Biomonitoring of intermittent rivers and ephemeral streams in Europe: current practice and priorities to enhance ecological status assessments

Intermittent rivers and ephemeral streams (IRES) are common across Europe and dominate some Mediterranean river networks. In all climate zones, IRES support high biodiversity and provide ecosystem services. As dynamic ecosystems that transition between flowing, pool, and dry states, IRES are typically poorly represented in biomonitoring programmes implemented to characterize EU Water Framework Directive ecological status. We report the results of a survey completed by representatives from 20 European countries to identify current challenges to IRES status assessment, examples of best practice, and priorities for future research. We identify five major barriers to effective ecological status classification in IRES: 1. the exclusion of IRES from Water Framework Directive biomonitoring based on their small catchment size; 2. the lack of river typologies that distinguish between contrasting IRES; 3. difficulties in defining the ‘reference conditions’ that represent unimpacted dynamic ecosystems; 4. classification of IRES ecological status based on lotic communities sampled using methods developed for perennial rivers; and 5. a reliance on taxonomic characterization of local communities. Despite these challenges, we recognize examples of innovative practice that can inform modification of current biomonitoring activity to promote effective IRES status classification. Priorities for future research include reconceptualization of the reference condition approach to accommodate spatiotemporal fluctuations in community composition, and modification of indices of ecosystem health to recognize both taxon-specific sensitivities to intermittence and dispersal abilities, within a landscape context

Mapping the temporary and perennial character of whole river networks

Knowledge of the spatial distribution of temporary and perennial river channels in a whole catchment is important for effective integrated basin management and river biodiversity conservation. However, this information is usually not available or is incomplete. In this study, we present a statistically based methodology to classify river segments from a whole river network (Deva-Cares catchment, Northern Spain) as temporary or perennial. This method is based on an a priori classification of a subset of river segments as temporary or perennial, using field surveys and aerial images, and then running Random Forest models to predict classification membership for the rest of the river network. The independent variables and the river network were derived following a computer-based geospatial simulation of riverine landscapes. The model results show high values of overall accuracy, sensitivity, and specificity for the evaluation of the fitted model to the training and testing data set (?0.9). The most important independent variables were catchment area, area occupied by broadleaf forest, minimum monthly precipitation in August, and average catchment elevation. The final map shows 7525 temporary river segments (1012.5 km) and 3731 perennial river segments (662.5 km). A subsequent validation of the mapping results using River Habitat Survey data and expert knowledge supported the validity of the proposed maps. We conclude that the proposed methodology is a valid method for mapping the limits of flow permanence that could substantially increase our understanding of the spatial links between terrestrial and aquatic interfaces, improving the research, management, and conservation of river biodiversity and functioning.We would like to thank the Journal Editor and the three referees for their comments and suggestions, which have greatly improved the manuscript. This study was partly funded by the Spanish Ministry of Economy and Competitiveness as part of the RIVERLANDS (Ref: BIA-2012–33572) and HYDRA (Ref: BIA-2015–71197) projects. Alexia María González-Ferreras is supported by a predoctoral research grant (Ref: BES-2013–065770) from the Spanish Ministry of Economy and Competitiveness, and José Barquín was supported by a Ramon y Cajal grant (Ref: RYC-2011–08313) from the Spanish Ministry of Economy and Competitiveness. We would like to thank the Government of Cantabria, the Principado de Asturias and the forest guards of the study areas for providing useful information. We would also like to acknowledge the Interautonomic Consortium of the Picos de Europa National Park and the Biodiversity Foundation from the Ministry of Agriculture, Food and Environment, for their advice and project support. Finally, we would also like to thank all the people involved in the field data collection, and those who read an early draft of the manuscript and suggested several improvements. The data and the data sources used in this study are cited and explained in the text. Readers can obtain further information about the data supporting the analysis and conclusions by contacting the corresponding author

An unusual cause of alveolar hemorrhage post hematopoietic stem cell transplantation: A case report

