SFS Annual Meeting

Jay Christensen (Primary Presenter/Author)
US EPA, Watershed & Ecosystem Characterization Division, Cincinnati, OH , christensen.jay@epa.gov;

Brian Pickard (Co-Presenter/Co-Author)
Tetra Tech, brian.pickard@tetratech.com;

Madeline Keefer (Co-Presenter/Co-Author)
tetratech, madeline.keefer@tetratech.com;

Ken Fritz (Co-Presenter/Co-Author)
US Environmental Protection Agency, Office of Research and Development, fritz.ken@epa.gov;

Heather Golden (Co-Presenter/Co-Author)
US EPA, Watershed & Ecosystem Characterization Division, Cincinnati, OH , golden.heather@epa.gov;

Laurie Alexander (Co-Presenter/Co-Author)
U.S. Environmental Protection Agency, Office of Research and Development, alexander.laurie@epa.gov;

Rose Kwok (Co-Presenter/Co-Author)
U.S. Environmental Protection Agency, kwok.rose@epa.gov;

Marc Weber (Co-Presenter/Co-Author)
US EPA, Pacific Ecological Systems Division, Corvallis, OR, weber.marc@epa.gov;

Charles Lane (Co-Presenter/Co-Author)
US EPA, Watershed & Ecosystem Characterization Division, Cincinnati, OH , lane.charles@epa.gov;

Abstract: Headwater streams provide essential functions in supporting healthy watersheds, yet headwaters are often under- and/or misrepresented in mapping due to cartographic or sensor constraints and dynamic flows. There is also ambiguity regarding the availability of mapped datasets in the US that are used for stream-related federal and state policies. We reviewed current federal, state and tribal geospatial stream datasets, focusing on headwater extent, flow permanence classifications and additional stream mapping methods that may inform dataset limitations. Federal and state datasets centered on the suite of National Hydrography Dataset (NHD) products, with one-third of the 143 state stream datasets derived from non-federal sources. Few tribal stream datasets exist or are publicly available. Streamflow permanence information was identified for 32 states; eleven state datasets enhanced the NHD classification or were independently developed. Mapping and classification methodologies were mostly undescribed if datasets were unique from the NHD. Promising LiDAR-based technologies combined with machine learning techniques are advancing stream mapping at limited extents. As high-resolution stream mapping is applied at broader scales, headwaters can more accurately be incorporated in water resources research and policy decisions.

Charles Hawkins (Co-Presenter/Co-Author)
Utah State University, chuck.hawkins@usu.edu;

Jennifer Courtwright (Primary Presenter/Author)
Utah State University National Aquatic Monitoring Center, jennifer.courtwright@usu.edu;

Abstract: Managers need tools to assess the ecological condition of streams in arid regions. Indices developed for streams in mesic regions often do not perform well in arid-region streams. The reasons for this poor performance may include failure to recognize and account for the factors that most strongly influence natural spatial and temporal variation in aquatic life, including variability in flow regimes. Here, we used data from 318 reference-quality streams in the arid, western USA to assess if assemblage composition was associated with different aspects of the flow regime and other physicoclimatic factors. These streams spanned a gradient of flow permanence and included nonperennial and perennial streams. Ordinations and a RIVPACS-type predictive model showed assemblage composition was weakly associated with flow and moderately associated with temperature. However, an O/E index derived from the RIVPACS model was too imprecise for regulatory use. We suspect invertebrate assemblages in these streams are likely in disequilibrium, and hence not predictable. We may need to rethink both how to best conceptualize the reference condition in such dynamic streams and what biological attributes are the most appropriate indicators of their ecological integrity. Round holes need round pegs.

Elisabeth Vogel (Co-Presenter/Co-Author)
Australian Bureau of Meteorology, Elisabeth.Vogel@bom.gov.au;

Ulrike Bende-Michl (Co-Presenter/Co-Author)
Australian Bureau of Meteorology, ulrike.bende-michl@bom.gov.au;

Mark Kennard (Co-Presenter/Co-Author)
Australian Rivers Institute, Griffith University, m.kennard@griffith.edu.au;

Songyan Yu (Primary Presenter/Author)
Australian Rivers Institute, Griffith University, sunny.yu@griffith.edu.au;

Abstract: Climate change is rapidly impacting the hydrological cycle and thus the availability of water to sustain freshwater biodiversity in intermittent rivers and streams. During extended dry periods, persistent riverine pools provide essential refuges for aquatic biodiversity in intermittent systems. However, our understanding of how surface water availability changes in response to projected increases in climate variability and extreme events such as droughts in Australia is critically lacking. The Australian Bureau of Meteorology has recently developed high resolution future projections of gridded daily runoff at the national scale. Taking advantage of these data, we simulated river discharge at a daily time step across south-east Queensland (SEQ) river networks for the recent-future period of 2006 - 2099. We further quantified spatio-temporal dynamics of streamflow intermittency and developed a statistical model to estimate future variations in surface water extent. Results showed that streamflow intermittency in SEQ was projected to increase under most climate change scenarios. This has significant implications for surface water persistence within intermittent streams, posing threats to obligate aquatic species surviving extended dry periods. This study can inform management and conservation of aquatic biodiversity in intermittent streams in a drying climate.

