The focus of this research was the mechanistic relationship between fluid flow,
spatial density, distribution, and metabolism of stream-dwelling insect larvae of the
caddisfly genus Glossosoma (Glossosomatidae: Trichoptera). Glossosoma are
ecologically important for many reasons, including that they are dominant grazers in lotic
food webs, are capable of suppressing stream periphyton, and act as an indicator of
stream health. A description is herein presented of fluid flow and stream bathymetry
environments where Glossosoma are often present. Predictive relationships for
Glossosoma spatial density are proposed from local fluid flow and channel bathymetry
variables. The research was conducted through a series of four separate studies. First,
habitat was quantified for larval Glossosoma in three coastal mountain streams in
northern California. Applying dimensional analysis, a functional relationship was
developed for predicting larval abundance. Variogram analysis of Glossosoma spatial
density and bed topography revealed overlap in the separation distance above which point
measurements were statistically independent. Second, field measurements were
conducted in Valley Creek, Minnesota and data were compared with the measurements in
the coastal mountain streams. Third, a computational model was employed to estimate
high resolution fluid flow variables along a riffle in Valley Creek. Simulation results
were verified and implemented in a predictive model for Glossosoma abundance. Fourth,
a laboratory study of Glossosoma metabolism under varying flow conditions revealed
generally increasing oxygen consumption with increasing fluid flow velocities. The proposed research will be instrumental for predicting not only how Glossosoma respond
to changes in fluid flow and stream bathymetry conditions, but also how these variables
influence larval spatial density, distribution, and behavior in lotic environments.
University of Minnesota Ph.D. dissertation. May 2013. Major: Civil Engineering. Advisor: Miki Hondzo. 1 computer file (PDF); vii, 142 pages.
Morris, Mark William Lehnardt.
The effects of fluid flow on the spatial density, distribution, and metabolism of larval Glossosoma.
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