Progress 10/01/99 to 09/30/05
Outputs
Many watersheds in the Midwest are undergoing rapid urbanization, which leads to greater imperviousness and increased storm runoff. Very little research has addressed the consequences of such land-use and hydrologic change on streams and their aquatic communities. We compared physical and ecological characteristics of eight streams in central Indiana ranging from low to high watershed imperviousness. Watersheds in the Indianapolis area have undergone rapid development and significantly increased stream flow in recent decades. Increased flow leads to stream channel enlargement, either by incision or lateral (bank) erosion. The study streams in this project were surveyed for geomorphic stability. Shear stress, bankfull flow, and bed mobilizing flow (Qcrit) were successful predictors of urbanization. Bed mobilization (scour) during storm flow is thought to be an important mechanism affecting the composition of stream communities. We sampled fish and macroinvertebrates in
each of the study streams to evaluate biological metrics as possible urbanization indicators. Overall quality of the fish community (as measured by the index of biotic integrity, IBI) declined with imperviousness. In particular, the proportion of darters and sculpins declined significantly with greater channel instability and imperviousness. Metrics were also evaluated for 35 aquatic insect families. While most of these metrics showed negative trends with increasing imperviousness, two were most significant: a decrease in the proportion of clinger taxa (insects susceptible to substrate scouring) and an increase in the ratio of Baetis to total Ephemeroptera. Both metrics showed a clear change at very low levels of urbanizations, levels at which streams still appear unimpacted (having a good riparian buffer, typical riffle-pool development, clean gravel, etc.). Freshwater mussels are of particular concern because many populations are declining throughout the region. We found that mussel
populations were reduced in the urban streams compared to rural streams of similar size. Sites with unstable channels and high shear stress were negatively correlated with the presence of mussels. Because of their slow growth, long life spans, poor dispersal, sensitivity to erosion, and complex reproductive requirements, freshwater mussels are especially vulnerable to physical habitat degradation. While hydrologic change is thought to be the primary non-point stressor on aquatic communities in urbanizing areas, habitat fragmentation often contributes as well. We studied headwater streams affected by downstream reservoirs (a form of fragmentation that limits dispersal of stream species). Two darter species and one sculpin species were found to have greater extinction probabilities and reduced colonization probabilities in fragmented streams. Since these are the same species previously shown to be most affected by urbanization, it is now clear that darters and sculpins are ideal
indicators for Midwestern streams undergoing a broader array of land-use changes.
Impacts
This project addressed the impacts of urbanization and habitat fragmentation on Midwestern stream communities, including native fishes, aquatic insects, and freshwater mussels. Adverse changes in all three groups were shown to be associated with urban hydrologic and habitat changes. Because the ecological responses are most clearly related to stream flow, which can be directly measured and modeled, specific design recommendations can now be made that will lead to better planning and more sustainable urban development in the future.
Publications
- Guenther, C. B. 2005. Response of fish assemblages to habitat fragmentation caused by downstream impoundments within the upper Wabash River basin, Indiana. Ph.D. thesis. Purdue University.
|
Progress 10/01/03 to 09/29/04
Outputs
Current research includes a more detailed characterization of habitats and stream communities affected by urbanization and similar land-use changes. Relatively few reference sites (those unimpacted by urbanization) were included in the original project, which limited the statistical power of our comparisons. Therefore sampling in 2003-2004 was expanded to include a much wider array of non-urban streams, as well as several fragmented stream systems (affected by dams) in north-central Indiana. We are using multivariate analysis to partition the observed variations in species abundance into those portions attributable to instream habitat and to broader watershed characteristics. Significant shifts in the relative abundance of specialist versus generalist fish species have been observed that can be attributed to habitat fragmentation. Darter species (fluvial specialists) were particularly affected by altered flow regimes. Stream habitat quality and macroinvertebrate
communities were also assessed at 22 sites in west-central Indiana, where typical best management practices (BMPs) have been installed to reduce impacts of nonpoint pollution. Local channelization (stream ditching) was found to be the single largest factor causing poor habitat quality and reduced species abundance. This stressor outweighed any other water quality or land use factor in predicting species distributions. Unchannelized stream reaches (14 of 22 sites) showed significant improvements in community structure downstream of typical BMPs.
