Jennifer Tank

University of Notre Dame | ND · Department of Biological Sciences

As global environmental change continues, animals face uncertain habitat availability and quality that influences life cycle phenology and population dynamics. For decades, the population abundance and emergence patterns of burrowing mayflies have been used as a sentinel for water quality changes in large freshwater systems around the world. Despit...

Understanding fate and transport within fluvial systems requires accurate modeling of breakthrough curve (BTC) tails, which often display non-Fickian behaviors. However, it is unclear how anomalous processes relate to the physical and biological characteristics of the stream ecosystem. We use the Stochastic Mobile Immobile model (SMIM) to determine...

Climate change is expected to alter nitrogen (N) export from Arctic rivers, with potential implications for fragile coastal ecosystems and fisheries. Yet, the directionality of change is poorly understood, as increased mobilization of N in a ‘thawing’ Arctic is countered by higher rates of vegetative uptake in a ‘greening’ Arctic, particularly in t...

Nutrient runoff from agricultural regions of the midwestern U.S. corn belt has degraded water quality in many inland and coastal water bodies such as the Great Lakes and Gulf of Mexico. Under current climate, observational studies have shown that winter cover crops can reduce dissolved nitrogen and phosphorus losses from row-cropped agricultural wa...

The Arctic is warming and significant changes to the landscape, including increased vegetative cover (“greening”), are expected in the near future. These landscape changes may alter nitrogen (N) availability in terrestrial, stream, and coastal ecosystems, where production is often N limited, but the exact changes in nutrient cycling are uncertain....

Environmental DNA (eDNA) in aquatic systems is a complex mixture that includes dissolved DNA, intracellular DNA, and particle-adsorbed DNA. Information about the various components of eDNA and their relative proportions could be used to discern target organism abundance and location. However, a limited knowledge of eDNA adsorption dynamics and inte...

Streams and rivers are key sources of nitrous oxide (N2O), which is a powerful greenhouse gas. Incomplete denitrification results in N2O production, which is controlled by nitrate (NO3−-N) and organic carbon (C) availability, as well as water temperature. Yet, few studies have experimentally isolated these drivers, especially in lotic systems. We u...

The use of environmental DNA (eDNA) as a sampling tool offers insights into the detection of invasive and/or rare aquatic species and enables biodiversity assessment without traditional sampling approaches, which are often labor-intensive. However, our understanding of the environmental factors that impact eDNA removal (i.e., how rapidly eDNA is re...

Most field studies of organic-matter decomposition in streams have been conducted in highly seasonal temperate zones during the autumn; few, however, have examined decomposition during other seasons or evaluated within-season variability in decomposition rates. To address these gaps, we performed a cotton-strip decomposition assay and measured stre...

Antibiotic resistance (AR) determinants are enriched in animal manures, a significant portion of which is land-applied as a soil amendment or as fertilizer, leading to potential AR runoff and microbial pollution in adjacent surface waters. To effectively inform AR monitoring and mitigation efforts, a thorough understanding and description of the pe...

Environmental DNA (eDNA) analysis is a powerful tool for remote detection of target organisms. However, obtaining quantitative and longitudinal information from eDNA data is challenging, requiring a deep understanding of eDNA ecology. Notably, if the various size components of eDNA decay at different rates, and we can separate them within a sample,...

Climate change will alter the flow availability and expected water allocations in international river treaties, many of which were designed using historical flow records. Effective transboundary treaties should anticipate these concerns and seek to satisfy the priorities of all riparian countries while being robust to impending changes in climate....

Nitrous oxide (N2O) is currently the leading ozone-depleting gas and is also a potent greenhouse gas. Predictions of N2O emissions from riverine systems are difficult and mostly accomplished via regression equations based on dissolved inorganic nitrogen (DIN) concentrations or fluxes, although recent studies have shown that hydromorphological chara...

Plain Language Summary Emissions of the ozone‐layer destructor and potent greenhouse gas nitrous oxide, N2O, from rivers are a function of both nitrate loads and stream flows. Here we answer the question of whether droughts and subsequent low flows may exacerbate climate change by increasing N2O emissions, thus forming positive feedback, which may...

Agriculturally-driven land use change and hydrologic modifications have influenced solute transport in midwestern U.S. streams. A clear understanding of the mechanisms driving nutrient export from agricultural watersheds will be critical in mitigating diffuse nutrient pollution, given anticipated shifts in hydrology associated with a changing clima...

