodiversity of vascular plants in the landscape context of the river area despite the fact that the River Orlice was fully regulated in the urban area of Hradec Králové and the surrounding parishes in the past. Nevertheless, the river area is of a natural character there and belongs to the Nature Park of Orlice since 1996. The local ecosystems are also a part of the important locality of the River Orlice and Elbe. The total of 449 taxons of vascular plants (on the level of species and sub-species) and species rich associations of aquatic and wetland plants were recorded in the study area. Conservation of the water regime in the fluvial landscape and suitable regulation interventions against some spreading invasive species are crucial for the continuing existence of the precious species composition. For this reason the article also includes some management steps.

The project of a canal connecting the three major Central European Rivers: the Danube, Oder and Elbe, is incorporated into a planned trans-European transport network system. Geographically, the course of the planned canal stretches into the territory of four Central European countries, predominantly that of the Czech Republic. The environmental impacts of the potential construction and operation of the Danube–Oder–Elbe (DOE) Canal is currently widely discussed by experts from various fields. This paper aims to assess some potential impacts of the canal on the alluvial landscapes in the Czech Republic. The method of geo-ecological assessment presented here applies GIS analyses at the larger landscape scale. The results of the geo-ecological assessment of potential impacts of the DOE Canal on the land-use of river floodplains, the fluvial dynamics of streams and the extent of their alluvial plains, and the quantified DOE Canal impact on protected areas and groundwater sources, are presented. The hydrological impact of the DOE Canal will affect a total of 1,975.4 km2 of river basins in the Czech Republic. The DOE Canal will affect 157 sites significant from the perspective of landscape and nature conservation, 7 nature parks and 113 existing water points which are used as groundwater sources. The results show that the most significant disruption of fluvial dynamics of the stream sediment regime would occur in the Protected Landscape Area of Litovelské Pomoraví. In general, the geo-ecological impact of the DOE Canal on the landscape will be very important.

Small, adventitious tributaries (<3 orders of magnitude smaller than the stream it flows into) are a conspicuous feature of many river-floodplain systems, but their value as fish reproduction and nursery habitat is not well understood compared to oxbow lakes and the main river channel ( MRC). Moreover, connectivity of tributaries to the MRC is often less impacted by anthropogenic modifications (e.g., dams and levees) compared to oxbow lakes. From April to July 2012, larval and juvenile fish were collected in the Fourche LaFave River (Arkansas, USA) system to better understand fish nursery habitat function of tributaries relative to oxbow lakes and the MRC. Nonmetric multidimensional scaling ordination of juvenile and larval fish genera revealed distinct fish assemblages in MRC and floodplain habitats. Ordination of juvenile fish at the species level resulted in distinct fish assemblages in tributary versus oxbow lake habitats. Tributaries had more unique species and higher abundance of shared species than oxbow lakes and MRC. Additionally, of the 46 species identified, all but six were collected in lower tributary reaches. Connectivity was strongly associated with both ordinations and was important in describing patterns of fish variation among habitats and between tributaries. Of the tributaries sampled, the least fragmented stream had the most similar fish assemblages between upper and lower sections. Findings of this study revealed tributaries are an important, yet overlooked, feature in the river-floodplain model. Especially in years of drought, channel-floodplain connectivity can be limited, but tributaries can be used by fishes for reproduction and nursery habitat. [ABSTRACT FROM AUTHOR]

The recent mollusc assemblages of the Vltava River, the longest river in the Czech Republic (430 km), and its valley were studied (South and Central Bohemia). Altogether, 162 species of terrestrial and freshwater molluscs representing 65% of the total Czech malacofauna, were recorded at 532 sites studied between 1940 and 2013. Considering high species richness and diversity of mollusc fauna, the Vltava River valley ranks among the malacologically richest areas in the Czech Republic despite (1) the strong migration barrier of the nine dams on the upper and middle river stretches, (2) the long-term human influence in a whole river valley during the Holocene and, (3) the intensive agriculture in the lower part of the river floodplain. The river phenomenon, partly developed in the upper river stretch and fully developed in the middle part of the river, is the leading cause of such remarkable species richness.