Impacts
Previous phases of this project emphasized the importance of land use characteristics within a watershed, especially imperviousness, as agents of change in stream ecosystems. Our study and others have demonstrated that urbanization causes hydrologic and morphologic changes in stream channels that stress native fish communities, even if water pollution is eliminated. Some of this habitat degradation can be minimized by the use of best management practices (BMPs) in and near the riparian corridor. In our most recent research, the additional importance of connectivity is highlighted. That means that stream systems and their fauna require naturally free-flowing water, a condition that is often impaired by dams, diversions, and other flow modifications. These agents of aquatic habitat fragmentation frequently occur in association with urban development in a watershed. New design concepts are needed if healthy aquatic communities are to survive in rapidly growing areas of
the Midwest.
Publications
- Sobecki, J. 2003. Assessing effectiveness and condition of BMPs in Indiana: introduction of a new evaluation tool. M.S. thesis. Purdue University.
- Lauer, T., and A. Spacie. 2004. Space as a limiting resource in freshwater systems: competition between zebra mussels (Dreissena polymorpha) and freshwater sponges (Porifera). Hydrobiologia 517:137-145.
- Spacie, A. 2004. Streams in transition: ecological responses to increasing urbanization. 21st Annual Water and the Future of Kansas Conference, March 11, 2004. Lawrence KS. (abstract).
- Sobecki, J., A. Spacie, and A. Lehnan. 2004. Response of Midwestern stream communities to riparian best management practices. American Water Resources. Assoc. Conference on Riparian Ecosystems and Buffers, Olympic Valley, CA. (abstract).
- Guenther, C., and A. Spacie. 2004. Assessing the impacts of channel fragmentation on stream fish communities in the Upper Wabash River drainage basin. American Fisheries Society. (abstract).
|
Progress 10/01/02 to 09/30/03
Outputs
Progress in 2003 focused on changes in stream fish communities related to land use. Twenty-four stream sites in central Indiana representing a gradient of land uses from agricultural to urban were sampled over two years to determine trends in fish community composition and related habitat variables. We found significant correlations between impervious area (urban land use), channel morphological change, reduced habitat quality, and the loss of sensitive components of the fish community. In particular, species that rely on a stable substrate for feeding and reproduction (darters, sculpins, and several minnow species) were absent from urban streams. Significant changes in both habitat quality and fish assemblage structure appear to occur at relatively low levels of urbanization (approximately 10% imperviousness), a finding that supports similar studies in streams of the east and west coasts. The changes were more clearly linked to physical / hydrologic changes rather
than to degraded water quality. A suite of urbanization indicators based on these results is currently under development. In a related project, a series of agricultural streams was evaluated for their responses to the presence of riparian BMPs (best management practices). These are standard practices such as vegetative filter strips that can be of use in both agricultural and urban settings. Significant improvements in stream habitat quality and stream macroinvertebrate communities at sites downstream of the BMPs were documented. This is one of the few studies that have actually investigated the beneficial effects on riparian BMPs on streams in the Midwest.
Impacts
This study has shown that relatively low levels of urbanization (approximately 10% impervious surfaces in a watershed) are related to negative changes in stream habitats and their associated fish communities. Sensitive species requiring good quality habitats and stable substrates become less common as urbanization proceeds in a midwestern watershed. The changes appear to be related to increased runoff and more unstable stream flow and are not caused simply by water pollution. Such changes in the fish community can be used as indicators of urbanization. An understanding of these physical and biological changes may lead to new or improved practices for protecting streams in urbanizing watersheds.
