Faculty and Staff Publications

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An introduction to legal research of Indigenous legal orders
(Emond Montgomery Publications, 2024) Asch, Jessica; Williamson, Tara
This chapter has been written with various audiences in mind, but with the overarching premise that if a reader is accessing this text, it is in the spirit of being a student of Indigenous law. This includes students of law or other disciplines, and legal educators, lawyers, and researchers. The authors come from a practice rooted in community-led research and partnership, so considerable emphasis is placed on ethical relationship-building and community engagement, which are cornerstones of their practice. The purpose of this research and writing may dictate the extent to which some of these practices will be relevant or the amount of attention they will require. For example, a student drafting a paper for a class may not engage in much primary research or embedded learning. Still, understanding the history, context, and importance of rigorous, ethical research in Indigenous law is imperative for responsible scholarship in the field.
Using fish to understand how cities affect sexual selection before and after mating
(Frontiers in Ecology and Evolution, 2022) Marques, Piatã; Zandonà, Eugenia; Amaral, Jeferson; Selhorst, Yasmin; El-Sabaawi, Rana; Mazzoni, Rosana; Castro, Letícia; Pilastro, Andrea
Urbanization transforms natural and agricultural areas into built landscapes. Such profound habitat alteration imposes strong pressure for phenotypic trait changes through processes related to natural and/or sexual selection. Evidence for how natural selection drives changes to traits in urban biota is increasing, but little is known about the role of sexual selection. In this study, we assess the effect of urbanization on the expression and interaction of males` pre-mating traits (body size and color) and a post-mating trait (sperm load). We used a widespread invasive species, the guppy (Poecilia reticulata), which is a well-known model for studying sexual selection, but has never been studied in urban systems for this purpose. We found that urbanization did not affect mean body size or condition, but it resulted in size-dependent reductions in the expression of orange and iridescent colors, as well as sperm load. Orange color was reduced in small urban guppies, while the iridescent colors were reduced in large urban guppies compared to non-urban guppies. Difference in sperm load was only found in large males, with lower sperm load in urban guppies. The relationship between orange color and sperm load was positive in urban guppies but negative in non-urban guppies, while the association between iridescent color and sperm load followed the opposite pattern. Our findings suggest that sexual selection on pre- and post-mating traits is weaker in urban than non-urban systems and that interactions between such traits are context dependent. These responses can be related to the pollution and altered visual environment of urban systems and provide an opportunity to advance our understanding of the mechanisms determining adaptation in cities.
Urbanization can increase the invasive potential of alien species
(Journal of Animal Ecology, 2020) Santana Marques, Piatã; Resende Manna, Luisa; Clara Frauendorf, Therese; Zandonà, Eugenia; Mazzoni, Rosana; El-Sabaawi, Rana
Alien species often flourish and become invasive in urban ecosystems. How and why invaders succeed in urban systems is an important, yet poorly understood, question. We investigate whether the success of urban invaders is related to changes in species traits that enhance invasive potential. We also explore whether a trophic mechanism helps explain the success of invaders in urban systems. We use the guppy Poecilia reticulata, a globally distributed alien species that has invaded both urban and non-urban systems, as our model. We first characterize the effect of urbanization on streams where guppies are present. We measure guppy invasion success using their population density and size-frequency. Then we assess how traits that are related to the potential of guppies to invade (life history and condition) respond to urbanization. Next, we explore how urbanization affects the availability of food for guppies and their diets. We also test if the presence of other fish species grants biological resistance to invasion by dampening guppy invasive potential. We find that urban streams have high concentrations of ammonium and faecal coliforms, indicating contamination from sewage. On average, guppy populations from urban streams have 26? higher density and larger body sizes than non-urban populations. Urban guppies are in better condition and have on average five more offspring than non-urban guppies. Urbanization increases the availability and consumption of highly nutritious food (chironomid larvae) by guppies. We find a positive relationship between the consumption of chironomids and both fecundity and condition. The presence of other fish species in urban streams often has a negative but small effect on guppy traits and density. Our data suggest a relaxation of trade-offs that shape life-history traits which is related to increased food resources in urban streams. These indicate that urbanization enhances the invasive potential of guppies through a trophic mechanism that simultaneously increases reproduction and somatic investment. Such mechanism is likely widespread because chironomids are often highly abundant in urban systems. Thus, not only guppies but also other invasive species can take advantage of such a resource to invest in traits that enhance invasion success.
