Influence of stream habitat alterations on dynamics of aquatic communities

Streams and rivers are a rare natural resource, and evaluation of stream alteration projects is a prerequisite for proactive management of these ecosystems. My research addressed questions concerning status of information on fish and macroinvertebrate community assessments of stream alteration projects, and two hypotheses explaining spatial variation of aquatic communities in a channelized warmwater stream in Mississippi and Alabama. A literature review was conducted to determine the number of publications examining community level responses to channelization and restoration projects and to compare characteristics of these assessments. Instream habitat, fishes, and macroinvertebrates were sampled three times from May to September 2000 in three channel types of Luxapalila Creek. Measurements of channel form in each channel type were obtained in July 2000. I addressed two hypotheses: (1) patterns of community structure among channel types were scale dependent, and (2) channel form, instream habitat, and aquatic communities were hierarchically related. I examined how patterns of taxa richness, evenness, and abundance among channel types differed with changing spatial resolution and community extent, and I assessed strength of the relationships among channel form, instream habitat, and aquatic communities.; I found that more information on community responses to stream alteration projects is available than indicated by a prior review. Assessments of stream alteration projects most frequently examined fish communities at limited spatial (one stream) and temporal (one year) extents. My literature review provided suggestions for design of future assessment projects that will assist with adaptive management of lotic ecosystems.; Patterns of community structure among channel types differed among spatial resolutions ranging from 5 m patches to 90 m sites, and among all community extents. I observed that the scale dependent nature of community structure influenced subsequent management interpretations. I also concluded that channel form, instream habitat, and aquatic communities were hierarchically related. The strongest correlations were observed between channel form and instream habitat, and instream habitat and aquatic communities. The nature of relationships among these components indicates that restoration of aquatic communities in streams that have undergone major modifications of channel form may not be feasible unless instream habitat and channel form are modified.