Ecology and Evolutionary Biology Commons^™

Integrated Management Of Billbugs (Coleoptera: Dryophthoridae) In Intermountain West Turfgrass, Madeleine M. Dupuy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Billbugs are a serious pest of turfgrass in the Intermountain West. Billbug larvae severely discolor and eventually kill turfgrass by feeding in stems, on roots, and on crowns of the plant. Billbugs are typically managed with preventive, calendar-based applications of insecticides. Most of our knowledge on the biology and management of billbugs comes from research in the eastern U.S, and little is known about billbug biology and best management practices in the Intermountain West. First, I examined the seasonal activity of billbug life stages in Intermountain West turfgrass and developed a predictive degree-day model to better time management strategies against …

Patterns Of Threatened Vertebrates Based On Trophic Level, Diet, And Biogeography, Shaley A. Valentine

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Humans have indirectly and directly contributed to the extinction of over 500 species within the past 500 years, a rate far higher than we have seen in the past. The high extinction rate and the fact that 18% of vertebrates may become extinct within the next century have pushed Earth into a biodiversity crisis. Understanding what makes species more at risk of extinction is needed to protect Earth’s biodiversity.

Generally, it is expected that predators have greater extinction risk than omnivores and herbivores because predators are larger in body size, depend on other animal species for food, need large home …

Biological Condition And Stressors Of Blm Wadeable Streams In Northeastern California And Northwestern Nevada, Nicole Cappuccio

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Taxpayer dollars can be used more efficiently by land management agencies to monitor streams if agency-wide monitoring protocols are adopted. To address this issue, the Bureau of Land Management (BLM) developed the National Aquatic Monitoring Framework (NAMF) to implement standardized assessments of stream condition and trend in the Western United States. As one of the first applications of the NAMF I sought to develop and apply an analytical framework to determine the biological condition of streams, extent of instream stressors and their impact on biological condition, and anthropogenic sources of stressors in Northeast California and Northwest Nevada over three years …

The Effects Of Enhanced Flows On Community Structure And Ecosystem Functioning In A Montane Utah River System, Joshua A. Epperly

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Due to growing human demands for freshwater within the last century, manmade flow alterations are now a common characteristic of rivers worldwide. Alterations to the volume and timing of flows in rivers are known to negatively impact aquatic biodiversity, biological productivity and ecosystem functions such as nutrient cycling. While previous research has focused on the effects of flow reductions and spates, there is a lack of knowledge on how high flows across longer timespans (i.e. ‘enhanced flows’) impact the structure of river communities and the integrity of ecosystem functions.

The Utah Reclamation, Mitigation and Conservation Commission has expressed interest in …

Invasive Phragmites Australis Management In Great Salt Lake Wetlands: Context Dependency And Scale Effects On Vegetation And Seed Banks, Christine B. Rohal

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Invasive plants can outcompete native plants, replacing diverse plant communities with monocultures, which can negatively impact the whole ecosystem. One invasive plant, Phragmites australis, has invaded wetlands across North America. In Utah’s Great Salt Lake, it has greatly reduced the area of native plants that are important habitat for migratory birds. Here we describe experiments that assess multiple treatments for Phragmites removal and evaluate the return of native plants after Phragmites management. The treatments were applied to Phragmites patches at two scales (small 1/4-acre plots and large 3-acre plots) and across multiple sites to evaluate how patch size and …

Effects Of Livestock Grazing Management Practices On Greater Sage-Grouse Nest And Female Survival, Seth J. Dettenmaier

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The decline in greater sage-grouse (Centrocercus urophasianus; sage-grouse) populations across western North America has been primarily attributed to loss and fragmentation of their sagebrush (Artemisia spp.) habitats. This habitat loss is largely the result of increased human activities, with grazing by domestic livestock as the most predominant land use across the sagebrush ecosystem in North America. The goal of my research was to increase our understanding of the effects of livestock on sage-grouse populations. I reviewed the peer-reviewed literature for all published studies that reported potential effects of grazing on grouse species worldwide. I found that there …

Development And Fitness Consequences Of Onshore Behavior Among Polar Bears In The Southern Beaufort Sea Subpopulation, Kate M. Lillie

