SFS Annual Meeting

Fernando Chaguaceda (Primary Presenter/Author,Co-Presenter/Co-Author)
Swedish University of Agricultural Sciences, fernando.chaguaceda@slu.se;

Abstract: Climate change is one of the most important threats to aquatic biodiversity, and is expected to cause changes in mean water temperatures, catchment properties and water quality in Arctic freshwaters. Climate-driven changes in inputs of nutrients and organic matter from the catchment are expected to affect community composition and ecosystem processes such as productivity. However, to date, there is limited mechanistic knowledge of how these multiple stressors affect both quantity and quality of primary producers, as well as the transfer of energy and nutrients to grazers. In this talk, we present details of combined bioassays that are designed to assess the effect of temperature, N:P ratios and organic carbon increase (“browning”) on the energy transfer in Arctic lake food webs. We describe a combination of different setups with batch-cultures of benthic and pelagic organisms (zooplankton, collectors, grazers and scrapers) and present approaches, challenges, and preliminary findings. The results of the bioassays will be used to validate climate-driven ecological predictions about basal resources in Arctic freshwater food webs, providing new insights into the response of primary producers and grazers to such stressors.

Chao Song (Primary Presenter/Author)
Taizhou University, songchaonk@163.com ;

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

Arial Shogren (Co-Presenter/Co-Author)
University of Alabama, ashogren@ua.edu;

Caroline Weidner (Co-Presenter/Co-Author)
Michigan State University, weidne11@msu.edu;

Frances Iannucci (Co-Presenter/Co-Author)
University of Alaska Fairbanks, fiannucci@alaska.edu;

Alexander Medvedeff (Co-Presenter/Co-Author)
University of Vermont, Alexander.Medvedeff@uvm.edu;

William Breck Bowden (Co-Presenter/Co-Author)
University of Vermont, breck.bowden@uvm.edu;

Abstract: Concentration-discharge (C-Q) relationships are often used to characterize solute fluxes from watersheds. However, the temporal variability of C-Q relationships is poorly characterized, especially in the Arctic watersheds. In general, C-Q relationships are controlled by solute availability in terrestrial sources and transport via hydrologic processes. We used three years of high-frequency measurements of dissolved organic carbon (DOC), nitrate (NO3), and Q from two Arctic watersheds to quantify C-Q slopes. We predicted that if there were source controls, the DOC C-Q slope would decrease over the season due to thickening active layer that allows deeper flow paths and greater DOC removal via mineralization. We also predicted that the NO3 C-Q slope would be lowest during peak growing season, as high biotic demand depletes NO3 in soils. If hydrology is the primary control, we expect C-Q slopes to vary with discharge consistently and have no seasonal patterns. We found that DOC and NO3 C-Q slopes vary among years and show no consistent variation over the season or ranges of discharge, indicating that neither terrestrial source or hydrology alone determines the temporal variability in C-Q relationships, adding complexity to Arctic watershed biogeochemical modeling efforts.

Amelia Grose (Co-Presenter/Co-Author)
Michigan State University, groseame@msu.edu ;

Raymond Lee (Co-Presenter/Co-Author)
Brigham Young University, ramalee420@gmail.com;

Adrian Rocha` (Co-Presenter/Co-Author)
University of Notre Dame, arocha1@nd.edu;

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

William Breck Bowden (Co-Presenter/Co-Author)
University of Vermont, breck.bowden@uvm.edu;

Arial Shogren (Co-Presenter/Co-Author)
University of Alabama, ashogren@ua.edu;

Benjamin Abbott (Co-Presenter/Co-Author)
Department of Earth and Environmental Sciences, Michigan State University, USA, benabbo@gmail.com;

Qiwen Zhang (Primary Presenter/Author)
Brigham Young University, qiwenzhang94@gmail.com;

