King, Ryan Steven, 1972-Lang, David A.Baylor University. Dept. of Biology.2007-12-032007-12-0320072007-12-03http://hdl.handle.net/2104/5071Includes bibliographical references (p. 62-73).In an initial experiment, I evaluated methodological considerations of using a novel nutrient-diffusing substrata (NDS) design to estimate the effect of nitrogen (N) and phosphorus (P) enrichment on alkaline phosphatase activity (APA) and N2 fixation. Diffusion rates were effectively estimated, and suggested that this NDS design may also be useful for long-term studies. Levels of APA and N2 fixation potential were substantial in controls, indicative of differential nutrient limitation in the periphyton. In a second experiment, I investigated the effect of ambient N and P concentrations on periphyton accrual, APA, and N2 fixation using a P gradient of selected stream sites, which incidentally served also as an N gradient. Presence of both APA and N2 fixation on controls, which decreased up the P gradient, suggested that periphyton communities were differentially limited by both N and P. This was further corroborated by responses to NDS enrichments of N and P.ix, 73 p. : ill., map.167900 bytes901001 bytesapplication/pdfapplication/pdfen-USBaylor University theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. Contact librarywebmaster@baylor.edu for inquiries about permission.Nutrient pollution of water.Freshwater ecology.ThesisWorldwide access