Intraspecific trait variation in urban stream ecosystems: Toward understanding the mechanisms shaping urban stream communities
(Freshwater Science, 2019) Marques, Piatã S.; Manna, Luisa R.; Mazzoni, Rosana; El-Sabaawi, Rana
The rapid expansion of urban centers is a critical threat to stream ecosystems, yet we currently lack mechanistic understanding of the effects of urbanization on stream communities. Here we explore how an intraspecific trait perspective can unveil mechanisms of change in urban stream communities. Intraspecific trait approaches are rarely used in urban aquatic ecosystems though their potential has been widely demonstrated in terrestrial systems. We begin by identifying several biotic and abiotic agents that can drive intraspecific trait changes in life history, behavior, morphology, and feeding in a range of urban stream organisms. We then propose that intraspecific trait-based approaches in urban streams can help explain the mechanisms underlying species persistence, biodiversity responses, functionality, and evolution and how they can potentially improve biomonitoring in urban streams. This trait-based information is essential to better understand, predict, and manage the impacts of urbanization on stream biota.
A new method to reconstruct quantitative food webs and nutrient flows from isotope tracer addition experiments
(The American Naturalist, 2020) López-Sepulcre, Andrés; Bruneaux, Matthieu; Collins, Sarah M.; El-Sabaawi, Rana; Flecker, Alexander S.; Thomas, Steven A.
Understanding how nutrients flow through food webs is central in ecosystem ecology. Tracer addition experiments are powerful tools to reconstruct nutrient flows by adding an isotopically enriched element into an ecosystem and tracking its fate through time. Historically, the design and analysis of tracer studies have varied widely, ranging from descriptive studies to modeling approaches of varying complexity. Increasingly, isotope tracer data are being used to compare ecosystems and analyze experimental manipulations. Currently, a formal statistical framework for analyzing such experiments is lacking, making it impossible to calculate the estimation errors associated with the model fit, the interdependence of compartments, and the uncertainty in the diet of consumers. In this article we develop a method based on Bayesian hidden Markov models and apply it to the analysis of 15 N ⁢‐NH4+ N15⁢‐NH4+ tracer additions in two Trinidadian streams in which light was experimentally manipulated. Through this case study, we illustrate how to estimate N fluxes between ecosystem compartments, turnover rates of N within those compartments, and the associated uncertainty. We also show how the method can be used to compare alternative models of food web structure, calculate the error around derived parameters, and make statistical comparisons between sites or treatments.
Using a space-for-time substitution approach to predict the effects of climate change on nutrient cycling in tropical island stream ecosystems
(Limnology and Oceanography, 2020) Frauendorf, Therese C.; MacKenzie, Richard A.; Tingley III, Ralph W.; Infante, Dana M.; El-Sabaawi, Rana
Climate change is expected to alter precipitation patterns worldwide, which can have direct effects on streamflow dynamics. In many tropical regions, climate-driven changes in rainfall are predicted to decrease streamflow and increase flash flooding, but the implications of these changes for stream ecosystem function are poorly understood. We used a rainfall gradient on Hawaii Island that mimics projected changes in rainfall and streamflow in order to estimate how climate change affects nutrient recycling. We measured per-capita excretion (nitrogen, phosphorus) and egestion rates of three dominant taxa (shrimp, caddisfly, midge) in eight streams along the gradient for 3 years. We scaled these rates to the population and community levels and measured nitrogen and phosphorus demand of the ecosystem to estimate if the relative contribution of nutrients supplied by invertebrates changes along the gradient. Across all three taxa, population egestion and excretion rates declined by 10-fold in drier streams. These declines were driven by lower population density, rather than differences in per-capita rates. Under the current climate scenario, community excretion supplied up to 70% of the nitrogen demand, which was 10-fold lower with projected changes in rainfall. Conversely, community excretion supplied up to 5% of the phosphorus demand, which did not vary across the rainfall gradient. This difference indicates that climate change may exacerbate nitrogen limitations in tropical island streams, and change the balance of nitrogen and phosphorus dynamics. Our study also demonstrates that space-for-time substitutions are a valuable tool to examine implications of climate change on ecosystem function in freshwater systems.
