SFS Annual Meeting

6/03/2024  |   10:30 - 10:45   |  Salon 10

ENTER THE MOSAIC: AQUATIC-TERRESTRIAL RECIPROCAL FLUXES AND DYNAMIC INTERDEPENDENCE ACROSS SPATIAL AND TEMPORAL SCALES IN NORTHERN YELLOWSTONE It is time to enter the mosaic. Two decades ago, Nakano and Murakami described a “dynamic interdependence” among aquatic and terrestrial food webs, and Polis called for integrating such cross-ecosystem linkages with landscape ecology to evaluate the "dynamics of spatially subsidized food webs.” Though the development of meta-community theory has answered this call conceptually, empirical tests remain limited. In Northern Yellowstone National Park, where a natural experiment created a mosaic of stream-riparian ecosystems, we investigated the spatial and temporal dynamics of reciprocal fluxes of invertebrates and the response by consumers. From 2018-2021, we intensively sampled eight headwater streams to characterize the reciprocal fluxes of aquatic and terrestrial invertebrates and the response by fish, birds, bats, and spiders. We evaluated sites individually as well as how they contributed to the meta-community. Within sites, reciprocal fluxes of invertebrates were asynchronous throughout the year and were tracked by consumers. Across sites, the magnitude of reciprocal fluxes varied 20–175% depending on the date, revealing asynchronies across the meta-community. These asynchronies were associated with variation in habitat characteristics, including willow vs. herbaceous vegetation and temperature, and compositional differences among sites. Consumer traits, such as hawking vs. gleaning birds and bats or benthic vs. surface foraging fish, mediated their response to the reciprocal fluxes. Northern Yellowstone remains a relative bastion of biophysical complexity, and our findings point to an empirical link between habitat complexity and the maintenance of biodiversity via aquatic-terrestrial reciprocal fluxes and dynamic interdependence across the mosaic.

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

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

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

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

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

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

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6/03/2024  |   10:45 - 11:00   |  Salon 10

REGIONAL IMPACTS OF INCREASING ATMOSPHERIC CO2 ON WATER USE EFFICIENCY AND RUNOFF Global changes in evapotranspiration rates have had important and diverse effects on water balances and runoff across the globe and are associated with environmental changes including increasing growing season length, temperatures, and atmospheric CO2. Increasing CO2 has a fertilizing effect on plants that has been attributed to increased nutrient and water use efficiency (WUE); water uptake does not necessarily increase proportionally to productivity. On the other hand, CO2 fertilization is associated with reduced stomatal conductance which leads to decreased evapotranspiration. Reductions in water uptake and evapotranspiration rates have been found to change global runoff rates. Gedney et al (2006) notably found that increasing CO¬2 leads to higher runoff on continental to global scales. However, a lot of uncertainty remains around how the effect of rising atmospheric CO2 will interact with climate change and increasing temperatures and vapor pressure deficits to impact evapotranspiration and runoff rates. This work aims to understand how rising CO2 affects water balances at a regional scale using a terrestrial ecosystem model. We used PnET, a process-based model that integrates site history and carbon, nitrogen, and water cycles to understand changes in forest dynamics, notably productivity. We hypothesize that the watershed response to rising CO2 will be an increase in runoff, until other variables like nitrogen availability constrain productivity. This work presents preliminary results on changing plant WUE and productivity, focusing on a temperate forest in the Northeastern U.S. Understanding changes in runoff and plant WUE have important implications for local water management practices, notably irrigation.

Lara Munro (Primary Presenter/Author), University of New Hampshire, lara.munro@grad.unh.edu;

Scott Ollinger (Co-Presenter/Co-Author), University of New Hampshire, scott.ollinger@unh.edu;

Wilfred M. Wollheim (Co-Presenter/Co-Author), University of New Hampshire, wil.wollheim@unh.edu;

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6/03/2024  |   11:00 - 11:15   |  Salon 10

