Mary Freeman is a research ecologist with the Eastern Ecological Science Center at Athens, GA.
She received a B.S. in biology (1979), a M.S. in entomology (1982) and a Ph.D. in forest resources (1990) from the University of Georgia. Before joining Patuxent, Mary conducted research for the U.S. Fish and Wildlife Service and the National Biological Service in Auburn, AL (1992-1996). Mary serves as affiliate faculty at the Odum School of Ecology, University of Georgia, and on the graduate faculties at the University of Georgia and Auburn University.
Science and Products
Assessing Faunal Recovery in a Headwater Stream
A catastrophic fish-kill in a small tributary stream of the Etowah River system (Dawson County, Georgia) has created the opportunity to assess faunal recovery, including recolonization by a federally-listed fish species (the Cherokee darter Etheostoma scotti). Fishes are expected to recolonize Flat Creek by moving upstream from downstream sources. In particular, Flat Creek flows into a larger...
Quantifying Restoration Benefits to Native Stream Fishes
This project is a collaboration of scientists from the USGS and University of Georgia to collect and analyze data describing how small-stream fishes use habitats created through stream restoration activities. The USFWS Region 4 requested this Science Support Partnership (SSP) project as a means to evaluate the effectiveness of stream restoration (primarily in north Georgia, and potentially in...
Synthesizing Multiple Long-Term Datasets to Test Flow Ecology Relationships for Fishes - Workshop
River ecosystems support a wide diversity of biota, including thousands of fish species, which are variously adapted to the dynamic environments provided by flowing-water habitats. One of the primary ways that human activities diminish the biological capacity of rivers is by altering the natural hydrologic variability of river systems through regulation and diversion of streamflow for other uses.
WaterSMART: Apalachicola/Chattahoochee/ Flint River (ACF) Basin
The Challenge: The DOI WaterSMART (Sustain and Manage America’s Resources for Tomorrow) initiative is developing data and tools to help water managers identify current and future water shortages, for humans and for freshwater ecosystems. Fishes, for example, can decline in diversity and abundance when streamflow becomes too low, for too long. However, ecologists find that effects of declining...
Quantifying Effects of Flow Variability on Riverine Biota
Stream and river biota around the world are imperiled by alterations to stream flow regimes that result from dams, land-use changes, water diversions and changing climate patterns. To manage and conserve stream-dependent species threatened by flow alterations, natural resource managers need quantitative information relating multiple aspects of ecological response to changes in a stream’s flow...
Southeast Regional Assessment Project (SERAP): Assessing Global Change Impacts on Natural and Human Systems in the Southeast
The Southeastern United States spans a broad range of physiographic settings and maintains exceptionally high levels of faunal diversity. Unfortunately, many of these ecosystems are increasingly under threat due to rapid human development, and management agencies are increasingly aware of the potential effects that climate change will have on these ecosystems. Natural resource managers and conserv
USGS-USFS Partnership to Help Managers Evaluate Conservation Strategies for Aquatic Ecosystems Based on Future Climate Projections
The Southeastern U.S. spans broad ranges of physiographic settings and contains a wide variety of aquatic systems that provide habitat for hundreds of endemic aquatic species that pose interesting challenges and opportunities for managers of aquatic resources, particularly in the face of climate change. For example, the Southeast contains the southernmost populations of the eastern brook trout and
Slow recovery of headwater-stream fishes following a catastrophic poisoning event
Fish collection data for surveys made at 5 localities in Flat Creek, Dawson County GA, on 6 dates that spanned a 4 to 18.5-month period following a catastrophic fish kill caused by a chemical spill near the headwater origin on Flat Creek. The data are: locality descriptions, water depth and velocity measurements made during fish sampling, and tabulated numbers and range in body length of individua
Annual survival, site fidelity, and longevity in the eastern population of the Painted Bunting (Passerina ciris)
Data comprise 6632 observations of individually banded Painted Buntings, captured and observed from 1999-2016 at 40 study locations on the southeastern Atlantic Coast (NC, SC, GA and FL, US).
