Stream aufwuchs accumulation
Abstract
I investigated the Aufwuchs accumulation process
on glass slides (chlorophyll, adenosine triphosphate, and
diatoms) in experimental streams near Glen Lyn VA (Phase I)
and in Stroubles Creek near Blacksburg VA (Phase II).
Depopulation experiments carried out during Phase I
supported my hypothesis that accumulation rates are
greater in reference than in depopulated streams. The
effects of depopulation on Aufwuchs biomass accumulation
disappeared in about two weeks indicating the rapidity of
recovery from short-term catastrophic events. Variability
anong replicate slides was generally lower after shorter
submergence times than after longer times.
In disturbance frequency experiments carried out
during Phase I, Aufwuchs accumulation depended on the
frequency of copper disturbance. Accumulation was faster
in the low stress streams (LSS) than in the high stress
streams (HSS) • Resistance of Aufwuchs conununities to an
additional Cu disturbance was greater in HSS than in LSS.
Resilience of Aufwuchs biomass to the additional disturbance
was lower in the LSS than in HSS. Stress resistance tended
to be an inverse function of community age and to be
greater in HSS than in LSS. Diatom species and diversity
were greater in LSS than in HSS.
In Stroubles Creek I tested the effect 6f five
factors on the Aufwuchs accumulation process and found
biomass accumulation was greater in summer than in fall,
in riffles than in pools, and in open than in shaded sites.
Accumulation differences were not significantly different
between upstream and downstream locations or between
depopulated and reference areas. Biomass accumulation
rates decreased inversely with submergence time. Biomass variability tended to be lower for shorter submergence times and in riffles than in pools. The autotrophic ratio decreased with submergence time. Diatom species number and diversities increased with submergence time.
Collections
- Doctoral Dissertations [14965]