Publications
- Wang, H., M. Hondzo, C. Xu, V. Poole, and A. Spacie. 2003. Dissolved oxygen dynamics of streams draining an urbanized and an agricultural catchment. Ecological Modeling. 160:145-161.
- Rich. C.F., Jr. 2003. Effects of urbanization on habitats and fish communities of Midwestern headwater streams. Ph.D. thesis. Purdue University. 127 pp.
|
Progress 10/01/01 to 09/30/02
Outputs
Specific objectives of the project are: (1) to develop predictive relationships among flow regime, channel stability, and stream community structure and function across a gradient of land uses in agricultural and urbanizing watersheds; (2) to identify and test key factors limiting stream community structure and function; and (3) to formulate design criteria for protection of stream communities in urbanizing areas based on land use, hydrology, channel characteristics, and aquatic species present. The first objective has been accomplished by examining recent data sets on land use, stream channel morphology, water quality, invertebrates, and algae for a range of urbanizing watersheds in the eastern corn belt ecoregion of Indiana (Tippecanoe and Marion Counties). Data for these counties has been evaluated to determine significant correlations among land use (as percent imperviousness), channel stability (shear stress, median substrate size, probability of exceedence of
critical flow), and various metrics characterizing stream community structure and function (such as percent omnivorous insects). In 2002 we have also extended the region studied to include a larger set of un-urbanized watersheds beyond those available in the original two counties. Preliminary results show that aquatic communities in urban streams become dominated by generalist organisms with short life cycles that can tolerate relatively large changes in flow and streambed movement. Some taxa, such as freshwater mussels and darters (fish) are particularly susceptible to displacement by scouring flows. The channels themselves often become less stable, leading to increased bank erosion and downstream siltation.
Impacts
Land use changes in a watershed can directly affect streams and their communities by altering hydrologic patterns. We are currently developing predictive relationships between the amount of imperviousness in a watershed (an indicator of urbanization) and stream community health. In 2002 we have expanded our study to include a range of non-urban land uses. This information will be valuable to regional planners and resource agencies.
Publications
- Myers-Kinzie, M., A. Spacie, C. Rich, and M. Doyle. 2002. Relationship of unionid mussel occurrence to channel stability in urban streams. Verh. Internat. Verein. Limnologie 28:1-5.
|
Progress 10/01/00 to 09/30/01
Outputs
Many watersheds across the midwestern USA are urbanizing at unprecedented rates. As forest and farmland is converted to residential and commercial uses, the imperviousness of the watershed typically increases, changing the hydrologic response of streams draining the area. This project focuses on the relationship between urban runoff, stream channel characteristics, and the responses of downstream aquatic communities. Specific objectives of the project are: (1) to develop predictive relationships among flow regime, channel stability, and stream community structure and function across a gradient of land uses in agricultural and urbanizing watersheds; (2) to identify and test key factors limiting stream community structure and function; and (3) to formulate design criteria for protection of stream communities in urbanizing areas based on land use, hydrology, channel characteristics, and aquatic species present. The first objective has been accomplished by examining
recent data sets on land use, stream channel morphology, water quality, invertebrates, and algae for a range of urbanizing watersheds in the eastern cornbelt ecoregion of Indiana (Tippecanoe and Marion Counties). The data are currently being evaluated to determine significant correlations among land use (as percent imperviousness), channel stability (shear stress, median substrate size, probability of exceedence of critical flow), and various metrics characterizing stream community structure and function (such as percent omnivorous insects). Preliminary results show that aquatic communities in urban streams become dominated by generalist organisms with short life cycles that can tolerate relatively large changes in flow and streambed movement. Some taxa, such as freshwater mussels and darters (fish) are particularly susceptible to displacement by scouring flows. The channels themselves often become less stable, leading to increased bank erosion and downstream siltation. Recognizing
and understanding this pattern can lead to better decisions related to agricultural land development, urban planning, and infrastructure design. The project will also develop and test practical ecosystem indicators of urbanization that will be useful to resource managers evaluating current stream community conditions prior to or during rapid urbanization.
