SFS Annual Meeting

Marina Tagliaferro (Primary Presenter/Author)
Centro Austral de Investigaciones Científicas (CADIC-CONICET), azulmarinita@gmail.com;

Verónica Díaz Villanueva (Co-Presenter/Co-Author)
INIBIOMA-CONICET, diazv@comahue-conicet.gob.ar ;

Laura Wolisnki (Co-Presenter/Co-Author)
CADIC-CONICET, lauriw@gmail.com ;

Claudia Boy (Co-Presenter/Co-Author)
CADIC-CONICET, claudiaboy@gmail.com ;

Abstract: We evaluated the impact of galls on two aquatic detritivores comparing the consumption of galled with ungalled leaves and the effect of this consumption on detritivore nutrient content. The amphipod Hyalella curvispina and larvae of the caddisfly Monocosmoecus hyadesi were chosen as detritivores. Fungal biomass, carbon (C), nitrogen (N), and phosphorus (P) were measured in leaves and detritivores and C:N:P molar ratios were calculated. Galled leaves had higher N and ergosterol content, and lower C:N ratios than ungalled leaves. Galled leaf consumption was higher than the ungalled for both detritivores. The two species differed in N and C (caddisfly > amphipod), and P (caddisfly < amphipod) content. The N:P ratio of the amphipod was similar to the ungalled control leaf ratio and increased when fed on galled leaves. In contrast, the N:P ratio of the caddisfly was much higher than the ungalled leaves and decreased when fed on galled leaves. Galls alter nutrient content in leaves and increase fungal biomass. Both detritivore species were highly homeostatic with regard to C:N ratio, but the caddisfly could overcome the limiting P content by increasing consumption.

Ruby Ghosh (Primary Presenter/Author)
OptiO2, Inc., ghosh@optio2.com;

Dean Shooltz (Co-Presenter/Co-Author)
Opti O2, LLC, shooltz@optio2.com;

Michael Freeman (Co-Presenter/Co-Author)
Opti O2, LLC, freeman@optio2.com;

Reza Loloee (Co-Presenter/Co-Author)
Opti O2, LLC, loloee@optio2.com;

Abstract: Dissolved oxygen (DO) dynamics at various land-water interfaces within a watershed play a critical role in catalyzing biogeochemical reactions and are affected by in-situ biological processes. Quantifying these processes requires continuous in-situ measurements at both high enough frequency to capture details such as changes in microbial respiration and long enough duration to observe annual effects. Our novel optical oxygen sensing technology provides real-time (every min) DO data from streams as well as in-situ deployments in saturated/unsaturated sediments. These continuous measurements are obtained without removal or recalibration of the probe over multiple seasons (currently up to 29 months). We report on three case studies: (i) groundwater-surface water interactions within the hyporheic zone of an alpine stream from a 15-month record of spatially resolved DO measurements directly within the stream-bed, (ii) snowmelt driven biogeochemical processes in the hillslope to floodplain continuum over three consecutive years and (iii) observation of tidally driven DO pulses in a coastal watershed. Our high frequency measurements provide insights into ecosystem scale processes from the effects of snow drought in an alpine watershed to how rapid shifts in redox state influence carbon cycling in a tidal river-floodplain.

David Walters (Primary Presenter/Author)
United States Geological Survey, waltersd@usgs.gov;

Sarah Janssen (Co-Presenter/Co-Author)
USGS, sjanssen@usgs.gov;

Joel Hoffman (Co-Presenter/Co-Author)
U.S. Environmental Protection Agency, hoffman.joel@epa.gov;

Marc Mills (Co-Presenter/Co-Author)
United States Environmental Protection Agency, mills.marc@epa.gov;

Jim Lazorchak (Co-Presenter/Co-Author)
United States Environmental Protection Agency, Office of Research and Development, Center for Environmental Measurement and Modeling, Cincinnati, OH 45268, lazorchak.jim@epa.gov;

