Longitudinal patterns of macroinvertebrate functional feeding groups in a Chinese river system: A test for river continuum concept (RCC)

Abstract

During April of 2007, macroinvertebrate assemblages were sampled across 43 sites in the Chishui River system, located in southwestern China. The aims are two-fold: (i) to examine the degree to which macroinvertebrate functional feeding groups (FFGs) correspond to prediction of the river continuum concept (RCC), and (ii) to determine the relationships between environmental variables and FFG structure. A synthetic environmental factor (the first axis of a Principal Component Analysis of altitude, distance from source, channel width, and stream order) was used as a measure of stream longitudinal gradient to examine RCC prediction. The RCC prediction held for richness, shredders, and scrapers by decreasing and increasing. Collector-filters and predators did not present any significant trend along the longitudinal gradient. Collector-gatherers significantly increased along the Chishui river continuum, which seems not exactly fall into with the prediction of the RCC, but is accordant with the central RCC theme: longitudinal distributions of FFGs follow longitudinal patterns in basal resources. After redundancy analysis (RDA), four variables (altitude, channel width, silt and clay, and cobble) were significant predictors of community variance. The RCC generally applies to running waters on this subtropical Asian river system. Additional theoretical and field studies across a broad array of Asian streams could be done to refine RCC and FFG classification in the future.