Rachel Stubbington (Co-Presenter/Co-Author)
Nottingham Trent University, rachel.stubbington@ntu.ac.uk;

Vicenç Acuña (Co-Presenter/Co-Author)
Catalan Institute for Water Research (ICRA), vacuna@icra.cat;

Michael Bogan (Co-Presenter/Co-Author)
School of Natural Resources and the Environment, The University of Arizona, mbogan@email.arizona.edu;

Núria Cid (Co-Presenter/Co-Author)
INRAE, nuria.cid-puey@inrae.fr;

Nuria Bonada (Co-Presenter/Co-Author)
University of Barcelona, bonada@ub.edu;

Thibault Datry (Co-Presenter/Co-Author)
INRAE, France, Thibault.datry@inrae.fr;

Richard Storey (Co-Presenter/Co-Author)
National Institute of Water and Atmospheric Research, New Zealand, richard.storey@niwa.co.nz;

Paul J. Wood (Co-Presenter/Co-Author)
Loughborough University, P.J.Wood@lboro.ac.uk;

Albert Ruhi (Co-Presenter/Co-Author)
Department of Environmental Science, Policy, and Management, University of California, Berkeley, albert.ruhi@berkeley.edu;

Ross Vander Vorste (Primary Presenter/Author)
Rivers Study Center and Department of Biology - University of Wisconsin La Crosse , vandervorste.ross@gmail.com;

Abstract: Intermittent rivers are pervasive across nearly every climate type. However, it is unknown whether biodiversity responses to drying are similar across different climates. We gathered a global dataset capturing responses of aquatic invertebrate communities to river drying, which includes 112 sites spanning a gradient of climatic aridity. We measured the effects of river drying on taxonomic richness, temporal ??diversity (turnover and nestedness components, and relative abundance of aquatic invertebrates with strategies that confer resilience (or resistance) to drying. Taxonomic richness recovered from drying similarly across the aridity gradient and the turnover component of ??diversity (i.e. species replacements over time) largely accounted for differences in community composition before versus after drying. However, increasing aridity was associated with greater nestedness?driven compositional changes at intermittent sites – that is, after drying communities became subsets of those before drying. Thus, climatic context can explain variation in community responses to drying, suggesting that increased aridity will constrain biodiversity responses at regional scales. Considering climatic context in hydroecological research may help improve predictions of the local impacts of hydrological disturbance by identifying climate regions where communities are more (or less) sensitive to extremes.

Fran Sheldon (Primary Presenter/Author)
Australian Rivers Institute, Griffith University, Australia, f.sheldon@griffith.edu.au;

Abstract: The Barwon-Darling is one of Australia’s most hydrologically variable dryland river systems, with periods of low flow and small flow pulses, or freshes, punctuated by large overbank flows that fuel large scale riverine productivity. The Barwon-Darling River and its associated tributaries is also a highly developed river system with more than 50% of the in-channel flows extracted for agriculture. During 2018-2019 the northern Murray-Darling Basin was in severe drought with very little inflows into the tributaries – this made national and international headlines with the large fish kills at Menindee in December 2019 and January 2019. By late 2019 the river had mostly dried in its lower reaches between Bourke and Menindee with catastrophic consequences for both fauna and flora and there was no water for irrigation. Since the DRAFT Interim Unregulated Flow Management Plan for the Barwon-Darling River was published in 1992 there have been a number of attempts to have the low flows in the Barwon-Darling protected from extraction. Have we left it too late? Is the Barwon-Darling to be Australia’s Aral Sea or Colorado River?

Andre Siebers (Co-Presenter/Co-Author)
Centre for Freshwater Ecosystems, La Trobe University, Wodonga, VIC, 3690, Australia, andre.siebers@eawag.ch ;

Amael Paillex (Co-Presenter/Co-Author)
ECOTEC Environment SA, 1203, Geneva, Switzerland, amael.paillex@eawag.ch;

Benjamin Misteli (Co-Presenter/Co-Author)
ECOBIO, UMR 6553, CNRS, Université de Rennes 1, Rennes, France, bmisteli@student.ethz.ch;

Edwin Peeters (Co-Presenter/Co-Author)
Aquatic Ecology and Water Quality Management group, Wageningen University & Research, P.O. Box 47, 6700 AA Wageningen, The Netherlands, edwin.peeters@wur.nl;

Christopher Robinson (Co-Presenter/Co-Author)
Swiss Federal Institute of Aquatic Science and Technology, EAWAG ; Aquatic Ecology dpt., Christopher.robinson@eawag.ch;

Annemieke Drost (Primary Presenter/Author)
Eawag & Wageningen University, annemieke.drost@hotmail.nl;

Abstract: Changing weather patterns and receding glaciers are projected to increase flow intermittency in alpine streams globally, with strong effects on biodiversity and functional processes. We conducted a before-after-control-impact (BACI) flow experiment to examine the effects of intermittency on an alpine headwater stream. We monitored macroinvertebrates, periphyton and benthic organic matter over three years. Flow in one channel was manipulated to simulate the onset of increased summer intermittency (June-September) over two consecutive years, while an adjacent channel served as a control. Before manipulation, both channels had similar ecological properties. Multi-year flow manipulation caused a reduction in rheophilic macroinvertebrate density, macroinvertebrate density and taxa number. Periphyton and benthic organic matter did not differ between channels. Recovery of the macroinvertebrate community following the experimental flow intermittency took more than a year, which is discussed in the context of macroinvertebrate life histories, dispersal limitation and biotic interactions. Climate change induced shifts in stream flow regimes may lead to a fundamental shift in macroinvertebrate assemblages with local extinctions of specialized rheophilic species.