BACKGROUND: Hematopoietic stem cell transplantation is being increasingly used in cancer therapy. Diffuse alveolar hemorrhage, an early complication of stem cell transplant, results from bacterial, viral and fungal infections, coagulopathy, and engraftment syndrome, or can be idiopathic. Diffuse alveolar hemorrhage associated with Strongyloides stercoralis hyperinfection in stem cell transplant patients has been rarely reported. CASE PRESENTATION: We describe an unusual cause of alveolar hemorrhage post hematopoietic stem cell transplant due to Strongyloides hyperinfection. Therapy with parenteral ivermectin and thiabendazole was initiated but the patient deteriorated and died of respiratory failure and septic shock. CONCLUSION: Strongyloides stercoralis hyperinfection is an unusual cause of alveolar hemorrhage early after hematopoietic stem cell transplant with very high mortality

A comparison of biotic groups as dry-phase indicators of ecological quality in intermittent rivers and ephemeral streams

Intermittent rivers and ephemeral streams (IRES) are dynamic ecosystems that shift between aquatic and terrestrial states. IRES are widespread, abundant and increasing in extent, but developing biomonitoring programmes to determine their ecological quality is challenging. To date, quality assessments have focused on the aquatic organisms present during wet phases, whereas dry-phase communities remain poorly characterized. We examined multiple biotic groups present in dry IRES channels, to compare assemblages at sites impacted and unimpacted by human activity and to evaluate the potential of each group as an ecological quality indicator. We explored existing, unpublished data for three biotic groups: an aquatic microflora (diatoms), an aquatic fauna (the invertebrate ‘seedbank’), and a mixed flora (aquatic and terrestrial plants); notably, we did not source data for terrestrial assemblages with high potential to act as indicators. Diatom and plant assemblage composition differed between impacted and unimpacted sites, and the latter assemblages were more diverse and included more indicator taxa. Invertebrate seedbank taxa richness was higher at unimpacted sites but compositional differences were not detected, probably due to the coarse taxonomic resolution to which abundant taxa were identified. Performance of standard indices of ecological quality was variable, but differences were identified between impacted and unimpacted conditions for all biotic groups. Our results can inform the enhancement of biomonitoring programmes designed to characterize IRES ecological quality in relation to legislative targets. We highlight the need to integrate wet- and dry-phase survey data in holistic quality assessments. Although we suggest diatoms, aquatic plants and the aquatic invertebrate seedbank as having the potential to inform assessment of dry-phase ecological quality, we highlight the need for research to further characterize these aquatic groups and, crucially, to explore terrestrial assemblages with high potential to act as dry-phase quality indicators

Towards an improved understanding of biogeochemical processes across surface-groundwater interactions in intermittent rivers and ephemeral streams

Surface-groundwater interactions in intermittent rivers and ephemeral streams (IRES), waterways which do not flow year-round, are spatially and temporally dynamic because of alternations between flowing, non-flowing and dry hydrological states. Interactions between surface and groundwater often create mixing zones with distinct redox gradients, potentially driving high rates of carbon and nutrient cycling. Yet a complete understanding of how underlying biogeochemical processes across surface-groundwater flowpaths in IRES differ among various hydrological states remains elusive. Here, we present a conceptual framework relating spatial and temporal hydrological variability in surface water-groundwater interactions to biogeochemical processing hotspots in IRES. We combine a review of theIRES biogeochemistry literature with concepts of IRES hydrogeomorphology to: (i) outline common distinctions among hydrological states in IRES; (ii) use these distinctions, together with considerations of carbon, nitrogen, and phosphorus cycles within IRES, to predict the relative potential for biogeochemical processing across different reach-scale processing zones (flowing water, fragmented pools, hyporheic zones, groundwater, and emerged sediments); and (iii) explore the potential spatial and temporal variability of carbon and nutrient biogeochemical processing across entire IRES networks. Our approach estimates the greatest reach-scale potential for biogeochemical processing when IRES reaches are fragmented into isolated surface water pools, and highlights the potential of relatively understudied processing zones, such as emerged sediments. Furthermore, biogeochemical processing in fluvial networks dominated by IRES is likely more temporally than spatially variable. We conclude that biogeochemical research in IRES would benefit from focusing on interactions between different nutrient cycles, surface-groundwater interactions in non-flowing states, and consideration of fluvial network architecture. Our conceptual framework outlines opportunities to advance studies and expand understanding of biogeochemistry in IRES