Abstract: Water chemistry in stream networks is important for indicating ecosystem response to environmental change at medium to large scales, especially in Arctic ecosystems experiencing rapid changes in climate and disturbance. However, observing large-scale patterns of water chemistry is still difficult in these remote ecosystems. We used an aerial sampling method to collect stream samples from 60 locations 6 times over two years, including longitudinal sampling of two large Arctic rivers and 42 smaller watersheds, half of which were affected by an intense tundra wildfire 10 years prior. Using a multi-proxy approach, we calculated spatial persistence and temporal synchrony to characterize water chemistry's spatiotemporal variability. We found several unexpected longitudinal patterns from the large rivers among seasons, including persistent discontinuities for some solutes, indicating either hydrological or biogeochemical processes occurring with strong seasonal cycles. The high spatial persistence of solutes suggested that occasional synoptic sampling can characterize longer-term nutrient state in Arctic flowscapes. Simultaneously, the discrete temporal synchrony uncovered the dissimilar response to ecological changes among burned and unburned watersheds. Our results demonstrated that the wildfire did not fundamentally alter the ecohydrological patterns across solutes, though factors controlling water chemistry changed.

Jennifer Lento (Co-Presenter/Co-Author)
Canadian Rivers Institute, Department of Biology, University of New Brunswick, jlento@gmail.com;

Maria Kahlert (Co-Presenter/Co-Author)
Department of Aquatic Sciences and Assessment, SLU, Uppsala, Sweden, Maria.Kahlert@slu.se;

Isabelle Lavoie (Co-Presenter/Co-Author)
Institut National de la Recherche Scientifique, Centre Eau Terre Environnement, isabelle.lavoie@inrs.ca;

Daniel Bogan (Co-Presenter/Co-Author)
Alaska Center for Conservation Science at University of Alaska Anchorage, dlbogan@alaska.edu;

Jordan Musetta-Lambert (Co-Presenter/Co-Author)
Environment and Climate Change Canada, jordan.musetta-lambert@canada.ca;

Joseph Culp (Co-Presenter/Co-Author)
Wilfrid Laurier University, jculp@wlu.ca;

Willem Goedkoop (Co-Presenter/Co-Author)
Dept Aquatic Sciences & Assessment, Swedish Univ Agricultural Sciences, Willem.Goedkoop@slu.se;

Rebecca Shaftel (Co-Presenter/Co-Author)
Alaska Center for Conservation Science at University of Alaska Anchorage, rsshaftel@alaska.edu;

Dag Hessen (Co-Presenter/Co-Author)
UiO-University of Oslo, d.o.hessen@mn.uio.no;

Kirsten Christoffersen (Co-Presenter/Co-Author)
University of Copenhagen, kchristoffersen@bio.ku.dk;

Fernando Chaguaceda (Co-Presenter/Co-Author)
Swedish University of Agricultural Sciences, chagua1932@gmail.com;

Brianna Levenstein (Primary Presenter/Author)
Canadian Rivers Institute, Department of Biology, University of New Brunwsick, brianna.levenstein@unb.ca;

Abstract: Assessments of diversity in Arctic freshwaters generally focus on structural diversity, i.e., the number and composition of taxa at local or regional scales. However, changes in community structure may not result in alterations to ecosystem function if there is strong niche overlap among taxa, leading to functional redundancy. In Arctic freshwaters, where the number of taxa is often limited due to harsh environmental conditions, functional diversity and redundancy have not been widely studied, despite the importance of understanding how ecosystem function may change with a warming climate. Furthermore, northward range expansion may alter functional composition of these systems as taxa that occupy a different functional niche are introduced. In this presentation, we will provide an overview of the approach being taken in the ARCTIC-BIODIVER project to quantify functional diversity of Arctic freshwaters across the circumpolar region, including compilation of circumpolar trait data, selection of relevant traits, preliminary patterns of trait distribution along latitudinal gradients and a comparison to patterns in structural diversity of the circumpolar region.