Greg Peterson (Co-Presenter/Co-Author)
U.S. Environmental Protection Agency, Peterson.Greg@epa.gov;

Anne Cotter (Co-Presenter/Co-Author)
USEPA/NHEERL/MED, Duluth, MN, Cotter.Anne@epa.gov;

Collin A. Eagles-Smith (Co-Presenter/Co-Author)
US Geological Survey, ceagles-smith@usgs.gov ;

Dr. David Krabbenhoft (Co-Presenter/Co-Author)
U.S Geological Survey, Wisconsin Water Science Center, Middleton, WI, dpkrabbe@usgs.gov;

Abstract: Mercury (Hg) isotopes are increasingly used to identify environmental sources of Hg. Aquatic insects move Hg to terrestrial food webs, but it is unclear if Hg isotopes are conserved during this process. We measured Hg isotopes in spiders, benthic insects, and prey fish in the St. Louis River (SLR, Duluth, MN) and a nearby reference watershed. The lower SLR has industrial Hg sources, whereas the reference watershed receives Hg via atmospheric deposition. Spatial variation in ?202Hg in spiders tracked those of aquatic species. Depleted ?202Hg values confirmed atmospheric source in the reference watershed and the upper SLR. Enriched ?202Hg signatures in the lower SLR confirmed industrial Hg sources to aquatic and riparian food webs. Aquatic insect ?202Hg was strongly correlated with fish ?202Hg (r2 = 0.66) and spider ?202Hg (r2 = 0.75). We found limited evidence of enriched ?202Hg between insects and fish, but not between insects and spiders, suggesting trophic fractionation of Hg isotopes varies across food web pathways. Hg isotope source signatures in aquatic food webs are conserved and transferred into riparian ecosystems, demonstrating the export of legacy Hg in river sediments to floodplain food webs.

Rachel Hartnett (Co-Presenter/Co-Author)
Oklahoma State University, rachel.hartnett@okstate.edu;

Thomas Parr (Co-Presenter/Co-Author)
U.S. National Park Service, thomas.parr@ou.edu;

Caryn Vaughn (Co-Presenter/Co-Author)
University of Oklahoma, cvaughn@ou.edu;

Jonathan Lopez (Primary Presenter/Author)
University of Oklahoma, jwlopez@ou.edu;

Abstract: Hotspots of nutrient cycling created by freshwater mussel beds have cascading effects on food webs and ecosystem function. Studies of these ecosystem-level effects have thus far been focused on changes in macronutrient – nitrogen (N) and phosphorus (P) – availability driven by mussel excreta. However, mussel beds may alter the cycling of other biologically necessary, but less abundant elements. For example, calcium (Ca) cycling may be affected by the balance between sequestration and dissolution of Ca in mussel shells. Cycling of micronutrients such as iron (Fe) and other transition metals may be altered by mussel burrowing and the associated oxidation of the sediment. We explored the elemental landscape of mussel beds in the Ouachita Highlands by sampling for a suite of elements in nearby water, sediments, and macrophytes. We found differences in Ca, P, and Fe availability in the environment between mussel bed sites and non-mussel sites. The influence of mussel beds on nutrient element availability has important implications for riverine and riparian ecosystems. Alterations to nutrient availability in these systems may benefit important species from fish to game and livestock species which use the river for drink and forage.