SEED: A framework for integrating ecological stoichiometry and eco-evolutionary dynamics
(Ecology Letters, 2023) El-Sabaawi, Rana; Lemmen, Kimberley D.; Jeyasingh, Punidan D.; Declerck, Steven A. J.
Characterising the extent and sources of intraspecific variation and their ecological consequences is a central challenge in the study of eco-evolutionary dynamics. Ecological stoichiometry, which uses elemental variation of organisms and their environment to understand ecosystem patterns and processes, can be a powerful framework for characterising eco-evolutionary dynamics. However, the current emphasis on the relative content of elements in the body (i.e. organismal stoichiometry) has constrained its application. Intraspecific variation in the rates at which elements are acquired, assimilated, allocated or lost is often greater than the variation in organismal stoichiometry. There is much to gain from studying these traits together as components of an ‘elemental phenotype’. Furthermore, each of these traits can have distinct ecological effects that are underappreciated in the current literature. We propose a conceptual framework that explores how microevolutionary change in the elemental phenotype occurs, how its components interact with each other and with other traits, and how its changes can affect a wide range of ecological processes. We demonstrate how the framework can be used to generate novel hypotheses and outline pathways for future research that enhance our ability to explain, analyse and predict eco-evolutionary dynamics.
Thermal performance of ecosystems: Modeling how physiological responses to temperature scale up in communities
(Journal of Theoretical Biology, 2024) Febvre, Camille; Goldblatt, Colin; El-Sabaawi, Rana
Understanding how ecosystems respond to their environmental temperature is a major challenge. Thermodynamic constraints on species’ metabolic rates are expected to affect ecosystem characteristics, but species interactions and interspecific variation in physiological thermal response curves (TRC) may obscure ecosystem-level responses to temperature. As a result, macroecological patterns related to temperature are still poorly understood. We investigate how physiological TRC scale up to ecosystem-level thermal responses by modifying the Tangled Nature (TaNa) model, a stochastic network model of ecology and evolution. We include new parameterizations that make reproduction, death, and mutation temperature-dependent. We find that ecosystem survival probability depends on how the minimum fitness required for species survival varies with temperature. The thermal response of ecosystem survival probability is the only ecosystem property that is sensitive to interspecific variation in TRC. Species richness scales up directly from the TRC of mutation rate, and average species population sizes are inversely related to mutation rate, with Species Abundance Distributions (SADs) exhibiting more rare species in warmer temperatures. Interactions between species are also inversely related to mutation, with positive interactions occurring more frequently in colder temperatures. The abundance of surviving ecosystems is not sensitive to temperature. This work helps clarify the specific relationships between physiological responses to temperature and ecosystem-level repercussions when species are interacting and adapting to their thermal environments.
Mass and heat transfer resistivities at liquid–vapor interfaces: Beyond the ideal gas
(International Journal of Heat and Mass Transfer, 2025) Struchtrup, Henning
The classical Hertz–Knudsen–Schrage (HKS) model for non-equilibrium mass and heat transfer across liquid–vapor interfaces is extended to account for real gas effects and non-linearity. Specifically, the HKS relations are re-derived for a temperature and velocity dependent condensation coefficient (Tsuruta et al., 1999) and combined with real gas property relations derived from the Enskog–Vlasov (EV) equation (Struchtrup and Frezzotti, 2022). The resulting non-linear Tsuruta–EV–HKS model is valid for mass and heat transfer up to the critical point. The resulting interfacial resistivities exhibit marked dependence on temperature, with resistivities strongly decreasing towards the critical point, as well as non-linear dependence on mass and heat flux.
