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SFS Annual Meeting

Tuesday, May 21, 2019
14:00 - 15:30

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14:00 - 14:15: / 253 AB AQUATIC PRIMARY PRODUCTIVITY AND ITS DRIVERS IN A TROPICAL RIVER FLOODPLAIN

5/21/2019  |   14:00 - 14:15   |  253 AB

AQUATIC PRIMARY PRODUCTIVITY AND ITS DRIVERS IN A TROPICAL RIVER FLOODPLAIN Floodplain wetlands are some of the most productive and biodiverse ecosystems on earth. The wetland systems of the Mitchell River floodplain, located in the dry tropics of Australia, provide a major subsidy of energy resources for large mobile consumers in the river system. The basal energy source comes from aquatic algal production that is influenced by different characteristic of the floodplain environment. Our aim is to use these relationships to identify and map important ‘hotspot’ areas of production that are important in sustaining aquatic food webs. Measurements were made across a range of different types of wetlands (palustrine, lacustrine and riverine) and different habitats (emergent macrophytes, floating macrophytes, submerged macrophytes and open water). Key drivers of algal production differed among wetlands rather than among different habitats. At lacustrine wetlands, euphotic depth correlated with primary productivity, whilst within open water habitats, total phosphorus concentration was more highly correlated. Identifying these key drivers of algal production will enable us to model the effects of changes in floodplain inundation from water resource development and floodplain development associated with the proposed agricultural development in the catchment.

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


Michele Burford (Co-Presenter/Co-Author), Australian Rivers Institute, Griffith University, Queensland, Australi, m.burford@griffith.edu.au;


Fernanda Adame (Co-Presenter/Co-Author), Australian Rivers Institute, Griffith University, f.adame@griffith.edu.au;


BIANCA MOLINARI (Primary Presenter/Author), Australian Rivers Institute, Griffith University, bianca.molinari@griffithuni.edu.au;


Ben Stewart-Koster (Co-Presenter/Co-Author), Australian Rivers Institute, Griffith University, b.stewart-koster@griffith.edu.au;


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14:15 - 14:30: / 253 AB INTERACTIVE EFFECTS OF TEMPERATURE AND NITROGEN AVAILABILITY ON PRIMARY AND SECONDARY PRODUCERS

5/21/2019  |   14:15 - 14:30   |  253 AB

INTERACTIVE EFFECTS OF TEMPERATURE AND NITROGEN AVAILABILITY ON PRIMARY AND SECONDARY PRODUCERS Altered temperature and nutrient regimes are important global drivers of ecological change. While each of these drivers has been intensively studied independently, less is known about how food webs and ecosystem processes respond to their interactive effects. We examined how four Icelandic streams, representing a gradient of mean annual temperatures (8°C-15°C), responded to whole-stream nitrogen (N) enrichment. We expected differences in community structure, basal resource availability, and metabolic rates across the thermal gradient, and thus divergent responses to N enrichment. Specifically, we predicted that: 1) N enrichment would alter primary producer community composition by reducing the abundance of non-palatable N2-fixing cyanobacteria in warm streams, and 2) increased production of palatable algae would enhance secondary production in warm, N-rich streams. Under ambient nutrient conditions, primary production increased with temperature, but biomass of palatable algae decreased by 47%. Following N enrichment, primary production was amplified across the thermal gradient, while biomass of palatable algae increased by 79%. We predict that these changes to the resource base will cascade to secondary producers, propagating the interactive effects of temperature and N enrichment to multiple properties of food web structure and dynamics.

Kate Henderson (Primary Presenter/Author), Montana State University, kahenderson121@gmail.com;


Wyatt Cross (Co-Presenter/Co-Author), Montana State University, wyatt.cross@montana.edu ;


Jonathan Benstead (Co-Presenter/Co-Author), The University of Alabama, jbenstead@ua.edu;


Gisli Gislason (Co-Presenter/Co-Author), University of Iceland, gisli@ui.is;


James Hood (Co-Presenter/Co-Author), The Ohio State University, hood.211@osu.edu;


Alexander D. Huryn (Co-Presenter/Co-Author), The University of Alabama, huryn@ua.edu;


Philip Johnson (Co-Presenter/Co-Author), University of Alabama, pjohnson@eng.ua.edu;


