PARENT SESSION
Poster Session # 22: Late-Breaking Newsworthy Posters
Friday, August 8 Presentation from 8:30 AM to 10:00 AM. SITCC Exhibit Hall B.
Relative response of consumers, resources, and ecosystem function to nutrient enrichment in a detritus-based system.
Rosemond, Amy*,1, Suberkropp, Keller2, Cross, Wyatt1, Greenwood, Jennifer1, Gulis, Vladislav2, 4, Mulholland, Pat3, Wallace, James1, Weyers, Holly1, 5, Benstead, Jonathon1, Hilten, Roger1, 1 University of Georgia, Athens, GA2 University of Alabama, Tuscaloosa, AL4 University of Coimbra, Coimbra, Portugal3 Oak Ridge National Laboratory, Oak Ridge, TN5 USGS MD-DC-DE District, Dover, DE
ABSTRACT- We continuously added N and P to a headwater stream for 2 yrs to determine the response of a detritus-based ecosystem to nutrient enrichment. Treatment effects were compared to a reference stream and variables were measured in both streams for 1 year prior to enrichment. We compared the magnitude of the effects of enrichment on organisms (fungi, bacteria, invertebrates), resources (leaf litter standing crop, algal biomass) and functional measures (decay rate of leaves, whole-stream respiration) following 1 and 2 years of enrichment. All variables changed in direction and magnitude consistent with a relatively large response to nutrient enrichment. Enrichment of the system resulted in increased microbial and invertebrate biomass and production, increased respiration of organisms associated with leaves and wood, increased decay rates of organic matter, and increased whole stream respiration as well as gross primary productivity. Roughly half of the measured effects on organisms and resources became reduced in magnitude from yr 1 to yr 2, whereas the magnitude of all functional measures of ecosystem response increased through time. The response we observed to nutrient enrichment in a detritus based system resulted, on average, in more than a doubling of biomass or rate after one year of enrichment indicating the profound effects that moderate levels of enrichment can have in detritus-based systems.
Key words: detritus, aquatic, ecosystem, enrichment