This paper presents a research of floodplain mollusc communities of the Jizera River (the Elbe tributary, North Bohemia, Czech Republic). Altogether, 101 mollusc species (100 species of gastropods, one species of bivalve) were recorded at 55 selected sites during previous and recent researches in 1945–1997 and 2002–2009, representing 40% of the total Czech malacofauna. The upper well-preserved stretch of the river hosts a rich forest mollusc fauna with some rare woodland species e.g. Arion intermedius, Cochlodina dubiosa corcontica, Daudebardia brevipes, D. rufa, Vertigo alpestris and Vitrea subrimata. Impoverish assemblages of the lower stretch are represented by some common or open/semi-open country species, because the river flows there through the landscape of an intensive agricultural land use and high settlement density. Despite, the occurrence of 31 rare species (four of them endangered, eight vulnerable, and 19 near threatened) was recorded at the upper stretch of the Jizera River alluvium, which provides an important refuge for these mollusc faunas.

This paper presents a research of the floodplain mollusc communities of the Ploučnice River (Elbe tributary, North Bohemia, Czech Republic). Altogether, 66 mollusc species (65 species of gastropods, one species of bivalve) were recorded in the 35 floodplain forest sites during the research between 2007 and 2011, representing 27% of the total Czech malacofauna. More than a half of all species represents the common forest species (52% of all recorded species) with some rare woodland species as Aegopinella nitidula, Daudebardia rufa, Macrogastra ventricosa, Oxychilus depressus, O. glaber and two endangered species Clausilia bidentata and Daudebardia brevipes. Rare wetland species protected by the NATURA system Vertigo angustior and vulnerable V. antivertigo were also found. The occurrence of these rare species (two of them endangered, three vulnerable, and 11 near threatened) makes the Ploučnice river alluvium as an important mollusc refugium of prime conservation importance in this fragmented Czech landscape of long-term agricultural land use.

This paper presents a research of floodplain mollusc assemblages of the Úštěcký Brook catchment basin (Elbe tributary, North Bohemia, Czech Republic). Altogether, 71 mollusc species (69 species of Gastropoda, 2 species of Bivalvia) were recorded in the study sites between 2007 and 2011, representing 29% of the total Czech malacofauna. The common forest species dominated (41% of all recorded species) and included some rare woodland species as Daudebardia rufa, Discus perspectivus, Macrogastra ventricosa, and Sphyradium doliolum. Rare wetland species protected by the NATURA system Vertigo angustior and endangered wetland species Vallonia enniensis were also found. The richest assemblages occurred on the upper part of the brook, while the lower part was very species poor due to agriculture land use in this fertile floodplain. A small calcareous moorland, situated in the northeastern vicinity of Úštěk Town (north Bohemia) includes a Holocene mollusc succession that was subdivided into three local mollusc zones: I – basal zone with marked numbers of Discus ruderatus, Vertigo geyeri and numerous aquatic taxa, II – with forest species including Platyla polita and III – dominated by open-ground and catholic species. Despite the specific conditions of the moorland habitat the succession largely corresponds with the standard developmental pattern of the mollusc fauna in the zone of mid-European uplands. Of particular interest is the developmental break reflected by the poor fauna in the layer 3. The malacofauna of the Úštěcký Brook can be used as a model of alluvial mollusc assemblages of the brook floodplain that is situated in the warm area of Central Europe with long-term history of agriculture land use.

The recent molluscan assemblages of all floodplain forests on the 256 km long Ohře River were studied (West and Northwest Bohemia, Czech Republic). Altogether, 75 species of terrestrial Gastropoda representing 30% of the total Czech malacofauna, were recorded at sites selected during previous and recent research from 1950−2010. The Ohře malacofauna is impoverished of many forest and floodplain species in comparison to molluscan assemblages of smaller Bohemian rivers to the west and northwest. The richest molluscan assemblages occur on the upper part of the river, while the middle and lower parts are very poor. Low alpha-diversity of these parts of the Ohře River can be explained by (1) intensive agriculture in floodplain areas of the middle part of the river, (2) the migration barrier of the Nechranice Dam between the upper and middle river parts, and (3) long-term human influence on the lower part of the Ohře River during the Holocene.