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Polar bears (Ursus maritimus) are experiencing rapid and substantial changes to their environment due to global climate change. Polar bears of the southern Beaufort Sea (SB) have historically spent most of the year on the sea ice. However, recent reports from Alaska indicate that the proportion of the SB subpopulation observed onshore during late summer and early fall has increased considerably. Previous research suggests that the number of polar bears onshore is linked to sea ice conditions and the availability of subsistence-harvested whale carcasses, which are referred to as bone piles. My objectives were to determine the development …

Molecular Adaptations For Sensing And Securing Prey And Insight Into Amniote Genome Diversity From The Garter Snake Genome, Blair W. Perry, Daren C. Card, Joel W. Mcglothlin, Giulia I.M. Pasquesi, Richard H. Adams, Drew R. Schield, Nicole R. Hales, Andrew B. Corbin, Jeffery P. Demuth, Federico G. Hoffmann, Michael W. Vandewege, Ryan K. Schott, Nihar Bhattacharyya, Belinda S.W. Chang, Nicholas R. Casewell, Gareth Whiteley, Jacobo Reyes-Velasco, Stephen P. Mackessy, Tony Gamble, Kenneth B. Storey, Kyle K. Biggar, Courtney N. Passow, Chih-Horng Kuo, Suzanne E. Mcgaugh, Anne M. Bronikowski, A.P. Jason De Koning, Scott V. Edwards, Michael E. Pfrender, Patrick Minx, Edmund D. Brodie Jr., Edmund D. Brodie Jr., Wesley C. Warren, Todd A. Castoe

Biology Faculty Publications

Colubridae represents the most phenotypically diverse and speciose family of snakes, yet no well-assembled and annotated genome exists for this lineage. Here, we report and analyze the genome of the garter snake, Thamnophis sirtalis, a colubrid snake that is an important model species for research in evolutionary biology, physiology, genomics, behavior, and the evolution of toxin resistance. Using the garter snake genome, we show how snakes have evolved numerous adaptations for sensing and securing prey, and identify features of snake genome structure that provide insight into the evolution of amniote genomes. Analyses of the garter snake and other squamate reptile …

Genomic Variation Of Introduced Salvinia Minima In Southeastern United States, Carol A. Rowe, Donald P. Hauber, Paul G. Wolf

Ecology Center Publications

Common salvinia, Salvinia minima Baker (Salviniaceae), is a small, floating aquatic fern native to Central and South America that has invaded fresh water bodies in southeastern United States since the 1930s. We examined genetic variation across much of the introduced range of this species in the United States using codominant RAD-seq markers. Data from over 600 variable loci showed a reduction in heterozygosity from east to west in addition to a corresponding trend in assignment of samples to one of two genetic groups. Our data are consistent with previous published work and with the hypothesis that common salvinia had a …

It's Time To Listen: There Is Much To Be Learned From The Sounds Of Tropical Ecosystems, Jessica L. Deichmann, Orlando Acevedo-Charry, Leah Barclay, Zuzana Burivalova, Marconi Campos-Cerqueira, Fernando D'Horta, Edward T. Game, Benjamin L. Gottesman, Patrick J. Hart, Ammie K. Kalan, Simon Linke, Leandro Do Nascimento, Bryan Pijanowski, Erica Staaterman, T. Mitchell Aide

Wildland Resources Faculty Publications

Knowledge that can be gained from acoustic data collection in tropical ecosystems is low‐hanging fruit. There is every reason to record and with every day, there are fewer excuses not to do it. In recent years, the cost of acoustic recorders has decreased substantially (some can be purchased for under US$50, e.g., Hill et al. 2018) and the technology needed to store and analyze acoustic data is continuously improving (e.g., Corrada Bravo et al. 2017, Xie et al. 2017). Soundscape recordings provide a permanent record of a site at a given time and contain a wealth of …

Fitness Consequences Of Interspecific Nesting Associations Among Cavity-Nesting Birds, James C. Mouton, Thomas E. Martin

