Mary Freeman, Ph.D.
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
Filter Total Items: 108
A method to assess longitudinal riverine connectivity in tropical streams dominated by migratory biota
1. One way in which dams affect ecosystem function is by altering the distribution and abundance of aquatic species. 2. Previous studies indicate that migratory shrimps have significant effects on ecosystem processes in Puerto Rican streams, but are vulnerable to impediments to upstream or downstream passage, such as dams and associated water intakes where stream water is withdrawn for human water
Authors
K.E. Crook, C. M. Pringle, Mary C. Freeman
Application of a multistate model to estimate culvert effects on movement of small fishes
While it is widely acknowledged that culverted road-stream crossings may impede fish passage, effects of culverts on movement of nongame and small-bodied fishes have not been extensively studied and studies generally have not accounted for spatial variation in capture probabilities. We estimated probabilities for upstream and downstream movement of small (30-120 mm standard length) benthic and wat
Authors
J.R. Norman, M.M. Hagler, Mary C. Freeman, B. J. Freeman
Stream fish occurrence in response to impervious cover, historic land use, and hydrogeomorphic factors
We evaluated competing models explaining the occurrence of five stream fishes in an urbanizing watershed to determine the relative importance of (a) impervious surface and other indicators of current land use, (b) historic land use (e.g., agriculture, impoundments), and (c) hydrogeomorphic characteristics (e.g., stream size, elevation, geology). For four of five species, the best-supported models
Authors
Seth J. Wenger, James Peterson, Mary C. Freeman, Byron J. Freeman, D. David Homans
Quantifying the extent of river fragmentation by hydropower dams in the Sarapiquí River Basin, Costa Rica
Costa Rica has recently experienced a rapid proliferation of dams for hydropower on rivers draining its northern Caribbean slope. In the Sarapiquí River Basin, eight hydropower plants were built between 1990 and 1999 and more projects are either under construction or proposed. The majority of these dams are small (<15 m tall) and operate as water diversion projects.While the potential environmenta
Authors
Elizabeth P. Anderson, Catherine M. Pringle, Mary C. Freeman
Estimating species occurrence, abundance, and detection probability using zero-inflated distributions
Researchers have developed methods to account for imperfect detection of species with either occupancy (presence-absence) or count data using replicated sampling. We show how these approaches can be combined to simultaneously estimate occurrence, abundance, and detection probability by specifying a zero-inflated distribution for abundance. This approach may be particularly appropriate when patte
Authors
S.J. Wenger, Mary C. Freeman
A new species of Percina (Perciformes: Percidae) from the Apalachicola River drainage, southeastern United States
Percina crypta, the Halloween Darter, is described as a new species endemic to the Chattahoochee and Flint River systems in Georgia and Alabama. Percina crypta differs from sympatric Percina nigrofasciata in having narrowly separated dorsal saddles (inter-saddle spaces typically less than or equal to saddle width, compared to frequently wider than saddle width in P. nigrofasciata), in usually poss
Authors
Mary C. Freeman, B. J. Freeman, N.M. Burkhead, C.A. Straight
Hydrologic connectivity and the contribution of stream headwaters to ecological integrity at regional scales
Cumulatively, headwater streams contribute to maintaining hydrologic connectivity and ecosystem integrity at regional scales. Hydrologic connectivity is the water-mediated transport of matter, energy and organisms within or between elements of the hydrologic cycle. Headwater streams compose over two-thirds of total stream length in a typical river drainage and directly connect the upland and rip
Authors
Mary C. Freeman, C. M. Pringle, C.R. Jackson
Riparian influences on stream fish assemblage structure in urbanizing streams
We assessed the influence of land cover at multiple spatial extents on fish assemblage integrity, and the degree to which riparian forests can mitigate the negative effects of catchment urbanization on stream fish assemblages. Riparian cover (urban, forest, and agriculture) was determined within 30 m buffers at longitudinal distances of 200 m, 1 km, and the entire network upstream of 59 non-neste
Authors
A.H. Roy, B. J. Freeman, Mary C. Freeman
Water Availability for Ecological Needs in the Upper Flint River Basin, Georgia
No abstract available.
