SFS Annual Meeting

5/21/2019  |   11:00 - 11:15   |  151 G

DEVELOPING METHODS FOR ASSESSING WATER QUALITY IN STREAMS WHEN THERE’S NO WATER Non-perennial streams lack year-round flow, represent much of the U.S. stream length, and collectively affect downstream waters. Under the Clean Water Act, states, territories, and tribes must have water quality standards for their jurisdictional waters. Evaporative crystallization and biotic assimilation on benthic surfaces are retention mechanisms that may signal recent water quality for non-perennial streams that are often dry when water quality would otherwise be monitored. We conducted a stream mesocosm experiment to determine if, upon rewetting, dry substrates (unglazed tiles and gravel) will release nitrogen and phosphorus that reflect 2-month experimental dosing concentrations (nominal N/P ppb range: 240/40 to 3300/400). Substrates were dried for 69d before rewetting with deionized water. Water was collected from all 6 treatments at 2 and 48h after rewetting and after 72h for the lowest and highest concentrations. Rewetted-nutrient concentrations were generally linear with dose 2h after rewetting and remained so after 48h among the 3 lower doses for tiles and at least the 4 highest doses for gravel. Dose-response modeling is presented to characterize the resolution of the method. Our results indicate rewetting substrates from non-perennial streams has potential as a rapid monitoring method.

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


Christopher Nietch (Co-Presenter/Co-Author), U.S. Environmental Protection Agency, nietch.christopher@epa.gov;


Roger Burke (Co-Presenter/Co-Author), U. S. Environmental Protection Agency, burke.roger@epa.gov;


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5/21/2019  |   11:15 - 11:30   |  151 G

DEVELOPMENT AND APPLICATION OF PREDICTIVE MODELS FOR SURFACE WATER EXTENT TO IDENTIFY AQUATIC REFUGIA IN EASTERN AUSTRALIA Aquatic biota living in intermittent streams rely on remnant surface water to survive during extended dry periods and recolonize newly established habitats when flow resumes. However, research on the spatial and temporal dynamics of surface water extent for entire river networks is scarce. We first demonstrate a newly developed methodology for rapid surface water assessment in the field, and then develop predictive models relating observed water extent to environmental attributes at a large number of surveyed stream reaches in eastern Australian coastal catchments. We use the models to predict daily variations in surface water dynamics throughout entire river networks over the past century (1911 – 2017), based on available long-term environmental attributes. We find descriptors of surface water extent can be accurately modelled, with good internal and external validation performance. Long-term variations in surface water extent were highly dynamic through space and time, although the overall length of river network with surface water remained relative stable from year to year. Our study presents a practical approach to quantifying and predicting variations in surface water extent and also provides valuable insights into the potential priority conservation areas for aquatic biota.

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;


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;


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5/21/2019  |   11:30 - 11:45   |  151 G

DIGGING DEEPER: HOW ALPHA AND BETA DIVERSITIES OF MULTIDIMENSIONAL COMMUNITIES RESPOND TO DRYING IN DYNAMIC RIVERS Drying represents the primary determinant of aquatic biodiversity in temporary rivers. However, research focuses on benthic invertebrates in surface sediments, inadequately representing a connected community that extends into the subsurface. We explored invertebrate responses to longitudinal changes in water permanence in the vertical dimension. We compared benthic and hyporheic responses in terms of assemblage composition, alpha diversity and beta diversity. Contrasting with benthic reductions and despite compositional changes, hyporheic alpha diversity remained stable except at long drying durations, and the hyporheic occurrence of some taxa increased with drying. These results collectively suggest that the hyporheic zone can act as a drying refuge for benthic taxa. Beta diversity increased or remained stable for benthic communities, but remained stable or decreased for their hyporheic counterparts, likely reflecting contrasts in the influence of mass effects and environmental filtering on temporal variability in community composition. We found no evidence of decreasing dissimilarity between benthic and hyporheic communities with decreasing permanence, suggesting hyporheic assemblages as having distinct biodiversity value. As temporary rivers increase in extent due to global change, we highlight that recognizing the vertical dimension can enable holistic understanding of community responses to drying.

