Darren Johnson is a Statistician at the USGS Wetland and Aquatic Research Center.
Darren provides statistical advice and consultation in areas applying to the development of research plans, sampling designs, the selection of statistical analyses, assistance with statistical analyses, conducting analyses for scientists, review of plans, reports, and publications for statistical procedures.
Education and Certifications
University of Louisiana at Lafayette
Doctor of Philosophy
08/1995The Ohio State University
Masters of Applied Statistics
06/1989The Ohio State University
Bachelor of Science
06/1988
Science and Products
Effects of shading on the rare plant species, Physostegia correllii (Lamiaceae)
The original distribution of the study species Physostegia correllii included freshwater floodplains of large rivers in the southcentral U.S. (Colorado, Rio Grande, Mississippi). Experiments to determine the effects of shading on P. correllii were conducted using short-term shade cloth treatments (full sunlight vs. 30% shading for 2-3 weeks). Mean height and cover responses of individuals were det
Establishing a standard ploidy assessment method using grass carp from Ohio, 2015-2016
In 2015-2016, the Ohio Division of Wildlife's undercover law enforcement purchased 1,200 grass carp (Ctenopharyngodon idella). Fish heads and eyeballs were sent overnight to U.S. Geological Survey Wetland and Aquatic Research Center for ploidy analysis. Field and laboratory standard operating procedures were established and followed. Fish lengths, fish weights, and eyeball weights were obtained fr
Filter Total Items: 29
Decadal shifts in the population growth, regeneration, and health of Taxodium distichum in swamps of the Cache River Watershed, Illinois
Population projection models based on long-term trends in regeneration and tree survival can be used to predict the future stability of swamp forest species using water management. Population growth and regeneration of a foundational tree species in North American cypress swamps (Taxodium distichum) were compared in the Cache River watershed of southern Illinois USA over several decades. This stud
Authors
Beth Middleton, Darren Johnson
Nonlinear patterns of surface elevation change in coastal wetlands: The value of generalized additive models for quantifying rates of change
In the face of accelerating climate change and rising sea levels, quantifying surface elevation change dynamics in coastal wetlands can help to develop a more complete understanding of the implications of sea-level rise on coastal wetland stability. The surface elevation table-marker horizon (SET-MH) approach has been widely used to quantify and characterize surface elevation change dynamics in co
Authors
Laura Feher, Michael Osland, Darren Johnson, James Grace, Glenn R. Guntenspergen, David R. Stewart, Carlos A. Coronado-Molina, Fred H. Sklar
Presence of hummock and hollow microtopography reflects shifting balances of shallow subsidence and root zone expansion along forested wetland river gradients
Tidal freshwater forested wetlands (TFFWs) are in an active phase of transition to tidal marsh with sea level rise and salinity incursion along the Atlantic and Gulf Coasts of the United States (U.S.). A prominent feature of TFFWs is hummock/hollow microtopography where hollows represent the flat, base-elevation of the floodplain where inundation occurs relatively frequently, while hummocks provid
Authors
Ken Krauss, Gregory B. Noe, Jamie A. Duberstein, Nicole Cormier, Andrew From, Tom Doody, William H. Conner, Donald Cahoon, Darren Johnson
Local weather and endogenous factors affect the initiation of migration in short- and medium-distance songbird migrants
Migratory birds employ a variety of mechanisms to ensure appropriate timing of migration based on integration of endogenous and exogenous information. The cues to fatten and depart from the non-breeding area are often linked to exogenous cues such as temperature or precipitation and the endogenous program. Shorter distance migrants should rely heavily on environmental information when initiating m
Authors
Theodore J. Zenzal, Darren Johnson, Frank R. Moore, Zoltán Németh
Effects of shading on the rare plant species, Physostegia correllii (Lamiaceae) and Trillium texanum (Melanthiaceae)
Rare plant species that are constrained by shading may be threatened by a lack of natural disturbance that removes overhanging vegetation. The original distribution of the study species Physostegia correllii (Lundell) Shinners included freshwater floodplains of large rivers in the southcentral U.S. (Colorado, Rio Grande, and Mississippi rivers). A second species, Trillium texanum Buckley was found
Authors
Beth Middleton, Casey R. Williams, Chris Doffitt, Darren Johnson
Surface elevation change dynamics in coastal marshes along the northwestern Gulf of Mexico: Anticipating effects of rising sea-level and intensifying hurricanes
