Macroinvertebrate community structure, functional organization, production, and energy flow in a Colorado Plains Stream.

摘要

This study describes the response of macroinvertebrate communities to urbanization and agricultural activities from the perspectives of community structure, functional organization, and energy flow. Sampling sites were located above these major impacts (reference site) and along the reach at sites variously influenced by organic enrichment, eutrophication, and salinization. The most important water chemistry variables associated with macroinvertebrate assemblage structure, abundance, and diversity were cations (e.g. Na, K, Mg, and Ca ions) and inorganic nutrients. The major variable of benthic organic matter was the presence of aquatic vascular plants which act as a spatial structure for benthic macroinvertebrate. The alternations of physicochemical characteristics and food resource availability in the stream ecosystem were reflected by the variations in functional organization of macroinvertebrate communities. The abundance and production of collector-gatherers were significantly dominant at the most impacted sites. Inversely, the density and production of scrapers and shredders were much reduced at these sites. Amorphous detritus and diatoms were the most important energy base in the stream reach. Amorphous detritus and diatoms supported 41–47% and 25–42% of macroinvertebrate production, respectively. Of the measured food resources available, the non-Tanypodinae midges consumed 56% (site 1), 93% (site 2), and 61% (site 3) of the total.