Longitudinal and Seasonal Variation in Macroinvertebrate Taxonomic and Functional Feeding Group Composition of a Central Texas Stream
Solanik, Darrel C.
Many temperate streams show strong seasonal changes in the taxonomic and trophic composition of macroinvertebrate communities. However, few studies have been conducted concerning the macroinvertebrate taxonomic and functional feeding group composition of central Texas streams. The objectives of this study were to determine patterns of longitudinal variation in macroinvertebrate taxonomic and functional feeding group composition of Cibolo Creek, and how these patterns were affected by both season and intermittency. Cibolo Creek originates as springs and is a subtropical fourth order stream at its confluence with the San Antonio River. The stream has three distinct sections with the upper and lower sections having perennial flows and the middle section having intermittent flows. Twelve stations were quantitatively and qualitatively sampled quarterly along the 250 kilometer length from the headwaters to confluence with the San Antonio River. Ninety-eight taxa of macroinvertebrates were collected from Cibolo Creek consisting primarily of immature insects. Macroinvertebrate abundances and dominant taxa varied among sites and by season although no consistent patterns were observed. Functional feeding group composition showed little variation in that collectors dominated both longitudinally and seasonally. Intermittent sites showed a decrease in macroinvertebrate abundance from February 1993 to May 1993. Analysis of macroinvertebrate composition by Rapid Bioassessment showed that biological conditions generally improved at greater distances downstream from the wastewater treatment plants that discharge effluent into Cibolo Creek.
Benthos, Texas, Cibolo Creek, invertebrates
Solanik, D.C. (1996). Longitudinal and seasonal variation in macroinvertebrate taxonomic and functional feeding group composition of a central Texas stream (Unpublished thesis). Southwest Texas State University, San Marcos, Texas.