Aspen Bibliography

Interspecific aggregations of prey may provide benefits by mitigating predation risk, but they can also create costs if they increase competition for resources or are more easily detectable by predators. Variation in predation risk and resource availability may influence the occurrence and fitness effects of aggregating in nature. Yet tests of such possibilities are lacking. Cavity-nesting birds provide an interesting test case. They compete aggressively for resources and experience low nest predation rates, which might predict dispersion, but across 19 years of study we found that they commonly aggregate by sharing nest trees. Tree sharing was more common when aspen …

Removal Of Invasive Plants From Pando Exclosure 2018, Marc Coles-Ritchie

Aspen Bibliography

On July 10-11, 2018 volunteers and staff from Great Old Broads for Wilderness and Grand Canyon Trust removed invasive plants from the Pando exclosure, a fenced portion of the Pando Clone aspen forest adjacent to Fish Lake, in Central Utah. This area has been fenced to restore a portion of the Pando Clone that has been lacking recruitment for decades, by protecting young aspen from browsing by deer and cattle. We have been removing invasive species for five years from this exclosure.

The 2018 trip included 10 women and one staffer of Great Old Broads for Wilderness, from the states …

Phytochemical Screening Of Quaking Aspen (Populus Tremuloides) Extracts By Uplc-Qtof-Ms And Evaluation Of Their Antimicrobial Activity, Annabelle St-Pierre, Dorian Blondeau, André Lajeunesse, Julien Bley, Nathalie Bourdeau, Isabel Desgagné-Penix

Aspen Bibliography

The continual emergence of pathogen resistance is a recurring challenge and pushes for the development of antimicrobial compounds. Here, we investigated compounds from quaking aspen trees (Populus tremuloides) as potential antimicrobial agents. Several extractions using different solvents were realized, and corresponding antimicrobial activity was tested against eight microorganisms. Results revealed that polar extraction solvents including water, ethanol and methanol gave the best extraction yields (>15.07%). Minimal inhibition concentration (MIC) and minimal bactericidal/fungicidal concentration (MBC/MFC) demonstrated that water extracts had the best antimicrobial activity by a weak to moderate inhibition of growth of all eight tested microorganisms in addition to …

Development Of On-Shore Behavior Among Polar Bears (Ursus Maritimus) In The Southern Beaufort Sea: Inherited Or Learned?, Kate M. Lillie, Eric M. Gese, Todd C. Atwood, Sarah A. Sonsthagen

Wildland Resources Faculty Publications

Polar bears (Ursus maritimus) are experiencing rapid and substantial changes to their environment due to global climate change. Polar bears of the southern Beaufort Sea (SB) have historically spent most of the year on the sea ice. However, recent reports from Alaska indicate that the proportion of the SB subpopulation observed on-shore during late summer and early fall has increased. Our objective was to investigate whether this on-shore behavior has developed through genetic inheritance, asocial learning, or through social learning. From 2010 to 2013, genetic data were collected from SB polar bears in the fall via hair snags …

Fern Genomes Elucidate Land Plant Evolution And Cyanobacterial Symbioses, Fay-Wei Li, Paul Brouwer, Lorenzo Carretero-Paulet, Shifeng Cheng, Jan De Vries, Pierre-Marc Delaux, Ariana Eily, Nils Koppers, Li-Yaung Kuo, Zheng Li, Mathew Simenc, Ian Small, Eric Wafula, Stephany Angarita, Michael S. Barker, Andrea Bräutigam, Claude Depamphilis, Sven Gould, Prashant S. Hosmani, Yao-Moan Huang, Bruno Huettel, Yoichiro Kato, Xin Liu, Steven Maere, Rose Mcdowell, Lukas A. Mueller, Klaas G. J. Nierop, Stefan A. Rensing, Tanner A. Robison, Carl J. Rothfels, Erin M. Sigel, Yue Song, Prakash R. Timilsena, Yves Van De Peer, Hongli Wang, Per K. I. Wilhelmsson, Paul G. Wolf, Xun Xu, Joshua P. Der, Henriette Schluepmann, Gane K.-S. Wong, Kathleen M. Pryer

Biology Faculty Publications

Ferns are the closest sister group to all seed plants, yet little is known about their genomes other than that they are generally colossal. Here, we report on the genomes of Azolla filiculoides and Salvinia cucullata (Salviniales) and present evidence for episodic whole-genome duplication in ferns—one at the base of ‘core leptosporangiates’ and one specific to Azolla. One fern-specific gene that we identified, recently shown to confer high insect resistance, seems to have been derived from bacteria through horizontal gene transfer. Azolla coexists in a unique symbiosis with N2-fixing cyanobacteria, and we demonstrate a clear pattern of cospeciation between …

The Role Of Small Ruminants On Global Climate Change, Alda Lúcia Gomes Monteiro, Amanda Moser Coelho Da Fonseca Faro, Mylena Taborda Piquera Peres, Rafael Batista, Cesar Henrique Espirito Candal Poli, Juan J. Villalba

Wildland Resources Faculty Publications

Global warming, as a consequence of excessive CO2 production mainly due to anthropogenic actions, is one of the main concerns of society due to the effects it can cause in the survival of humans, plants and animals. Several climatic consequences have already been reported, such as warming the oceans and changing biodiversity in various regions of the planet. One of the greenhouse gases responsible for global warming, which causes a lot of concern, is methane gas from digestion of food by ruminants. Besides that, emissions of greenhouse gases are represented also by waste management, rice cultivation, burning of residues from …

Competition And Coexistence In Plant Communities: Intraspecific Competition Is Stronger Than Interspecific Competition, Peter B. Adler, Danielle Smull, Karen H. Beard, Ryan T. Choi, Tucker J. Furniss, Andrew Kulmatiski, Joan M. Meiners, Andrew T. Tredennick, Kari E. Veblen

Ecology Center Publications

Theory predicts that intraspecific competition should be stronger than interspecific competition for any pair of stably coexisting species, yet previous literature reviews found little support for this pattern. We screened over 5400 publications and identified 39 studies that quantified phenomenological intraspecific and interspecific interactions in terrestrial plant communities. Of the 67% of species pairs in which both intra‐ and interspecific effects were negative (competitive), intraspecific competition was, on average, four to five‐fold stronger than interspecific competition. Of the remaining pairs, 93% featured intraspecific competition and interspecific facilitation, a situation that stabilises coexistence. The difference between intra‐ and interspecific effects tended …

Diel Predator Activity Drives A Dynamic Landscape Of Fear, Michel T. Kohl, Daniel R. Stahler, Matthew C. Metz, James D. Forester, Matthew J. Kauffman, Nathan Varley, P. J. White, Douglas W. Smith, Daniel R. Macnulty

Ecology Center Publications

A “landscape of fear” (LOF) is a map that describes continuous spatial variation in an animal's perception of predation risk. The relief on this map reflects, for example, places that an animal avoids to minimize risk. Although the LOF concept is a potentially unifying theme in ecology that is often invoked to explain the ecological and conservation significance of fear, little is known about the daily dynamics of an LOF. Despite theory and data to the contrary, investigators often assume, implicitly or explicitly, that an LOF is a static consequence of a predator's mere presence within an ecosystem. We tested …

Improved Prediction Of Stream Flow Based On Updating Land Cover Maps With Remotely Sensed Forest Change Detection, Alexander J. Hernandez, Sean P. Healey, Hongsheng Huang, R. Douglas Ramsey

Wildland Resources Faculty Publications

The water balance in a watershed can be disrupted by forest disturbances such as harvests and fires. Techniques to accurately and efficiently map forest cover changes due to disturbance are evolving quickly, and it is of interest to ask how useful maps of different types of disturbances over time can be in the prediction of water yield. We assessed the benefits of using land cover maps produced at annual vs. five-year intervals in the prediction of monthly streamflows across 10 watersheds contained entirely within the US National Forest System. We found that annually updating land cover maps with forest disturbance …

Empirical Correspondence Between Trophic Transfer Efficiency In Freshwater Food Webs And The Slope Of Their Size Spectra, Thomas Mehner, Betty Lischke, Kristin Scharnweber, Katrin Attermeyer, Soren Brothers, Ursula Gaedke, Sabine Hilt, Sandra Brucet

Watershed Sciences Faculty Publications

The density of organisms declines with size, because larger organisms need more energy than smaller ones and energetic losses occur when larger organisms feed on smaller ones. A potential expression of density-size distributions are Normalized Biomass Size Spectra (NBSS), which plot the logarithm of biomass independent of taxonomy within bins of logarithmic organismal size, divided by the bin width. Theoretically, the NBSS slope of multi-trophic communities is exactly 1.0 if the trophic transfer efficiency (TTE, ratio of production rates between adjacent trophic levels) is 10% and the predator-prey mass ratio (PPMR) is fixed at 104 . Here we provide evidence …