Agriculture alters the biogeochemical cycling of nutrients such as nitrogen (N), phosphorus (P), and silicon (Si) which contributes to the stoichiometric imbalance among these nutrients in aquatic systems. Limitation of Si relative to N and P can facilitate the growth of non-siliceous, potentially harmful, algal taxa which has severe environmental...

Environmental impacts on freshwater ecosystems persist due to inputs of excess fertilizer to agricultural landscapes. Conservation efforts, such as cover crops, are being encouraged to reduce nitrogen (N) and phosphorus (P) runoff from fields, but their effects on working lands are rarely documented. We quantified reductions of nitrate-N and solubl...

Community science via a crowdsensing platform offers a unique approach to assess well water quality efficiently at a large scale by providing an infrastructure‐free solution and allowing the community to feel empowered to assess and protect their drinking water safety. Although nearly 40 million people rely on groundwater wells as the main source o...

Excess phosphorus (P) from agriculture is a leading cause of harmful and nuisance algal blooms in many freshwater ecosystems. Throughout much of the midwestern United States, extensive networks of subsurface tile drains remove excess water from fields and allow for productive agriculture. This enhanced drainage also facilitates the transport of P,...

In freshwater ecosystems, phosphorus (P) is often considered a growth-limiting nutrient. The use of fertilizers on agricultural fields has led to runoff-driven increases in P availability in streams, and the subsequent eutrophication of downstream ecosystems. Isolated storms and periodic streambed dredging are examples of two common disturbances th...

Stream metabolism, in the form of gross primary production (GPP) and ecosystem respiration (ER), is an important metric of stream ecosystem function, given GPP and ER are integrative measurements of basal ecosystem activity that are highly sensitive to environmental change. In agricultural streams of temperate North America GPP can be mediated by w...

The midwestern United States is a highly productive agricultural region, and extended crop‐free periods in winter/spring can result in nitrogen (N) and phosphorus (P) losses to waterways that degrade downstream water quality. Planting winter cover crops can improve soil health while reducing nutrient leaching from farm fields during the fallow peri...

A significant fraction of Earth's land surface is used for agriculture, which has led to extensive modification and degradation of streams and rivers. Although highly modified, agricultural streams offer important opportunities for advancing our understanding of agroecosystems and applying the principles of translational ecology. Using examples fro...

Large wood (LW) additions are commonly used to restore degraded streams, particularly in regenerating forests that have low LW recruitment due to past logging. While the short‐term effects of LW input on stream structure and function are well studied, the long‐term dynamics of added wood are less documented. We assessed the long‐term movement and c...

Environmental proteins (eProteins), such as Cry proteins associated with genetically engineered (GE) organisms, are present in ecosystems worldwide, but only rarely reach concentrations with detectable ecosystem-level impacts. Despite their ubiquity, the degradation and fate of Cry and other eProteins are mostly unknown. Here, we report the results...

Lotic and lentic ecosystems are traditionally viewed as dominated by either benthic or water column processes. However, mid-sized rivers represent a transition zone where both benthic and water column processes may both contribute substantially to ecosystem dynamics. Ecosystem processes such as gross primary production (GPP), ecosystem respiration...

Phosphorus (P) enrichment of headwater agricultural streams due to the runoff of fertilizers can lead to the eutrophication of downstream aquatic ecosystems. Agriculture is intensive but heterogeneous in the Mississippi River Basin, with a mixture of pasture, row crops, and patches of confined animal feedlot operations (CAFOs). Many studies have ev...

In agricultural streams, constructed floodplains have been shown to expand bioreactive surface area and enhance nitrate (NO3⁻-N) removal via microbial denitrification, thereby reducing export to downstream ecosystems. At the Shatto Ditch Watershed (Indiana, USA), 0.6 km of two-stage ditch was constructed at the watershed outlet in 2007, while an ad...

Subsurface tile drainage speeds water removal from agricultural fields that are historically prone to flooding. While managed drainage systems improve crop yields, they can also contribute to the eutrophication of downstream ecosystems, as tile‐drained systems are conduits for nutrients to adjacent waterways. The changing climate of the Midwestern...

Conversion of landscapes to large-scale agriculture has substantially increased the loading of bioavailable nitrogen (N) to stream networks through extensive artificial drainage and fertilizer application. Floodplain restoration may enhance N cycling in agricultural stream systems by increasing residence time of floodwaters in contact with bioreact...

Headwaters suffer from reduced leaf and wood inputs and retention capacity from historical land actions like watershed logging and agriculture. When in-stream wood is reduced, stream retention capacity declines and subsequent changes in streamwater flow-paths and patterns of deposition alter decomposition and primary production that influence secon...