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


Romain Sarremejane (Co-Presenter/Co-Author), Nottingham Trent University, romain.sarremejane02@ntu.ac.uk;


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


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5/21/2019  |   11:45 - 12:00   |  151 G

DYNAMIC STREAM NETWORK INTERMITTENCE EXPLAINS EMERGENT DISSOLVED ORGANIC CARBON CHEMOSTASIS IN HEADWATERS Dissolved organic carbon (DOC) concentrations are highly variable among headwaters, with variation typically decreasing with watershed area. To test our hypothesis that streamflow intermittence is an important source of variation in DOC, we sampled water chemistry across a 25.5-km2 watershed in southeastern Idaho during spring, summer, and fall. Across seasons, DOC variability collapsed at a consistent location (~1.5 km2), which coincided with the watershed area where variability in streamflow intermittence also collapsed. We developed temporal, spatial, and spatiotemporal metrics of streamflow intermittence and related these to DOC concentrations. Streamflow intermittence was a strong predictor of DOC across seasons, but different metrics predicted DOC depending on season. A metric that captured spatial connectivity to sources was a significant predictor of DOC during high flows, when DOC is typically controlled by transport. In contrast, a temporal metric that captured legacies of drying at a point was predictive of DOC during the late growing season, when DOC is typically controlled by instream processes. The effects of intermittence on DOC extend beyond temporal legacies at a point. Spatial patterns of intermittence upstream are critical for understanding spatial patterns of DOC, even in perennial reaches.

Rebecca Hale (Primary Presenter/Author), Smithsonian Environmental Research Center, haler@si.edu;
Rebecca Hale is an ecosystem ecologist who works at the interface of biogeochemistry, hydrology, and society. In addition to traditional ecological methods, she adapts concepts and tools from geography, sociology, and history to ask fundamental ecosystem ecology questions in non-traditional settings. She works within and across cities and rural areas at local to regional scales.

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


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5/21/2019  |   12:00 - 12:15   |  151 G

ARE NON-PERENNIAL STREAMS CONSIDERED EQUALLY VALUABLE AND WORTHY OF CONSERVATION AS PERENNIAL STREAMS? Current paradigms in river science and management have emerged largely from studies of perennial rivers. This lack of scientific attention to and conservation efforts for intermittent and ephemeral streams may have biased public perceptions about temporary rivers and their ecological importance. Understanding the social perception of non-perennial streams can help improve the management actions aimed at their conservation, and guide science communication to improve public awareness of these ecosystems. We carried out an image-based survey about the perception of non-perennial streams with undergraduate and graduate students of three US universities located in different climate contexts: University of California at Berkeley (Mediterranean climate), University of Arizona (desert climate), and University of Washington (Oceanic climate). The survey displayed nine stream images representing different hydrological statuses: flowing, isolated pools, and dry riverbeds. Observers were asked to evaluate each image for seven aspects: aesthetics, naturalness, habitat for biodiversity, habitat for fish, need of human intervention to improve the system, importance for human well-being, and worthy of conservation. Survey responses show that non-perennial streams are generally less valued than their perennial counterparts. However, climate context and other factors influence respondents’ valuation of these ecosystems.

Pablo Rodríguez-Lozano (Primary Presenter/Author), Department of Geography, University of the Balearic Islands, 07122 Palma, Spain, pablo.rodriguez@uib.es;


Cleo Woelfle-Erskine (Co-Presenter/Co-Author), University of Washington, cleowe@uw.edu;


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


Stephanie Carlson (Co-Presenter/Co-Author), Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, U.S., smcarlson@berkeley.edu;


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5/21/2019  |   12:15 - 12:30   |  151 G

EXTREME DROUGHT LIMITS SURVIVAL OF ENDANGERED COHO SALMON IN INTERMITTENT STREAMS Droughts are becoming more frequent and severe throughout the world. Despite evidence that droughts can extirpate populations of freshwater biota, there is also growing recognition of the importance of habitat refugia in buffering drought impacts. In this study, we explored the role of intermittent stream pools in sustaining populations of endangered coho salmon (Oncorhynchus kisutch). We used mark-recapture techniques to quantify over-summer survival of juvenile coho in stream pools across eight study reaches during California’s record-breaking drought. We explored spatial variability in salmon survival within and among reaches and quantified the effects of abiotic environmental variables and intraspecific salmon density on cumulative survival estimates. Our results show that some stream reaches acted as refugia and maintained survival similar to non-drought years. Within reaches, we also found that some pools sustained fish throughout the summer, whereas others dried completely. Duration of pool disconnection was the most influential variable in predicting over-summer survival. Few, if any, salmon survived when pools were disconnected for longer than 40 days. Our results underscore the importance of intermittent streams as habitat refugia, but also highlight their vulnerability to extreme droughts.

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


Mariska Obedzinski (Co-Presenter/Co-Author), California Sea Grant, mobedzinski@ucsd.edu;


Sarah Nossaman Pierce (Co-Presenter/Co-Author), California Sea Grant, snossamanpierce@ucsd.edu;


Ted Grantham (Co-Presenter/Co-Author), University of California, Berkeley, tgrantham@berkeley.edu;


Stephanie Carlson (Co-Presenter/Co-Author), Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, U.S., smcarlson@berkeley.edu;


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