Luke C Loken
Luke Loken is a Hydrologist with the Upper Midwest Water Science Center.
I am a hydrologist with the U.S. Geological Survey with a broad ecological background. My research focuses on hydrology and biogeochemistry in aquatic ecosystems at a range of ecological-scales. Some topics include: 1) The causes and consequences of spatial heterogeneity of water chemistry in lakes, rivers, and estuaries. 2) Drivers and patterns of ecosystem processes (metabolism, nutrient cycling, population dynamics). 3) The persistence of human-derived material (fertilizers, pesticides, chemicals) in river networks across landscapes.
Education and Certifications
Ph.D., Freshwater and Marine Sciences, University of Wisconsin-Madison, 2018
M.S., Freshwater and Marine Sciences, University of Wisconsin-Madison, 2014
B.S., Biology, University of Michigan, 2006
Affiliations and Memberships*
Center for Limnology (CFL) Affiliate
The Long-Term Ecological Research Network (LTER)
American Geophysical Union (AGU)
Association for the Sciences of Limnology and Oceanography (ASLO)
Society of Freshwater Sciences (SFS)
Science and Products
Below are data associated with this staff profile.
Below are publications associated with this staff profile.
Filter Total Items: 24
Risk-based prioritization of organic chemicals and locations of ecological concern in sediment from Great Lakes tributaries Risk-based prioritization of organic chemicals and locations of ecological concern in sediment from Great Lakes tributaries
With improved analytical techniques, environmental monitoring studies are increasingly able to report the occurrence of tens or hundreds of chemicals per site, making it difficult to identify the most relevant chemicals from a biological standpoint. For this study, organic chemical occurrence was examined, individually and as mixtures, in the context of potential biological effects...
Authors
Austin K. Baldwin, Steven R. Corsi, Owen M. Stefaniak, Luke C. Loken, Daniel L. Villeneuve, Gerald T. Ankley, Brett R. Blackwell, Peter L. Lenaker, Michelle A. Nott, Marc A. Mills
Dispersion and stratification dynamics in the upper Sacramento River deep water ship channel Dispersion and stratification dynamics in the upper Sacramento River deep water ship channel
Hydrodynamics control the movement of water and material within and among habitats, where time-scales of mixing can exert bottom-up regulatory effects on aquatic ecosystems through their influence on primary production. The San Francisco Estuary (estuary) is a low-productivity ecosystem, which is in part responsible for constraining higher trophic levels, including fishes. Many research...
Authors
Leah Lenoch, Paul Stumpner, Jon R. Burau, Luke C. Loken, Steven Sadro
Assessment of multiple ecosystem metabolism methods in an estuary Assessment of multiple ecosystem metabolism methods in an estuary
Ecosystem metabolism is a key ecological attribute and easy to describe, but quantifying metabolism in estuaries is challenging. Properly scaling measurements through time and space requires consideration of hydrodynamics and mixing water from heterogeneous sources, making any estimation uncertain. Here, we compared three methods for modeling ecosystem metabolism in a portion of the...
Authors
Luke C. Loken, Erwin E Van Nieuwenhuyse, Randy A Dahlgren, Leah Kammel, Paul Stumpner, Jon R. Burau, Steven Sadro
Limited nitrate retention capacity in the Upper Mississippi River Limited nitrate retention capacity in the Upper Mississippi River
The Mississippi River and other large rivers have the potential to regulate nitrogen export from terrestrial landscapes, and thus mitigate eutrophication in downstream aquatic ecosystems. In large rivers, human-constructed impoundments and connected backwaters may facilitate nitrogen removal; however, the capacity of these features is poorly quantified and incompletely incorporated into...
Authors
Luke C. Loken, John T. Crawford, Mark M. Dornblaser, Robert G. Striegl, Jeffrey N. Houser, Peter A Turner, Emily H. Stanley
Spatial early warning signals in a lake manipulation Spatial early warning signals in a lake manipulation
Rapid changes in state have been documented for many of Earth's ecosystems. Despite a growing toolbox of methods for detecting declining resilience or early warning indicators (EWIs) of ecosystem transitions, these methods have rarely been evaluated in whole-ecosystem trials using reference ecosystems. In this study, we experimentally tested EWIs of cyanobacteria blooms based on changes...
Authors
Vince L. Butitta, Stephen R. Carpenter, Luke C. Loken, Michael L. Pace, Emily H. Stanley
Spatial heterogeneity of within-stream methane concentrations Spatial heterogeneity of within-stream methane concentrations
Streams, rivers, and other freshwater features may be significant sources of CH4 to the atmosphere. However, high spatial and temporal variabilities hinder our ability to understand the underlying processes of CH4 production and delivery to streams and also challenge the use of scaling approaches across large areas. We studied a stream having high geomorphic variability to assess the...