H. Maurice Valett (Co-Presenter/Co-Author)
University of Montana, Division of Biological Sciences, maury.valett@umontana.edu;

Colton Kyro (Primary Presenter/Author)
University of Montana, colton.kyro@umontana.edu;

Abstract: Owing to their relatively small size, the chemical composition of low-order streams is vulnerable to abrupt change driven by groundwater discharge. We quantified the movement of water and the associated concentration of dissolved inorganic nitrogen (DIN) from surface and shallow groundwater environments in a wetland-stream complex. The wetland-stream complex is embedded within a rural-agriculture setting that includes infiltration beds that discharge treated municipal effluent (DIN: 17.18 mg/L) into the local aquifer. Our objectives were to (1) determine the role groundwater-surface water exchange has on the abundance of nitrogen in the stream and (2) determine the effect a wetland has on the abundance of nitrogen in the stream. Groundwater inputs increased the stream’s DIN concentration by an order of magnitude (0.02 – 0.22 mg/L) accompanied by diel swings in over 0.15 mg/L. While an adjacent fen reduced DIN concentrations in groundwater flowpaths converging on the stream by as much as 70%, its influence on stream nitrogen abundance was negligible due to low volumetric discharge of water reflecting the importance of topographic relief and substrate permeability.

Iris Garthwaite (Primary Presenter/Author)
Northern Arizona University, ig334@nau.edu;

Angie Froedin-Morgensen (Co-Presenter/Co-Author)
The Evergreen State College, amorgensen@gmail.com;

Sorrel Hartford (Co-Presenter/Co-Author)
The Evergreen State College, harsor11@evergreen.edu;

Shannon Claeson (Co-Presenter/Co-Author)
USFS PNW Research Station, shannon.claeson@usda.gov;

Joy M. Ramstack Hobbs (Co-Presenter/Co-Author)
The Evergreen State College, hobbsj@evergreen.edu;

Carri LeRoy (Co-Presenter/Co-Author)
Evergreen State College, leroyc@evergreen.edu;

Abstract: The influences of inter- and intraspecific variation in leaf litter quality on aquatic food webs are important; however, there is also variation in the timing and type of organic matter inputs within a species based on plant phenophase, including litterfall and spring flowering, which may influence in-stream communities and ecosystem processes. We investigated how leaf and flower litters of a single willow shrub species (Salix sitchensis) influenced decomposition and invertebrate colonization in a headwater stream. We collected abscised willow catkins and leaves, measured initial chemistry, constructed and incubated litterbags for 5 weeks. We found significant differences between catkins and leaves, where catkins showed lower initial condensed tannins, less mass loss, and higher aquatic invertebrate colonization. Catkin structural complexity likely led to higher aquatic invertebrate abundance and diversity as well as altered community structure, indicating their unique contribution to stream ecosystems. While the ratio of reproductive inputs to leaves is low, we argue that the temporality of these two litter types may be important to aquatic-terrestrial organic matter processing, especially in the early summer to late autumn seasons.

Keeley MacNeill (Primary Presenter/Author)
Oregon State University, keeleymacneill@gmail.com;

Dana Warren (Co-Presenter/Co-Author)
Oregon State University, dana.warren@oregonstate.edu;

Allison Swartz (Co-Presenter/Co-Author)
Oregon State University, allison.swartz@oregonstate.edu;

Jeremy Brooks (Co-Presenter/Co-Author)
Idaho State University, broojer2@isu.edu;

Colden Baxter (Co-Presenter/Co-Author)
Idaho State University, baxtcold@isu.edu;

William J. Ripple (Co-Presenter/Co-Author)
Oregon State University, bill.ripple@oregonstate.edu;

Robert L. Beschta (Co-Presenter/Co-Author)
Oregon State University, robert.beschta@oregonstate.edu;

Abstract: Temperature is a fundamental control on ecological processes, and factors that alter thermal regimes can shift species interactions and ecosystem function. We compared thermal regimes of streams in Yellowstone National Park with contrasting degrees of ungulate browse, and, therefore, different amounts of woody riparian vegetation. Low vegetation density sites experience heavy riparian browse by bison (Bison bison), which are not currently limited by large carnivores. High vegetation density sites experience lower riparian browse by ungulates, partly due to restoration of large carnivores. We explored four aspects of summer temperature regime across five streams: daily-mean, daily-maximum, daily-range, and normalized daily temperature variation. Mean daily temperatures were not significantly correlated with streamside vegetation status. Two of three low vegetation streams had higher maximum temperatures than high-vegetation sites. Daily stream temperature range and normalized daily temperature variation, were significantly different between low- and high-vegetation sites. Daily ranges and normalized daily temperature variation were nearly twice as high in low vegetation sites as in high vegetation sites. Thus, preliminary results indicate terrestrial factors, including trophic cascades from predators, may alter stream temperature regimes, a key element controlling stream processes.

