Walker C. Pett1, Catherine A. Gibson2, and Catherine M. O'Reilly1. (1) Bard College, Annandale on Hudson, NY 12504, (2) Department of Biology and Environmental Studies Program, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866
Leaf litter, and associated microbial communities, influence nutrient processing in streams. In this study we examined the influence of leaf litter on uptake lengths of dissolved inorganic phosphate in the Coxing Kill, a small bedrock stream in the Shawangunk Mountains of New York. Mean background concentration of SRP was 11µg/L (8 to 19µg/L) and at the time of sampling, Q was 0.27m3/s. Nutrient enrichments were performed along a 200m reach using a Mariotte bottle, and samples were taken every 20m before and after the removal of leaf litter from the stream. Mean enriched concentration of P was 17µg/L before removal of leaf litter, and 31µg/L after removal, with concentrations decreasing markedly near the end of the reach where the stream substrate changed from relatively smooth bedrock to mostly rough cobbles and sand. The uptake length of P before removal of leaf litter was 142m and was 222m after removal. The increased uptake length of P after removal of leaf litter indicates that the microbial community on decomposing leaves in the stream contributes greatly to uptake of P, and demonstrates the importance of leaf litter in controlling downstream nutrient transport processes.