Filter Total Items: 99
Habitat associations of riverine fishes among rocky shoals
Understanding species' associations with physical habitat conditions is a fundamental goal of ecology. For organisms that occupy lotic ecosystems, relationships to streamflow are of particular importance, but these associations are unstudied for most species. We tested the predictability of fish–microhabitat relationships in river shoals (shallow, rocky areas with relatively swift water flow) usin
Seasonal variability in macroinvertebrate assemblages in paired perennial and intermittent streams in Costa Rica
Ecological effects of flooding and drying events are relatively understudied in the Neotropics and less is known about these hydrological extremes in intermittent streams. Neotropical headwater streams in Costa Rica provide opportunities to evaluate the response of macroinvertebrate communities to seasonal changes in flow regime in relatively human undisturbed systems. We quantified the effects of
Simple statistical models can be sufficient for testing hypotheses with population time series data
Time-series data offer wide-ranging opportunities to test hypotheses about the physical and biological factors that influence species abundances. Although sophisticated models have been developed and applied to analyze abundance time series, they require information about species detectability that is often unavailable. We propose that in many cases, simpler models are adequate for testing hypothe
Multispecies approaches to status assessments in support of endangered species classifications
Multispecies risk assessments have developed within many international conservation programs, reflecting a widespread need for efficiency. Under the United States Endangered Species Act (ESA), multispecies assessments ultimately lead to species-level listing decisions. Although this approach provides opportunities for improved efficiency, it also risks overwhelming or biasing the assessment proces
Toward improved prediction of streamflow effects on freshwater fishes
Understanding the effects of hydrology on fish populations is essential to managing for native fish conservation. However, despite decades of research illustrating streamflow influences on fish habitat, reproduction and survival, biologists remain challenged when tasked with predicting how fish populations will respond to changes in flow regimes. This uncertainty stems from insufficient understand
Effects of stream intermittency on minnow (Leuciscidae) and darter (Percidae) trophic dynamics in an agricultural watershed
Stream intermittency is predicted to increase where water withdrawals and climate warming are increasing. In regions coupled with high fish diversity, understanding how intermittency influences fish trophic ecology is critical for informing ecosystem function. This study compared fish diets across seasons in perennial and intermittent streams to estimate the immediate and cumulative effects of str
Do crayfish affect stream ecosystem response to riparian vegetation removal?
1. Riparian vegetation management alters stream basal resources, but stream ecosystem responses partly depend on top-down interactions with in-stream consumers. Large-bodied omnivores can exert particularly strong influences on stream benthic environments through consumption of food resources and physical disturbance of the benthos. Trophic dynamics studies conducted within the context of reach-sc
Integrating tracking and resight data enables unbiased inferences about migratory connectivity and winter range survival from archival tags
Archival geolocators have transformed the study of small, migratory organisms but analysis of data from these devices requires bias correction because tags are only recovered from individuals that survive and are re-captured at their tagging location. We show that integrating geolocator recovery data and mark–resight data enables unbiased estimates of both migratory connectivity between breeding a
Slow recovery of headwater-stream fishes following a catastrophic poisoning event
Accidental spills of chemicals and other pollutants can decimate populations of stream-dwelling species. Recovery from such accidents can be relatively fast and complete when the affected stream reaches can be recolonized from upstream and downstream sources. However, faunal recoveries from accidental spills that extirpate populations from entire headwater streams have not been extensively documen
Mixed evidence for biotic homogenization of southern Appalachian fish communities
Anthropogenic impacts on the landscape can drive biotic homogenization, whereby distinct biological communities become more similar to one another over time. Land-use change in the Southern Appalachian region is expected to result in homogenization of the highly diverse freshwater fish communities as in-stream habitat alterations favor widespread cosmopolitan species at the expense of more narrowl
A Bayesian framework for assessing extinction risk based on ordinal categories of population condition and projected landscape change
Many at-risk species lack standardized surveys across their range or quantitative data capable of detecting demographic trends. As a result, extinction risk assessments often rely on ordinal categories of risk based on explicit criteria or expert elicitation. This study demonstrates a Bayesian approach to assessing extinction risk based on this common data structure, using three freshwater mussel
Ecological forecasting—21st century science for 21st century management
