Research in Ecosystem Ecology & Stream Biogeochemistry
We seek to understand the influence of humans and climate change on stream ecosystems.
We are an ecosystem ecology and stream biogeochemistry lab that explores stream ecosystem function and nutrient transformations in both
human- and climate-impacted freshwater systems. Our research combines both field and laboratory studies, as well as the use of high-frequency sensing, to determine the mechanisms driving biogeochemical transformations and nutrient transport. Our research is grounded in translational ecology, in which our findings have real world impacts on conservation & restoration efforts and policy.
human- and climate-impacted freshwater systems. Our research combines both field and laboratory studies, as well as the use of high-frequency sensing, to determine the mechanisms driving biogeochemical transformations and nutrient transport. Our research is grounded in translational ecology, in which our findings have real world impacts on conservation & restoration efforts and policy.
Study Systems
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Agricultural Streams
We study agricultural systems from the Midwest to the Mississippi Delta Regions to determine the effects of agriculture on water quality. We also document the effects of restoration and conservation on nutrient retention and stream ecosystem function in agricultural streams. |
Intermittent Streams
We study intermittent streams across the USA to determine the effects on intermittent streams on downstream water quality, particularly focusing on sediments and nutrients. These systems are highly understudied, though they make up over half of the global stream miles. |
Arctic Streams
We study Arctic streams in Northeast Greenland to determine how basin-scale changes in permafrost thaw and Arctic "greening" alter long-term nutrient and sediment export to the fjord. Greenland makes up 27% of the land mass in the Arctic, yet little is known about its streams. |
Urban Streams
We study urban streams in Northwest Arkansas to determine the influence of rapid urbanization on water quality. NWA is one of the fastest growing regions in the country, with 30 people moving to the region each day, making it an ideal place to study urban water quality. |
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Our ToolkitIn the Speir Lab, we use many different approaches & tools to explore nutrient transport and transformation.
Some examples are listed below:
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Current Projects
The Arkansas Discovery Watershed Project
Many conservation studies are conducted at the field-scale; however, watershed-scale studies are essential to understand the efficacy of conservation at larger spatial scales. We are conducting biweekly synoptic sampling in Brush Creek, a subwatershed of the Beaver Lake Reservoir in Northwest Arkansas, to better understand the relationship between nutrient and sediment loss, livestock production, and conservation practices. The data collected here will be used as the foundation for the Arkansas Discovery Watershed Program, which will serve to expand the current Arkansas Discovery Farm Program. The outcomes of this project will provide data-rich support regarding the potential benefits of conservation implementation and the role of conservation in building sustainable cropping systems that preserve water quality.
Many conservation studies are conducted at the field-scale; however, watershed-scale studies are essential to understand the efficacy of conservation at larger spatial scales. We are conducting biweekly synoptic sampling in Brush Creek, a subwatershed of the Beaver Lake Reservoir in Northwest Arkansas, to better understand the relationship between nutrient and sediment loss, livestock production, and conservation practices. The data collected here will be used as the foundation for the Arkansas Discovery Watershed Program, which will serve to expand the current Arkansas Discovery Farm Program. The outcomes of this project will provide data-rich support regarding the potential benefits of conservation implementation and the role of conservation in building sustainable cropping systems that preserve water quality.
Project BEACON: Biochar Evaluation Across Catchments for Outreach and Nutrient management
Project BEACON evaluates biochar-amended poultry litter as an innovative solution to reduce nutrient runoff across multiple spatial scales: from laboratory experiments to edge-of-field monitoring to watershed-scale implementation. Building on nearly three years of baseline water quality data in the Brush Creek watershed, this project will link on-farm conservation practices to measurable improvements in downstream water quality. Through comprehensive monitoring, farmer-to-farmer demonstrations, and technical assistance to participating producers, the project will generate robust data on biochar's effectiveness in reducing phosphorus and nitrogen losses, while maintaining productive farming operations. The outcomes will provide evidence-based support for biochar adoption and contribute to the development of cost-share practice scenarios that promote sustainable agriculture and protect critical drinking water resources.
Project BEACON evaluates biochar-amended poultry litter as an innovative solution to reduce nutrient runoff across multiple spatial scales: from laboratory experiments to edge-of-field monitoring to watershed-scale implementation. Building on nearly three years of baseline water quality data in the Brush Creek watershed, this project will link on-farm conservation practices to measurable improvements in downstream water quality. Through comprehensive monitoring, farmer-to-farmer demonstrations, and technical assistance to participating producers, the project will generate robust data on biochar's effectiveness in reducing phosphorus and nitrogen losses, while maintaining productive farming operations. The outcomes will provide evidence-based support for biochar adoption and contribute to the development of cost-share practice scenarios that promote sustainable agriculture and protect critical drinking water resources.