Dramatic changes in ecosystem services have motivated recent work characterizing their interactions, including identifying trade-offs and synergies. Although time is arguably implicit in these ideas of trade-offs and synergies (e.g., temporal dynamics or changes in ecosystem services), such interactions are routinely inferred based on the spatial relationships among ecosystem services alone (e.g., spatial concordance of ecosystem services indicates synergies, whereas incongruence signifies trade-offs). The limitations of this approach have not been fully explored. We quantified ecosystem service interactions using correlations among contemporary ecosystem services and compared these results to those derived by incorporating change in ecosystem services from an earlier decade. To document change over ~60 years in an urbanizing floodplain, we used aerial photography to map multiple floodplain-associated ecosystem services. Our results demonstrate how incorporating landscape baselines can influence measured synergies and trade-offs. Spatial correlations among contemporary ecosystem services missed several interactions that were detected when using prior baseline ecosystem services. Ignoring the history of ecosystem services and their change over time may result in missed opportunities to foster their synergies and lead to unnecessary trade-offs. Efforts to incorporate ecosystem services into land management should include long-term monitoring and baseline reconstructions of ecosystem services. [ABSTRACT FROM AUTHOR]

Although it is not possible to completely eliminate flooding in an era of climate change and intensification of extreme weather events, effective flood prevention and management in river floodplains may make a significant contribution. The land use characteristics of a catchment and river valley determine, to a great extent, the functioning of a river floodplain, as well as the quantity and size of the flood pulses in the river. The paper is focused on the role played by ecohydrology in flood risk management and water quality. From the ecohydrological perspective, river floodplains are extremely important and capacious ecosystems which, being periodically flooded, absorb flood and pollutant peaks and may minimise the danger of flooding. Increased natural water retention capacity in floodplain areas and the whole basin in the face of progressive climate change is possible through three routes: the modelling of the hydrological budget of the catchment towards the sustainable ecohydrological management of floodplains, the optimal use of existing hydrotechnical infrastructure and the implementation of ecohydrological biotechnologies. Furthermore, with such a holistic perspective, the role of river floodplains is one that also enhances the resilience of the river basin against climate and anthropogenic change, as well as increasing flood safety, improving water quality and increasing its ecosystem services for society. [ABSTRACT FROM AUTHOR]

Spatial and temporal heterogeneity in Atchafalaya River Basin (ARB) physical and chemical characteristics are associated with floodplain inundation and rising water temperatures, resulting in extensive areas of the ARB that experience hypoxia (dissolved oxygen [DO] ≤2.0 mg/L) for several weeks to months throughout the annual flood pulse. Although red swamp crayfish Procambarus clarkii can tolerate relatively low DO concentrations, effects of chronic hypoxic exposure on wild populations have not been extensively studied. Here we compare population characteristics of P. clarkii from normoxic and chronically hypoxic locations in the southeastern ARB that were sampled semi-monthly during the 2008 and 2009 crayfish harvest periods. Carapace length and catch per unit effort (CPUE) of P. clarkii from normoxic and hypoxic locations were similar prior to hypoxia development during both sample years. Hypoxia developed when mean water temperature reached 20°C, and diurnal DO concentrations at hypoxic locations remained below 2.0 mg/L on every sample date during the period of environmental hypoxia. During this period in both sample years, P. clarkii at hypoxic locations had a significantly smaller mean carapace length and mean CPUE was lower on every sample date. [ABSTRACT FROM AUTHOR]

Dramatic changes in ecosystem services have motivated recent work characterizing their interactions, including identifying trade-offs and synergies. Although time is arguably implicit in these ideas of trade-offs and synergies (e.g., temporal dynamics or changes in ecosystem services), such interactions are routinely inferred based on the spatial relationships among ecosystem services alone (e.g., spatial concordance of ecosystem services indicates synergies, whereas incongruence signifies trade-offs). The limitations of this approach have not been fully explored. We quantified ecosystem service interactions using correlations among contemporary ecosystem services and compared these results to those derived by incorporating change in ecosystem services from an earlier decade. To document change over ~60 years in an urbanizing floodplain, we used aerial photography to map multiple floodplain-associated ecosystem services. Our results demonstrate how incorporating landscape baselines can influence measured synergies and trade-offs. Spatial correlations among contemporary ecosystem services missed several interactions that were detected when using prior baseline ecosystem services. Ignoring the history of ecosystem services and their change over time may result in missed opportunities to foster their synergies and lead to unnecessary trade-offs. Efforts to incorporate ecosystem services into land management should include long-term monitoring and baseline reconstructions of ecosystem services.