Authors
John T. Crawford, Luke C. Loken, William E. West, Benjamin Crary, Seth A. Spawn, Nicholas Gubbins, Stuart E. Jones, Robert G. Striegl, Emily H. Stanley
Non-USGS Publications**
Coyne, K. (2022), What You Think About How Soil and Water Health Connect May Be Wrong. CSA News, 67: 4-10. https://doi.org/10.1002/csan.20907
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Below are software associated with this staff profile.
Science and Products
Below are data associated with this staff profile.
Below are publications associated with this staff profile.
Filter Total Items: 24
Risk-based prioritization of organic chemicals and locations of ecological concern in sediment from Great Lakes tributaries Risk-based prioritization of organic chemicals and locations of ecological concern in sediment from Great Lakes tributaries
With improved analytical techniques, environmental monitoring studies are increasingly able to report the occurrence of tens or hundreds of chemicals per site, making it difficult to identify the most relevant chemicals from a biological standpoint. For this study, organic chemical occurrence was examined, individually and as mixtures, in the context of potential biological effects...
Authors
Austin K. Baldwin, Steven R. Corsi, Owen M. Stefaniak, Luke C. Loken, Daniel L. Villeneuve, Gerald T. Ankley, Brett R. Blackwell, Peter L. Lenaker, Michelle A. Nott, Marc A. Mills
Dispersion and stratification dynamics in the upper Sacramento River deep water ship channel Dispersion and stratification dynamics in the upper Sacramento River deep water ship channel
Hydrodynamics control the movement of water and material within and among habitats, where time-scales of mixing can exert bottom-up regulatory effects on aquatic ecosystems through their influence on primary production. The San Francisco Estuary (estuary) is a low-productivity ecosystem, which is in part responsible for constraining higher trophic levels, including fishes. Many research...
Authors
Leah Lenoch, Paul Stumpner, Jon R. Burau, Luke C. Loken, Steven Sadro
Assessment of multiple ecosystem metabolism methods in an estuary Assessment of multiple ecosystem metabolism methods in an estuary
Ecosystem metabolism is a key ecological attribute and easy to describe, but quantifying metabolism in estuaries is challenging. Properly scaling measurements through time and space requires consideration of hydrodynamics and mixing water from heterogeneous sources, making any estimation uncertain. Here, we compared three methods for modeling ecosystem metabolism in a portion of the...
Authors
Luke C. Loken, Erwin E Van Nieuwenhuyse, Randy A Dahlgren, Leah Kammel, Paul Stumpner, Jon R. Burau, Steven Sadro
Limited nitrate retention capacity in the Upper Mississippi River Limited nitrate retention capacity in the Upper Mississippi River
The Mississippi River and other large rivers have the potential to regulate nitrogen export from terrestrial landscapes, and thus mitigate eutrophication in downstream aquatic ecosystems. In large rivers, human-constructed impoundments and connected backwaters may facilitate nitrogen removal; however, the capacity of these features is poorly quantified and incompletely incorporated into...
Authors
Luke C. Loken, John T. Crawford, Mark M. Dornblaser, Robert G. Striegl, Jeffrey N. Houser, Peter A Turner, Emily H. Stanley
Spatial early warning signals in a lake manipulation Spatial early warning signals in a lake manipulation
Rapid changes in state have been documented for many of Earth's ecosystems. Despite a growing toolbox of methods for detecting declining resilience or early warning indicators (EWIs) of ecosystem transitions, these methods have rarely been evaluated in whole-ecosystem trials using reference ecosystems. In this study, we experimentally tested EWIs of cyanobacteria blooms based on changes...
Authors
Vince L. Butitta, Stephen R. Carpenter, Luke C. Loken, Michael L. Pace, Emily H. Stanley
Spatial heterogeneity of within-stream methane concentrations Spatial heterogeneity of within-stream methane concentrations
Streams, rivers, and other freshwater features may be significant sources of CH4 to the atmosphere. However, high spatial and temporal variabilities hinder our ability to understand the underlying processes of CH4 production and delivery to streams and also challenge the use of scaling approaches across large areas. We studied a stream having high geomorphic variability to assess the...
Authors
John T. Crawford, Luke C. Loken, William E. West, Benjamin Crary, Seth A. Spawn, Nicholas Gubbins, Stuart E. Jones, Robert G. Striegl, Emily H. Stanley
Non-USGS Publications**
Coyne, K. (2022), What You Think About How Soil and Water Health Connect May Be Wrong. CSA News, 67: 4-10. https://doi.org/10.1002/csan.20907
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Below are software associated with this staff profile.
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government