Research Projects

Current Projects

Duke nano mesocosms

Environmental implications of nanoparticles in aquatic ecosystems

We are collaborating with Cole Matson (Baylor) and Emily Bernhardt (Duke) on a 5-year NSF study on effects of nanoparticles (NPs) on aquatic ecosystem structure and functioning using Duke's wetland mesocosm facility. At Baylor, we are using the BEAR stream facility to contrast chronic vs pulse additions of NPs as well as a chronic dosing of titanium NPs in whole-effluent from the City of Waco's wastewater treatment plant. Our lab focuses on trophic transfer and biodistribution of nanoparticles in aquatic food webs. CEINT homepage

Alder_salmon.jpg(w x h, 0 KB)

Alder + wetlands = salmon

Alder (a woody shrub) is able to fix atmospheric nitrogen. We believe it may help sustain productivity in small, salmon rearing streams on the Kenai Peninsula, Alaska. Unfortunately, many consider it a nuisance! Similarly, wetlands contribute dissolved organic matter that may fuel microbial production in streams. In summer 2013, we performed whole stream nitrogen and organic carbon enrichments to link N and C to juvenile salmonid production. Currently, we are studying the effects of headwaters on downstream ecosystems (at least through 2019).

Ecological thresholds: theory and methods

Matt Baker (University of Maryland, Baltimore Co.) and King have made some methodological advances in the arena of ecological thresholds. In early 2010, we introduced TITAN (Threshold Indicator Taxa Analysis) as a new approach to detecting and interpreting synchronous declines in multiple species along environmental gradient. TITAN is currently being used by several states in support of developing numerical water quality criteria. Refinements and extensions of our approachar are perpetually in the works.


Urbanization and flow permanence control biological condition of southwestern streams

We are working with the City of Austin to model the effects of urbanization and flow permanence on macroinvertebrate community structure of streams in Edwards Plateau and Texas Blackland Prairies. The goal, initially, was to help scale their Environmental Integrity Index to account for the natural effects of flow permanence on stream biota, but in the process made some exciting discoveries. Currently, we are modeling diatom assemblage responses to point and nonpoint nutrient sources in addition to flow and impervious cover. City of Austin Env. Integrity Index (link)

Recently completed projects (within 2 years)


Oklahoma Scenic Rivers Joint Phosphorus Study

We were selected by a joint committee from Oklahoma and Arkansas to perform a multi-year field study to determine a threshold level of phosphorus that results in a significant shift toward nuisance algal biomass, degraded aesthetics, and poor water quality (e.g., dissolved oxygen). This study is the culmination of over 3 decades of legal issues between these two states, including a Supreme Court decision in 1992 that determined an upstream state cannot violate the water quality standards of a downstream state. The $600,000 study was completed in December 2016, resulting in a definitive, unanimous agreement betweeen the two states. Check out the "Research Spotlight" for details.


Effects of Pulsed Atrazine Exposures on Autotrophs Using Field-Based Stream Mesocosms

We directed a $1,150,000 project designed to assess the response of autotrophic (algae, macrophytes) ecosystem components to pulsed atrazine exposures in streams. Atrazine is the most widely used herbicide in North America and EPA currently is reevaluating how much atrazine is too much for streams. Our study was the first to simulate atrazine exposures as they really occur--as pulsed runoff events that closely mimic a stream hydrograph, the biggest weakness identified by the USEPA's Scientific Advisory Panel among all previous studies. The BEAR stream mesocosm facility was used for this study and was published in ET&C within less than 1 year of completion. Link to SAP report


Genetic variation of populations of coho salmon and Dolly Varden in Alaska

Pat Danley's lab lead a study with us to characterize genetic diversity of two salmonid species within and among river basins on the lower Kenai Peninsula, Alaska, a region with a burgeoning human population and heavy pressure on inland fisheries.

mtm wv

Cumulative effects of mountaintop removal mining on stream ecosystems in Appalachia

We are collaborating with Emily Bernhardt's lab at Duke to study the effects of alkaline mine drainage associated with mountaintop removal mining. This type of mining results in highly elevated dissolved solids, particularly sulfate, and sharp declines in stream biodiversity at low levels of mining. Current work involves modeling efforts led by Kris Voss to refine the decision framework used to define water quality criteria, or more specifically, conductivity thresholds associated with surface mining.