Mathis L. Messager (Primary Presenter/Author)
Department of Geography, McGill University, Canada | RiverLy Research Unit, INRAE, France, mathis.messager@mail.mcgill.ca;

Bernhard Lehner (Co-Presenter/Co-Author)
McGill University, Montreal, bernhard.lehner@mcgill.ca;

Charlotte Cockburn (Co-Presenter/Co-Author)
Dartmouth College, Charlotte.Cockburn.GR@dartmouth.edu;

Nicolas Lamouroux (Co-Presenter/Co-Author)
RiverLY Research Unit, National Institute for Agricultural and Environmental Research (INRAE), nicolas.lamouroux@inrae.fr;

Hervé Pella (Co-Presenter/Co-Author)
RiverLY Research Unit, National Institute for Agricultural and Environmental Research (INRAE), herve.pella@inrae.fr;

Ton Snelder (Co-Presenter/Co-Author)
LWP limited, ton@landwaterpeople.co.nz;

Klement Tockner (Co-Presenter/Co-Author)
Senckenberg Society for Nature Research, & Department of BioSciences, Goethe-University, Frankfurt, Germany, klement.tockner@senckenberg.de;

Tim Trautmann (Co-Presenter/Co-Author)
Institute of Physical Geography, Goethe University Frankfurt, Frankfurt am Main, Germany, t.trautmann@em.uni-frankfurt.de;

Caitlin Watt (Co-Presenter/Co-Author)
Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, caitlinwatt1@gmail.com;

Thibault Datry (Co-Presenter/Co-Author)
INRAE, France, Thibault.datry@inrae.fr;

Abstract: Flowing waters play a unique role in supporting global biodiversity, biogeochemical cycles, and human societies. While the importance of permanent watercourses is well recognized, the prevalence, value and fate of non-perennial rivers and streams that periodically cease to flow tend to be overlooked, if not ignored. This oversight contributes to the degradation of the main source of water and livelihood for millions of people. Here we show that water ceases to flow for at least one day per year along the majority of the world’s rivers by length. Leveraging global information on the hydrology, climate, geology, and surrounding land cover of the Earth’s river network, we predict that non-perennial rivers occur within all climates and biomes, and on every continent. Our findings question the assumptions underpinning foundational river concepts across scientific disciplines. To understand and adequately manage the world’s flowing waters, their biodiversity and functional integrity, a paradigm shift is needed towards a new conceptual model of rivers that includes flow intermittence. By mapping the distribution of non-perennial rivers and streams, we provide a stepping-stone towards addressing this grand challenge in freshwater science.

Teresa Silverthorn (Primary Presenter/Author)
INRAE, teresa.silverthorn@inrae.fr;

Thibault Datry (Co-Presenter/Co-Author)
INRAE, France, Thibault.datry@inrae.fr;

Abdelkader Azougui (Co-Presenter/Co-Author)
INRAE, abdelkader.azougui@inrae.fr;

Vincent Chanudet (Co-Presenter/Co-Author)
EDF, France, vincent.chanudet@edf.fr;

Abstract: Understanding human impacts on earth’s ecosystems is a critical challenge of the 21st century. Climate change, water abstraction, and water retention structures are predicted to increase the frequency and intensity of hydrological droughts worldwide. The drying of surface water is a disturbance that can fragment the river network. From a meta-ecosystem perspective, drying alters the lateral, vertical, and longitudinal flows of organisms, energy and resources across ecosystems. This fragmentation can influence biodiversity and important ecosystem functions such as the processing of carbon and nitrogen, and associated fluxes of greenhouse gases (GHGs). This proposed research will use chamber methods and automated analyzers, to measure CO2, CH4, and N2O at 20 reaches, across various hydrological conditions, throughout an intermittent river network, the Albarine, in Jura, France. In parallel, we will characterize reach-scale environmental conditions and the distribution and diversity of microbial and invertebrate decomposer communities. As hypothesized, preliminary results suggest there is spatial variability in GHG fluxes at the network scale related to substrate availability, flow regime and fragmentation level, and the distribution of decomposer communities. This research will help inform the management and conservation of intermittent rivers under increasing global threats.

Mark Kennard (Primary Presenter/Author)
Australian Rivers Institute, Griffith University, m.kennard@griffith.edu.au;

Songyan Yu (Co-Presenter/Co-Author)
Australian Rivers Institute, Griffith University, sunny.yu@griffith.edu.au;

Nick Bond (Co-Presenter/Co-Author)
La Trobe University, n.bond@latrobe.edu.au;

Stuart Bunn (Co-Presenter/Co-Author)
Australian Rivers Institute, Griffith University, Australia, s.bunn@griffith.edu.au;

Abstract: The hydrologic variability of intermittent streams means that the spatial distribution of aquatic refuges within river networks and the temporal dynamics of hydrological connectivity between them are critical for the persistence of aquatic biodiversity. We demonstrate a new approach to identify surface waterbodies as potential refuges for freshwater biodiversity in intermittent river networks and systematically prioritise them for efficient on-ground conservation management. The approach used models of spatio-temporal variation in daily streamflow, surface water extent, hydrological connectivity and aquatic biodiversity distributions within river networks of eastern Australia. Streamflow intermittency and surface water extent was highly dynamic through space and time over the past century. A subset of highly irreplaceable aquatic refuges for freshwater biodiversity were identified that were widely-distributed throughout the river networks, encompassing main stems to headwater streams. A set of on-ground conservation management actions to maintain the refugial-values of these areas is recommended to minimize disturbance from livestock and feral animals, pollution, water extraction, and other threats. Our study presents a novel and practical approach to identify priority aquatic refuges for targeted conservation management to enhance the resistance and resilience of freshwater biodiversity in intermittent stream ecosystems.