Katie Fogg (Primary Presenter/Author)
Montana State University, s.katie.fogg@gmail.com;

Geoffrey Poole (Co-Presenter/Co-Author)
Montana State University, Montana Institute on Ecosystems, gpoole@montana.edu ;

Scott O'Daniel (Co-Presenter/Co-Author)
Confederated Umatilla Tribes, scottodaniel@ctuir.org;

Ann Marie Reinhold (Co-Presenter/Co-Author)
Montana State University, Montana Institute on Ecosystems, reinhold@montana.edu;

Byron Amerson (Co-Presenter/Co-Author)
Montana State University, byron.amerson@gmail.com;

Abstract: In streams with expansive, coarse-grained alluvial aquifers, hyporheic zones are often wide and shallow – a geometry which allows for heat exchange with the atmosphere through overlying floodplain sediments. Therefore, we hypothesized that shade on floodplain sediments leads to less conduction of atmospheric heat to the hyporheic zone, and thus cooler hyporheic water temperatures. Using a groundwater energy flux model, we examined how the presence or absence of floodplain shade interacted with hydraulic conductivity and depth to water table affected hyporheic zone temperatures. Model results showed floodplain shade affected hyporheic zone temperatures; the effects being greater at longer flow paths, lower hydraulic conductivity values, and with thinner overlying floodplain sediments. Thus, in addition to stream-surface shade, floodplain shade may be an important factor in mitigating stream channel temperatures and promoting cold-water habitats in streams where hyporheic zones are shallow and laterally expansive.

Darin Kopp (Primary Presenter/Author)
U.S. Environmental Protection Agency, Kopp.Darin@epa.gov;

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

Abstract: Aquatic insect larvae metamorphose into flying terrestrial adults that subsidize terrestrial ecosystems with energy and nutrients. The magnitude of this effect should be controlled by the quantity of insects that emerge from aquatic ecosystems, but it is not clear how climate change could impact aquatic insect emergence. Here, we modeled 1) production of emergent aquatic insects per-unit area from 92 studies and 2) surface area of streams from 2,077 measurements of wetted stream width under present-day climate and two climate scenarios for 2070. We then extrapolate these results to the nearly 2.3 million streams of the contiguous United States and explore how the quantity of emergent aquatic insects may or may not satisfy the metabolic demands of common avian aerial insectivores. Our estimates suggest that these ecosystems can export 78,197 (95% PI: 2,155 - 2.19 x 106) metric tons of insect biomass under present-day conditions, and that climate change could increase emergent biomass by 250% in some regions while decreasing it by 50% in others. Collectively, our results demonstrate that climate change effects on one ecosystem will resonate throughout other ecosystems due to cross-ecosystem linkages.

Christina Fulghum (Co-Presenter/Co-Author)
Savannah River Ecology Laboratory-University of Georgia, cfulghum@uga.edu;

Angela Lindell (Co-Presenter/Co-Author)
Savannah River Ecology Laboratory-University of Georgia, lindell@srel.uga.edu;

Paul Stankus (Co-Presenter/Co-Author)
Savannah River Ecology Laboratory-University of Georgia, stankus@srel.uga.edu;

Erin Spivey (Co-Presenter/Co-Author)
Savannah River Ecology Laboratory--UGA, Erin.Spivey@uga.edu;

Dean Fletcher (Primary Presenter/Author)
Savannah River Ecology Laboratory-University of Georgia, fletcher@srel.uga.edu;