Accelerated sea-level rise and intensifying hurricanes highlight the need to better understand surface elevation change in coastal wetlands. We used the surface elevation table-marker horizon approach to measure surface elevation change in 14 coastal marshes along the northwestern Gulf of Mexico, within five National Wildlife Refuges in Texas (USA). During the 2014–2019 study period, the mean rate
Authors
Jena A. Moon, Laura Feher, Tiffany C. Lane, William Vervaeke, Michael Osland, Douglas M. Head, Bogdan Chivoiu, David R. Stewart, Darren Johnson, James Grace, Kristine L. Metzger, Nicole M. Rankin
Juvenile African clawed frogs (Xenopus laevis) express growth, metamorphosis, mortality, gene expression, and metabolic changes when exposed to thiamethoxam and clothianidin
Neonicotinoids (NEO) represent the main class of insecticides currently in use, with thiamethoxam (THX) and clothianidin (CLO) primarily applied agriculturally. With few comprehensive studies having been performed with non-target amphibians, the aim was to investigate potential biomarker responses along an adverse outcome pathway of NEO exposure, whereby data were collected on multiple biological
Authors
Jill Jenkins, Katherine R. Hartop, Ghadeer Bukhari, Debra E. Howton, Kelly Smalling, Scott Mize, Michelle Hladik, Darren Johnson, Rassa Dale, Bonnie L. Brown
The Louisiana Amphibian Monitoring Program from 1997 to 2017: Results, analyses, and lessons learned
To determine trends in either frog distribution or abundance in the State of Louisiana, we reviewed and analyzed frog call data from the Louisiana Amphibian Monitoring Program (LAMP). The data were collected between 1997 and 2017 using North American Amphibian Monitoring Program protocols. Louisiana was divided into three survey regions for administration and analysis: the Florida Parishes, and 2
Authors
Jacoby Carter, Darren Johnson, Jeff Boundy, William Vermillion
Establishment of baseline cytology metrics in nestling American kestrels (Falco sparverius): Immunomodulatory effects of the flame retardant isopropylated triarylphosphate isomers
Avian populations must mount effective immune responses upon exposure to environmental stressors such as avian influenza and xenobiotics. Although multiple immune assays have been tested and applied to various avian species, antibody-mediated immune responses in non-model avian species are not commonly reported due to the lack of commercially available species-specific antibodies. The objectives o
Authors
Jill Jenkins, Brooke A Baudoin, Darren Johnson, Kim J. Fernie, Heather M. Stapelton, Natalie K. Karouna-Renier
Home ranges and movements of two diamondback terrapins (Malaclemys terrapin macrospilota) in northwest Florida
The diamondback terrapin (Malaclemys terrapin) is a small estuarine turtle distributed along the Atlantic and Gulf Coasts of the USA that is threatened by drowning in crab pots, road mortality, exploitation in the pet trade, and habitat loss. Little is known about the movement patterns and home ranges of these turtles, particularly along the U.S. Gulf of Mexico coast. Satellite tags were deployed
Authors
Margaret Lamont, Darren Johnson, Daniel J. Catizone
Movements of marine and estuarine turtles during Hurricane Michael
Natural disturbances are an important driver of population dynamics. Because it is difficult to observe wildlife during these events, our understanding of the strategies that species use to survive these disturbances is limited. On October 10, 2018, Hurricane Michael made landfall on Florida’s northwest coast. Using satellite and acoustic telemetry, we documented movements of 6 individual turtles:
Authors
Margaret M. Lamont, Darren Johnson, Daniel J. Catizone
Variation in species composition, size and fitness of two multi-species sea turtle assemblages using different neritic habitats
The neritic environment is rich in resources and as such plays a crucial role as foraging habitat for multi-species marine assemblages, including sea turtles. However, this habitat also experiences a wide array of anthropogenic threats. To prioritize conservation funds, targeting areas that support multi-species assemblages is ideal. This is particularly important in the Gulf of Mexico where resto
Authors
Margaret M. Lamont, Darren Johnson
Non-USGS Publications**
K. Krishnamoorthy, Darren J. Johnson (1997) Combining Independent Information in a Multivariate Calibration Problem. Journal of Multivariate Analysis 61(2):171-186[3]
Darren J. Johnson & K. Krishnamoorthy (1996) Combining Independent Studies in a Calibration Problem. Journal of the American Statistical Association, Volume 91, 1707-1715[23]
Darren J. Johnson & K. Krishnamoorthy (1996) Combining Independent Studies in a Calibration Problem. Journal of the American Statistical Association, Volume 91, 1707-1715[23]