Impacts
This project evaluates the response of stream organisms and their habitats to increased stream flow variability and related hydrologic changes associated with urbanization. The amount of impervious surface area in a watershed (roofing, roads, etc.) is thought to cause degradation of aquatic communities, stream channel structure, and water quality. Biological indicators developed in this project will contribute to improved stream protection practices and watershed planning.
Publications
- Myers-Kinzie, M., A. Spacie, C. Rich, and M. Doyle. 2001. Relationship of unionid mussel occurrence to channel stability in urban streams. Verh. International Verein. Limnologie (in press).
- Deitch, Matthew. 2001. Effects of physical factors on periphyton communities in urbanizing Midwestern streams. M.S. thesis. Purdue University.May 2001.
- Deitch, M., and A. Spacie. 2001. Effects of storm-induced disturbances on periphyton communities: an experiment in artificial streamside channels. Presented at: SIL Melbourne, Feb. 4-9 (published abstract).
- Spacie, A. J.M. Harbor, M. Hondzo, and B.A.Engel. 2000. Development and evaluation of ecosystem indicators for urbanizing Midwestern watersheds. Proceedings: 2000 STAR Ecosystem Indicators Workshop. U.S. EPA National Center for Environmental Research. Las Vegas, NV. EPA 600/R-00/017.
- Myers-Kinzie, M. and A. Spacie. 2000. The response of benthic insect communities to urbanization in small midwestern watersheds. North American Benthological Assocn. annual meeting, Keystone CO. May 28-June 1 (published abstract).
|
Progress 10/01/99 to 09/30/00
Outputs
Many watersheds across the midwestern USA are urbanizing at unprecedented rates. As forest and farmland is converted to residential and commercial uses, the imperviousness of the watershed typically increases, changing the hydrologic response of streams draining the area. This project focuses on the relationship between urban hydrology and stream community structure and function, with stream channel characteristics as the linking factor. Specific objectives of the project are: (1) to develop predictive relationships among flow regime, channel stability, and stream community structure and function across a gradient of land uses in agricultural and urbanizing watersheds; (2) to identify and test key factors limiting stream community structure and function; and (3) to formulate design criteria for protection of stream communities in urbanizing areas based on land use, hydrology, and channel characteristics. The first objective has been accomplished by examining recent
data sets on land use, stream channel morphology, water quality, invertebrates, and algae for a range of urbanizing watersheds in the eastern cornbelt ecoregion of Indiana (Tippecanoe and Marion Counties). The data are being tested using multivariate statistics to determine significant correlations among land use (as percent imperviousness), channel stability (shear stress, median substrate size, probability of exceedence of critical flow), and various metrics characterizing stream community structure and function (such as percent omnivorous insects. Preliminary results show that aquatic communities in urban streams become dominated by generalist organisms that can tolerate relatively large changes in flow and streambed movement. The channels themselves often become less stable, leading to increased bank erosion and downstream siltation. The length of time since the watershed was urbanized has an effect on this pattern since stream channels go through a readjustment following
hydrologic change. Recognizing and understanding this pattern can lead to better decisions related to agricultural land development, urban planning, and infrastructure design. The project will also develop and test practical ecosystem indicators of urbanization that will be useful to resource managers evaluating current stream community conditions prior to or during rapid urbanization.
Impacts
A better understanding of the relationship between urbanization patterns and stream quality will contribute to sustainable watershed development. Related land-use issues such as farm land preservation, urban planning, and infrastructure design can be evaluated in light of their impacts on stream community health.
Publications
- Doyle, M.W., J.M. Harbor, C.F. Rich, and A. Spacie. 2000. Examining the effects of urbanization on streams using indicators of geomorphic stability. Physical Geography 2000 21:155-181.
|
|