By Danial J. Sullivan
U.S. Geological Survey, Madison, WS
The full report is available in pdf. Links to the pdf.
Fish community data were collected by the U.S. Geological Survey
(USGS) at 12 sites in 1996
in the Wapsipinicon, the Cedar, the Iowa, and the Skunk River Basins in eastern Iowa. The study was done as part of the National Water-Quality Assessment (NAWQA) Program of the USGS. This report presents an evaluation of the fish communities, the composition and conditions of the fish communities,and by relating these compositions and conditions to a variety of habitat and water-quality factors.
A total of 56 fish species representing 13 families were collected
from among the 12 sites in 1996. The family with the most species
represented were the minnows with 20. The number of individuals
of all species collected in one sampling pass ranged from 472
at the Iowa River near Rowan to 2,072 at Wolf Creek near Dysart.
Fish community composition was similar among many of the stream
sites. The fish community at 4 of the 5 stream sites, as well
as at 2 of the large-river sites, was similar to the reference
site, the Wapsinicon River near Tripoli, an indication that fish
communities across the study unit are similar. The sites that
were the least similar to any of the other sites include Flood
Creek, a stream site, and the Skunk River at Augusta large-river
site. The fish communities at both of these sites were dominated
by relatively few species, many of which are tolerant or represent
degraded environmental conditions.
Biplots of detrended correspondence analysis ordinations indicate
a gradient from the stream sites to the large-river sites. The
detrended correspondence analysis ordination also indicates that
the stream sites are more closely clustered than the large-river
sites. The large-river sites were more likely to have their ordination
driven by one or two dominant species, while several species occurred
in similar relative abundance at many of the stream sites.
Several indexes of biotic integrity (IBI) based on fish community
were applied to the data
and results were generally comparable. In general, the IBIs indicate higher biotic integrity at the stream sites than the large-river sites. Based on IBI classifications, fish communities at most sites were degraded compared to reference conditions. The fish communities at the 12 study sites appear to be related to a number of environmental factors. Obvious differences in fish communities occur between the stream sites and the large-river sites, the result of differences in both physical and chemical characteristics of the streams. Important physical factors related to fish communities included several directly related to stream size as well as human population density and percent of rowcrops in the watershed. Chemical factors that were important included median total phosphorus, suspended-sediment, and dissolved organic carbon concentrations.
Description of the study area
Study design and methods
Fish communities of stream sites in Eastern Iowa Basins
Fish community composition
Fish community conditions
Relations between fish community composition and conditions and environmental factors
Summary and conclusions
The text and graphics are presented here in pdf format (print quality):
The full report is 1.1 MB
If you have Adobe Acrobat Reader installed on your computer, you may view and/or print the PDF version of this report. If you do not have Acrobat Reader, you may download it here.
Users with visual disabilities can visit this site for conversion tools and information to help make PDF files accessible.
|USGS||Water||Biology||Geology||Mapping||WRI Pubs||Water Related Pubs|
of the Interior, U.S. Geological
Last updated: Tuesday, 30-Jul-2002 15:38:54 EDTPrivacy Statement || Disclaimer || Accessibility