Daniel Bogan (Co-Presenter/Co-Author)
Alaska Center for Conservation Science at University of Alaska Anchorage, dlbogan@alaska.edu;

Birgit Hagedorn (Co-Presenter/Co-Author)
Sustainable Earth Research LLC, birgit.hagedorn@searchlc.com ;

Erin Larson (Co-Presenter/Co-Author)
University of Alaska-Anchorage, ern.larson@gmail.com;

Dustin Merrigan (Co-Presenter/Co-Author)
Alaska Center for Conservation Science, University of Alaska Anchorage, dwmerrigan@alaska.edu;

Sarah O'Neal (Co-Presenter/Co-Author)
University of Washington, soneal@uw.edu;

Daniel Rinella (Co-Presenter/Co-Author)
U.S. Fish and Wildlife Service, daniel_rinella@fws.gov;

Carol Ann Woody (Co-Presenter/Co-Author)
Fisheries Research and Consulting, drcawoody@gmail.com;

Rebecca Shaftel (Primary Presenter/Author)
Alaska Center for Conservation Science at University of Alaska Anchorage, rsshaftel@alaska.edu;

Abstract: The Kvichak and Nushagak watersheds support some of the largest sockeye salmon runs in Bristol Bay, which is the largest wild sockeye salmon producing region in the world. These valuable fishery resources are under threat from climate change and potential massive-scale mining. A probabilistic survey was conducted in 2015 in 40 wadeable streams of the Lime Hills Ecoregion, which includes the upper parts of the Nushagak and Kvichak watersheds on State lands open to mineral development and including the Pebble Prospect. Data collection included stream physical and chemical conditions, in addition to sampling fish, macroinvertebrate, and diatom communities. Ten sites from the 2015 survey were sampled annually through 2019 to provide a five-year dataset of inter-annual variation in taxonomic persistence and stability. A total of 12 fish species, 120 macroinvertebrate genera, and 312 diatom species were identified in wadeable stream habitats. We used these data to model biodiversity patterns in response to environmental conditions across the study area.This is the first probabilistic dataset of freshwater biological diversity for this region and provides an important baseline against which future changes can be measured.

Ada Pastor (Primary Presenter/Author)
Aarhus University, adapastor@bio.au.dk;

Louis J. Skovsholt (Co-Presenter/Co-Author)
Department of Biology, Aarhus University, Louis.Skovsholt@niwa.co.nz;

Kirsten Christoffersen (Co-Presenter/Co-Author)
University of Copenhagen, kchristoffersen@bio.ku.dk;

Naicheng Wu (Co-Presenter/Co-Author)
Aarhus University, naichengwu88@gmail.com;

Tenna Riis (Co-Presenter/Co-Author)
Aarhus University, Denmark, Tenna.riis@bio.au.dk;

Abstract: Global change is particularly affecting the Arctic, with drastic landscape changes. However, it is still unclear how these changes modify the biogeochemical constituents reaching Arctic freshwaters. Here, we examined how catchment properties influence stream nitrogen and dissolved organic carbon concentrations in High Arctic. We sampled two contrasting streams (10-15 stations) in Northeast Greenland (74ºN). For each station, we measured water hydrochemistry and estimated the geomorphology and vegetation cover of sub-watershed areas. Although the reduced geographical extension, streams showed a clear altitudinal gradients in vegetation, from upstream low to high cover in the valley, and geomorphological landforms, with high coverage of bedrock and solifluction sheets in the uphill and alluvial sedimentation areas in the valley. Hydrochemistry changed downstream and correlated with changes in both vegetation and geomorphology. Low vegetation and high bedrock and solifluction related to high concentrations of nitrate, whereas higher vegetation related to higher dissolved organic carbon concentrations. These results suggest that climate change inducing alterations to vegetation cover and geomorphology disturbance in high Arctic catchments will affect stream hydrochemistry, with potential effects in stream productivity, trophic relations as well as change of solute export to downstream coastal areas.

