SFS Annual Meeting

6/04/2024  |   10:30 - 10:45   |  Salon 3/4

Hyporheic Sessions Introduction

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6/04/2024  |   10:45 - 11:00   |  Salon 3/4

AMPHIBITIC STONEFLIES (PLECOPTERA) ARE INTEGRATORS OF ECOSYSTEM PROCESSES IN ALLUVIAL AQUIFERS OF GRAVEL-BED RIVER FLOODPLAINS Over 50 years ago nymphs of the Plecoptera species, Paraperla frontalis Banks, 1906 (Plecoptera: Chloroperlidae), were shown to exist in a shallow floodplain aquifer of the Tobacco River, a gravel-bed river in western Montana and later they were documented throughout the main stems of the Flathead River system. Nymphs are almost never found in surface waters, until they emerge on the river shorelines. As teneral adults, they mate and subsequently deposit fertilized eggs into the river. This novel life cycle is termed “amphibitic.” Over the years we and others have found P. wilsoni Ricker, 1965 (Plecoptera: Chloroperlidae), Kathroperla perdita Banks, 1920 (Plecoptera: Kathroperlidae), and 5 species of Isocapnia Banks, 1938 (Plecoptera: Capniidae), including long-winged and brachypterous adults and wingless dwarfs (male and female), occupying amphibitic niches in the alluvial aquifers of rivers in Washington, Idaho, Colorado, Alaska and British Columbia. These stoneflies are remarkably tolerant of hypoxia which allows them to exist as abundant consumers in aquifer food webs subsidized by ancient methane. Indeed, stonefly tissues contain carbon that is up to 7000 years old, underscoring the existence of a strong interaction involving the uptake of labile carbon derived from methanogenic and methanotrophic process in aquifers. Details of life cycles, trophic relationships, distribution and abundance have been documented by a suite of studies on the Nyack Floodplain of the Middle Flathead River, Montana. In this paper we review the ecophysiology and ecology of these unique stoneflies in the context of their functional role in gravel-bed river ecosystems.

Rachel Malison (Primary Presenter/Author), Flathead Lake Biological Station, The University of Montana, rachel.malison@umontana.edu;

Amanda DelVecchia (Co-Presenter/Co-Author), University of North Carolina at Chapel Hill, amanda.delvecchia@unc.edu;

J. Joseph Giersch (Co-Presenter/Co-Author), Flathead Lake Biological Station, jgiersch@usgs.gov;

Jack Stanford (Co-Presenter/Co-Author), Flathead Lake Biological Station-University of Montana, jack.stanford@umontana.edu;

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6/04/2024  |   11:00 - 11:15   |  Salon 3/4

Flood Ecology: Defining and Expanding an Insufficiently Studied Research Discipline Flooding has been a historical cause of death and destruction on an epic scale. Societal perceptions of floods are, therefore, typically negative, although scientists and natural resource managers have long recognized the importance of floods in riverine and terrestrial ecology. Like other ecological disturbances, such as fire, flooding intersects many aspects of ecology and society. But unlike fire, flooding has received relatively minor attention within the disturbance ecology literature. Although fire ecology is a discipline in its own right, as shown by the published papers on this topic, flood ecology does not have the same disciplinary recognition or cohesive body of work. Here we summarize some of the roles of floods in river ecosystems, describe how floods are considered in disturbance ecology, and compare and contrast the framing of fire ecology and flood ecology. We define flood ecology as: “A scientific discipline concerned with the proximate and ultimate ecological roles of overbank flow in river-floodplain ecosystems, the interactions between flooding and the abiotic and biotic components of aquatic and terrestrial ecosystems, including humans, and its role as an ecosystem process.” We call for an increased emphasis in this component of river science. We contend here that the absence of a discipline of flood ecology has constrained progress in our understanding of how rivers function. Finally, we propose a series of questions that we believe a discipline of flood ecology should address.

James H. Thorp (Primary Presenter/Author,Co-Presenter/Co-Author), University of Kansas/Kansas Biological Survey, thorp@ku.edu;

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6/04/2024  |   11:15 - 11:30   |  Salon 3/4

Can channel re-alignment rehabilitate hyporheic exchange? Lessons from a 15-year monitoring experiment of pre- and post-restoration stream temperature. Stream restoration plans credit channel realignment with many potential benefits, including enhanced hyporheic exchange and associated implications for stream thermal regimes. We compiled 15 years of stream temperature data from the inflow and outflow of three contiguous stream reaches in Meacham Creek, Oregon, USA , each ~1.5 km in length. The central reach was the site of a major channel realignment effort, with the upstream reach designated as a “control” and the downstream reach a thermal “recovery” reach. We expected consistent temperature dynamics over time in the control reach, a temporal step-change in the thermal regime of the restoration reach (pre- vs. post-restoration), and longitudinal recovery of the pre-restoration thermal regime in the recovery reach. Most of our predictions were not borne out in the data. Rather, the data showed that: 1) the thermal regime of Meacham varies annually, perhaps associated with natural variation in hyporheic exchange caused by flood-driven channel realignment; 2) any beneficial reduction in daily temperature range caused by enhanced hyporheic exchange was accompanied by an increase in daily mean temperature (likely due to loss of channel and floodplain shade during channel realignment); and 3) the thermal effects of channel realignment increased over the post-restoration period, perhaps due to the initial recovery of stream-side shade and natural channel adjustments initiated by the engineered realignment. The data suggest that channel realignment may yield improved hyporheic exchange rates. However, the associated benefits may be context dependent rather than ubiquitous and may arise indirectly from post-restoration channel migration.