Jon Olafsson (Co-Presenter/Co-Author), Iceland Marine and Freshwater Research Institute, jon.s.olafsson@hafogvatn.is;


Jill Welter (Co-Presenter/Co-Author), St. Catherine University, jrwelter@stkate.edu;


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14:30 - 14:45: / 253 AB ABIOTIC DRIVERS OF SPATIAL AND TEMPORAL PATTERNS OF PRIMARY PRODUCERS IN A MID-SIZED RIVER

5/21/2019  |   14:30 - 14:45   |  253 AB

ABIOTIC DRIVERS OF SPATIAL AND TEMPORAL PATTERNS OF PRIMARY PRODUCERS IN A MID-SIZED RIVER The identity and biomass of stream primary producers is determined by multiple abiotic factors including light, nutrients, and hydrology, which vary by season and are mediated by habitat characteristics, such as substrate type. How these abiotic factors drive patterns in primary producer identity and biomass through time and space, and how these producer shifts affect stream metabolism is not well understood. We compared monthly biomass of major primary producer types (macrophytes, benthic algae, filamentous algae, and phytoplankton) over the course of two years with river flow metrics. We hypothesized that differences in producer growth form (e.g., filamentous algae versus an erect macrophyte) would translate into differences in susceptibility to hydrologic events. Preliminary analyses showed a strong response of biomass of the dominant macrophyte, Podostemum ceratophyllum, to antecedent low flow magnitude (R2 = 0.73). We did not find similar predictive relationships for biomass of other producer types with minimum or maximum stream discharge. By determining the drivers of spatial and temporal patterns of primary producers, and later coupling these with producer types’ corresponding productivity and respiration rates, we aim to identify mechanisms by which abiotic factors affect stream metabolism.

Caitlin Conn (Primary Presenter/Author), University of Georgia, caitlin.conn25@uga.edu;


Amy Rosemond (Co-Presenter/Co-Author), University of Georgia, rosemond@uga.edu;


Phillip Bumpers (Co-Presenter/Co-Author), Odum School of Ecology, University of Georgia, bumpersp@gmail.com;


Mary Freeman (Co-Presenter/Co-Author), US Geological Survey, mcfreeman@usgs.gov;


Kyle McKay (Co-Presenter/Co-Author), US Army Corps of Engineers, kyle.mckay@usace.army.mil;


Todd Rasmussen (Co-Presenter/Co-Author), University of Georgia, trasmuss@uga.edu;


Seth Wenger (Co-Presenter/Co-Author), Odum School of Ecology, University of Georgia, swenger@uga.edu;


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14:45 - 15:00: / 253 AB RIVER MANAGEMENT ALTERS ECOSYSTEM METABOLISM IN THE LARGE OLIGOTROPHIC KOOTENAI RIVER

5/21/2019  |   14:45 - 15:00   |  253 AB

RIVER MANAGEMENT ALTERS ECOSYSTEM METABOLISM IN THE LARGE OLIGOTROPHIC KOOTENAI RIVER Recovery efforts for endangered Kootenai River white sturgeon, including modified Libby Dam operations and habitat restoration, have been implemented in the transboundary (U.S. – Canada) Kootenai River watershed. We characterized the response of gross primary production (GPP) and ecosystem respiration (ER) in reaches with unregulated flow, regulated flow, nutrient addition, and habitat restoration. GPP and ER generally increased downstream from reaches with unregulated flow (3.07 ± 0.14 GPP, -3.19 ± 0.17 ER, g O2 m-2 d-1, mean ± standard error) to regulated flow (6.14 ± 0.19, -7.51 ± 0.1 9), nutrient addition (7.28 ± 0.16, -7.15 ± 0.16), and habitat restoration (12.14 ± 0.96, -15.77 ± 1.77). As biofilm accumulated in this nutrient poor river, we observed low initial values in spring (2.96 ± 0.11, -5.60 ± 0.20), followed by elevated values in mid-summer (8.59 ± 0.16, -8.55 ± 0.20), and a return to low values in late summer and fall (5.76 ± 0.20, -6.20 ± 0.32), although the timing of elevated GPP and ER differed among reaches. As reflected by GPP and ER, river management may alter the timing and amount of autochthonous carbon available to the food web.