Floodplain restoration constructed via the two-stage ditch in agricultural streams has the potential to enhance nutrient retention and prevent the eutrophication of downstream ecosystems. Identifying the role of biotic and abiotic factors influencing soluble reactive phosphorus (SRP) retention in floodplains is of interest given that changing redox...

The effect of environmental policy on water resources is often challenging to evaluate due to dynamic interactions between people and water, particularly in data-scarce watersheds. Increasing interactions between society and hydrology present a need to understand causal relations for improved assessment and prediction in complex human-water systems...

Organisms exert multiple, and often contrasting, influences on ecosystems. During their spawning runs, Pacific salmon (Oncorhynchus spp.) deliver nutrients to freshwater ecosystems, but also disturb benthic sediments during upstream migration and nest building. The relative importance of these contrasting roles is not well understood, especially in...

In low‐gradient, macrophyte‐rich rivers, we expect that the significant change in macrophyte biomass among seasons will strongly influence both biological activity and hydraulic conditions resulting in significant effects on nutrient dynamics. Understanding seasonal variation will improve modelling of nutrient transport in river networks, including...

Sampling water for environmental DNA ( eDNA ) is an emerging tool for documenting species presence without direct observation, allowing for earlier detection and faster response than conventional sampling methods in aquatic ecosystems. However, current understanding of how eDNA is transported in streams and rivers remains imprecise, with uncertaint...

The majority of maize planted in the US is genetically-engineered to express insecticidal properties, including Cry1Ab protein, which is designed to resist the European maize borer (Ostrinia nubilalis). After crop harvest, these proteins can be leached into adjacent streams from crop detritus left on fields. The environmental fate of Cry1Ab protein...

Accumulation of plastic litter is accelerating worldwide. Rivers are a source of microplastic (i.e., particles <5 mm) to oceans, but few measurements of microplastic retention in rivers exist. We adapted spiraling metrics used to measure particulate organic matter transport to quantify microplastic deposition using an outdoor experimental stream. W...

Assessments of riverine ecosystem health and water quality require knowledge of how headwater streams transport and transform nutrients. Estimates of nutrient demand at the watershed scale are commonly inferred from reach‐scale solute injections, which are typically reported as uptake velocities (vf). Multiple interacting processes control vf, maki...

Rapid, sensitive, and quantitative protein detection is critical for many applications in medicine, environmental monitoring, and the food industry. Advancements in detection of proteins include the use of antigen-antibody binding; however, many current methods are time-consuming and have limiting factors such as low sensitivity and the inability t...

Agricultural land use in the Midwestern U.S. is the major source of nitrogen (N) causing recurring hypoxia in the northern Gulf of Mexico. Despite efforts to reduce losses, N export from tile-drained, agricultural watersheds throughout the Corn Belt persists. The use of effective agricultural conservation practices can reduce N loss from fields, ye...

• Understanding the mechanisms that control gross primary production (GPP) and ecosystem respiration (ER) is important in open‐canopy streams, particularly as their prevalence increases across the landscape with the expansion of human land use. • We measured resazurin (raz) transformation to resorufin (rru) as an indicator of ER in two contrasting...

The application of environmental DNA (eDNA) to infer species presence in aquatic ecosystems has become an invaluable tool for both the ecology and management of aquatic ecosystems. However, we are only beginning to understand how environmental conditions influence eDNA detection and persistence in freshwaters. Here, we examined the degradation dyna...

Substrate heterogeneity and biofilm colonization in streams vary across both time and space, but their relative contribution to reach-scale nutrient uptake is difficult to partition. We performed multiple short-term nutrient additions over a 4-mo colonization sequence in 4 small, groundwater-fed, experimental streams. We quantified the influence of...

• Wetlands are often biogeochemical hotspots, and they can remove excess N via denitrification and assimilatory uptake. Wetlands are also susceptible to plant invasions, but the effect of invasive plants on denitrification in freshwater wetland sediments is not well‐studied. • Two distinct mechanisms suggest the potential for invasive plants to alt...

In this chapter, we describe nutrient limitation in stream ecosystems, the problems associated with elevated nutrient loading caused by human activities in the watershed, and how streams process and transform nutrients prior to downstream export. We provide a basic method for quantifying nutrient limitation of stream biofilms using nutrient diffusi...

Human activities create threats that have consequences for freshwater ecosystems and, in most watersheds, observed ecological responses are the result of complex interactions among multiple threats and their associated ecological alterations. Here we discuss the value of considering multiple threats in research and management, offer suggestions for...

