SFS Annual Meeting

5/22/2018  |   14:00 - 14:15   |  410 A

ECOLOGICAL RELEVANCE OF CLIMATE-INDUCED TRENDS IN STREAMFLOW ATTRIBUTES AT A CONTINENTAL SCALE We assessed trends (1955-2014) in ten streamflow attributes at 599 gaged watersheds across the conterminous United States. All sites had continuous daily flow records for 60 years and experienced minimal changes in land/water use over the period. In addition, we quantified how indicators of biological integrity are related to anthropogenic changes in the same set of streamflow attributes using a larger set of gaging sites where the effects of climate had been statistically removed, but effects of land/water use retained. Climate-induced trends were statistically likely at the majority of assessed sites for most streamflow attributes. Regional patterns in streamflow trends largely coincided with known patterns in precipitation and air temperature over the last six decades. Statistically significant and biologically interpretable associations between biological integrity and streamflow attributes were found in all regions. These associations suggest that climate-induced trends to streamflow over the last 60 years have been similar in magnitude to changes caused by land/water use. Further, in some regions climate-induced effects on streamflow are likely additive to those due to land/water use, whereas in other regions the climate-related effects are ameliorated by land/water use.

Daren Carlisle (Primary Presenter/Author), U.S. Geological Survey, dcarlisle@usgs.gov;


David Wolock (Co-Presenter/Co-Author), U.S. Geological Survey, dwolock@usgs.gov;


Greg McCabe (Co-Presenter/Co-Author), U.S. Geological Survey, gmccabe@usgs.gov;


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5/22/2018  |   14:15 - 14:30   |  410 A

STREAM COMMUNITIES EXCEED ECOLOGICAL THRESHOLDS DUE TO DROUGHT INTENSIFICATION: EVIDENCE FROM A LARGE SCALE MESOCOSM EXPERIMENT Droughts are predicted to intensify in the future, potentially causing many running waters to exceed key ecological thresholds. The effects of these events have not been assessed directly because the required continuous drought disturbance gradient is rarely encountered in natural streams. To address this research gap we established a highly resolved, drought intensity gradient using large, once through, mesocosm channels enabling macroinvertebrate community response to be quantified. Threshold changes were detected for >60% of the most abundant invertebrate taxa, with sudden population crashes or irruptions in response to increased drought intensity. Step-changes were most pronounced at moderate drought (~50% wetted area remaining); predatory midge larvae irrupted as channels fragmented into isolated pools, with corresponding collapses in prey populations. These findings, highlight the sensitivity of predatory-prey dynamics to drought, especially for the smaller body size classes as opposed to just the larger taxa as typically assumed. These findings suggest drought transforms fundamental food web properties (i.e. predator: prey ratios and community size structure) long before complete surface water loss. Hence, river ecosystems are likely to be particularly sensitive to future changes in precipitation patterns and population driven abstraction demands.

Thomas Aspin (Co-Presenter/Co-Author), Univerisity of Birmingham, TWA436@student.bham.ac.uk;
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Victoria Milner (Co-Presenter/Co-Author), University of Worcester, v.milner@worc.ac.uk;


Mark Trimmer (Co-Presenter/Co-Author), Queen Mary University of London, mtrimmer@qmw.ac.uk;


Guy Woodward (Co-Presenter/Co-Author), Imperial College London, gu.woodward@imperial.ac.uk;


Mark Ledger (Co-Presenter/Co-Author), University of Birmingham, m.e.ledger@bham.ac.uk;


Kieran Khamis (Primary Presenter/Author), University of Birmingham, k.khamis@bham.ac.uk;


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5/22/2018  |   14:30 - 14:45   |  410 A

ARCTIC RIVER ICINGS: SENSORS OF RAPIDLY CHANGING CLIMATE, HYDROLOGY, AND RIVER ECOSYSTEM CONDITIONS? Recent climate change has profoundly impacted Arctic ecosystems, including notable declines in temporal and spatial extents of sea and lake ice. However, river icing has received little attention. These poorly-documented icings, sometimes also called aufeis or naled, are seasonal surficial ice accumulations that can be >10km2 in area and >10m thick. They form when water from a spring, river, or other source flows onto an already frozen surface, where it is exposed to subfreezing temperatures. Given their size and location, icings may have a large impact on the hydrology, geomorphology, and ecology of Arctic river environments. To begin revealing the dynamics and functions of these icings, we examine how icings are changing in response to a warming Arctic. We used daily satellite imagery of northern Alaska from 2000-2015 to evaluate if icings are becoming smaller or disappearing earlier in the summer. From 147 icing features examined, 84 are either becoming smaller or disappearing earlier; none are becoming larger or disappearing later. The declines are remarkably rapid and suggest that river ecosystems with icings are rapidly changing. Thus, river icings are promising sensors of broader changes to Arctic river environments.