Corey Krabbenhoft (Primary Presenter/Author)
University of Minnesota, cakrabbe@gmail.com;

George Allen (Co-Presenter/Co-Author)
Texas A&M University, geoallen@tamu.edu;

Julian Olden (Co-Presenter/Co-Author)
University of Washington, olden@uw.edu;

Peirong Lin (Co-Presenter/Co-Author)
Princeton University, peironglinlin@gmail.com;

Sarah Godsey (Co-Presenter/Co-Author)
Idaho State University, godsey@isu.edu;

Daniel Allen (Co-Presenter/Co-Author)
The Pennsylvania State University, dca5269@psu.edu;

Hylke Beck (Co-Presenter/Co-Author)
Princeton University, hylke.beck@gmail.com;

Amy Burgin (Co-Presenter/Co-Author)
University of Kansas, burginam@ku.edu;

Ryan Burrows (Co-Presenter/Co-Author)
Australian Rivers Institute, Griffith University, ryan.burrows@unimelb.edu.au;

Katie Costigan (Co-Presenter/Co-Author)
University of Louisiana Lafayette, costigan@louisiana.edu;

Thibault Datry (Co-Presenter/Co-Author)
INRAE, France, Thibault.datry@inrae.fr;

Amanda DelVecchia (Co-Presenter/Co-Author)
University of North Carolina at Chapel Hill, amanda.delvecchia@unc.edu;

Walter Dodds (Co-Presenter/Co-Author)
Kansas State University, wkdodds@ksu.edu;

Catherin Franklin (Co-Presenter/Co-Author)
Texas A&M University, cafranklin@tamu.edu;

Ken Fritz (Co-Presenter/Co-Author)
US Environmental Protection Agency, Office of Research and Development, fritz.ken@epa.gov;

Rebecca Hale (Co-Presenter/Co-Author)
Smithsonian Environmental Research Center, haler@si.edu;

Nate Jones (Co-Presenter/Co-Author)
University of Alabama, cnjones7@ua.edu;

Meryl Mims (Co-Presenter/Co-Author)
Virginia Tech, mims@vt.edu;

Albert Ruhi (Co-Presenter/Co-Author)
Department of Environmental Science, Policy, and Management, University of California, Berkeley, albert.ruhi@berkeley.edu;

Margaret Shanafield (Co-Presenter/Co-Author)
Flinders University, margaret.shanafield@flinders.edu.au;

Adam Ward (Co-Presenter/Co-Author)
Indiana University, adamward@indiana.edu;

Margaret Zimmer (Co-Presenter/Co-Author)
University of California, Santa Cruz, margaret.zimmer@ucsc.edu;

Samuel Zipper (Co-Presenter/Co-Author)
Kansas Geological Survey, University of Kansas, samzipper@ku.edu;

Abstract: Streamflow gages are paramount for understanding the function and management of freshwater ecosystems. Globally, gages are distributed sparsely along rivers and streams, and may not capture the full hydrological, morphological, and environmental diversity of fluvial systems. Here we evaluate whether a global network of river gages (n=17,406) accurately represents the global diversity of river flow regimes, channel morphology, river size, physiographic conditions, and anthropogenic stressors. Multivariate analyses of stream reach attributes indicated that gage placement is biased toward large, perennial rivers with a high degree of human impact. We also find that gages are sparsely distributed in protected areas and in arid regions with non-perennial flow regimes. As a result, landscape diversity and anthropogenic factors that influence the global stream network are not adequately represented by the existing gage network. Furthermore, underrepresented river and stream types are those typically identified as critical to freshwater conservation efforts. This disparity impacts our ability to make accurate hydrological projections or informed conservation and water management decisions based on gage datasets and underscores the need to consider landscape heterogeneity in global gage placement.

Romain Sarremejane (Primary Presenter/Author)
Nottingham Trent University, romain.sarremejane@gmail.com;

Gabriel Singer (Co-Presenter/Co-Author)
University of Innsbruck, gabriel.singer@uibk.ac.at;

Thibault Datry (Co-Presenter/Co-Author)
INRAE, France, Thibault.datry@inrae.fr;

Abstract: River networks can be conceptualized as meta-ecosystems, i.e. a set of sub-ecosystems in which organisms and resources (e.g. carbon) are exchanged laterally (riparian-aquatic linkage) and horizontally from up- to downstream. Drying fragments river ecosystems, altering exchanges between sub-ecosystems but also creating mismatches between resource availability and organism activity. Such mismatches can alter functioning locally and scale up to modify energy and matter fluxes at the meta-ecosystem scale. To determine how drying structures organic matter (OM) quantity and quality, consumer communities and their activity (decomposition, respiration) we will monitor 20 river sites (including the riverbed and the riparian zone) within an intermittent river network. By comparing OM stocks and quality, consumer communities and their activity among three hydrological phases and across aquatic-terrestrial boundaries we will identify when and where drying creates mismatches and affects ecosystem functioning. We predict that mismatches will be stronger at sites with low connectivity and high drying frequencies than at well-connected permanent reaches. As climate change is exacerbating river network drying a robust framework to understand the spatiotemporal dynamic of resources and their processing by diverse communities of organisms is crucially needed to inform river management strategies.

Jaye Lobegeiger (Co-Presenter/Co-Author)
Department of Environment and Science, jaye.lobegeiger@des.qld.gov.au;

Alisa Starkey (Co-Presenter/Co-Author)
Ozius Pty Ltd, alisa.starkey@ozius.com.au;

Kate Hodges (Co-Presenter/Co-Author)
Department of Environment and Science, kate.hodges@des.qld.gov.au;

Jonathan Marshall (Primary Presenter/Author)
Queensland Department of Environment and Science, jonathan.marshall@des.qld.gov.au;

Abstract: Flow intermittency subjects fish populations to frequent drought disturbance. Their population viability depends on waterhole refuges for individuals to survive drought (resistance) and recolonisation by recruitment and dispersal once flow returns (resilience). We combined remote-sensed mapping of waterholes that lasted through extreme drought in the northern Murray Darling Basin, Australia, with assessment of the impacts of in-stream barriers on limiting opportunities for fish to move after drought. At peak drought, waterholes were few and generally small – representing only 11% of the total channel network. Most instream structures were small (mean 3 m height) but reduced fish movement opportunities on average by 87% and up to 100%. This large impact is a consequence of flow intermittency and is likely to reduce the capacity of depleted regional fish populations to recover after drought. Combining information on risks from limited refuge habitat during drought and reduced movement opportunity following drought identified river segments where drought poses the greatest risk to local fish population viability. This approach, considering resistance and resilience processes, is transferable to assessing and prioritising the management of drought and barrier risks to fish population viability in any non-perennial river setting.