Subsurface tile drainage has been used around the globe to lower the water table and drain soils that are seasonally or perennially wet making them suitable for agriculture and/or increasing productivity. However, tile drainage systems have a negative impact on water quality of adjacent streams and ditches due to the transport of excess fertilizer...

Along the river network, water, sediment, and nutrients are transported, cycled, and altered by coupled hydrological and biogeochemical processes. Our current understanding of the rates and processes controlling the cycling and removal of dissolved inorganic nutrients in river networks is limited due to a lack of empirical measurements in large, (n...

Studies of trophic-level material and energy transfers are central to ecology. The use of isotopic tracers has now made it possible to measure trophic transfer efficiencies of important nutrients and to better understand how these materials move through food webs. We analyzed data from thirteen (15) N-ammonium tracer addition experiments to quantif...

Headwater streams remove, transform, and store inorganic nitrogen (N) delivered from surrounding watersheds, but excessive N inputs from human activity can saturate removal capacity. Most research has focused on quantifying N removal from the water column over short periods and in individual reaches, and these ecosystem-scale measurements suggest t...

The insecticidal Cry1Ab protein expressed by transgenic (Bt) maize can enter adjacent water bodies via multiple pathways, but its fate in stream ecosystems is not as well studied as in terrestrial systems. In this study, we used a combination of field sampling and laboratory experiments to examine the occurrence, leaching, and degradation of solubl...

Co-injections of conservative tracers and nutrients are commonly used to assess travel time distributions and nutrient removal in streams. However, in-stream tracer data often lack information on long-term hyporheic storage, and removal rate coefficients are often assumed to be uniform despite plentiful evidence that microbially-mediated transforma...

Advances in detection of genetic material from species in aquatic ecosystems, including environmental DNA (eDNA), have improved species monitoring and management. eDNA from target species can readily move in streams and rivers and the goal is to measure it, and with that infer where and how abundant species are, adding great value to delimiting spe...

Accurately estimating watershed nutrient export can be challenging as traditional monitoring approaches using grab samples often underestimate nutrient loads during storms. Continuous nitrate-N sensors offer an opportunity to examine nutrient dynamics on a more resolved temporal scale that could help document benefits of conservation and restoratio...

Traditional monitoring approaches using grab samples can present limitations to accurately estimating watershed nutrient export during storms. Continuous nitrate-N sensors offer an opportunity to examine nutrient dynamics on a more resolved temporal scale that could help document benefits of conservation and restoration. We deployed continuous nitr...

Western Lake Erie Basin (WLEB) is the most intensively farmed region of the Great Lakes. Because of the flat topography and poorly-drained soils many farmers rely on drainage management practices (e.g., subsurface tile drainage, ditch channelization) to maintain productive agriculture. However, these practices also facilitate the delivery of excess...

While environmental DNA (eDNA) is now being regularly used to detect rare and elusive species, detection in lotic environments comes with a caveat: the species being detected is likely some distance upstream from the point of sampling. Here we conduct a series of semi-natural stream experiments to test the sensitivity of new digital droplet PCR (dd...

Streambed substrates harbor a rich biome responsible for biogeochemical processing in riverine waters. Beyond their biological role, the presence of benthic and hyporheic biofilms can play an important role in influencing large-scale transport of solutes, even for conservative tracers. As biofilms grow and accumulate biomass, they actively interact...

Detecting environmental DNA (eDNA) in water samples is a powerful tool in determining the presence of rare aquatic species. However, many open questions remain as to how biological and physical conditions in flowing waters influence eDNA. Motivated by what one might find in a stream/river benthos we conducted experiments in continuous flow columns...

Excess nitrogen (N) causes numerous water quality problems, and in the upper Mississippi River Basin, much of the excess N results from landscape modifications necessary for row crop agriculture. Several conservation practices reduce N export, but cost estimates for these practices are often lacking, which can inhibit decisions by farmers and polic...

Freshwater mussels are in decline worldwide, but it remains challenging to link specific stressors to mussel declines. The clubshell mussel (Pleurobema clava) is a federally endangered species that spends most of its life completely buried beneath stream sediments. We tested the hypothesis that clubshell’s decline stems, in part, from low pore wate...

Riverine biogeochemical processes are understudied relative to headwaters, and reach-scale processes in rivers reflect both the water column and sediment. Denitrification in streams is difficult to measure, and is often assumed to occur only in sediment, but the water column is potentially important in rivers. Dissolved nitrogen (N) gas flux (as di...