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Title: Influence of spatial resolution on assessing channelization impacts on fish and macroinvertebrate communities in a warmwater stream in the southeastern United States

Author
item Smiley, Peter - Rocky
item DIBBLE, ERIC - MISSISSIPPI STATE UNIV

Submitted to: Environmental Monitoring and Assessment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/2007
Publication Date: 6/13/2007
Citation: Smiley, P.C., Dibble, E.D. 2007. Influence of spatial resolution on assessing channelization impacts on fish and macroinvertebrate communities in a warmwater stream in the southeastern United States. Environmental Monitoring and Assessment. Available: http://www.springerlink.com/content/e164065033417664/?p=2077e7e75dc94a549c1410823e5d8421&pi=0. 2008 In print 138:17-29.

Interpretive Summary: The spatial and temporal dimensions of a study may influence the observed results of environmental assessments designed to evaluate the impacts of stream habitat alterations (i.e., stream channelization, impoundments, installation of erosion control structures, etc.). Typically, the size of the sampling unit is determined by convention and the numbers of samples collected are based on available time and funds. The influence of spatial resolution (i.e., the size of the sampling unit and the number of sampling units) on the observed results and interpretations derived from assessments of stream channelization and other habitat modifications has not been investigated. We examined if the observed results and the interpretations from an environmental assessment of channelization impacts on fish and macroinvertebrate communities differed among three spatial resolutions. The majority of our response variables exhibited different patterns among channel types at different spatial resolutions. Additionally, our interpretations of channelization impacts on fish and macroinvertebrates were dependent on spatial resolution. Our results suggest that spatial resolution can influence the observed results and interpretations derived from assessments of channelization and other stream habitat alterations. This finding has implications for the design of environmental assessments aimed at determining the impacts of anthropogenic habitat alterations on lotic ecosystems. Our results suggest that scientific evaluations of stream habitat alterations should be conducted at multiple spatial resolutions. The use of multi-resolution assessments will lead to a greater understanding of the impacts of stream habitat alterations and ensure the accurate usage of research results to guide the management of lotic ecosystems.

Technical Abstract: The choice of spatial and temporal scale in the design of environmental assessments may influence the observed results. One method of assessing the impact of stream habitat alterations involves the comparison of response variables among treatments (i.e., impacted and unimpacted sites). Yet, the influence of spatial resolution on the patterns of response variables among treatments in assessments of stream channelization and other types of stream habitat alterations has not been evaluated. We examined how patterns of 10 community response variables among channel types and how our interpretations of channelization impacts on fish and macroinvertebrate communities in a warmwater stream in Mississippi and Alabama differed among three spatial resolutions. Four fish and three macroinvertebrate community response variables exhibited different patterns among channel types at different spatial resolutions. Our interpretations of the impacts of channelization on fish and macroinvertebrate communities differed among spatial resolutions. The impacts of channelization on fish communities ranged from a negative impact to a negative impact with potential community recovery occurring in the historically channelized reach. Channelization impacts on macroinvertebrate communities ranged from inconclusive results to a negative impact. Our results suggest that spatial resolution can influence the observed results and interpretations of the impacts of stream habitat alterations.