John Hammond (Co-Presenter/Co-Author)
USGS, jhammond@usgs.gov;

Samuel Zipper (Co-Presenter/Co-Author)
Kansas Geological Survey, University of Kansas, samzipper@ku.edu;

Margaret Zimmer (Co-Presenter/Co-Author)
University of California, Santa Cruz, margaret.zimmer@ucsc.edu;

Margaret Shanafield (Co-Presenter/Co-Author)
Flinders University, margaret.shanafield@flinders.edu.au;

Kendra Kaiser (Co-Presenter/Co-Author)
Boise State University, kendrakaiser@boisestate.edu;

Sarah Godsey (Co-Presenter/Co-Author)
Idaho State University, godsey@isu.edu;

Nate Jones (Co-Presenter/Co-Author)
University of Alabama, cnjones7@ua.edu;

Ryan Burrows (Co-Presenter/Co-Author)
Australian Rivers Institute, Griffith University, ryan.burrows@unimelb.edu.au;

Meryl Mims (Co-Presenter/Co-Author)
Virginia Tech, mims@vt.edu;

Thibault Datry (Co-Presenter/Co-Author)
INRAE, France, Thibault.datry@inrae.fr;

Stephanie Kampf (Co-Presenter/Co-Author)
Colorado State University, Stephanie.Kampf@colostate.edu;

Walter Dodds (Co-Presenter/Co-Author)
Kansas State University, wkdodds@ksu.edu;

Corey Krabbenhoft (Co-Presenter/Co-Author)
University of Minnesota, krabb012@umn.edu;

Joanna Blaszczak (Co-Presenter/Co-Author)
University of Nevada, Reno, jblaszczak@unr.edu;

Michelle Busch (Co-Presenter/Co-Author)
University of Kansas, m.h.busch@ku.edu;

Adam Price (Co-Presenter/Co-Author)
University of California Santa Cruz, adnprice@ucsc.edu;

Kate Boersma (Co-Presenter/Co-Author)
University of San Diego, kateboersma@sandiego.edu;

Adam Ward (Co-Presenter/Co-Author)
Indiana University, adamward@indiana.edu;

Julian Olden (Co-Presenter/Co-Author)
University of Washington, olden@uw.edu;

George Allen (Co-Presenter/Co-Author)
Texas A&M University, geoallen@tamu.edu;

Katie Costigan (Co-Presenter/Co-Author)
University of Louisiana Lafayette, costigan@louisiana.edu;

Rebecca Hale (Co-Presenter/Co-Author)
Smithsonian Environmental Research Center, haler@si.edu;

Amy Burgin (Co-Presenter/Co-Author)
University of Kansas, burginam@ku.edu;

Daniel Allen (Primary Presenter/Author)
The Pennsylvania State University, dca5269@psu.edu;

Abstract: More than half of the Earth’s rivers and streams lack perennial flow. These systems are critical to ecosystems and society, and are the subject of policy debate. Yet, we lack a comprehensive understanding of the drivers of spatial and temporal patterns in non-perennial flow regimes. Here we analyze non-perennial flow regimes at 540 U.S. Geological Survey stream gages across the contiguous U.S. We focused on three non-perennial flow signatures: annual no-flow duration, dry-down period, and no-flow timing. At the continental scale, aridity was the primary driver of these metrics, but at regional scales unique combinations of climatic, physiographic, and anthropogenic drivers emerged. Preliminary results indicate that half of gages exhibit a significant change through time in at least one no-flow metric, with changes in no-flow duration being observed at 41% of gages. We observed regional differences in these changes with widespread drying in the southern U.S. and wetting in the northern U.S. Our results suggest that climate and land cover are drivers of non-perennial flow, and changes therein are causing shifts in non-perennial conditions across the U.S.

Pierre Chanut (Primary Presenter/Author)
EAWAG (Swiss Federal Institute of Aquatic Science and Technology), pierre.chanut@eawag.ch;

Annemieke Drost (Co-Presenter/Co-Author)
Eawag & Wageningen University, annemieke.drost@hotmail.nl;

Andre Siebers (Co-Presenter/Co-Author)
Centre for Freshwater Ecosystems, La Trobe University, Wodonga, VIC, 3690, Australia, andre.siebers@eawag.ch ;

Amael Paillex (Co-Presenter/Co-Author)
ECOTEC Environment SA, 1203, Geneva, Switzerland, amael.paillex@eawag.ch;

Christopher Robinson (Co-Presenter/Co-Author)
Swiss Federal Institute of Aquatic Science and Technology, EAWAG ; Aquatic Ecology dpt., Christopher.robinson@eawag.ch;

Abstract: Stream intermittency is expected to intensify in the Alps, with increasing temperatures and changing precipitation regimes. Yet, the ecological effects of increasing flow intermittency remain understudied in alpine streams, largely because of the difficulty to characterize intermittency at fine temporal and spatial scales. Here, modified light sensors were used to record flow presence/absence hourly over a year in 30 streams of the Val Roseg, a glacierized alpine catchment in South East Switzerland. Benthic macroinvertebrates were sampled at three dates and we investigated how structural and functional attributes of the macroinvertebrate communities changed along a gradient of flow intermittency. We found a weaker effect of intermittency on community composition than expected, suggesting that communities might be well adapted to flow cessation. However, and quite surprisingly, alpha diversity and taxonomic richness were lowest in permanent, groundwater-fed streams where assemblages were dominated by Diptera. This appeared to result from habitat differences, with higher organic matter content and stable temperature regimes in permanent streams. These findings could have large implications for our understanding of biodiversity maintenance and metacommunity dynamics in intermittent alpine catchments, where permanent streams might not act as species-rich drought refugia.

