Fish communities and their
relation to physical and chemical characteristics of streams from
selected environmental settings in the Lower Susquehanna River Basin,
1993-95
Michael D. Bilger and Robin A. Brightbill
Studies of fish-community composition were conducted annually in selected
reaches (from 100 to 303 meters in length) on seven streams from June
1993 to June 1995 within the Lower Susquehanna River Basin. In 1994,
additional reaches were selected on three of the streams, resulting in a
total of 28 samples. The study reaches were selected on the basis of type
of bedrock and land use/land cover; the major emphasis was on
agricultural land use or areas in transition from agricultural to
commercial, industrial, and residential land uses. At each reach,
environmental characteristics consisting of instream and riparian habitat
conditions, hydrology, and water quality were determined. The relation of
fish communities at these reaches to physical and chemical
characteristics of streams was analyzed to determine if the fish
communities differed temporally or spatially. Data were analyzed by
parametric and multivariate techniques.
During the course of the study, a total of 33,143 fish were collected,
consisting of 39 species representing 8 families. Cyprinidae (minnows)
were dominant with 17 species, followed by Centrarchidae (sunfishes) with
7 species and Percidae (perches and darters) with 4 species. Three
species-blacknose dace (Rhinichthys atratulus), white sucker (Catostomus
commersoni), and the sculpins (Cottus spp)-accounted for 49 percent of
the total fish collected.
The environmental variables most closely related to the fish communities
present at the reaches were mean channel width, mean water temperature,
mean canopy angle, and suspended-sediment concentrations. These variables
accounted for about 79 percent of the variation in the
environmental-species relation. Channel width and mean water temperature
are correlated with stream size variables. The stream size gradient is
the most influential variable to the fish communities studied in the
Lower Susquehanna River Basin.
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