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 regime. This research contributes flow-ecology relations for streams in the southeast US, where managers are concerned about effects of flow alteration on the ability of systems to support species-rich assemblages of fishes and invertebrates, including imperiled taxa.
The Challenge: Ecologists have shown that many ecological processes in rivers, including organism growth, reproduction, survival and dispersal, are attuned to natural patterns of streamflow variability. However, to predict how riverine biota will respond to flow alteration caused by, for example, water diversions and dam operations, ecologists need to understand the mechanisms through which changes in streamflow affect plant and animal populations. Therefore, we are conducting field studies and analyses to test hypothesized effects of streamflow variability on population (survival, reproduction, extirpation, colonization) and trophic (primary production and consumption) dynamics.
The Science: We are quantifying spatial and temporal variation in multiple biological responses in relation to streamflow dynamics and across gradients of streamflow variability. Our studies include: mark-recapture to estimate fish survival and production of juveniles in relation to river flow patterns; comparison of fish communities between flow-regulated rivers with differing dam operations; monthly sampling to track persistence of small-bodied fishes in perennial streams affected by groundwater pumping; analyses of long-term (20-yr) monitoring data to assess high- and low-flow effects on fish community dynamics; and experimental manipulation to measure effects of variation in hydraulic conditions on biomass accrual by a submerged macrophtye.
The Future: Our studies are providing data and insights on how aquatic biota – especially fishes, invertebrates and macrophytes – may respond to changes in patterns of streamflow variability in southeastern U.S. rivers and streams, with potential relevance to other ecological systems that have strong effects of abiotic drivers. One of our goals is to use quantitative relationships between streamflow variability and biological processes to develop tools that allow stakeholders to forecast changes in riverine communities and productivity given shifts in streamflow regimes resulting from changes in climate, land use, and water management.
Below are publications associated with this project.
Identifying life history traits that promote occurrence for four minnow (Leuciscidae) species in intermittent Gulf Coastal Plain streams
Water velocity regulates macro-consumer herbivory on the benthic macrophyte Podostemum ceratophyllum Michx.
Long-term (37 years) impacts of low-head dams on freshwater shrimp habitat connectivity in northeastern Puerto Rico
Adaptive management of flows from R.L. Harris Dam (Tallapoosa River, Alabama)—Stakeholder process and use of biological monitoring data for decision making
Long-term monitoring data provide evidence of declining species richness in a river valued for biodiversity conservation
Ecology of the macrophyte Podostemum ceratophyllum Michx. (Hornleaf riverweed), a widespread foundation species of eastern North American rivers
Organic-matter retention and macroinvertebrate utilization of seasonally inundated bryophytes in a mid-order Piedmont River
Application of effective discharge analysis to environmental flow decision-making
Evidence of population resistance to extreme low flows in a fluvial-dependent fish species
Below are partners associated with this project.
- Overview
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 regime. This research contributes flow-ecology relations for streams in the southeast US, where managers are concerned about effects of flow alteration on the ability of systems to support species-rich assemblages of fishes and invertebrates, including imperiled taxa.
The Challenge: Ecologists have shown that many ecological processes in rivers, including organism growth, reproduction, survival and dispersal, are attuned to natural patterns of streamflow variability. However, to predict how riverine biota will respond to flow alteration caused by, for example, water diversions and dam operations, ecologists need to understand the mechanisms through which changes in streamflow affect plant and animal populations. Therefore, we are conducting field studies and analyses to test hypothesized effects of streamflow variability on population (survival, reproduction, extirpation, colonization) and trophic (primary production and consumption) dynamics.
The Science: We are quantifying spatial and temporal variation in multiple biological responses in relation to streamflow dynamics and across gradients of streamflow variability. Our studies include: mark-recapture to estimate fish survival and production of juveniles in relation to river flow patterns; comparison of fish communities between flow-regulated rivers with differing dam operations; monthly sampling to track persistence of small-bodied fishes in perennial streams affected by groundwater pumping; analyses of long-term (20-yr) monitoring data to assess high- and low-flow effects on fish community dynamics; and experimental manipulation to measure effects of variation in hydraulic conditions on biomass accrual by a submerged macrophtye.
The Future: Our studies are providing data and insights on how aquatic biota – especially fishes, invertebrates and macrophytes – may respond to changes in patterns of streamflow variability in southeastern U.S. rivers and streams, with potential relevance to other ecological systems that have strong effects of abiotic drivers. One of our goals is to use quantitative relationships between streamflow variability and biological processes to develop tools that allow stakeholders to forecast changes in riverine communities and productivity given shifts in streamflow regimes resulting from changes in climate, land use, and water management.
- Publications
Below are publications associated with this project.