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

Arial Shogren (Co-Presenter/Co-Author)
University of Alabama, ashogren@ua.edu;

Frances Iannucci (Co-Presenter/Co-Author)
University of Alaska Fairbanks, fiannucci@alaska.edu;

William Breck Bowden (Co-Presenter/Co-Author)
University of Vermont, breck.bowden@uvm.edu;

Alexander Medvedeff (Co-Presenter/Co-Author)
University of Vermont, Alexander.Medvedeff@uvm.edu;

Emma Haines (Primary Presenter/Author)
Department of Earth and Environmental Sciences, Michigan State University, hainesem@msu.edu;

Abstract: In river networks where streams and lakes are hydrologically connected, the interaction of streams and lakes often influence the resulting biogeochemical signals of the river network. However, the influence of stream-lake interactions on biogeochemical fluxes in permafrost-dominated landscapes has not been studied extensively. This study uses novel high-frequency concentration and discharge data from the inflow and outflow of an Arctic lake on the North Slope of Alaska to explore if and how stream-lake interactions modulate riverine solute exports. The small (0.25km2) lake is located in the headwaters of a river network underlain by continuous permafrost. During the 2019 thaw season (June-August), in-situ sensors located at the inflow and outflow of the lake measured dissolved organic carbon (DOC), nitrate (NO3-), and discharge (Q) every 15 minutes. Concentration-discharge (CQ) analysis during five storm events show consistent NO3- dilution and DOC enrichment at the inflow site. In contrast, lake outflow data indicate that the lake controls CQ patterns, with NO3- enriching and DOC diluting during storms. These high-frequency CQ results suggest that stream-lake interactions modulate watershed solute export, which is an exciting and understudied aspect of Arctic ecosystems.

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

Benjamin Abbott (Co-Presenter/Co-Author)
Brigham Young University, Department of Plant and Wildlife Sciences, benabbott@byu.edu;

Frances Iannucci (Co-Presenter/Co-Author)
University of Alaska Fairbanks, fiannucci@alaska.edu;

Alexander Medvedeff (Co-Presenter/Co-Author)
University of Vermont, Alexander.Medvedeff@uvm.edu;

William Breck Bowden (Co-Presenter/Co-Author)
University of Vermont, breck.bowden@uvm.edu;

Arial Shogren (Primary Presenter/Author)
University of Alabama, ashogren@ua.edu;

Abstract: Climate change is rapidly altering ecological processes of Arctic ecosystems, yet predicting paired biogeochemical responses in rivers remains a major challenge. To address this knowledge gap, we measured dissolved [C]arbon and [N]itrogen from two Arctic watersheds, the Kuparuk River and Oksrukuyik Creek. These watersheds represent low-gradient, high-productivity landscapes characteristic of the Alaskan North Slope. In both watersheds, we deployed high-frequency in situ stream sensors that measured the absorbance spectra of stream water for four consecutive thaw seasons (2017-2020), capturing a wide range of flow and ecological conditions. From the sensor spectra, we developed robust time-series of dissolved organic C (DOC), nitrate (NO3-), total Kjeldahl N (TKN), and total dissolved N (TDN), and explored C and N concentration-discharge (CQ) responses. In both watersheds, we found that DOC and NO3- behaved asynchronously, where NO3- largely diluted (slope<0) while DOC enriched (slope>0). In contrast, DOC and TKN or TDN synchronously enriched (slope>0) during high flows, likely the result of organic-N flushing. Our use of optical sensors provides a high-precision solution for estimating biogeochemical export behavior in remote watersheds, which could improve our characterization of a changing Arctic.

Amelia Grose (Primary Presenter/Author)
Michigan State University, groseame@msu.edu ;

Qiwen Zhang (Co-Presenter/Co-Author)
Brigham Young University, qiwenzhang94@gmail.com;

Benjamin Abbott (Co-Presenter/Co-Author)
Brigham Young University, Department of Plant and Wildlife Sciences, benabbott@byu.edu;

Raymond Lee (Co-Presenter/Co-Author)
Brigham Young University, raymond.lee@byu.edu;

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

Arial Shogren (Co-Presenter/Co-Author)
University of Alabama, ashogren@ua.edu;

Greg Carling (Co-Presenter/Co-Author)
Brigham Young University, greg.carling@byu.edu;

William Breck Bowden (Co-Presenter/Co-Author)
University of Vermont, breck.bowden@uvm.edu;