Natural resource managers are coping with rapid changes in both environmental conditions and ecosystems. Enabled by recent advances in data collection and assimilation, short-term ecological forecasting may be a powerful tool to help resource managers anticipate impending near-term changes in ecosystem conditions or dynamics. Managers may use the information in forecasts to minimize the adverse ef
By
Ecosystems, Water Resources, Wildlife Program (unpublished), Contaminant Biology, Environmental Health Program, Science Analytics and Synthesis (SAS), Patuxent Wildlife Research Center, Eastern Ecological Science Center, Fort Collins Science Center, Kansas Water Science Center, Maryland-Delaware-D.C. Water Science Center, National Wildlife Health Center, New Jersey Water Science Center, Pacific Island Ecosystems Research Center, Southwest Biological Science Center, Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center
Science and Products
- Science
Assessing Faunal Recovery in a Headwater Stream
A catastrophic fish-kill in a small tributary stream of the Etowah River system (Dawson County, Georgia) has created the opportunity to assess faunal recovery, including recolonization by a federally-listed fish species (the Cherokee darter Etheostoma scotti). Fishes are expected to recolonize Flat Creek by moving upstream from downstream sources. In particular, Flat Creek flows into a larger...Quantifying Restoration Benefits to Native Stream Fishes
This project is a collaboration of scientists from the USGS and University of Georgia to collect and analyze data describing how small-stream fishes use habitats created through stream restoration activities. The USFWS Region 4 requested this Science Support Partnership (SSP) project as a means to evaluate the effectiveness of stream restoration (primarily in north Georgia, and potentially in...Synthesizing Multiple Long-Term Datasets to Test Flow Ecology Relationships for Fishes - Workshop
River ecosystems support a wide diversity of biota, including thousands of fish species, which are variously adapted to the dynamic environments provided by flowing-water habitats. One of the primary ways that human activities diminish the biological capacity of rivers is by altering the natural hydrologic variability of river systems through regulation and diversion of streamflow for other uses.WaterSMART: Apalachicola/Chattahoochee/ Flint River (ACF) Basin
The Challenge: The DOI WaterSMART (Sustain and Manage America’s Resources for Tomorrow) initiative is developing data and tools to help water managers identify current and future water shortages, for humans and for freshwater ecosystems. Fishes, for example, can decline in diversity and abundance when streamflow becomes too low, for too long. However, ecologists find that effects of declining...Quantifying Effects of Flow Variability on Riverine Biota
Stream and river biota around the world are imperiled by alterations to stream flow regimes that result from dams, land-use changes, water diversions and changing climate patterns. To manage and conserve stream-dependent species threatened by flow alterations, natural resource managers need quantitative information relating multiple aspects of ecological response to changes in a stream’s flow...Southeast Regional Assessment Project (SERAP): Assessing Global Change Impacts on Natural and Human Systems in the Southeast
The Southeastern United States spans a broad range of physiographic settings and maintains exceptionally high levels of faunal diversity. Unfortunately, many of these ecosystems are increasingly under threat due to rapid human development, and management agencies are increasingly aware of the potential effects that climate change will have on these ecosystems. Natural resource managers and conservUSGS-USFS Partnership to Help Managers Evaluate Conservation Strategies for Aquatic Ecosystems Based on Future Climate Projections
The Southeastern U.S. spans broad ranges of physiographic settings and contains a wide variety of aquatic systems that provide habitat for hundreds of endemic aquatic species that pose interesting challenges and opportunities for managers of aquatic resources, particularly in the face of climate change. For example, the Southeast contains the southernmost populations of the eastern brook trout and - Data
Slow recovery of headwater-stream fishes following a catastrophic poisoning event
Fish collection data for surveys made at 5 localities in Flat Creek, Dawson County GA, on 6 dates that spanned a 4 to 18.5-month period following a catastrophic fish kill caused by a chemical spill near the headwater origin on Flat Creek. The data are: locality descriptions, water depth and velocity measurements made during fish sampling, and tabulated numbers and range in body length of individuaAnnual survival, site fidelity, and longevity in the eastern population of the Painted Bunting (Passerina ciris)
Data comprise 6632 observations of individually banded Painted Buntings, captured and observed from 1999-2016 at 40 study locations on the southeastern Atlantic Coast (NC, SC, GA and FL, US). - Publications
Filter Total Items: 99
Habitat associations of riverine fishes among rocky shoals
Understanding species' associations with physical habitat conditions is a fundamental goal of ecology. For organisms that occupy lotic ecosystems, relationships to streamflow are of particular importance, but these associations are unstudied for most species. We tested the predictability of fish–microhabitat relationships in river shoals (shallow, rocky areas with relatively swift water flow) usinSeasonal variability in macroinvertebrate assemblages in paired perennial and intermittent streams in Costa Rica