Alisha Steward (Primary Presenter/Author)
Department of Environment and Science, Queensland Government; Australian Rivers Institute, Griffith University, alisha.steward@qld.gov.au;

Thibault Datry (Co-Presenter/Co-Author)
INRAE, France, Thibault.datry@inrae.fr;

Simone Langhans (Co-Presenter/Co-Author)
Basque Centre for Climate Change (BC3); Department of Zoology, University of Otago, simone.langhans@gmail.com;

Abstract: Intermittent rivers and ephemeral streams (IRES) are the most abundant waterways on earth. They can support a diverse and often abundant terrestrial and semi-aquatic invertebrate (TSAI) fauna. TSAIs can inhabit a variety of habitats, including the shoreline, the surface of exposed gravel bars, unsaturated gravels, dry riverbeds, riparian zones, and floodplains. Much less is known about the species composition and ecological roles of TSAIs of IRES than their aquatic counterparts, with TSAIs being largely overlooked in conceptual models, legislation, policy, and ecological monitoring. Here we introduce TSAIs, and present conceptual models describing how they respond to hydrological changes in IRES. We then test these models with data collected during wet and dry phases in IRES from Australia and France. These generic models can be utilised by water managers and policy makers, ensuring that both wet and dry phases are considered in the management and protection of IRES. IRES should be viewed as a habitat continuum through time, with taxa from a pool of aquatic, semi-aquatic and terrestrial invertebrates inhabiting at any hydrological stage. We call for collaboration among terrestrial, lentic, and lotic ecologists to further explore these invertebrates and ecosystems.

Lluís Gómez-Gener (Co-Presenter/Co-Author)
Centre for Research on Ecology and Forestry Application (CREAF), gomez.gener87@gmail.com;

María Isabel Arce (Co-Presenter/Co-Author)
University of Murcia, maris.arcesan@gmail.com;

Shai Arnon (Co-Presenter/Co-Author)
Ben-Gurion University of the Negev, sarnon@bgu.ac.il;

Susana Bernal (Co-Presenter/Co-Author)
Center for Advanced Studies of Blanes (CEAB-CSIC), Spain, sbernal@ceab.csic.es;

Rossano Bolpagni (Co-Presenter/Co-Author)
Parma University, rossano.bolpagni@unipr.it;

Thibault Datry (Co-Presenter/Co-Author)
INRAE, France, Thibault.datry@inrae.fr;

Giulia Gionchetta (Co-Presenter/Co-Author)
Eawag, Swiss Federal Institute of Aquatic Science and Technology, giulia.gionchetta@gmail.com;

Hans-Peter Grossart (Co-Presenter/Co-Author)
Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), hgrossart@igb-berlin.de;

Clara Mendoza-Lera (Co-Presenter/Co-Author)
Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, clara.mendozalera@rptu.de ;

Vivien Pohl (Co-Presenter/Co-Author)
Technological University Dublin, c13337426@mytudublin.ie;

Ute Risse-Buhl (Co-Presenter/Co-Author)
RPTU, Ecology Department, ute.risse-buhl@rhrk.uni-kl.de;

Oleksandra Shumilova (Co-Presenter/Co-Author)
Free University of Berlin, Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany, ashumylova@gmail.com;

Ourania Tzoraki (Co-Presenter/Co-Author)
University of the Aegean, rania.tzoraki@aegean.gr;

Daniel von Schiller (Co-Presenter/Co-Author)
University of Barcelona, d.vonschiller@ub.edu;

Alexander Weigand (Co-Presenter/Co-Author)
National Museum of Natural History Luxembourg, alexander.weigand@mnhn.lu;

Gabriele Weigelhofer (Co-Presenter/Co-Author)
Institute of Hydrobiology and Aquatic Ecosystem Management, University of Natural Resources and Life Sciences, Vienna, Austria, gabriele.weigelhofer@wcl.ac.at;

Dominik Zak (Co-Presenter/Co-Author)
Aarhus University, doz@bios.au.dk;

Annamaria Zoppini (Co-Presenter/Co-Author)
National Research Council (IRSA-CNR), zoppini@irsa.cnr.it;

Andre Siebers (Primary Presenter/Author)
La Trobe University, andre.siebers@outlook.com;

Abstract: In river networks, the rates, type, and location of biogeochemical processes are strongly influenced by the temporal and spatial distribution of surface water-groundwater (SW-GW) hydrological connections. However, most of our current understanding in the field is based on studies that use perennially-flowing rivers and streams as model systems. Here, we outline a conceptual framework for predicting the effects of intermittent streamflow and drying events on biogeochemical processes across river networks, which was developed in collaboration by members of the European SMIRES (Science and Management of Intermittent Rivers and Ephemeral Streams) network. Beginning with extensive literature reviews of hydrological and biogeochemical research in intermittent rivers, we used conceptual models of SW-GW hydrological connectivity to predict the diversity and rates of biogeochemical processes across intermittent rivers networks. These predictions then allow us to identify key knowledge gaps and make recommendations for future research into the biogeochemistry of intermittent rivers and ephemeral streams.