Bridging Knowledge Cultures: Rebalancing Power in the Co-Construction of Knowledge
(Brill, 2024) Lepore, Walter; Hall, Budd L.; Tandon, Rajesh
Establishing truly respectful, mutually beneficial, and equitable knowledge creation partnerships with diverse communities poses significant challenges for academia. Bridging Knowledge Cultures provides valuable insights into the dynamics involved and the obstacles encountered when attempting to establish meaningful research partnerships between different knowledge domains. This book goes beyond exploration by offering practical recommendations to overcome these challenges and forge effective collaboration between mainstream research institutions and community groups and organizations. This book includes ten compelling case studies conducted by research and training hubs established through the global Knowledge for Change Consortium. These case studies encompass community-university research partnerships across various geographical locations, tackling a wide range of societal issues and acknowledging the wealth of knowledge created by local communities. The overarching goal of this book is to inspire the next generation of researchers and professionals to embrace the richness of diverse perspectives and knowledge cultures. By advocating for the construction of "bridges" through practical approaches, the book encourages a shift from competition to collaboration in research. Ultimately, it aims to foster an environment where different forms of knowledge can intersect and thrive, leading to a more inclusive and comprehensive understanding of the world around us.
Should we think of observationally constrained multidecade climate projections as predictions?
(Science Advances, 2025) Li, Tong; Zwiers, Francis W.; Zhang, Xuebin
Empirical evidence indicates that the range of model-projected future warming can be successfully narrowed by conditioning the projected warming on past observed warming. We demonstrate that warming projections conditioned on the entire instrumental annual surface temperature record are of sufficiently high quality and should be considered as long-term predictions rather than merely as projections. We support this view by considering the skill of predicted 20- and 50-year lead temperature changes under the Shared Economic Pathway (SSP)1-2.6 and SSP5-8.5 emission scenarios in climates of different sensitivities. Using climate model simulations, we show that adjusting raw multimodel projections of future warming with the Kriging for Climate Change (KCC) method eliminates most biases and reduces the uncertainty of warming projections irrespective of the sensitivity of the climate being considered. Simpler methods, or using only the more recent part of the temperature record, provide less effective constraints. The high-skill future warming predictions obtained via KCC have a serious place in informing global climate policies.
Land temperature and hydrological conditions over B.C. in 2024
(Department of Fisheries and Oceans, 2025) Curry, Charles L.; Lang, Kristyn; Dah, Abigail
2024 was the second warmest year since 1940 in B.C., exceeded only by record warm temperatures in 2023. Snowpack increased from well below-normal to below-normal through the early winter, decreasing again to well below-normal by late spring. Compared to 2023 drought conditions were less severe overall; however, basins in the Northeast continued to experience extreme drought. The annual mean temperature in B.C. is increasing and can be distinguished from natural variability over the analyzed period of 1940-2024. Annual precipitation, however, exhibits no significant province-wide trend over that period.
Land temperature and hydrological conditions over B.C. in 2023
(Department of Fisheries and Oceans, 2024) Curry, Charles L.; Lang, Kristyn
In 2023, B.C. experienced record warm annual, summer and fall temperatures and well below-normal annual precipitation. Snowpack was generally below-normal through the winter, rapidly decreasing to well below-normal by June 1st due to early snowmelt across the province. In late summer and fall, severe drought conditions were experienced nearly everywhere in B.C., coinciding with record warm temperatures and below-normal precipitation. The trend in annual mean temperature in B.C. is positive and can be distinguished from natural variability over the analyzed period, 1950-2023. Annual precipitation, however, exhibits no significant trend over that period.
Constraining the entire Earth system projections for more reliable climate change adaptation planning
(Science Advances, 2025) Li, Chao; Zwiers, Francis W.; Zhang, Xuebin; Fischer, Erich M.; Du, Fujun; Liu, Jieyu; Wang, Jianyu; Liang, Yongxiao; Li, Tong; Yuan, Lina
The warming climate is creating increased levels of climate risk because of changes to the hazards to which human and natural systems are exposed. Projections of how those hazards will change are affected by uncertainties in the climate sensitivity of climate models, among other factors. While the level-of-global-warming approach can circumvent model climate sensitivity uncertainties in some applications, practitioners faced with specific adaptation responsibilities often find such projections difficult to use because they generally require time-oriented information. Earth system projections following specified emissions scenarios can, however, be constrained by applying the level-of-global-warming approach to observationally constrained warming projections to yield more reliable time-oriented projections for adaption planning and implementation. This approach also allows individual groups to produce consistent and comparable assessments of multifaceted climate impacts and causal mechanisms, thereby benefiting climate assessments at national and international levels that provide the science basis for adaptation action.
