HR: 1330h
AN: NB33N-08    [Abstracts]
TI: Meiofauna Responses to Mechanical Disturbances in Stream Mesocosms on the Illinois River, Arkansas (U. S. A.)
AU: * Brown, A V
EM: artbrown@uark.edu
AF: University of Arkansas, Science and Engineering 622, Fayetteville, AR 72701 United States
AU: Reese, R A
EM: rareese@uark.edu
AF: University of Arkansas, Science and Engineering 622, Fayetteville, AR 72701 United States
AB: Benthic meiofauna responses to mechanical disturbance of the substrate was studied in August, 2003 on the Illinois River, Arkansas, (U. S. A.) in stream mesocosms. The Illinois River is a gravel/bed, riffle/pool stream located in the Ozark Highlands. Three levels of disturbance (undisturbed, moderate/frequent, and severe/infrequent) were assigned randomly to twelve stream mesocosms. After 18 days, substrate samples were taken from each mesocosm using a core sampler. Planktonic and natural stream bed samples were taken every third day during the study to identify potential colonizers and to serve as a reference. Within the mesocosms, four of the 17 taxa found and total density of meiofauna L^-1 of substrate were significantly different between treatments with the undisturbed channels having higher densities than the severe/ frequent treatment. Total meiofauna densities L^-1 in the undisturbed treatment, 4471.9 ± 1308 (2 s. e.), were significantly higher than either of the other treatment levels (F = 15.43, P = 0.001). Chironomidae and Ephemeroptera were numerically dominant in undisturbed channels but both were significantly reduced by the treatments (F = 12.28, P = 0.003; F = 61.22, P < 0.000 respectively). Shannon's diversity index ('H) was highest in the moderate/frequent treatment reflecting the increase in evenness.
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly