We completed a three-year pre-construction monitoring plan
of two Pennsylvania streams that encompassed measurements of biotic communities
and physicochemical variables in order to evaluate the future effectiveness of
a planned natural stream channel restoration project designed to reduce stream
erosion, sedimentation and nutrient influx. To meet this objective we assessed
forested (control) and impaired sites in the South and East Codorus Creek branches
within the Susquehanna River watershed. Our pre-restoration data support that
the fish communities were significantly different between sites evidenced by
the lower number of parasitized fish, greater biomass, and greater numbers of
salmonids (10 fold increase) and other pollution intolerant fish at the control
sites. The higher total phosphorus concentrations and suspended sediments in
the impaired sites mostly likely explain the low number of pollution intolerant
species and the need for restoration in these impaired areas. The lack of
significant differences in either diversity or evenness between the control and
impaired sites stresses the importance of why fish communities and overall
stream ecosystem health are assessed by the calculation of multiple
metrics.