Abstract: Ecosystem response to climate change is dependent on changes in hydrology. Stable water isotopes (18O and 2H) are often used to determine stream source waters, enabling deeper understanding of ecological patterns and watershed processes. However, few water isotope studies exist in Arctic watersheds, which are characterized by rapidly changing landscapes and unique hydrology due to underlying permafrost. To begin addressing this gap, we analyzed 18O and 2H from three rivers and their tributaries on the North Slope of Alaska. We synoptically sampled 25 mainstem sites and 42 tributaries six times over the course of two summers, under “dry” and “wet” conditions. We explored spatial and temporal patterns in 18O and 2H, and linked isotope patterns to trends in nutrient concentrations and fluxes throughout the streams. In general, tributaries showed greater 18O and 2H enrichment than the mainstem and showed a strong latitudinal pattern that reflected position in the watershed. Temporal differences in 18O and 2H indicated varying sources of water throughout the thaw season. These suggested spatio-temporal changes in water sources highlight the need for collection of additional stable water isotope data throughout the Arctic to monitor ecosystem change.

Benjamin Abbott (Primary Presenter/Author)
Brigham Young University, Department of Plant and Wildlife Sciences, benabbott@byu.edu;

Ethan Wologo (Co-Presenter/Co-Author)
Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA, ethan.wolo@gmail.com;

Sarah Shakil (Co-Presenter/Co-Author)
University of Alberta, shakil@ualberta.ca;

Scott Zolkos (Co-Presenter/Co-Author)
Woods Hole Research Center, zolkos@ualberta.ca;

Sadie Textor (Co-Presenter/Co-Author)
Florida State University, textor.sadie@gmail.com;

Jane Klassen (Co-Presenter/Co-Author)
Montana State University, janeklassen@gmail.com;

Robert G. M. Spencer (Co-Presenter/Co-Author)
Florida State University, rgspencer@magnet.fsu.edu;

David C. Podgorski (Co-Presenter/Co-Author)
Florida State University, Podgorski@magnet.fsu.edu;

Suzanne Tank (Co-Presenter/Co-Author)
University of Alberta, suzanne.tank@ualberta.ca ;

Michelle Baker (Co-Presenter/Co-Author)
Utah State University, michelle.baker@usu.edu;

Jonathan A. O'Donnell (Co-Presenter/Co-Author)
National Parks Service, Jonathan_O'Donnell@nps.gov;

Kimberly Wickland (Co-Presenter/Co-Author)
U.S. Geological Survey, kpwick@usgs.gov;

Sydney S. W. Foks (Co-Presenter/Co-Author)
U.S. Geological Survey, sfoks@usgs.gov;

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

Joseph Lee-Cullin (Co-Presenter/Co-Author)
Department of Earth and Environmental Sciences, Michigan State University, USA, cullinjo@msu.edu;

Futing Liu (Co-Presenter/Co-Author)
Chinese Academy of Sciences, liufuting@ibcas.ac.cn;

Yuanhe Yang (Co-Presenter/Co-Author)
Chinese Academy of Sciences, yhyang@ibcas.ac.cn;

Pirkko Kortelainen (Co-Presenter/Co-Author)
Finnish Environment Institute, pirkko.kortelainen@ymparisto.fi;

Jaana Kolehmainen (Co-Presenter/Co-Author)
Finnish Environmental Institute SYKE, Jaana.Kolehmainen@ymparisto.fi;

Joshua F. Dean (Co-Presenter/Co-Author)
University of Liverpool, Joshua.Dean@liverpool.ac.uk;

Jorien E. Vonk (Co-Presenter/Co-Author)
Vrije Universiteit Amsterdam, j.e.vonk@vu.nl;

Robert Holmes (Co-Presenter/Co-Author)
Woods Hole Research Center, rmholmes@whrc.org;

Gilles Pinay (Co-Presenter/Co-Author)
CNRS, gilles.pinay@ens-lyon.fr;

Michaela M. Powell (Co-Presenter/Co-Author)
Montana State University, michaelamariepowell@gmail.com;

Jansen Howe (Co-Presenter/Co-Author)
Brigham Young University, jansen.howe35@gmail.com;

Rebecca Frei (Co-Presenter/Co-Author)
Brigham Young University, Department of Plant and Wildlife Sciences, beccafrei@gmail.com;