**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.
Science and Products
- Data
Effects of shading on the rare plant species, Physostegia correllii (Lamiaceae)
The original distribution of the study species Physostegia correllii included freshwater floodplains of large rivers in the southcentral U.S. (Colorado, Rio Grande, Mississippi). Experiments to determine the effects of shading on P. correllii were conducted using short-term shade cloth treatments (full sunlight vs. 30% shading for 2-3 weeks). Mean height and cover responses of individuals were detEstablishing a standard ploidy assessment method using grass carp from Ohio, 2015-2016
In 2015-2016, the Ohio Division of Wildlife's undercover law enforcement purchased 1,200 grass carp (Ctenopharyngodon idella). Fish heads and eyeballs were sent overnight to U.S. Geological Survey Wetland and Aquatic Research Center for ploidy analysis. Field and laboratory standard operating procedures were established and followed. Fish lengths, fish weights, and eyeball weights were obtained fr - Publications
Filter Total Items: 29
Decadal shifts in the population growth, regeneration, and health of Taxodium distichum in swamps of the Cache River Watershed, Illinois
Population projection models based on long-term trends in regeneration and tree survival can be used to predict the future stability of swamp forest species using water management. Population growth and regeneration of a foundational tree species in North American cypress swamps (Taxodium distichum) were compared in the Cache River watershed of southern Illinois USA over several decades. This studAuthorsBeth Middleton, Darren JohnsonNonlinear patterns of surface elevation change in coastal wetlands: The value of generalized additive models for quantifying rates of change
In the face of accelerating climate change and rising sea levels, quantifying surface elevation change dynamics in coastal wetlands can help to develop a more complete understanding of the implications of sea-level rise on coastal wetland stability. The surface elevation table-marker horizon (SET-MH) approach has been widely used to quantify and characterize surface elevation change dynamics in coAuthorsLaura Feher, Michael Osland, Darren Johnson, James Grace, Glenn R. Guntenspergen, David R. Stewart, Carlos A. Coronado-Molina, Fred H. SklarPresence of hummock and hollow microtopography reflects shifting balances of shallow subsidence and root zone expansion along forested wetland river gradients
Tidal freshwater forested wetlands (TFFWs) are in an active phase of transition to tidal marsh with sea level rise and salinity incursion along the Atlantic and Gulf Coasts of the United States (U.S.). A prominent feature of TFFWs is hummock/hollow microtopography where hollows represent the flat, base-elevation of the floodplain where inundation occurs relatively frequently, while hummocks providAuthorsKen Krauss, Gregory B. Noe, Jamie A. Duberstein, Nicole Cormier, Andrew From, Tom Doody, William H. Conner, Donald Cahoon, Darren JohnsonLocal weather and endogenous factors affect the initiation of migration in short- and medium-distance songbird migrants
Migratory birds employ a variety of mechanisms to ensure appropriate timing of migration based on integration of endogenous and exogenous information. The cues to fatten and depart from the non-breeding area are often linked to exogenous cues such as temperature or precipitation and the endogenous program. Shorter distance migrants should rely heavily on environmental information when initiating mAuthorsTheodore J. Zenzal, Darren Johnson, Frank R. Moore, Zoltán NémethEffects of shading on the rare plant species, Physostegia correllii (Lamiaceae) and Trillium texanum (Melanthiaceae)
Rare plant species that are constrained by shading may be threatened by a lack of natural disturbance that removes overhanging vegetation. The original distribution of the study species Physostegia correllii (Lundell) Shinners included freshwater floodplains of large rivers in the southcentral U.S. (Colorado, Rio Grande, and Mississippi rivers). A second species, Trillium texanum Buckley was foundAuthorsBeth Middleton, Casey R. Williams, Chris Doffitt, Darren JohnsonSurface elevation change dynamics in coastal marshes along the northwestern Gulf of Mexico: Anticipating effects of rising sea-level and intensifying hurricanes