Riparian spiders are affected by the aquatic stressors artificial light at night and invasive signal crayfish in riparian stream mesocosms Aquatic ecosystems face multiple abiotic and biotic anthropogenic stressors. These stressors can extend beyond ecosystem boundaries and cascade to consumers in receiving riparian ecosystems through the alteration of aquatic prey subsidy fluxes. Artificial light at night (ALAN) and the invasive signal crayfish Pacifastacus leniusculus are recognized as significant threats to freshwater biodiversity in Europe. We investigated the effects of ALAN and the signal crayfish on riparian spider communities via alterations of aquatic insect emergence in a mesocosm experiment. The Riparian Stream Mesocosm (RSM) facility includes 16 replicated units, each of them containing an artificial flume (15 m long, ~1 m wide and ~10 cm deep) fed by river water and an adjacent terrestrial habitat (3 m width) from the flume bank, which allowed us to perform such an experiment in close-to-field conditions. The co-occurrence of crayfish and ALAN resulted in a 36% reduction of emergence rate compared to the control. We found a positive correlation between insect emergence rates and spider individuals, particularly for the riparian web-building spiders Tetragnatha extensa and Linyphiidae, indicating indirect negative effects of ALAN and signal crayfish. The study also revealed that the direction and strength of the crayfish and ALAN effects were taxon- and time-dependent. This study provides evidence that the signal crayfish and ALAN can reduce insect emergence, resulting in cascade effects on riparian spider communities. These findings underscore the importance of considering multiple anthropogenic stressors and their interactions in environmental management strategies to protect the connected freshwater and riparian biodiversity.

Alessandro Manfrin (Primary Presenter/Author), University of Kaiserslautern-Landau (RPTU), SystemLink, alessandro.manfrin@hotmail.com;

Jens Schirmel (Co-Presenter/Co-Author), University of Kaiserslautern-Landau (RPTU), jens.schirmel@rptu.de;

Marina Arias (Co-Presenter/Co-Author), Instituto de Limnología “Dr. Raúl A. Ringuelet”, arias@ilpla.edu.ar;

Mirco Bundschuh (Co-Presenter/Co-Author), University of Kaiserslautern-Landau (RPTU), mirco.bundschuh@rptu.de;

Ralf Schulz (Co-Presenter/Co-Author), University of Kaiserslautern-Landau (RPTU), r.schulz@rptu.de;

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6/03/2024  |   11:15 - 11:30   |  Salon 10

Impacts of a range shifting caddisfly on cross-ecosystem subsidies Mounting pressures of climate change are forcing more species to shift their range upslope or poleward in latitude. These range shifts are often assumed to have negative impacts on recipient communities and ecosystems by introducing new competitors or predators. One recent range shift we observed may be going against this trend by increasing resources in an alpine landscape. Caddisfly Nemotaulius hostilis, recently expanded its elevational range in a pond complex located in the western Colorado Rocky Mountains. This range shift leads to the question: How will the introduction of a range-shifting caddisfly impact the subsidy export from ponds? To examine these impacts, we designed a two-year survey utilizing emergence traps on seven ponds to quantify aquatic insect emergence weekly from June – August. Results show that N. hostilis provides a new pulse of early season biomass due to their unique phenology which results in emergence before other large-bodied aquatic insects in the system. Additionally, N. hostilis makes significant contributions to the total biomass of subsidy exports from ponds housing N. hostilis. To conclude, a range shifting species is having a positive impact on the subsidy export from ponds to the terrestrial environment. While range shifts are often regarded negatively, this study demonstrates how positive ecosystem impacts may be derived from range shifting species.

Parker Bausman (Primary Presenter/Author), University of Maine , parker.bausman@maine.edu;

Hamish Greig (Co-Presenter/Co-Author), University of Maine, hamish.greig@maine.edu;

Jared Balik (Co-Presenter/Co-Author), Western Colorado University, jbalik@western.edu;

Elliot Johnston (Co-Presenter/Co-Author), Tetra Tech, elliot.johnston@tetratech.com;

Scott Thomas (Co-Presenter/Co-Author), Murray State, scott06thomas@gmail.com;

Destiny Thorndike (Co-Presenter/Co-Author), University of Maine , destiny.thorndike@maine.edu;

Howard Whiteman (Co-Presenter/Co-Author), Murray State University, hwhiteman@murraystate.edu;

