Ec. Phillips et Rv. Kilambi, HABITAT TYPE AND SEASONAL EFFECTS ON THE DISTRIBUTION AND DENSITY OF PLECOPTERA IN OZARK STREAMS, ARKANSAS, Annals of the Entomological Society of America, 87(3), 1994, pp. 321-326
Plecoptera nymphs were collected from coarse woody debris (CWD) and be
nthic habitats from the White River, Illinois River, and Clear Creek o
f Northwest Arkansas from February 1991 through February 1992. Two-way
analysis of variance comparing habitat type and season showed signifi
cant main effects. Densities were significantly greater in benthic hab
itats than on CWD and greater during winter and spring than during sum
mer and fall. Significant two-way interactions were found between habi
tat type and season. Multiple regression analysis revealed a significa
nt relationship among the seasonal density of winter stoneflies and fl
ow rate, water temperature, and dissolved oxygen; densities increased
as water temperature decreased and as dissolved oxygen concentration a
nd flow rate increased. Densities of stonefly species with slow univol
tine, semivoltine, or fast univoltine spring and summer life cycles sh
owed no significant relationship with these factors. Two-way analysis
of variance indicated that most species inhabiting coarse woody debris
are found on wood with loose bark or wood that is well decayed and ha
s many interstitial spaces. Prostoia completa (Walker) was the only sp
ecies whose abundance was influenced by the volume of biofilm present
on CWD and increased biofilm volume led to increased density. These re
sults suggest that benthic habitats are preferred by most species of P
lecoptera, but that CWD may also be an important habitat type for some
species.