ABSTRACT River floodplains act as sinks for fine-sediment and sediment-associated contaminants. Increasing recognition of their environmental importance has necessitated a need for an improved understanding of the fate and residence times of overbank sediment deposits over a broad range of timescales. Most existing investigations have focused on medium-term accretion rates, which represents net deposition from multiple flood events over several decades. In contrast, the fate of recently-deposited sediment during subsequent overbank events has received only limited attention. This paper presents a novel tracing-technique for documenting the remobilization of recent overbank sediment on river floodplains during subsequent inundation events, using the artificial radionuclides, caesium-134 (134Cs) and cobalt-60 (60Co). The investigation was conducted within floodplains of the Rivers Taw and Culm in Devon, UK. Small quantities of fine-sediment (< 63 µm dia.), pre-labelled with known activities of either 134Cs or 60Co, were deposited at 15 locations across each floodplain. Surface inventories, measured before and after three consecutive flood events, were used to estimate sediment loss (in g m-2). Significant reductions provided evidence of the remobilization of the labelled sediment by inundating floodwaters. Spatial variations in remobilization were related to localized topography. Sediment remobilized during the first two events for the River Taw floodplain were equivalent to 63 · 8% and 11 · 9%, respectively, of the original mass. Equivalent values for the River Culm floodplain were 49 · 6% and 12 · 5%, respectively, of the original mass. Sediment loss during the third event proved too small to be attributed to remobilization by overbank floodwaters. After the third event, a mean of 22 · 5% and 35 · 2% of the original mass remained on the Taw and Culm floodplains, respectively. These results provide evidence of the storage of the remaining sediment. The findings highlight the importance of remobilization of recently-deposited sediment on river floodplains during subsequent overbank events and demonstrate the potential of the tracing-technique. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Floodplains play essential roles in the ecological functions of regional environments. The merging and coalescence of bacterial communities in aquatic environments results in periodic patterns driven by regular hydrological activities, which may, in turn, influence ecological activities. However, the degree of bacterial community coalescence in the lateral and vertical directions as well as the underlying hydrological mechanism of floodplain ecosystems is poorly understood. Therefore, we investigated the spatiotemporal patterns and coalescence processes of planktonic and sedimentary bacterial communities during normal and high-water periods in a floodplain ecosystem of the Yellow River source region. We classified bacterial operational taxonomic units (OTUs) based on 16S rRNA gene sequencing, and quantified community coalescence by calculating the proportions of overlapping OTUs, the contributions of upstream sources to downstream sinks, and positive/negative cohesion. The results revealed major differences in the composition and diversity of planktonic and sedimentary bacterial communities. Bacterial community diversity in the high-water period was higher than in the normal period. Laterally, hydrological connectivity promoted the immigration and coalescence of bacterial communities to oxbow lakes in both the mainstream and tributaries, with the coalescence degree of planktonic bacteria (2.9%) higher than that of sedimentary bacteria (1.7%). Vertically, the coalescence degree of mainstream planktonic and sedimentary bacterial communities was highest, reaching 2.9%. Co-occurrence network analysis revealed that hydrological connectivity increased the complexity of the bacterial network and enhanced the coalescence of keystone species to oxbow lakes. Furthermore, community coalescence improved the competitiveness and dispersal of bacterial communities. This study demonstrated that coalescence of bacterial communities is driven by hydrological connectivity in a floodplain ecosystem. Further studies should investigate the processes of bacterial community coalescence in floodplains in more detail, which could provide new approaches for environmental protection and ecological function preservation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Pan, Liu, Chen, Sun, Zhao and Huang.)