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

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

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6/04/2024  |   11:30 - 11:45   |  Salon 3/4

Hyporheic exchange in Texas Rivers: links between hyporheic zone properties and invertebrate community metrics The hyporheic zone (HZ) is a region of permeable sediments below streams and rivers that affects water quality and ecosystem health. The HZ serves as refuge and habitat for temporary and resident taxa that constitute a substantial proportion of whole-stream invertebrate diversity and abundance. Permeability and hydraulic gradients control fluxes of water and solutes into, out of, and through the HZ and are primary drivers of hyporheic community structure. Our aim is to better understand how permeability and fluxes influence variability in HZ invertebrate community composition. Using data collected in 2021-2022, relationships between HZ hydraulic characteristics (hydraulic conductivity (K), specific discharge, and gradient) and invertebrate richness and abundance were quantified at 49 sites across Texas, USA. At each site, gradient and K were directly measured at 3-5 shallow wells. Invertebrates were collected from each well and identified to the lowest practical level in the laboratory. Invertebrates in the HZ make up a substantial proportion of whole stream secondary production, and per-site invertebrate abundances ranged from 60-14,590 individuals. Preliminary results suggest a strong, positive relationship between K and invertebrate abundance and richness but relationships between specific discharge and community metrics are less apparent. Climate change can influence stream flow variability, solute transport, and HZ hydraulic properties, influencing how invertebrates utilize the HZ as habitat and refuge. In particular, increased frequency of low flow conditions will likely have negatively impacts on both HZ specific conductivity and specific discharge in turn affecting HZ invertebrate community structure.

Caroline Mierzejewski (Primary Presenter/Author), Department of Biology, Texas State University, San Marcos, Tx., usd3@txstate.edu;

Benjamin Schwartz (Co-Presenter/Co-Author), Department of Biology, Texas State University, San Marcos, Tx., bs37@txstate.edu;

Benjamin Hutchins (Co-Presenter/Co-Author), Edwards Aquifer Research and Data Center, Texas State University, San Marcos, Tx., bh1333@txastate.edu;

Garrett Menichino (Co-Presenter/Co-Author), Environmental Laboratory, U.S. Army Engineer Research and Development Center, Garrett.T.Menichino@usace.army.mil;

Ashley Casarez (Co-Presenter/Co-Author), Department of Biology, Texas State University, San Marcos, Tx., atc72@txstate.edu;

Eryl Austin-Bingamon (Co-Presenter/Co-Author), Department of Biology, Texas State University, San Marcos, Tx., eea37@txstat.edu;

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6/04/2024  |   11:45 - 12:00   |  Salon 3/4

Can gravel extraction be restorative and how do different methodologies affect native fish? Braided rivers are globally important ecosystems that support countless plant and animal species, yet they are facing increasing human-induced pressures. Consequently, restoration efforts are being dedicated to these threatened environments. However, floodplain restorations pose a significant challenge owing to their intricate habitat complexity and spatiotemporal dynamics. Therefore, to further the understanding of braided river functioning and restoration requirements, novel restoration practices including commercial gravel extraction are being trialled. To determine the feasibility of this approach, I assessed how native fish communities and fish physiology respond to an innovative gravel extraction technique that aims to restore braided river functioning in comparison to a traditional method. Fish and habitat variables were surveyed, and a subset of fish was euthanized to allow the identification of gut contents and parasites, and to extract sagittal otoliths to count their annual growth increments and estimate growth rates. Fish from the traditional method exhibited faster growth in addition to higher parasite loads. Prey composition of fish collected from the traditional method contained more stress-tolerant macroinvertebrate taxa. The novel method displayed enhanced environmental variables analogous with floodplain diversity and differences in fish community composition, but no variation in native fish diversity. Gravel resources from braided rivers are in high demand and the ecological impacts of gravel extraction vary depending on the desired outcomes and methodologies used. Successfully implementing gravel extraction methods that simultaneously contribute to the restoration of floodplains and provide aggregates for human use would bring mutual benefits to both humans and the natural environment.

Eva De Jong (Primary Presenter/Author), University of Otago, dejev118@student.otago.ac.nz;

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