High Interspecific Variation In Nutrient Excretion Within A Guild Of Closely Related Caddisfly Species, Jared A. Balik, Brad W. Taylor, Susan E. Washko, Scott A. Wissinger

Watershed Sciences Faculty Publications

Understanding the amount of variation in functional traits between closely related species within guilds is critical for understanding links between community composition and ecosystem processes. Nutrient excretion is an important link between animals and their environments, and aquatic invertebrate communities can supply a considerable proportion of ecosystem nutrient demand via excretion. We quantified nitrogen (N) and phosphorus (P) excretion rates of 10 species of larval caddisflies that inhabit high‐elevation ponds and wetlands to determine the magnitude of variation in nutrient excretion within this guild. We found considerable interspecific variation in biomass‐specific excretion of nitrogen (eightfold differences), phosphorus (sevenfold differences), and …

On The Relationship Between Phylogenetic Diversity And Trait Diversity, Caroline M. Tucker, T. Jonathan Davies, Marc W. Cadotte, William D. Pearse

Biology Faculty Publications

Niche differences are key to understanding the distribution and structure of biodiversity. To examine niche differences, we must first characterize how species occupy niche space, and two approaches are commonly used in the ecological literature. The first uses species traits to estimate multivariate trait space (so‐called functional trait diversity, FD); the second quantifies the amount of time or evolutionary history captured by a group of species (phylogenetic diversity, PD). It is often—but controversially—assumed that these putative measures of niche space are at a minimum correlated and perhaps redundant, since more evolutionary time allows for greater accumulation of trait changes. This …

The Influence Of Multiyear Drought-Driven Habitat Loss On The Bear Lake Sculpin (Cottus Extensus) And The Bear Lake Strain Of The Bonneville Cutthroat Trout (Oncorhynchus Clarkii Utah), Hayley C. Glassic

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Multiyear drought is expected to increase in occurrence and severity in dry regions across the world, such as the American Southwest, endangering native species and ecosystem health. The effects of multiyear drought are often worsened by human water use for consumption, energy production, and agriculture, which, in lakes and reservoirs, cause reduced lake elevation. Reductions in lake elevation may leave previously submerged habitat stranded along shorelines and make tributaries inaccessible to fishes. Here, we show that decreasing lake elevation, associated with drought and water withdrawal, reduces the availability of shoreline cobble habitat to fishes and increases tributary distance by creating …

Using Remotely Piloted Aircraft And Infrared Technology To Detect And Monitor Greater Sage-Grouse, Thomas R. Thompson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In wildlife management, using cutting edge technology and science to monitor greater sage-grouse (Centrocercus urophasianus; sage-grouse) populations, enables land managers to better assess the impact of their management decisions. Having precise counts of sage-grouse lek attendance, and specifically male lek attendance, is an important metric used to evaluate population status and response to conservation actions (Gifford et.al, 2013, Dahlgren et al., 2016). Leks are seasonal breeding sites where males perform a ritualistic courtship dance for females.

Our case study examined if a Remotely Piloted Aircraft (RPA) was effective in detecting, and counting, sage-grouse during the lek season (early …

Novel Treatments For Native Forb Restoration In The Great Basin, Adam J. Fund

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Public land management agencies, conservation organizations, and landowners are interested in expanding the diversity of plant species used in rangeland restoration seedings. While the restoration of native grasses and shrubs in the Great Basin has become increasingly successful, restoration of native forbs continues to be problematic. In the Great Basin, soil water availability and soil fungal pathogens are thought to limit to restoration success. During the course of two years, we conducted two field experiments at three sites in the Great Basin that spanned a latitudinal gradient encompassing different precipitation and temperature patterns.