Amanda Klemmer (Co-Presenter/Co-Author), University of Maine, klemmer.amanda@maine.edu;

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6/03/2024  |   11:30 - 11:45   |  Salon 10

Terrestrial-Aquatic Connections: Invasive Ailanthus altissima leaf decomposition in freshwater ecosystems and impacts on macroinvertebrate communities Introductions of invasive plant species to riparian zones can impact nearby freshwater ecosystems by altering the composition of leaf litter available to freshwaters that serve as critical habitat and food resources for aquatic biota. The deciduous Tree of Heaven (Ailanthus altissima; [TOH]) is an invasive species that impacts terrestrial ecosystems; however, little research has focused on potential impacts on freshwater ecosystems. This study aims to understand if TOH leaf litter 1) decomposes at different rates compared to native species’ leaf litter, and 2) supports a unique macroinvertebrate community compared to native species’ leaf litter. Frémont's cottonwood (Populus fremontii) and London Planetree (Plantanus acerifolia) were used as comparisons to TOH. Leaf packs contained 3 g of invasive, native, or mix of all leaf types (n = 35 leaf packs/treatment/habitat). Leaf packs were anchored in a perennial pond and a headwater stream site and harvested every 2 weeks. Macroinvertebrates were identified to Family level and sorted by functional feeding group. The remaining leaf litter was dried and weighed to identify the decomposition rates. While this study is still underway, preliminary results suggest that TOH leaf litter 1) breakdown rate was the fastest compared to other litter treatments, and 2) is supporting a unique macroinvertebrate community dominated by Collector-gatherers and Shredders, which might be linked with the rapid fragmentation of TOH in the stream site compared to the pond site. Understanding how common invasive species impact terrestrial-aquatic connections may help support future freshwater management efforts.

Jonathan Juarez (Primary Presenter/Author), California State University Bakersfield, j_juarez123@yahoo.com;

Rae McNeish (Co-Presenter/Co-Author), California State University Bakersfield, rae.mcneish@gmail.com;

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6/03/2024  |   11:45 - 12:00   |  Salon 10

The Novel Winter Cash Cover Crop Pennycress Promotes Stream Health with Economic Benefit to Producers Nutrient export from intensive row crop agriculture, particularly in the Upper Midwestern United States, negatively impacts local and downstream ecosystem structure and function. To maintain stream and river health, techniques to reduce nutrient loss must be implemented in Midwestern agriculture. Winter cover crops, e.g., cereal rye, winter oats, tillage radish, used in Illinois cover less than 10% of fields. The novel cover crop, pennycress (Thlaspi arvense), is one of several winter oilseed crops that may provide cool season revenue for farmers and may function as an effective cover crop. Our goal is to understand the potential for pennycress to reduce nutrient export in tile drained fields, which are common in the agricultural Midwest. We used replicate (n=3) 0.8 ha plots comparing soil porewater nutrient reductions in pennycress and fertilized pennycress relative to fallow winter conditions for four years. Pennycress reduced soil porewater nitrate-nitrogen by 53.3% and fertilized pennycress by 33.8% relative to fallow reference conditions. In the pennycress treatment, nitrate-nitrogen concentrations fell from 14.0 mg/L (15.1 mg/L in fertilized pennycress) in March to 1.4 mg/L (6.1 mg/L in fertilized pennycress) in June, showing an improved ability to sequester nutrients over the course of the growing season. We demonstrate that pennycress has significant potential to reduce nutrient loss from commercial agricultural systems in Illinois. However, we also found that early season establishment is crucial, and fertilization of pennycress may negatively impact the potential to reduce nutrient loss.

Ryan Meyer (Primary Presenter/Author), Illinois State University, ryantmeyer98@gmail.com;

William Perry (Co-Presenter/Co-Author), Illinois State University, wlperry@ilstu.edu;

Nicholas Heller (Co-Presenter/Co-Author), Illinois State University, njhelle@ilstu.edu;

Robert Rhykerd (Co-Presenter/Co-Author), Illinois State University, rrhyker@ilstu.edu;

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