Jay Zarnetske (Primary Presenter/Author), Department of Earth and Environmental Sciences, Michigan State University, jpz@msu.edu;


Tamlin Pavelsky (Co-Presenter/Co-Author), University of North Carolina at Chapel Hill, pavelsky@unc.edu;


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5/22/2018  |   14:45 - 15:00   |  410 A

MULTISPECIES FRESHWATER CONSERVATION PLANNING IN RESPONSE TO CLIMATE CHANGE IN THE SOUTHEASTERN UNITED STATES Streamflow and water temperature are key variables influencing the distribution of freshwater fishes, and climate-induced changes in these variables are expected to alter aquatic ecosystems. Using the species distribution model Maxent, we predicted baseline (1975–1994) and future (2060–2080) suitable habitat distributions of 88 species in the Mobile River Basin (MRB) using streamflow and water temperature estimates for each time period generated by the Soil and Water Assessment Tool hydrologic model. Maxent-generated distributions were then input into Zonation software, which selects areas of conservation prioritization by identifying regions that contain suitable habitat for high levels of biodiversity. Zonation analyses were conducted for baseline and future conditions as well as for transitions between the two periods. All Zonation scenarios were then averaged to identify areas of high conservation value across all time periods. Areas of high conservation value are largely concentrated on eastern portion of the MRB, with a majority (50.5%) of the best 5% of streams being located within the Coosa and Tallapoosa River systems. Understanding which areas may contain suitable habitat for high levels of freshwater biodiversity can help natural resource managers better prepare for potential alterations in species composition.

Michelle VanCompernolle (Primary Presenter/Author), Indiana University, mvancomp@iu.edu;


Darren Ficklin (Co-Presenter/Co-Author), Indiana University, dflickin@indiana.edu;


Jason Knouft (Co-Presenter/Co-Author), Saint Louis University, jason.knouft@slu.edu;


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5/22/2018  |   15:00 - 15:15   |  410 A

SUNSET ON STATIONARITY: THE IMPLICATIONS OF CLIMATE CHANGE AND VARIABILITY AND ON THE ASSESSMENT OF ENVIRONMENTAL FLOW REGIMES The Natural Flow Paradigm provides the conceptual underpinning of much current environmental flows science and management. When applied in current environmental flows assessments, the natural flow regime is defined based on the range and variation of flows over recent history, with empirical or statistical modelling used to compare impacted and natural reference conditions. There are three considerations for this current approach. Firstly, most approaches to modelling flow-ecology relationships do not represent the internal dynamics of ecological processes, and assume stationarity in driving variables. Secondly, the use of historical streamflows observations to underpin assessments provides only a single representation of potential future sequences. Thirdly, there is an implicit assumption of a stationary climate, yet we know changing climate will significantly alter flow regimes. We argue that significant conceptual changes are required in the Anthropocene to the way we model and determine environmental water needs. To demonstrate, we use a hypothetical species across a range of real river systems with different flow variability. We challenge scientists and managers to reconsider some of the basic assumptions that continue to underpin both the hydrological analysis and ecological models used to inform ecological flows assessments.

Avril Horne (Primary Presenter/Author), The University of Melbourne, avril.horne@unimelb.edu.au;


Rory Nathan (Co-Presenter/Co-Author), The University of Melbourne, rory.nathan@unimelb.edu.au;


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


LeRoy Poff (Co-Presenter/Co-Author), Colorado State University, n.poff@rams.colostate.edu;


J. Angus Webb (Co-Presenter/Co-Author), University of Melbourne, angus.webb@unimelb.edu.au;


Jun Wang (Co-Presenter/Co-Author), The University of Melbourne, junw6@student.unimelb.edu.au;


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5/22/2018  |   15:15 - 15:30   |  410 A

HYDROCLIM: A CONTINENTAL-SCALE DATABASE OF CONTEMPORARY AND FUTURE STREAMFLOW AND WATER TEMPERATURE ESTIMATES FOR AQUATIC BIODIVERSITY STUDIES Streamflow and water temperature are primary factors influencing the traits, distribution, and diversity of freshwater species. Ongoing changes in climate are causing directional alteration of these environmental conditions. Accurate estimation of these variables is critical for predicting the responses of species to ongoing changes in freshwater habitat, yet ecologically relevant high-resolution data describing variation in streamflow and water temperature across North America are not available. To address this issue, we are developing the “HydroClim” database, which will provide web-accessible (www.hydroclim.org) historical and projected monthly streamflow and water temperature data for stream sections in all major watersheds across the United States and Canada from 1950-2099. These data will also be integrated with FishNet 2 (www.fishnet2.net), an online biodiversity database that provides open access to over 2 million localities of freshwater fish species in the United States and Canada, thus allowing for the characterization of the habitat requirements of freshwater species across this region. HydroClim should provide a vast array of opportunities for a greater understanding of freshwater systems in the United States and Canada in the coming century.

Darren Ficklin (Co-Presenter/Co-Author), Indiana University, dflickin@indiana.edu;


Henry Bart (Co-Presenter/Co-Author), Tulane University, hbartjr@tulane.edu;


Nelson Odume (Co-Presenter/Co-Author), Institute for Water Research, Rhodes University, Grahamstown, n.odume@ru.ac.za;


Jason Knouft (Primary Presenter/Author), Saint Louis University, jason.knouft@slu.edu;


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