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QuEST: Quantifying Ecosystem transport across Space and Time
Understanding the controls on the transport of water, energy, and nutrients from terrestrial landscapes to headwater streams remains a fundamental challenge in ecosystem and catchment science. There remain key knowledge and data gaps regarding how the dynamic hydrologic expansion and contraction of headwater networks influences downstream systems, blurring our ability to use catchment-scale signals fully as indicators of upstream impacts. This knowledge is essential to improve ecohydrological understanding and prediction of how, where, and when network expansion and contraction impact carbon, nutrient, and material export in response to systemic land use and climate change, and will be vital to inform earth system science models that predict catchment responses to changing flow regimes. The Speir Lab's role on this Department of Energy-funded project primarily focuses on (1) conducting synoptic campaigns of catchment-wide stream chemistry to evaluate how small headwater tributaries impose variability observed at coarser spatial scales and (2) deploying high-frequency water quality sensors nested across catchments to capture how stream network expansion and contraction dynamics change carbon, nutrient, and material exports across climatic conditions. |
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Sediment Export from Unpaved Roads
In Arkansas, over 85% of county roads are unpaved, driving water quality degradation via sediment loading to waterways. Excess sediment loss to adjacent waterways, especially during storm events, can block sunlight to the water column, decreasing primary productivity and increasing contaminant and nutrient concentrations. Previous studies on the effects of unpaved roads on sediment loss have primarily been conducted in forestry settings in the Northwest USA; few studies explore the impacts in rural watersheds dominated by pasture in the Southern US. As such, we are sampling Brush Creek, a key tributary of Beaver Lake Reservoir with over 90% unpaved roads, to understand both local and watershed-scale controls on sediment loss from unpaved roads. Since February 2024, we have collected total suspended sediments (TSS) samples at three different road crossing types (bridge, culvert, direct stream crossings), along with targeted storm sampling to capture TSS loss under a range of flow conditions. Overall, conclusions on sediment loss from unpaved roads can inform targeted implementation of best management practices to reduce sediment loss and help maintain downstream water quality across Arkansas. |
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Effects of Lake Conway Draining on Water Quality
Many reservoirs across Arkansas and much of the Southeastern USA were built to function for 50-100 years. Lake Conway in central Arkansas is now >75 years old and has experienced significant issues with sedimentation and invasive species. This, in turn, has affected recreational fisheries and decreased the average depth of the reservoir, putting it at an increased risk of harmful algal blooms. As a result, the Arkansas Game & Fish Commission began a project in September 2023 to conduct full reservoir draining to compact sediments and help restore the lake. However, the impacts of full reservoir draining on nutrient cycling and downstream water quality are largely unknown. Therefore, the objective of the proposed project is to determine the nutrient stores in reservoir sediments and assess the potential for release of nutrients when the lake is refilled. We are quantifying sediment nutrient stores and conducting experiments to determine the potential risk of nutrient loss to downstream systems upon rewetting. As many reservoirs are reaching their “age limit,” this work relevant to water quality in both Arkansas and across the Southeast. |
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Nitrous Oxide Production/Emissions from Tailwater Recovery Systems
Given the role of agriculture in contributing nitrous oxide to the atmosphere, paired with the need for enhanced conservation across the agricultural landscape, it is critical that we document the role of conservation practices in contributing to or reducing GHG emissions. One practice of particular concern in Eastern Arkansas is irrigation tailwater recovery systems, used for surface water capture and irrigation water reuse. However, evidence regarding the production or emissions of GHGs from tailwater recovery systems in Arkansas is largely non-existent. This compromises the ability of this practice to be considered “climate-smart,” in turn affecting the eligibility of this practice for certain conservation implementation funds (e.g., Inflation Reduction Act funds). As such, we are monitoring nitrous oxide emissions and production from irrigation tailwater recovery systems on Discovery Farms in Eastern Arkansas. This project aims to provide support for tailwater recovery systems as a climate-smart conservation practice producers can implement to balance production needs and a healthy planet. Our aim is to provide data-rich support for the adoption of tailwater recovery systems as an NRCS-approved climate-smart agricultural practice.
Given the role of agriculture in contributing nitrous oxide to the atmosphere, paired with the need for enhanced conservation across the agricultural landscape, it is critical that we document the role of conservation practices in contributing to or reducing GHG emissions. One practice of particular concern in Eastern Arkansas is irrigation tailwater recovery systems, used for surface water capture and irrigation water reuse. However, evidence regarding the production or emissions of GHGs from tailwater recovery systems in Arkansas is largely non-existent. This compromises the ability of this practice to be considered “climate-smart,” in turn affecting the eligibility of this practice for certain conservation implementation funds (e.g., Inflation Reduction Act funds). As such, we are monitoring nitrous oxide emissions and production from irrigation tailwater recovery systems on Discovery Farms in Eastern Arkansas. This project aims to provide support for tailwater recovery systems as a climate-smart conservation practice producers can implement to balance production needs and a healthy planet. Our aim is to provide data-rich support for the adoption of tailwater recovery systems as an NRCS-approved climate-smart agricultural practice.