Authors
M. Brian Gregory, Mary Freeman, W. Brian Hughes
Unionid habitat and assemblage composition in coastal plain tributaries of the Flint River (Georgia)
Effective conservation of mussels in streams of the lower Flint River basin, southwest Georgia, requires more rigorous understanding of mussel-habitat associations and factors shaping assemblage composition in stream reaches. We surveyed mussels and habitat conditions at 46 locations, and used regression, correlation and multivariate direct gradient analysis (Canonical Correspondence Analyses) to
Authors
P. Gagnon, W. Michener, M. Freeman, J. Brim-Box
Analysis of spawning behavior, habitat, and season of the federally threatened Etheostoma scotti, Cherokee darter (Osteichthyes: Percidae)
Etheostoma scotti (Cherokee darter) is a member of the subgenus Ulocentra and a federally threatened endemic to the Etowah River system, GA. Field observations of spawning behavior of the Cherokee darter were made at five stream sites to identify spawning season and habitat over two field seasons. Cherokee darters primarily spawn in pool habitats between mid-March and early June, at temperatures
Authors
C.M. Storey, B.A. Porter, Mary C. Freeman, B. J. Freeman
Ecological consequences of hydropower development in Central America: Impacts of small dams and water diversion on neotropical stream fish assemblages
Small dams for hydropower have caused widespread alteration of Central American rivers, yet much of recent development has gone undocumented by scientists and conservationists. We examined the ecological effects of a small hydropower plant (Dona Julia Hydroelectric Center) on two low-order streams (the Puerto Viejo River and Quebradon stream) draining a mountainous area of Costa Rica. Operation
Authors
Elizabeth P. Anderson, Mary C. Freeman, C. M. Pringle
Science and Products
Filter Total Items: 108
A method to assess longitudinal riverine connectivity in tropical streams dominated by migratory biota
1. One way in which dams affect ecosystem function is by altering the distribution and abundance of aquatic species. 2. Previous studies indicate that migratory shrimps have significant effects on ecosystem processes in Puerto Rican streams, but are vulnerable to impediments to upstream or downstream passage, such as dams and associated water intakes where stream water is withdrawn for human water
Authors
K.E. Crook, C. M. Pringle, Mary C. Freeman
Application of a multistate model to estimate culvert effects on movement of small fishes
While it is widely acknowledged that culverted road-stream crossings may impede fish passage, effects of culverts on movement of nongame and small-bodied fishes have not been extensively studied and studies generally have not accounted for spatial variation in capture probabilities. We estimated probabilities for upstream and downstream movement of small (30-120 mm standard length) benthic and wat
Authors
J.R. Norman, M.M. Hagler, Mary C. Freeman, B. J. Freeman
Stream fish occurrence in response to impervious cover, historic land use, and hydrogeomorphic factors
We evaluated competing models explaining the occurrence of five stream fishes in an urbanizing watershed to determine the relative importance of (a) impervious surface and other indicators of current land use, (b) historic land use (e.g., agriculture, impoundments), and (c) hydrogeomorphic characteristics (e.g., stream size, elevation, geology). For four of five species, the best-supported models
Authors
Seth J. Wenger, James Peterson, Mary C. Freeman, Byron J. Freeman, D. David Homans
Quantifying the extent of river fragmentation by hydropower dams in the Sarapiquí River Basin, Costa Rica
Costa Rica has recently experienced a rapid proliferation of dams for hydropower on rivers draining its northern Caribbean slope. In the Sarapiquí River Basin, eight hydropower plants were built between 1990 and 1999 and more projects are either under construction or proposed. The majority of these dams are small (<15 m tall) and operate as water diversion projects.While the potential environmenta
Authors
Elizabeth P. Anderson, Catherine M. Pringle, Mary C. Freeman