Ecological effects of flooding and drying events are relatively understudied in the Neotropics and less is known about these hydrological extremes in intermittent streams. Neotropical headwater streams in Costa Rica provide opportunities to evaluate the response of macroinvertebrate communities to seasonal changes in flow regime in relatively human undisturbed systems. We quantified the effects ofSimple statistical models can be sufficient for testing hypotheses with population time series data
Time-series data offer wide-ranging opportunities to test hypotheses about the physical and biological factors that influence species abundances. Although sophisticated models have been developed and applied to analyze abundance time series, they require information about species detectability that is often unavailable. We propose that in many cases, simpler models are adequate for testing hypotheMultispecies approaches to status assessments in support of endangered species classifications
Multispecies risk assessments have developed within many international conservation programs, reflecting a widespread need for efficiency. Under the United States Endangered Species Act (ESA), multispecies assessments ultimately lead to species-level listing decisions. Although this approach provides opportunities for improved efficiency, it also risks overwhelming or biasing the assessment procesToward improved prediction of streamflow effects on freshwater fishes
Understanding the effects of hydrology on fish populations is essential to managing for native fish conservation. However, despite decades of research illustrating streamflow influences on fish habitat, reproduction and survival, biologists remain challenged when tasked with predicting how fish populations will respond to changes in flow regimes. This uncertainty stems from insufficient understandEffects of stream intermittency on minnow (Leuciscidae) and darter (Percidae) trophic dynamics in an agricultural watershed
Stream intermittency is predicted to increase where water withdrawals and climate warming are increasing. In regions coupled with high fish diversity, understanding how intermittency influences fish trophic ecology is critical for informing ecosystem function. This study compared fish diets across seasons in perennial and intermittent streams to estimate the immediate and cumulative effects of strDo crayfish affect stream ecosystem response to riparian vegetation removal?
1. Riparian vegetation management alters stream basal resources, but stream ecosystem responses partly depend on top-down interactions with in-stream consumers. Large-bodied omnivores can exert particularly strong influences on stream benthic environments through consumption of food resources and physical disturbance of the benthos. Trophic dynamics studies conducted within the context of reach-scIntegrating tracking and resight data enables unbiased inferences about migratory connectivity and winter range survival from archival tags
Archival geolocators have transformed the study of small, migratory organisms but analysis of data from these devices requires bias correction because tags are only recovered from individuals that survive and are re-captured at their tagging location. We show that integrating geolocator recovery data and mark–resight data enables unbiased estimates of both migratory connectivity between breeding aSlow recovery of headwater-stream fishes following a catastrophic poisoning event
Accidental spills of chemicals and other pollutants can decimate populations of stream-dwelling species. Recovery from such accidents can be relatively fast and complete when the affected stream reaches can be recolonized from upstream and downstream sources. However, faunal recoveries from accidental spills that extirpate populations from entire headwater streams have not been extensively documenMixed evidence for biotic homogenization of southern Appalachian fish communities
Anthropogenic impacts on the landscape can drive biotic homogenization, whereby distinct biological communities become more similar to one another over time. Land-use change in the Southern Appalachian region is expected to result in homogenization of the highly diverse freshwater fish communities as in-stream habitat alterations favor widespread cosmopolitan species at the expense of more narrowlA Bayesian framework for assessing extinction risk based on ordinal categories of population condition and projected landscape change
Many at-risk species lack standardized surveys across their range or quantitative data capable of detecting demographic trends. As a result, extinction risk assessments often rely on ordinal categories of risk based on explicit criteria or expert elicitation. This study demonstrates a Bayesian approach to assessing extinction risk based on this common data structure, using three freshwater musselEcological forecasting—21st century science for 21st century management
Natural resource managers are coping with rapid changes in both environmental conditions and ecosystems. Enabled by recent advances in data collection and assimilation, short-term ecological forecasting may be a powerful tool to help resource managers anticipate impending near-term changes in ecosystem conditions or dynamics. Managers may use the information in forecasts to minimize the adverse efByEcosystems, Water Resources, Wildlife Program (unpublished), Contaminant Biology, Environmental Health Program, Science Analytics and Synthesis (SAS), Patuxent Wildlife Research Center, Eastern Ecological Science Center, Fort Collins Science Center, Kansas Water Science Center, Maryland-Delaware-D.C. Water Science Center, National Wildlife Health Center, New Jersey Water Science Center, Pacific Island Ecosystems Research Center, Southwest Biological Science Center, Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center