Mélanie Milin (Primary Presenter/Author)
University of Huddersfield, melanie.milin@hud.ac.uk;

Matthew Hill (Co-Presenter/Co-Author)
University of Huddersfield, m.hill@hud.ac.uk;

Richard Chadd (Co-Presenter/Co-Author)
Environment Agency (UK), richard.chadd@environment-agency.gov.uk;

Victoria Milner (Co-Presenter/Co-Author)
University of Huddersfield, v.milner@hud.ac.uk;

Ian Maddock (Co-Presenter/Co-Author)
University of Worcester , i.maddock@worc.ac.uk;

Abstract: Temporary rivers are characterised by flow cessation, and thus shift between lotic, lentic and dry habitat phases that are spatio-temporally dynamic. Even though temporary rivers support high biodiversity, they are still often overlooked in biomonitoring programmes and need better protection. Temporary rivers in temperate regions require adapted metrics to evaluate the drought effects on macroinvertebrates communities. The Drought Effect of Habitat Loss on Invertebrates (DEHLI) index was developed to assess the effect of drying on macroinvertebrates by giving taxa numeric values that reflect their ability to survive and their association with a key habitat drying stage in a river. The DEHLI index has shown to effectively characterize macroinvertebrate community responses to drying but has been tested so far on a narrow range of river types in England. We are using a 5-year dataset comprising seasonal macroinvertebrate community samples, river types (i.e. altitude, catchment size, geology) and daily discharge for 76 sites across England to investigate the DEHLI index application across multiple rivers typologies. Mixed-effects models will be used to disentangle the effects of flow intermittence and river typology on the ability of DEHLI to quantify drought effects on macroinvertebrates communities.

Bálint Pernecker (Primary Presenter/Author)
University of Pécs, Department of Hydrobiology, balintpernecker@gmail.com;

Zoltán Csabai (Co-Presenter/Co-Author)
University of Pécs, Department of Hydrobiology, csabai@gamma.ttk.pte.hu;

Abstract: There is no information on the desiccation resistance strategies for any members of the stream dwelling dragonfly genus, Cordulegaster, including Cordulegaster heros. Because the hyporheic zone is one of the most important refugia in case of dryings, we hypothesized that the larvae use burrowing behaviour to survive. In this three-week-long simulated drought experiment, we recorded larval survival rates, and tested the effects of sediment particle size and the body size of larvae on burrowing behaviour. Eighty (sixty drought treated and twenty control) larvae were involved in the experiment. Larvae were put into flowing water, into separate special compartments; one day later the flow was ceased and then the water level was gradually decreased. Approximately 15% of larvae could survive the three weeks of drying. The survival probability of drought treated larvae was significantly increased if animals burrowed into the sediment. The survival probability was higher in case of fine sediment. Size of the larvae only affected the depth of the burrowing. However, two thirds of the larvae did not dig into the sediment, which implies that surviving via burrowing is not the only mechanism of the species for withstanding droughts.

Amy Burgin (Co-Presenter/Co-Author)
University of Kansas, burginam@ku.edu;

Jessica Wilhelm (Primary Presenter/Author)
University of Kansas, wilhelmjf1@gmail.com;

Abstract: Intermittent streams are terrestrial aquatic interfaces; ecosystems that cyclically switch between phases of saturation across space and time. Cyclic changes between wet and dry stream conditions in the hyporheic zones of intermittent streams may impact biogeochemical processes. Here, we evaluate hydro-biogeochemical dynamics in two intermittent headwaters of a tributary to the Kansas River watershed, linking the presence and absence of water flow using temperature and electrical resistivity sensors with in-stream nutrient chemistry (NO3-, SRP). Additionally, we tested trail cameras as a method for capturing continuous stage measurements. Understanding temporal and spatial driven surface water availability in intermittent streams will help to predict patterns of expansion and contraction. We explore the variability of surface water in intermittent streams and the complex hydrology and biogeochemical dynamics. It is especially important to link changes in the availability of water in intermittent streams to biogeochemical reactions since the spatial and temporal extent of the dry phase of intermittent streams may change as a result of climate change.

Zeus Freixinos (Primary Presenter/Author)
Department of Ecology and Hydrology, University of Murcia, Campus de Espinardo, 30100,Spain, zfreixinos@gmail.com;

Rosa Gómez (Co-Presenter/Co-Author)
Department of Ecology and Hydrology, University of Murcia, 30100 Murcia, Spain., rgomez@um.es;

Paloma Alcorlo (Co-Presenter/Co-Author)
Department of Ecology, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049, Madrid, Spain, paloma.alcorlo@uam.es;

Jesús Miñano (Co-Presenter/Co-Author)
Department of Ecology and Hydrology, University of Murcia, Campus de Espinardo, 30100,Spain, jmm@um.es;

María Mar Sánchez-Montoya (Co-Presenter/Co-Author)
Department of Ecology and Hydrology, University of Murcia, Campus de Espinardo, 30100,Spain, marsanch@um.es;

Abstract: Saline streams in semi-arid regions are frequently affected by flow intermittence. Both salinity and intermittency are natural stressors that shape biological communities. However, we know little about their effects on aquatic invertebrates and even less on terrestrial invertebrate communities. Here, we examined changes in the structure and composition of both invertebrate communities along drying in two intermittent saline streams (SE Spain), distinguishing the wet, contraction and dry phases. We sampled instream aquatic invertebrates during the aquatic phases and terrestrial invertebrates in channels and its shoreline during the three phases. For both communities and in both streams, the greatest abundance and richness occurred during the contraction phase. The aquatic and terrestrial composition significatively differed among phases in both studied streams. Coleoptera, Ephemeroptera, Heteroptera and Odonata were the most important taxa in explaining differences, with their highest abundances in the contraction phase. Formicidae, Araneae and Hemiptera were responsible for terrestrial differences, with higher abundances in the contraction and dry than in the wet phase. These findings report the significant effect of intermittence on invertebrate communities in saline streams, with the contraction phase particularly contributing to the diversity of the communities.