Identifying life history traits that promote occurrence for four minnow (Leuciscidae) species in intermittent Gulf Coastal Plain streams
- Life history traits of stream fishes partly reflect adaptations to disturbance regimes, which in turn shape assemblage composition via environmental filters. In this study, we focused on life history traits of four morphologically similar leuciscid species in coastal plain streams of southwestern GA that are shifting from historically perennial to intermittent flow. We evaluated differences in rAuthorsJessica L. Davis, Mary Freeman, Stephen W. GolladayWater velocity regulates macro-consumer herbivory on the benthic macrophyte Podostemum ceratophyllum Michx.
1) Macrophytes influence aquatic ecosystems by increasing habitat complexity and providing trophic resources for aquatic fauna. While herbivory on freshwater macrophytes is widely documented in lakes, low-velocity riverine habitats, the influence of herbivory on macrophytes in higher-velocity habitats has rarely been examined. 2) We investigated the hypothesis that high water velocity can reducAuthorsJames L Wood, Jon W Skaggs, Caitlin C Conn, Mary FreemanLong-term (37 years) impacts of low-head dams on freshwater shrimp habitat connectivity in northeastern Puerto Rico
Freshwater migratory shrimp in Puerto Rico depend on watershed connectivity, from stream headwaters to the ocean, to complete their life cycle. Moreover, shrimp populations in different watersheds are known to be connected in an island-wide metapopulation. However, low-head dams paired with water intakes on streams draining the El Yunque National Forest (EYNF) reduce streamflow. Here, we examine tAuthorsJessica Chappell, S. Kyle McKay, Mary Freeman, Catherine M. PringleAdaptive management of flows from R.L. Harris Dam (Tallapoosa River, Alabama)—Stakeholder process and use of biological monitoring data for decision making
Adaptive management has been applied to problems with multiple conflicting objectives in various natural resources settings to learn how management actions affect divergent values regarding system response. Hydropower applications have only recently begun to emerge in the field, yet in the specific example reported herein, stakeholders invested in determining the best management alternatives for aAuthorsElise R. Irwin, Mary Freeman, James Peterson, Kathryn D.M. Kennedy, M. Clint Lloyd, Kristie M. Ouellette Coffman, Ely Kosnicki, Tom HessLong-term monitoring data provide evidence of declining species richness in a river valued for biodiversity conservation
Free-flowing river segments provide refuges for many imperiled aquatic biota that have been extirpated elsewhere in their native ranges. These biodiversity refuges are also foci of conservation concerns because species persisting within isolated habitat fragments may be particularly vulnerable to local environmental change. We have analyzed long-term (14- and 20-y) survey data to assess evidence oAuthorsMary Freeman, Megan M. Hagler, Phillip M. Bumpers, Kit Wheeler, Seth J. Wenger, Byron J. FreemanEcology of the macrophyte Podostemum ceratophyllum Michx. (Hornleaf riverweed), a widespread foundation species of eastern North American rivers
Podostemum ceratophyllum, commonly called Hornleaf Riverweed, occurs in mid-order montane and piedmont rivers of eastern North America, where the plant grows submerged and attached to rocks and stable substrates in swift, aerated water. Multiple studies, mostly conducted in the southern portions of the plant’s range, have shown that Podostemum can variously influence benthic communities in flowingAuthorsJames Wood, Mary FreemanOrganic-matter retention and macroinvertebrate utilization of seasonally inundated bryophytes in a mid-order Piedmont River
There is increased understanding of the role of bryophytes in supporting invertebrate biomass and for their influence on nutrient cycling and carbon balance in aquatic systems, but the structural and functional role of bryophytes growing in seasonally inundated habitats is substantially less studied. We conducted a study on the Middle Oconee River, near Athens, GA, to assess invertebrate abundanceAuthorsJames Wood, Meryom Pattillo, Mary FreemanApplication of effective discharge analysis to environmental flow decision-making
Well-informed river management decisions rely on an explicit statement of objectives, repeatable analyses, and a transparent system for assessing trade-offs. These components may then be applied to compare alternative operational regimes for water resource infrastructure (e.g., diversions, locks, and dams). Intra- and inter-annual hydrologic variability further complicates these already complex enAuthorsS. Kyle McKay, Mary Freeman, A.P. CovichEvidence of population resistance to extreme low flows in a fluvial-dependent fish species
Extreme low streamflows are natural disturbances to aquatic populations. Species in naturally intermittent streams display adaptations that enhance persistence during extreme events; however, the fate of populations in perennial streams during unprecedented low-flow periods is not well-understood. Biota requiring swift-flowing habitats may be especially vulnerable to flow reductions. We estimatedAuthorsRachel A. Katz, Mary Freeman - Partners
Below are partners associated with this project.