Effects of a labile carbon addition on a North Carolina headwater stream food web
Wilcox, Heidi S.
MetadataShow full item record
We added dextrose during two eight-week periods (summer and autumn) to a headwater stream in North Carolina, U.S.A. Bacterial densities were significantly higher in the treatment reach during both additions. Increased microbial growth led to higher respiration rates on leaf disks and a three-fold increase in instantaneous growth rates of Chironomidae larvae. Collector-gatherer and predator abundance and biomass in bedrock habitats increased significantly during the summer addition. No functional feeding group in bedrock habitat increased in abundance during the autumn addition; however, shredder biomass increased significantly. In mixed substrates, shredder abundance and scraper biomass increased significantly during the autumn addition. All functional feeding groups assimilated isotopically distinct dextrose during additions. Assimilation of dextrose, measured by stable isotope analysis, and increases in insect abundance and biomass suggest that the added carbon was an important food resource, particularly for consumers of heterotrophic organisms and biofilm.