Bright but flickering lights of sustainable, community-based groundwater supply and management: ASADAS in Costa Rica
(Environmental Research Letters, 2025) Madrigal-Ballestero, Róger; Gleeson, Tom; López-Ruiz, Mariaclara; Castillo-Cruz, Aaron Benhur
Groundwater, a quintessential invisible natural resource, is often misunderstood and mismanaged due to scale and management approaches as well as geographic and disciplinary biases (Giordano 2009, Gleeson et al 2020, Lall et al 2020). While groundwater management and sustainability discussions typically focus on large scales, such as regional aquifers and global analyses (Scanlon et al 2023), it is crucial to recognize that groundwater systems and sustainability occur across multiple scales (Foster et al 2013), from individual wells to large aquifers and even global virtual groundwater trade (Dalin et al 2017).
Groundwaterscapes: A global classification and mapping of groundwater's large-scale socioeconomic, ecological, and Earth system functions
(Water Resources Research, 2024) Huggins, Xander; Gleeson, Tom; Villholth, Karen G.; Rocha, Juan C.; Famiglietti, James S.
Groundwater is a dynamic component of the global water cycle with important social, economic, ecological, and Earth system functions. We present a new global classification and mapping of groundwater systems, which we call groundwaterscapes, that represent predominant configurations of large-scale groundwater system functions. We identify and map 15 groundwaterscapes which offer a new lens to conceptualize, study, model, and manage groundwater. Groundwaterscapes are derived using a novel application of sequenced self-organizing maps that capture patterns in groundwater system functions at the grid cell level (∼10 km), including groundwater-dependent ecosystem type and density, storage capacity, irrigation, safe drinking water access, and national governance. All large aquifer systems of the world are characterized by multiple groundwaterscapes, highlighting the pitfalls of treating these groundwater bodies as lumped systems in global assessments. We evaluate the distribution of Global Groundwater Monitoring Network wells across groundwaterscapes and find that industrial agricultural regions are disproportionately monitored, while several groundwaterscapes have next to no monitoring wells. This disparity undermines the ability to understand system dynamics across the full range of settings that characterize groundwater systems globally. We argue that groundwaterscapes offer a conceptual and spatial tool to guide model development, hypothesis testing, and future data collection initiatives to better understand groundwater's embeddedness within social-ecological systems at the global scale.
The influence of topography on the global terrestrial water cycle
(Reviews of Geophysics, 2025) Gnann, Sebastian; Baldwin, Jane W.; Cuthbert, Mark O.; Gleeson, Tom; Schwanghart, Wolfgang; Wagener, Thorsten
Topography affects the distribution and movement of water on Earth, yet new insights about topographic controls continue to surprise us and exciting puzzles remain. Here we combine literature review and data synthesis to explore the influence of topography on the global terrestrial water cycle, from the atmosphere down to the groundwater. Above the land surface, topography induces gradients and contrasts in water and energy availability. Long-term precipitation usually increases with elevation in the mid-latitudes, while it peaks at low- to mid-elevations in the tropics. Potential evaporation tends to decrease with elevation in all climate zones. At the land surface, topography is expressed in snow distribution, vegetation zonation, geomorphic landforms, the critical zone, and drainage networks. Evaporation and vegetation activity are often highest at low- to mid-elevations where neither temperature, nor energy availability, nor water availability—often modulated by lateral moisture redistribution—impose strong limitations. Below the land surface, topography drives the movement of groundwater from local to continental scales. In many steep upland regions, groundwater systems are well connected to streams and provide ample baseflow, and streams often start losing water in foothills where bedrock transitions into highly permeable sediment. We conclude by presenting organizing principles, discussing the implications of climate change and human activity, and identifying data needs and knowledge gaps. A defining feature resulting from topography is the presence of gradients and contrasts, whose interactions explain many of the patterns we observe in nature and how they might change in the future.