Didac Jorda (Co-Presenter/Co-Author)
Catalan Institute for Water Research (ICRA), djorda@icra.cat;

Ernesto Pasten (Co-Presenter/Co-Author)
Catalan Institute for Water Research (ICRA), epasten@icra.cat;

Laia Verdura (Co-Presenter/Co-Author)
Catalan Institute for Water Research (ICRA), lverdura@icra.cat;

Laurie Boithias (Co-Presenter/Co-Author)
GÉOSCIENCES ENVIRONNEMENT TOULOUSE, laurie.boithias@get.omp.eu;

Adria Riu (Co-Presenter/Co-Author)
Catalan Institute for Water Research (ICRA), ariu@icra.cat;

Vicenç Acuña (Co-Presenter/Co-Author)
Catalan Institute for Water Research (ICRA), vacuna@icra.cat;

Sergi Sabater (Co-Presenter/Co-Author)
Catalan Institute for Water Research (ICRA), Girona, Spain, ssabater@icra.cat;

Oriana Llanos (Primary Presenter/Author)
Catalan Institute for Water Research (ICRA), ollanos@icra.cat;

Abstract: Non-perennial rivers and streams are ubiquitous globally, especially in semi-arid and arid landscapes. Nonetheless, despite their prevalence worldwide, non-perennial systems have been under-represented in the hydrology research, and our understanding of their hydrology is minimal compared to perennial systems. Predicting the availability of freshwater resources is essential, especially in the Mediterranean area, where most of the agricultural systems depend on precipitation and irrigation. The modelling of these dynamic systems remains a challenge. Most of the existing models focus on continuously flowing rivers, without addressing some relevant characteristics of these systems as the spatio-temporal intermittency patterns. In our study, we implemented a watershed-scale hydrological model on a Mediterranean intermittent basin, using the Soil and Water Assessment Tool program. The model was calibrated using data from 2 gauging stations located at the mainstem, and 14 stage recorders dispersed across the river network. Simulation results and observed flow intermittency patterns were analyzed. Furthermore, we also simulated climate change scenarios and compared the flow intermittency patterns with the current ones. Results indicate longer duration of the non-flow period, with most of the stream network turning ephemeral and with few and isolated stretches remaining permanent.

Shang Gao (Co-Presenter/Co-Author)
University of Oklahoma, shang.gao@ou.edu;

Thomas Neeson (Co-Presenter/Co-Author)
University of Oklahoma, neeson@ou.edu;

Daniel Allen (Co-Presenter/Co-Author)
The Pennsylvania State University, dca5269@psu.edu;

Megan C. Malish (Primary Presenter/Author)
University of Oklahoma, megan.malish@ou.edu;

Abstract: Stream drying is thought to have an important, but understudied, influence on ecosystem structure and function. Previous research has indicated that changes in climate have the potential to reduce habitat availability and connectivity for fish in non-perennial streams. Here, we aim to understand how historical fish assemblages are related to spatiotemporal drying patterns in the headwaters of the Blue River, Oklahoma, and how stream drying under future climate scenarios may alter these assemblages. We integrated historical fish occurrence data with hydrologic model outputs for historic and future climate scenarios. Using the hydrologic model outputs, we calculated metrics of stream connectivity and flow variability (wetted length, dendritic connectivity index, and ecologically scaled landscape index) at a daily timestep for both historical and future climate scenarios. We describe how species assemblages, species probability of detection, and watershed connectivity may change in the future and vary among future climate scenarios. Our approach will provide insight on how climate induced changes in stream drying patterns may affect distributions of fish species in the Southern Plains region of the United States.

Jessica Corman (Co-Presenter/Co-Author)
University of Nebraska-Lincoln, jcorman3@unl.edu;

Steven Thomas (Co-Presenter/Co-Author)
University of Alabama, sathomas16@ua.edu;

Eric Moody (Co-Presenter/Co-Author)
Middlebury College, ekmoody@middlebury.edu;

Annie Blalock (Primary Presenter/Author)
Middlebury College, ablalock@middlebury.edu;

Abstract: Natural and anthropogenic disturbances are causing declines in biodiversity, greater intermittency of formerly perennial streams, and increased frequency and intensity of flood and drought events. Associated variation in basal resource stoichiometry and flow regime alter P availability, which alters competitive dynamics and drives functional trait diversity of aquatic communities. To examine the response of aquatic insect communities to varying elemental and hydrological environments, we investigated the relationship between functional diversity of benthic macroinvertebrate communities, basal resource stoichiometry, and flow regime using data from 17 lotic NEON sites. Shannon diversity and functional richness negatively correlated with algal C:P. Shannon diversity and functional dispersion negatively correlated with hydrograph skewness. The functional trait composition of sites with the lowest functional dispersion, all found in the interior of the U.S., showed that dominant traits were small body size, fast seasonal development, and univoltinism. These results indicate basal resource stoichiometry and flow regime similarly constrain insect life histories while differentially impacting functional trait diversity. Climate change and human impact will exacerbate these constraints which, as indicated by our results, will further reduce functional and taxonomic diversity of aquatic communities.