Assistant Unit Leader - Arkansas Cooperative Fish and Wildlife Research Unit
Research Interests
My research has focused on factors affecting population and community dynamics of freshwater fish and invertebrates, especially the role of disturbance in community dynamics, impacts of introduced species in aquatic ecosystems, and aquatic ecosystem conservation. My recent research includes studying, 1) classification of Arkansas flow regimes and developing ecological-flow response relationships and environmental flows assessment for the Ozark region, 2) factors affecting distribution and abundance of the endangered yellowcheek darter, 3) distribution, population genetics and factors affecting imperiled coldwater crayfish, 4) effects of drought and episodic drying on stream fish and invertebrate population and community dynamics, 5) effects of stream drying on fish and invertebrate refuge use and species persistence, 6) models to forecast effects of potential climate change scenarios on fish refuge use and species persistence, 7) influence of drying on fish and crayfish consumers and how they in turn affect stream ecosystem structure and function, 8) the relationship between land use, flow regime, habitat complexity and fish assemblage structure, 9) the potential spread of invasive species and mechanisms of displacement on native species, 10) the influence of abiotic and biotic factors on habitat selection by stream fish and crayfish, and 11) the effect of catch and release areas on movement and mortality of resident rainbow and brown trout in cold tailwater rivers and the relationship between forage base and trout production in these special regulation areas. As part of this work, I attempt to bridge the gap between studies done at small spatial scales and the larger spatial scales necessary to understand how disturbance and movement affect population and community dynamics in stream ecosystems. These projects and related work are carried out using a combination of observation, experimentation in the field and lab, and modeling approaches.
Teaching Interests
I teach Biometry, Fish Ecology and Conservation Biology. I also teach seminars in current topics in Ecology, Conservation Biology and Fisheries.
Professional Experience
Assistant Unit Leader, Arkansas Cooperative Fish and Wildlife Research Unit, 2000-
Education and Certifications
PhD, University of Pittsburgh, 1990
MS, Eastern Michigan University, 1982
BS, Michigan State University, 1977
Science and Products
Filter Total Items: 31
Hydrologic variation influences stream fish assemblage dynamics through flow regime and drought
Hydrologic variation can play a major role in structuring stream fish assemblages and relationships between hydrology and biology are likely to be influenced by flow regime. We hypothesized that more variable flow regimes would have lower and more variable species richness, higher species turnover and lower assemblage stability, and greater abiotic environment-fish relationships than more stable f
Modeling effects of disturbance across life history strategies of stream fishes
A central goal of population ecology is to establish linkages between life history strategy, disturbance, and population dynamics. Globally, disturbance events such as drought and invasive species have dramatically impacted stream fish populations and contributed to sharp declines in freshwater biodiversity. Here, we used RAMAS-Metapop to construct stage-based demographic metapopulation models for
Effect of stream permanence on predation risk of lotic crayfish by riparian predators
Given the importance of crayfish in stream ecosystems, gaining insight into the role of stream permanence in maintaining predator–prey interactions is critical. Our objectives were to determine the influence of stream permanence and season on crayfish predation and assess the role of stream permanence and crayfish density on the presence of predators, while accounting for imperfect detection. We c
Predicting hydrologic disturbance of streams using species occurrence data
Aquatic organisms have adapted over evolutionary time-scales to hydrologic variability represented by the natural flow regime of rivers and streams in their unimpaired state. Rapid landscape change coupled with growing human demand for water have altered natural flow regimes of many rivers and streams on a global scale. Climate non-stationarity is expected to further intensify hydrologic variabili
Population characteristics of Ozark Bass (Ambloplites constellatus) in the upper White River basin of northern Arkansas
Ozark Bass (Ambloplites constellatus) is an understudied, endemic fish species in the Upper White River Basin of northern Arkansas. This study was part of an effort by fisheries managers to gather baseline data about the Ozark Bass to aid in understanding population dynamics and contribute to the limited data available for use in determining the efficacy of harvest regulations. Select population c
Changes in body condition and diet of lotic Smallmouth Bass across two flow regimes during summer months at the southern extent of their native range
The Ozark Plateau is located at the southern extent of native Smallmouth Bass Micropterus dolomieu range and water temperature and drought conditions during summer months may potentially affect growth of Smallmouth Bass in this region. Groundwater streams in the region do not warm to the same extent as runoff streams during summer months and could provide a thermal refuge habitat for Smallmouth Ba
Flow alteration-ecology relationships in Ozark Highland streams: Consequences for fish, crayfish and macroinvertebrate assemblages
We examined flow alteration-ecology relationships in benthic macroinvertebrate, fish, and crayfish assemblages in Ozark Highland streams, USA, over two years with contrasting environmental conditions, a drought year (2012) and a flood year (2013). We hypothesized that: 1) there would be temporal variation in flow alteration-ecology relationships between the two years, 2) flow alteration-ecology re
Flow-ecology relationships are spatially structured and differ among flow regimes
In streams, hydrology is a predominant driver of ecological structure and function. Providing adequate flows to support aquatic life, or environmental flows, is therefore a top management priority in stream systems.
Flow regime classification is a widely accepted approach for establishing environmental flow guidelines. However, it is surprisingly difficult to quantify relationships between hydrol
Modelling effects of invasive species and drought on crayfish extinction risk and population dynamics
Hydrological alteration, which may be exacerbated by climate change, is known to facilitate aquatic species invasion. Altered hydrology, invasive species, and the additive effects of these stressors pose a threat to aquatic biodiversity.Understanding extinction risk in the context of these stressors is crucial for prioritizing conservation efforts. As case studies, three narrow‐ranged endemic cray
Modelling effects of invasive species and drought on crayfish extinction risk and population dynamics
Hydrological alteration, which may be exacerbated by climate change, is known to facilitate aquatic species invasion. Altered hydrology, invasive species, and the additive effects of these stressors pose a threat to aquatic biodiversity.Understanding extinction risk in the context of these stressors is crucial for prioritizing conservation efforts. As case studies, three narrow-ranged endemic cray
Forecasting effects of angler harvest and climate change on smallmouth bass abundance at the southern edge of their range
Climate change will affect stream systems in numerous ways over the coming century. Globally, streams are expected to experience changes in temperature and flow regime. Previous work has indicated that these changes will likely affect fish distributions, but little work has been conducted examining population level effects of climate change on warmwater fish at the warmest portion of their range.
