Experimental evidence quantifying the role of benthic invertebrates in organic matter dynamics of headwater streams
Journal Article: Freshwater Biology
By Thomas F. Cuffney, J. Bruce Wallace, and G. John Lugthart
Abstract
1. The insecticide methoxychlor was applied
seasonally to one of three small headwater
streams in the southern Appalachian Mountains
in North Carolina, U.S.A. The initial application
caused massive invertebrate drift (>1,000,000
organisms/week) and resulted in a community
with few shredders and reduced abundances
of most insect taxa.
2. Bacterial densities and microbial respiration
rates were not affected by treatment.
3. Disruption of the invertebrate community
resulted in significant reductions in leaf
litter processing rates (5074% reduction
depending on leaf species) and in the amount
of leaf litter processed annually (reduction
of 2528%).
4. Reductions in leaf litter processing
rates resulted in significant reductions
in fine particulate organic matter (FPOM)
export. Declines in both concentration and
total export were detectable within 1 week
of treatment. Annual FPOM export was reduced
to 33% of pretreatment levels. Alteration
to the invertebrate community had a much
greater effect on FPOM export than a severe
(50200 year) drought.
6. Course particulate organic matter (CPOM)
export was not significantly influenced
by treatment but was influenced by hydrologic
differences among years.
Citation:
Cuffney, T.F., Wallace, J.B., and Lugthart, G.J., 1990, Experimental evidence quantifyig the role of benthic invertebrates in organic matter dynamics of headwater streams: Freshwater Biology, v. 23, p. 281-299.
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