Rising temperatures drive lower summer minimum flows across hydrologically diverse catchments in British Columbia
(Water Resources Research, 2025) Ruzzante, S. W.; Gleeson, Tom
Excessively low stream flows harm ecosystems and societies, so two key goals of low-flow hydrology are to understand their drivers and to predict their severity and frequency. We show that linear regressions can accomplish both goals across diverse catchments. We analyze 230 unregulated moderate to high relief catchments across rainfall-dominated, hybrid, snowmelt-dominated, and glacial regimes in British Columbia, Canada, with drainage areas spanning 5 orders of magnitude from 0.5 to 55,000 km2. Summer low flows are decreasing in rainfall-dominated and hybrid catchments but have been stable in catchments that remain snowmelt or glacial-dominated. However, we find that since 1950 approximately one third of snowmelt-dominated catchments have transitioned to a hybrid rain-snow regime. The declines in rainfall-dominated and hybrid catchments are dominantly driven by summer precipitation and temperature, and only weakly influenced by winter storage. We apply this understanding to create regression models that predict the minimum summer flow using monthly temperature and precipitation data. These models outperform distributed process-based models for every common goodness-of-fit metric; the performance improvement is mostly a result of abandoning the requirement to simulate all parts of the annual hydrograph. Using these regression models we reconstruct streamflow droughts and low flow anomalies from 1901 to 2022. We reproduce recent drying trends in rainfall-dominated and hybrid catchments, but also show that present conditions are comparable to those seen one hundred years ago. However, anomalously low flows last century were caused by large precipitation deficits while current declines are driven by rising summer temperatures despite near-normal precipitation.
Current trends and biases in groundwater modelling using the community-driven groundwater model portal (GroMoPo)
(Hydrogeology Journal, 2025) Zamrsky, Daniel; Ruzzante, Sacha; Compare, Kyle; Kretschmer, Daniel; Zipper, Sam; Befus, Kevin M.; Reinecke, Robert; Pasner, Yara; Gleeson, Tom; Jordan, Kristen; Cuthbert, Mark; Castronova, Anthony M.; Wagener, Thorsten; Bierkens, Marc F. P.
Groundwater, Earth’s largest nonfrozen freshwater reservoir, is vital for water supply security. Groundwater models help to manage complex domestic, agricultural, and industrial water demands while preserving ecosystem health under climate change. The community-driven groundwater model portal (GroMoPo) hosts groundwater model metadata to analyse biases and distribution of groundwater models. Over 450 models are currently featured on GroMoPo, with most models from high-GDP countries at local-to-regional scales. The GroMoPo initiative addresses current knowledge gaps and facilitates future collaboration and data sharing.
Comparing global violations of environmentally critical groundwater discharge thresholds
(Water Resources Research, 2024) Marinelli, B. P. P.; Mohan, C.; Gleeson, Tom; Ludwig, F.; de Graaf, I. E. M.
Groundwater is a crucial resource to support surface water bodies via groundwater discharge. In this study, we applied two methods of estimating global environmentally critical groundwater discharge, defined as the flux of groundwater to streamflow necessary to maintain a healthy environment, from 1960 to 2010: the Presumptive Standard stipulates that a standard proportion of groundwater discharge should be maintained at all timesteps, while the Q* is a low-flow index that focuses on critical periods. We calculated these critical flow thresholds using simulated natural groundwater discharge, and estimated violations of the thresholds when human-impacted groundwater discharge dropped too low. Our global assessment of the frequency and severity of violations over all timesteps in our study period showed that the Presumptive Standard estimated more frequent and severe violations than the Q*, but that the spatial patterns were similar for both methods. During low-flow periods, when the relative importance of groundwater to support streamflow is greatest, both methods estimated similar magnitudes of violation frequency and severity. We further compared our results to a method of estimating environmentally critical streamflow, Variable Monthly Flow, which does not explicitly consider groundwater. From the differences in violation frequency between these groundwater-centric and surface water-centric methods, we evaluated the influence of including groundwater contributions to streamflow in environmental flow assessments. Our results show that including groundwater in such assessments is particularly important for regions with high groundwater demands in the drier climates of the world, while it is less important for regions with low groundwater demands and more humid climates.

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