Estimating species occurrence, abundance, and detection probability using zero-inflated distributions
Researchers have developed methods to account for imperfect detection of species with either occupancy (presence-absence) or count data using replicated sampling. We show how these approaches can be combined to simultaneously estimate occurrence, abundance, and detection probability by specifying a zero-inflated distribution for abundance. This approach may be particularly appropriate when patte
Authors
S.J. Wenger, Mary C. Freeman
A new species of Percina (Perciformes: Percidae) from the Apalachicola River drainage, southeastern United States
Percina crypta, the Halloween Darter, is described as a new species endemic to the Chattahoochee and Flint River systems in Georgia and Alabama. Percina crypta differs from sympatric Percina nigrofasciata in having narrowly separated dorsal saddles (inter-saddle spaces typically less than or equal to saddle width, compared to frequently wider than saddle width in P. nigrofasciata), in usually poss
Authors
Mary C. Freeman, B. J. Freeman, N.M. Burkhead, C.A. Straight
Hydrologic connectivity and the contribution of stream headwaters to ecological integrity at regional scales
Cumulatively, headwater streams contribute to maintaining hydrologic connectivity and ecosystem integrity at regional scales. Hydrologic connectivity is the water-mediated transport of matter, energy and organisms within or between elements of the hydrologic cycle. Headwater streams compose over two-thirds of total stream length in a typical river drainage and directly connect the upland and rip
Authors
Mary C. Freeman, C. M. Pringle, C.R. Jackson
Riparian influences on stream fish assemblage structure in urbanizing streams
We assessed the influence of land cover at multiple spatial extents on fish assemblage integrity, and the degree to which riparian forests can mitigate the negative effects of catchment urbanization on stream fish assemblages. Riparian cover (urban, forest, and agriculture) was determined within 30 m buffers at longitudinal distances of 200 m, 1 km, and the entire network upstream of 59 non-neste
Authors
A.H. Roy, B. J. Freeman, Mary C. Freeman
Water Availability for Ecological Needs in the Upper Flint River Basin, Georgia
No abstract available.
Authors
M. Brian Gregory, Mary Freeman, W. Brian Hughes
Unionid habitat and assemblage composition in coastal plain tributaries of the Flint River (Georgia)
Effective conservation of mussels in streams of the lower Flint River basin, southwest Georgia, requires more rigorous understanding of mussel-habitat associations and factors shaping assemblage composition in stream reaches. We surveyed mussels and habitat conditions at 46 locations, and used regression, correlation and multivariate direct gradient analysis (Canonical Correspondence Analyses) to
Authors
P. Gagnon, W. Michener, M. Freeman, J. Brim-Box
Analysis of spawning behavior, habitat, and season of the federally threatened Etheostoma scotti, Cherokee darter (Osteichthyes: Percidae)
Etheostoma scotti (Cherokee darter) is a member of the subgenus Ulocentra and a federally threatened endemic to the Etowah River system, GA. Field observations of spawning behavior of the Cherokee darter were made at five stream sites to identify spawning season and habitat over two field seasons. Cherokee darters primarily spawn in pool habitats between mid-March and early June, at temperatures
Authors
C.M. Storey, B.A. Porter, Mary C. Freeman, B. J. Freeman
Ecological consequences of hydropower development in Central America: Impacts of small dams and water diversion on neotropical stream fish assemblages
Small dams for hydropower have caused widespread alteration of Central American rivers, yet much of recent development has gone undocumented by scientists and conservationists. We examined the ecological effects of a small hydropower plant (Dona Julia Hydroelectric Center) on two low-order streams (the Puerto Viejo River and Quebradon stream) draining a mountainous area of Costa Rica. Operation
Authors
Elizabeth P. Anderson, Mary C. Freeman, C. M. Pringle