Intermittent rivers and ephemeral streams: what water managers need to know

Peer reviewe

Unlocking our understanding of intermittent rivers and ephemeral streams with genomic tools

Intermittent rivers and ephemeral streams (IRES) – waterways in which flow ceases periodically or that dry completely – are found worldwide, and their frequency and extent are expected to increase in the future in response to global climate change and growing anthropogenic demand for fresh water. Repeated wet–dry cycles generate highly dynamic settings within river networks composed of aquatic and terrestrial habitats, which act as evolutionary triggers for aquatic and terrestrial biota. Drying also alters functions and processes within river networks, with consequences for ecosystem services. Despite the emergence of promising conceptual and methodological developments, our understanding of the occurrence and diversity of organisms in these ecosystems is limited primarily due to their coupled aquatic–terrestrial characteristics. Novel genomic tools based on high-throughput sequencing have the potential to tackle unanswered questions of pivotal importance to predict future change in IRES. Here, we outline why genomic tools are needed to assess these dynamic ecosystems from the population to the metacommunity scale, and their potential role in bridging ecological–evolutionary dynamics

The response of perennial and temporary headwater stream invertebrate communities to hydrological extremes

The headwaters of karst rivers experience considerable hydrological variability, including spates and streambed drying. Extreme summer flooding on the River Lathkill (Derbyshire, UK) provided the opportunity to examine the invertebrate community response to unseasonal spate flows, flow recession and, at temporary sites, streambed drying. Invertebrates were sampled at sites with differing flow permanence regimes during and after the spates. Following streambed drying at temporary sites, dewatered surface sediments were investigated as a refugium for aquatic invertebrates. Experimental rehydration of these dewatered sediments was conducted to promote development of desiccation-tolerant life stages. At perennial sites, spate flows reduced invertebrate abundance and diversity, whilst at temporary sites, flow reactivation facilitated rapid colonisation of the surface channel by a limited number of invertebrate taxa. Following streambed drying, 38 taxa were recorded from the dewatered and rehydrated sediments, with Oligochaeta being the most abundant taxon and Chironomidae (Diptera) the most diverse. Experimental rehydration of dewatered sediments revealed the presence of additional taxa, including Stenophylax sp. (Trichoptera: Limnephilidae) and Nemoura sp. (Plecoptera: Nemouridae). The influence of flow permanence on invertebrate community composition was apparent despite the aseasonal high-magnitude flood events

Rethinking ecosystem service indicators for their application to intermittent rivers

In these times of strong pressure on aquatic ecosystems and water resources due to climate change and water abstraction, intermittent rivers and ephemeral streams (IRES) (rivers that periodically cease to flow and/or dry) have become valuable assets. Indeed, not only do they supply water but they also offer services for humanity. Despite a growing recognition towards IRES, information for assessing their ecosystem services (ES) remains scarce. In a first step, an international interdisciplinary group of researchers developed a methodological framework to acknowledge ES provided by IRES using 109 indicators. A subset of selected ES indicators was then applied to two case studies: the Rio Seco in the Algarve (Portugal) and the Giofyros River in Crete (Greece). This paper discusses the applicability of these indicators, including the temporal and spatial variability of IRES flow regimes. Aspects of the framework, such as the methods and time required for data collection, the nature (demand or supply) and functionality of each indicator are discussed. The new framework accounts for flow intermittence in ES analyses and can help scientists and water managers to i) increase the ease and justification for IRES use in management approaches and ii) improve their conservation and restoration with a comprehensive set of appropriate indicators for IRES. In addition, the comprehensive nature of the proposed indicators ensures that they can be understood by a broad audience and easily applicable. Since they were designed through a public participation process, the setting has been prepared for holistic stakeholder analysis and education around IRES functions and associated ES. From a management point of view, it would be particularly relevant to perform an economic evaluation with this new framework to understand the value of each ES category and their trade-offs. For the scientific community, however, it is important to consider public preferences to design socially accepted policies. The proposed indicators can successfully bridge these elements, hereby establishing a solid basis for the assessment of ES provided by IRES.info:eu-repo/semantics/publishedVersio