In the first experiment, we evaluated two …

Foraging Behavior, Taxonomy, And Morphology Of Bees (Hymenoptera: Apoidea), With An Emphasis On Perdita (Hymenoptera: Andrenidae), Zachary M. Portman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Bees are the most important pollinators of flowering plants and are necessary for pollinating both wild plants and many of the crops that produce the food we eat. There are many different species of bees, with about 20,000 species worldwide and 4,000 species in the United States. Even though bees are important pollinators, there is still much we do not know about how many species there are and their biology. In order to better understand the species and their biology, I performed three projects that help fill these gaps by reviewing the species of a poorly known bee group, examining …

Assessment Of A Seedling-Based Approach To Aspen Restoration In The Intermountain West, Alexander Addison Howe

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Quaking aspen (Populus tremuloides) is an important species ecologically and culturally in the western U.S., where it is one of the only broadleaf trees in the mostly conifer-dominated forests. Aspen management in the West has focused on regenerating existing stands vegetatively through root suckering, however this approach is restricted to locations where aspen currently exists and limits the genetic diversity of aspen populations. Planting nursery-grown aspen seedlings offers a potential method for overcoming these limitations, but it has received little attention in the U.S. Intermountain West (IW) to date. In order for this approach to be more broadly …

The Relationship Between Measures Of Annual Livestock Disturbance In Western Riparian Areas And Stream Conditions Important To Trout, Salmon, And Char, Lindsey M. Goss, Brett B. Roper

Watershed Sciences Faculty Publications

Managing livestock disturbance in riparian zones in a manner that provides economic returns to ranchers while protecting streams is an important aspect of rangeland management on public lands in the western United States. Attempts to balance economic and ecologic outcomes have been made more difficult due to the presence of several salmonid species that are protected under the Endangered Species Act. One approach to proper management of livestock use near streams has been to define the allowable limits of disturbance using 2 metrics, streambank alteration and stubble height. We evaluated 153 stream reaches within the Interior Columbia Basin to determine …

Weak Interspecific Interactions In A Sagebrush Steppe? Conflicting Evidence From Observations And Experiments, Peter B. Adler, Andrew R. Kleinhesselink, Giles Hooker, Joshua B. Taylor, Brittany J. Teller, Stephen P. Ellner

Wildland Resources Faculty Publications

Stable coexistence requires intraspecific limitations to be stronger than interspecific limitations. The greater the difference between intra‐ and interspecific limitations, the more stable the coexistence, and the weaker the competitive release any species should experience following removal of competitors. We conducted a removal experiment to test whether a previously estimated model, showing surprisingly weak interspecific competition for four dominant species in a sagebrush steppe, accurately predicts competitive release. Our treatments were (1) removal of all perennial grasses and (2) removal of the dominant shrub, Artemisia tripartita. We regressed survival, growth, and recruitment on the locations, sizes, and species identities …

Light May Have Triggered A Period Of Net Heterotrophy In Lake Superior, Soren Brothers, Paul Sibley

Ecology Center Publications

Recent studies of Lake Superior, the Earth's largest freshwater lake by surface area, describe it as net heterotrophic (primary production < community respiration), making it a net source of carbon dioxide (CO2) to the atmosphere. This conclusion is largely based on measurements made between 1998 and 2001. We present a long‐term (1968–2016) analysis of ice‐free (April–November) surface oxygen (O2) saturation data collected by monitoring agencies. These data indicate that Lake Superior's surface waters are typically supersaturated with dissolved O2 from May to September (May–September mean is 103.5% ± 0.6%; pooled mean from April, October, and November is 97.6% ± 1.1%, standard error of the mean). However, these data also support prior studies which describe a state of net heterotrophy from 1998 to 2001. We investigated potential triggers for a transient heterotrophic period and discuss the sources of organic carbon necessary to fuel net heterotrophy in a large oligotrophic lake. We conclude that net heterotrophy likely resulted from an increase in light period and penetration driven by declines in cloud cover, increases in water clarity, and a reduction of winter ice cover following the 1997–1998 El Niño. Together, these could have depleted a pre‐existing pool of dissolved organic carbon (DOC) via photomineralization and/or photochemical degradation. Our results indicate that Lake Superior is typically net autotrophic (calculated annual CO2 influx = ∼ 0.4 Tg C). These results highlight how water clarity and aquatic DOC pools may interact to induce net metabolic shifts in large oligotrophic aquatic ecosystems.