ABSTRACT

Feeding strategies are traits that reflect the adaptation of a species to environmental conditions. Macroinvertebrates are an important primary consumer in stream food webs, but the abiotic and biotic drivers of functional feeding groups (FFGs), which are categorized based on feeding strategies, require additional clarification. The aim of our study was to quantify the contributions of abiotic factors (water quality and land use at different scales) and biotic factors (important primary producers, such as epilithic diatoms) to the variation of FFGs of macroinvertebrates in the Jinshui River, upper Han River Basin, China, a subtropical mountain river. We conducted campaigns in the Jinshui River during high stream flow (August 2009), low flow (November 2009), and normal flow (April 2010). We performed redundancy analysis and multiple factor analysis to evaluate the relationships among riparian land use at different scales, water quality, the benthic diatom community, and FFGs. We found that water quality, especially the fluoride ion (F⁻), metals (chromium and cadmium), and chemical oxygen demand, significantly correlated with FFGs, and that the benthic diatom community, especially Ceratoneis arcus var. linearis f. recta and Denticula tenuis, explained a high proportion of the variation in FFGs. The benthic diatom community was significantly correlated with water quality, and variations in FFGs were poorly explained by upstream riparian land use at the entire upstream scale and reach scale (2 km upstream). Further, water quality and the benthic diatom community were significantly correlated with riparian land use at the reach scale. Our findings on how the water quality, riparian land use, and diatom community influence FFGs will provide the scientific foundation for biodiversity research of macroinvertebrate FFGs, conservation of the food web, and management of the riparian zone.