The influence of drought on flow‐ecology relationships in Ozark Highland streams
Drought and summer drying can have strong effects on abiotic and biotic components of stream ecosystems. Environmental flow‐ecology relationships may be affected by drought and drying, adding further uncertainty to the already complex interaction of flow with other environmental variables, including geomorphology and water quality.Environment–ecology relationships in stream communities in Ozark Hi
Science and Products
- Publications
Filter Total Items: 31
Hydrologic variation influences stream fish assemblage dynamics through flow regime and drought
Hydrologic variation can play a major role in structuring stream fish assemblages and relationships between hydrology and biology are likely to be influenced by flow regime. We hypothesized that more variable flow regimes would have lower and more variable species richness, higher species turnover and lower assemblage stability, and greater abiotic environment-fish relationships than more stable fModeling effects of disturbance across life history strategies of stream fishes
A central goal of population ecology is to establish linkages between life history strategy, disturbance, and population dynamics. Globally, disturbance events such as drought and invasive species have dramatically impacted stream fish populations and contributed to sharp declines in freshwater biodiversity. Here, we used RAMAS-Metapop to construct stage-based demographic metapopulation models forEffect of stream permanence on predation risk of lotic crayfish by riparian predators
Given the importance of crayfish in stream ecosystems, gaining insight into the role of stream permanence in maintaining predator–prey interactions is critical. Our objectives were to determine the influence of stream permanence and season on crayfish predation and assess the role of stream permanence and crayfish density on the presence of predators, while accounting for imperfect detection. We cPredicting hydrologic disturbance of streams using species occurrence data
Aquatic organisms have adapted over evolutionary time-scales to hydrologic variability represented by the natural flow regime of rivers and streams in their unimpaired state. Rapid landscape change coupled with growing human demand for water have altered natural flow regimes of many rivers and streams on a global scale. Climate non-stationarity is expected to further intensify hydrologic variabiliPopulation characteristics of Ozark Bass (Ambloplites constellatus) in the upper White River basin of northern Arkansas
Ozark Bass (Ambloplites constellatus) is an understudied, endemic fish species in the Upper White River Basin of northern Arkansas. This study was part of an effort by fisheries managers to gather baseline data about the Ozark Bass to aid in understanding population dynamics and contribute to the limited data available for use in determining the efficacy of harvest regulations. Select population cChanges in body condition and diet of lotic Smallmouth Bass across two flow regimes during summer months at the southern extent of their native range
The Ozark Plateau is located at the southern extent of native Smallmouth Bass Micropterus dolomieu range and water temperature and drought conditions during summer months may potentially affect growth of Smallmouth Bass in this region. Groundwater streams in the region do not warm to the same extent as runoff streams during summer months and could provide a thermal refuge habitat for Smallmouth BaFlow alteration-ecology relationships in Ozark Highland streams: Consequences for fish, crayfish and macroinvertebrate assemblages
We examined flow alteration-ecology relationships in benthic macroinvertebrate, fish, and crayfish assemblages in Ozark Highland streams, USA, over two years with contrasting environmental conditions, a drought year (2012) and a flood year (2013). We hypothesized that: 1) there would be temporal variation in flow alteration-ecology relationships between the two years, 2) flow alteration-ecology reFlow-ecology relationships are spatially structured and differ among flow regimes
In streams, hydrology is a predominant driver of ecological structure and function. Providing adequate flows to support aquatic life, or environmental flows, is therefore a top management priority in stream systems. Flow regime classification is a widely accepted approach for establishing environmental flow guidelines. However, it is surprisingly difficult to quantify relationships between hydrolModelling effects of invasive species and drought on crayfish extinction risk and population dynamics
Hydrological alteration, which may be exacerbated by climate change, is known to facilitate aquatic species invasion. Altered hydrology, invasive species, and the additive effects of these stressors pose a threat to aquatic biodiversity.Understanding extinction risk in the context of these stressors is crucial for prioritizing conservation efforts. As case studies, three narrow‐ranged endemic crayModelling effects of invasive species and drought on crayfish extinction risk and population dynamics
Hydrological alteration, which may be exacerbated by climate change, is known to facilitate aquatic species invasion. Altered hydrology, invasive species, and the additive effects of these stressors pose a threat to aquatic biodiversity.Understanding extinction risk in the context of these stressors is crucial for prioritizing conservation efforts. As case studies, three narrow-ranged endemic crayForecasting effects of angler harvest and climate change on smallmouth bass abundance at the southern edge of their range
Climate change will affect stream systems in numerous ways over the coming century. Globally, streams are expected to experience changes in temperature and flow regime. Previous work has indicated that these changes will likely affect fish distributions, but little work has been conducted examining population level effects of climate change on warmwater fish at the warmest portion of their range.The influence of drought on flow‐ecology relationships in Ozark Highland streams
Drought and summer drying can have strong effects on abiotic and biotic components of stream ecosystems. Environmental flow‐ecology relationships may be affected by drought and drying, adding further uncertainty to the already complex interaction of flow with other environmental variables, including geomorphology and water quality.Environment–ecology relationships in stream communities in Ozark Hi