Accelerated sea-level rise and intensifying hurricanes highlight the need to better understand surface elevation change in coastal wetlands. We used the surface elevation table-marker horizon approach to measure surface elevation change in 14 coastal marshes along the northwestern Gulf of Mexico, within five National Wildlife Refuges in Texas (USA). During the 2014–2019 study period, the mean rateAuthorsJena A. Moon, Laura Feher, Tiffany C. Lane, William Vervaeke, Michael Osland, Douglas M. Head, Bogdan Chivoiu, David R. Stewart, Darren Johnson, James Grace, Kristine L. Metzger, Nicole M. RankinJuvenile African clawed frogs (Xenopus laevis) express growth, metamorphosis, mortality, gene expression, and metabolic changes when exposed to thiamethoxam and clothianidin
Neonicotinoids (NEO) represent the main class of insecticides currently in use, with thiamethoxam (THX) and clothianidin (CLO) primarily applied agriculturally. With few comprehensive studies having been performed with non-target amphibians, the aim was to investigate potential biomarker responses along an adverse outcome pathway of NEO exposure, whereby data were collected on multiple biologicalAuthorsJill Jenkins, Katherine R. Hartop, Ghadeer Bukhari, Debra E. Howton, Kelly Smalling, Scott Mize, Michelle Hladik, Darren Johnson, Rassa Dale, Bonnie L. BrownThe Louisiana Amphibian Monitoring Program from 1997 to 2017: Results, analyses, and lessons learned
To determine trends in either frog distribution or abundance in the State of Louisiana, we reviewed and analyzed frog call data from the Louisiana Amphibian Monitoring Program (LAMP). The data were collected between 1997 and 2017 using North American Amphibian Monitoring Program protocols. Louisiana was divided into three survey regions for administration and analysis: the Florida Parishes, and 2AuthorsJacoby Carter, Darren Johnson, Jeff Boundy, William VermillionEstablishment of baseline cytology metrics in nestling American kestrels (Falco sparverius): Immunomodulatory effects of the flame retardant isopropylated triarylphosphate isomers
Avian populations must mount effective immune responses upon exposure to environmental stressors such as avian influenza and xenobiotics. Although multiple immune assays have been tested and applied to various avian species, antibody-mediated immune responses in non-model avian species are not commonly reported due to the lack of commercially available species-specific antibodies. The objectives oAuthorsJill Jenkins, Brooke A Baudoin, Darren Johnson, Kim J. Fernie, Heather M. Stapelton, Natalie K. Karouna-RenierHome ranges and movements of two diamondback terrapins (Malaclemys terrapin macrospilota) in northwest Florida
The diamondback terrapin (Malaclemys terrapin) is a small estuarine turtle distributed along the Atlantic and Gulf Coasts of the USA that is threatened by drowning in crab pots, road mortality, exploitation in the pet trade, and habitat loss. Little is known about the movement patterns and home ranges of these turtles, particularly along the U.S. Gulf of Mexico coast. Satellite tags were deployedAuthorsMargaret Lamont, Darren Johnson, Daniel J. CatizoneMovements of marine and estuarine turtles during Hurricane Michael
Natural disturbances are an important driver of population dynamics. Because it is difficult to observe wildlife during these events, our understanding of the strategies that species use to survive these disturbances is limited. On October 10, 2018, Hurricane Michael made landfall on Florida’s northwest coast. Using satellite and acoustic telemetry, we documented movements of 6 individual turtles:AuthorsMargaret M. Lamont, Darren Johnson, Daniel J. CatizoneVariation in species composition, size and fitness of two multi-species sea turtle assemblages using different neritic habitats
The neritic environment is rich in resources and as such plays a crucial role as foraging habitat for multi-species marine assemblages, including sea turtles. However, this habitat also experiences a wide array of anthropogenic threats. To prioritize conservation funds, targeting areas that support multi-species assemblages is ideal. This is particularly important in the Gulf of Mexico where restoAuthorsMargaret M. Lamont, Darren JohnsonNon-USGS Publications**
K. Krishnamoorthy, Darren J. Johnson (1997) Combining Independent Information in a Multivariate Calibration Problem. Journal of Multivariate Analysis 61(2):171-186[3]
Darren J. Johnson & K. Krishnamoorthy (1996) Combining Independent Studies in a Calibration Problem. Journal of the American Statistical Association, Volume 91, 1707-1715[23]
**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.