Ct. Robinson et Gw. Minshall, MACROINVERTEBRATE COMMUNITIES, SECONDARY PRODUCTION, AND LIFE-HISTORYPATTERNS IN 2 ADJACENT STREAMS IN IDAHO, USA, Archiv fur Hydrobiologie, 142(3), 1998, pp. 257-281
We compared community attributes, secondary production, and life histo
ries of macroinvertebrates in two adjacent streams with contrasting en
vironmental characteristics. Environmental variables (measured as coef
ficients of variation) were up to an order of magnitude greater in Lit
tle Lost River (Lost River) than in Birch Creek. Ln particular, the fl
ow regime was 12 x more variable in Lost River, a stream fed largely b
y surface runoff, than in Birch Creek, a groundwater-fed stream. Birch
Creek accumulated more annual degree days, had higher ionic concentra
tions, and developed greater periphyton biomass than Lost River. Altho
ugh? the mean density of macroinvertebrates was similar between the st
reams, species richness was higher and mean biomass was lower in Lost
River. Annual macroinvertebrate production was dominated by Chironomid
ae and was 1.6 x higher in Lost River than :Birch Creek. However, if C
hironomidae are excluded, total annual production was 1.5 x greater in
Birch Creek than in Lost River. Life cycles of some common taxa refle
cted the different environmental conditions in each stream. Our data s
upport the idea that certain attributes of macroinvertebrate assemblag
es (density, biomass, and production) are structured by environmental
factors regulating growth (e.g. water chemistry, thermal loading, peri
phyton), whereas other biotic attributes (e.g. species richness, assem
blage composition, and life histories) are more influenced by thermal
and flow regimes.