Sa. Frenzel et Rb. Swanson, RELATIONS OF FISH COMMUNITY COMPOSITION TO ENVIRONMENTAL VARIABLES INSTREAMS OF CENTRAL NEBRASKA, USA, Environmental management, 20(5), 1996, pp. 689-705
Nine sites on streams in the Platte River Basin in central Nebraska we
re sampled as part of the US Geological Survey's National Water-Qualit
y Assessment Program during 1993-1994. A combination of canonical corr
espondence analysis and an index of biotic integrity determined from f
ish community data produced complementary evaluations of water-quality
conditions. Results of the canonical correspondence analysis were use
ful in showing which environmental variables were significant in diffe
rentiating fish communities at the nine sites. Five environmental vari
ables were statistically significant in the analysis. Median specific
conductance of water samples collected at a site accounted for the lar
gest amount of variability in the species data. Although the percentag
e of the basin as cropland was not the first variable chosen ina forwa
rd selection process, it was the most strongly correlated with the fir
st ordination axis. A rangeland-dominated site was distinguished from
all others along that axis. Median orthophosphate concentration of sam
ples collected in the year up to the time of fish sampling was most st
rongly correlated with the second ordination axis. The index of biotic
integrity produced results that could be interpreted in terms of the
relative water quality between sites. Sites draining nearly 100% cropl
and had the lowest scores for two individual metrics of the index of b
iotic integrity that were related to species tolerance. Effective moni
toring of water quality could be achieved by coupling methods that add
ress both the ecological components of fish communities and their stat
istical relationships to environmental factors.