PARENT SESSION
Oral Session # 74: Riparian Ecology I: Nutrient Cycling; Decomposition.
Presiding: K Bushaw-Newton
Thursday, August 7. 8:00 AM to 11:30 AM, SITCC Meeting Room 205.
Detrital foodweb response to dissolved organic carbon and nutrient changes: Exploring Coastal Plain stream dynamics.
Baer, Nicholas*,1, Lamp, William1, 1 University of Maryland, College Park, MD
ABSTRACT- Changes in water quality can greatly affect the detrital foodweb. Rates of leaf decomposition have been shown to increase with nutrient enrichments. Other research has suggested that elevated DOC levels may cause a shift in the bacterial community and therefore changes in the detrital foodweb. Our study of two Coastal Plain watersheds in Maryland has demonstrated elevated phosphorus concentrations, ranging from 0.20 mgL-1 to 2.75 mgL-1, and low nitrate-N concentrations. In addition, Coastal Plain streams are often characterized by black or brown water containing high levels of dissolved organic carbon (DOC). Thus, we performed a laboratory experiment examining both microbial and macroinvertebrate response to changes in nitrogen, phosphorus and DOC. We hypothesized that increased DOC reduces leaf decomposition by the microbial community but not the isopod, Caecidotea communis. We also predicted an increase in detrital processing with elevated nitrogen concentrations. Microbes and Caecidotea communis were reared in artificial stream environments varying in nitrate, phosphorus and DOC concentrations. Microbial respiration, leaf decomposition rates, and isopod assimilation rates were measured to compare treatments. The results illustrate the relationship between nutrients, DOC, and leaf decomposition.
Key words: leaf decomposition, nutrients, detrital foodweb, dissolved organic carbon