Spatial habitat variation in a Great Plains river: effects on the fish assemblage and food web structure
by
Wesley W. Bouska
B.S., South Dakota State University, 2006
ABSTRACT
Improperly designed stream crossings may prohibit movement of stream fishes by
creating physical or behavioral barriers and may alter the form and function of
stream ecosystems. A mark-recapture and geomorphological study was conducted to
evaluate fish passage and stream morphology at three types of vehicle crossings
(compared to control sites) located on streams in the Flint Hills of Northeast
Kansas. We investigated five concrete box culverts, five low-water crossings
(concrete slabs vented by one or multiple culverts), and two single corrugated
culverts. A total of 6,433 fish were marked April to May 2007 and 709 were
recaptured June to August 2007. Fish passage occurred at all crossing types,
but upstream movement of recaptured fish was higher at controls (41.1%) than
at crossing reaches (19.1%) for low-water crossings. Control sites had more
species in common upstream and downstream than did crossings. There was reduced
overall abundance of fish upstream at low-water crossings, commonly percids and
centrarchids. A comparison of channel and road crossing dimensions showed that
box culverts and corrugated culverts would be more effective than low-water
crossings at transporting water, sediments, and debris during bankfull flows,
and fish passage at base flows. Upstream passage of Topeka shiner
(Notropis topeka), green sunfish (Lepomis cyanellus), red shiner
(Cyprinella lutrensis), and Southern redbelly dace (Phoxinus erythrogaster)
was tested through three simulated crossing designs (box culverts, round
corrugated culverts, and natural rock) across 11 different water velocities
(0.1 m/s to 1.1 m/s) in an experimental stream. Upstream movement did not
differ among designs, except natural rock crossings had lower movement than
box or corrugated culverts for red shiners. A greater proportion of Topeka
shiners moved upstream at higher velocities. These results suggest that
crossing type affects fish passage and the morphology of the stream, although
water velocity in different crossing designs alone may not be a determining
factor in fish passage. Low-water crossings had the greatest impact on fish
community and movement, but barriers to fish movement are likely caused by
other variables (e.g. perching). Use of properly designed crossing structures
has great promise in conserving critical stream habitat and preserving native
fish communities.