Lisa Kunza (Primary Presenter/Author), South Dakota School of Mines and Technology, lisa.kunza@sdsmt.edu;


Kurt Chowanski (Co-Presenter/Co-Author), South Dakota School of Mines and Technology, kurt.chowanski@sdsmt.edu;


Emily Stickney (Co-Presenter/Co-Author), South Dakota School of Mines and Technology, emily.stickney@mines.sdsmt.edu;


Laurel Genzoli (Co-Presenter/Co-Author), University of Montana, laurel.genzoli@umontana.edu;


Gregory Hoffman (Co-Presenter/Co-Author), US Army Corps of Engineers, Gregory.C.Hoffman@usace.army.mil;


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15:00 - 15:15: / 253 AB DETERMINING THE KEY DRIVERS OF STREAM FISH PRODUCTIVITY

5/21/2019  |   15:00 - 15:15   |  253 AB

DETERMINING THE KEY DRIVERS OF STREAM FISH PRODUCTIVITY Understanding how communities are influenced by environmental conditions is one of the main goals of ecology. Fish production represents a valuable metric to assess fish communities as it combines many different aspects of the constituent species into one quantitative measure. This metric can then be used to assess fish assemblages in stream systems and determine the impacts that adjacent aquatic and terrestrial conditions may have. Although earlier studies have assessed the effects of land use on stream fish assemblages, none have investigated how land use influences fish productivity. The goal of our research was to investigate how land use influence the productivity of stream fishes at a regional level. We approached this goal by compiling data from electrofishing samples of fish assemblages from streams across southern Ontario. We used data on land use, climate, and key stream characteristics to identify main drivers of stream fish productivity across southern Ontario. The significance of this research is that it will provide important insight into how these environmental factors explain variation in stream fish productivity and identify key measures associated with productivity.

Ian Richter (Primary Presenter/Author), University of Toronto, ian.richter@utoronto.ca;


Donald Jackson (Co-Presenter/Co-Author), University of Toronto, don.jackson@utoronto.ca;


Nicholas Jones (Co-Presenter/Co-Author), Ontario ministry of Natural Resources - Trent University, nicholas.jones@ontario.ca;


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15:15 - 15:30: / 253 AB HOW THE SPATIAL STRUCTURE OF LIGHT SHAPES METABOLIC REGIMES WITHIN AND ACROSS RIVER NETWORKS

5/21/2019  |   15:15 - 15:30   |  253 AB

HOW THE SPATIAL STRUCTURE OF LIGHT SHAPES METABOLIC REGIMES WITHIN AND ACROSS RIVER NETWORKS At the scale of river networks, metabolic regimes determine the amount and timing of energetic inputs to food webs; yet the emergent patterns of stream metabolism at network-scales are not well-constrained. Within a river reach, maximum, potential rates of gross primary production (GPP) are constrained by incident light. However, the underlying spatial structure of light available to stream autotrophs is rarely quantified across heterogeneous, dynamic river networks, challenging efforts to predict GPP at broad spatial scales. Here we consider five focal river networks distributed throughout the United States to explore how the spatial structure of light drives network-scale metabolic regimes. For each network, we used spatially-distributed estimates of light availability to map network-scale light distributions and model daily rates of potential GPP. In addition, we highlight one case study - New Hope Creek, NC - in which we compare predicted productivity to observed GPP time series, and show how the spatial structure of land use and hydrologic disturbance interacts with the physical template and distribution of light to influence network GPP. Knowing the spatial structure of the drivers of stream metabolism will improve our understanding of river network metabolic regimes.

Lauren Koenig (Primary Presenter/Author), University of Connecticut, Lauren.Koenig@uconn.edu;


Ashley Helton (Co-Presenter/Co-Author), University of Connecticut, ashley.helton@uconn.edu;


Philip Savoy (Co-Presenter/Co-Author), Duke University, prs15@duke.edu;


Alice Carter (Co-Presenter/Co-Author), Duke University, alicecarter05@gmail.com;


Eric Moore (Co-Presenter/Co-Author), University of Connecticut, eric.m.moore@uconn.edu;


Jim Heffernan (Co-Presenter/Co-Author), Duke University, james.heffernan@duke.edu;


Emily Bernhardt (Co-Presenter/Co-Author), Duke University, emily.bernhardt@duke.edu;


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