SECONDARY PRODUCTION OF RHYACOPHILA-MINORA, AMELETUS SP, AND ISONYCHIA-BICOLOR FROM STREAMS OF LOW AND CIRCUMNEUTRAL PH IN THE APPALACHIAN MOUNTAINS OF WEST-VIRGINIA

We estimated the secondary production of Rhyacophila minora, Ameletus sp., and Isonychia bicolor in three acidic streams and one circumneutr al stream in Randolph County, West Virginia. Quantitative benthic samp les were collected monthly from these second-order streams from Novemb er 1990 to October 1991. Mean pH values in the acidic streams were 4.5 , 4.8, and 4.8, and mean pH in the circumneutral stream was 6.7. Produ ction estimates for Rhyacophia minora in the acidic streams were 49.6, 19.2, and 15.8 mg m-2 y-1. Production of R. minora in the circumneutr al stream was 1.0 mg M-2 y-1. Ameletus sp. production estimates for th e acidic streams were 144.8, 176.8, and 208.3 mg m-2 y-1. Ameletus sp. production in the circumneutral stream was 7.4 Mg M-2 y-1. Secondary production of I. bicolor in the circumneutral stream was 116.6 mg M-2 y-1. No Isonychia were collected from the acidic streams. The higher p roduction of R. minora and Ameletus sp. in the acidic streams may be a ssociated with differences in macroinvertebrate community structure.