Samuel Bratsman (Co-Presenter/Co-Author)
Brigham Young University, Department of Plant and Wildlife Sciences, sbratsmanx@gmail.com;

Stephanie Ewing (Co-Presenter/Co-Author)
Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA, stephanie.ewing@montana.edu;

Abstract: Permafrost degradation delivers bioavailable dissolved organic matter (DOM) and inorganic nutrients to surface water networks. While these permafrost subsidies represent a small portion of total fluvial DOM, they could influence food webs and carbon balance via priming or nutrient effects. We investigated how addition of biolabile carbon and inorganic nutrients affected DOM decomposition with incubations of stream water from 23 locations in Asia, Europe, and North America. DOM loss ranged from 3% to 52%, showing a variety of longitudinal patterns within stream networks. DOM optical properties varied widely, but DOM showed compositional similarity based on FT?ICR MS analysis. Addition of acetate and nutrients decreased bulk DOM mineralization (i.e., negative priming), with more negative effects on biodegradable DOM but neutral or positive effects on stable DOM. Unexpectedly, acetate and nutrients triggered breakdown of colored DOM (CDOM), with median decreases of 1.6% in the control and 22% in the amended treatment. Additionally, the uptake of added acetate was strongly limited by nutrient availability across sites. These findings suggest that biolabile DOM and nutrients released from degrading permafrost may decrease background DOM mineralization but alter stoichiometry and light conditions in receiving waterbodies.

Jennifer Lento (Primary Presenter/Author)
Canadian Rivers Institute, Department of Biology, University of New Brunswick, jlento@gmail.com;

Brianna Levenstein (Co-Presenter/Co-Author)
Canadian Rivers Institute, Department of Biology, University of New Brunwsick, brianna.levenstein@unb.ca;

Annette Watson (Co-Presenter/Co-Author)
College of Charleston, WatsonAM@cofc.edu;

Ina Ivanova (Co-Presenter/Co-Author)
University of Charleston, ivanovaid@g.cofc.edu;

Jennie Knopp (Co-Presenter/Co-Author)
Oceans North, jennie.knopp@yahoo.com;

Abstract: Arctic Indigenous Peoples have for millennia relied on the ecosystem services provided by freshwaters, leading to a unique understanding of organisms and ecosystem processes and changes. Despite the importance of freshwater biodiversity and ecosystem services to Arctic Indigenous communities, there have been few attempts to summarize available Indigenous Knowledge (IK) of Arctic freshwaters and understand how conservation can benefit from such knowledge. We conducted a systematic literature review to summarize documented Arctic IK on freshwater biodiversity. Documented IK included species presence/richness, loss/gain of species, and habitat changes. Such information is vital to understanding changes in fish diversity, especially when long-term monitoring records do not exist. IK included habitat changes that are associated with a warming climate. Such observations by those who actively rely on Arctic freshwater ecosystem services signify that change is occurring and action is needed to mitigate the impacts on freshwaters. This study demonstrates that IK provides valuable information for determining Arctic freshwater biodiversity baselines and patterns of change.

Rebecca Frei (Co-Presenter/Co-Author)
Brigham Young University, Department of Plant and Wildlife Sciences, beccafrei@gmail.com;

Raymond Lee (Co-Presenter/Co-Author)
Brigham Young University, raymond.lee@byu.edu;

Tasha Griffin (Co-Presenter/Co-Author)
Brigham Young University, natasha.a.griffin@gmail.com;

Erin Jones (Co-Presenter/Co-Author)
Brigham Young University, erinfjones3@gmail.com;

Zachary Aanderud (Co-Presenter/Co-Author)
Brigham Young University, zachary_aanderud@byu.edu;

Arial Shogren (Co-Presenter/Co-Author)
University of Alabama, ashogren@ua.edu;

Frances Iannuci (Co-Presenter/Co-Author)
University of Vermont, fiannucc@gmail.com;

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

Samuel Bratsman (Co-Presenter/Co-Author)
Brigham Young University, Department of Plant and Wildlife Sciences, sbratsmanx@gmail.com;

Benjamin Abbott (Co-Presenter/Co-Author)
Brigham Young University, Department of Plant and Wildlife Sciences, benabbott@byu.edu;

William Breck Bowden (Co-Presenter/Co-Author)
University of Vermont, breck.bowden@uvm.edu;

Griffin Houston (Primary Presenter/Author,Co-Presenter/Co-Author)
Brigham Young University, griffinahouston@gmail.com;

Abstract: Many longitudinal differences in dissolved organic matter (DOM) exist in permafrost river networks. Downstream decreases in DOM biodegradability, age, and bulk concentration have been observed and interpreted as signs of in-stream microbial and photochemical processing. Alternatively or additionally, longitudinal patterns could be due to systematic differences in tributaries draining upland and lowland permafrost landscapes. Because vegetation type, flowpath, residence time, and microbial community differ with landscape position, the simple mixing of different water sources could create the observed longitudinal patterns of DOM in permafrost river networks. We tested this “dilution hypothesis” by quantifying DOM biodegradability and properties, microbial community, nutrient availability, and water chemistry in 140 catchments in Arctic Alaska ranging from 1-1000 km2. By comparing catchments of similar size but different landscape positions, we separated terrestrially-driven source effects from in-stream processing. We also used DNA amplicon sequencing to relate water chemistry and DOM biodegradability with microbial community.

Corrie Nyquist (Primary Presenter/Author)
Lund University, Sweden, nyqui095@alumni.umn.edu;

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

Bruce Vondracek (Co-Presenter/Co-Author)
Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota - Twin Cities, bvondrac@umn.edu;

Leonard C. Ferrington, Jr. (Co-Presenter/Co-Author)
University of Minnesota, ferri016@umn.edu;

Abstract: Climate change is predicted to warm Arctic and Subarctic temperatures at twice the rate of lower latitudes. In Iceland, chironomids emerge from streams throughout the summer and winter months. Warm air temperatures have been demonstrated to decrease longevities of adult cold-adapted chironomids collected in lower latitudes. Thus, warm air temperatures may alter similar aspects of life history for Icelandic chironomids emerging in summer. The goal of this project was to quantify the impact of warm air temperatures on longevity and timing of oviposition of adult summer-emerging chironomids in Iceland. Imagines were collected daily from 4 streams possessing a range of water temperatures (6-20°C) within the Hengill alpine geothermal valleys in 2019. Specimens were incubated at 6°C and 20°C in the laboratory post-collection and observed daily until dead. Longevity was significantly reduced in the warm treatment irrespective of stream site and adults oviposited significantly earlier at 20°C compared to adults held at 6°C. We found that chironomids emerging from both cold and warm streams in Iceland are equally susceptible to warming air temperature and may progress more rapidly through the adult phase of their life cycles.

Tanner Williamson (Primary Presenter/Author)
Michigan State University, tanner.williamson@gmail.com;

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

Arial Shogren (Co-Presenter/Co-Author)
University of Alabama, ashogren@ua.edu;

Amelia Grose (Co-Presenter/Co-Author)
Michigan State University, groseame@msu.edu ;

Abstract: The Arctic is warming at twice the rate of lower latitudes, altering the timing, volume, and pathways of water and solute movement through permafrost-underlain landscapes. Studying how climate change will manifest across the complex Arctic landscape is challenging, due to the interaction between landscape features and changing hydrology. Here, we apply an inductive inquiry approach to spatially-explicit landscape and stream solute chemistry data from repeated synoptic sampling events. Specifically, we leverage boosted regression tree (BRT) analyses to examine how landscape characteristics and season influence a suite of 40 stream solutes in 123 subcatchments nested within three watersheds on the North Slope of Alaska. The BRT approach revealed potentially critical links between landscape level watershed characteristics and solute concentrations in Arctic permafrost streams. Model predictive power varied widely for individual solutes (cross validation R2 range 0.007-0.915). Seasonality (early vs. late thaw) and watershed specific discharge frequently emerged as relatively high importance factors influencing stream solute chemistry. Interestingly, landscape characteristics that covered relatively small watershed areas were found to strongly influence some solutes. These findings offer critical insight into how climate change will interact with the complex Arctic landscape.