Abstract: When a dragonfly aquatic nymph emerges from a wetland, metals can be shed with their exuviae (nymph exoskeleton) or be incorporated into their body and enter the terrestrial food web as emergents fly away. Many dragonfly species emerge throughout an extended flying season, typically spring through late summer. Water quality in constructed wetlands can also temporally vary, particularly over the plant growing season that largely coincides with the dragonfly flying season. Consequently, burdens of metals accumulating in the emerging dragonfly or shed exuviae may vary throughout the season. We previously established elevated levels of metals in dragonfly nymphs from a constructed wetland on the Savannah River Site, SC, USA. We evaluated metal concentrations and masses of 12 metals accumulating in emergents and shed exuviae of three dragonfly species throughout a season. Whether higher concentrations of a specific element accumulated in the emergent versus exuviae was generally consistent among species and collection periods. However, substantial temporal differences in metal accumulation in both emergents and exuviae were observed. Generally, differences occurred in individual sampling events rather than gradual trends throughout the season. Patterns in metal accumulation were both element and species specific.

Michael Gilboy (Primary Presenter/Author)
The Ohio State University, gilboy.11@buckeyemail.osu.edu;

Abstract: Artificial light at night (ALAN) is a growing environmental stressor with documented ecological effects, especially at the individual and population levels. However, relatively few studies have addressed how ALAN impacts communities and ecosystems. Here, we investigate the potential effects of ALAN on mammal communities of riparian zones in the Columbus, Ohio Metropolitan Area. Our primary objectives are to quantify differences between lit and unlit reaches in: (1) mammal community composition and habitat use, and (2) the energetic reliance on terrestrially- versus aquatically-derived nutritional subsidies by small mammals. Although preliminary data show no differences in small species richness or mean mass of white-footed mice (Peromyscus leucopus) between lit and unlit sites, there is initial evidence of a trend of greater abundance of small mammals at lit sites. Moving forward, we anticipate that mammal communities will be characterized by a higher relative abundance of predators at lit ALAN sites and a reduced reliance on aquatically-derived nutritional subsidies. Our results will contribute to targeting lighting thresholds necessary to minimize disturbance to riparian ecosystems and inform urban and roadway-lighting management schemes.

Lindsey Reisinger (Co-Presenter/Co-Author)
University of Florida, lreisinger1@ufl.edu;

Alexander Reisinger (Co-Presenter/Co-Author)
University of Florida, reisingera@ufl.edu;

Rae Crandall (Co-Presenter/Co-Author)
University of Florida, raecrandall@ufl.edu;

Shirley Baker (Co-Presenter/Co-Author)
University of Florida, sbaker25@ufl.edu;

Samantha Howley (Primary Presenter/Author)
University of Florida, samanthathowley@gmail.com;

Abstract: Prescribed burns and wildfires alter nutrient dynamics and food webs within terrestrial and aquatic systems by remobilizing stored nutrients and altering dissolved organic matter quantity and quality. These ecological and biogeochemical effects have been widely studied in forests and streams of the Western United States. However, there are few studies of fire effects within the Southeastern United States, and even fewer in southeastern pine savanna wetlands, a common feature on the landscape. Here, we investigate the short- and long-term effects of fire regimes on southeastern pine savanna wetlands’ biodiversity and biogeochemical processes by sampling ~30 wetlands across North Central Florida. At each wetland, we are assessing the effects of fire regime (most recent burn, burn frequency in past 30-yrs, fuel load) on biofilm nutrient limitation and macroinvertebrate community composition and abundance. We hypothesize that a more intense fire regime will shift wetlands from phosphorus and nitrogen co-limitation to nitrogen-limited systems. In addition, we predict benthic invertebrate communities will shift from shredders to collectors and grazers with increasing fire regime intensity. Our results will help guide prescribed fire policy to better manage water resources, habitat, and biodiversity in Southeastern pine savannas.