A NOVEL METHOD OF MEASURING STREAM N CYCLING USING 15NH4+ IN RECIRCULATING CHAMBERS: EXAMINING THE EFFECTS OF DROUGHT ON BENTHIC N DYNAMICS
Climate change is increasing the frequency and intensity of droughts in the Great Plains. These droughts can lead to the disruption of longitudinal connections in streams, influencing numerous ecological processes including nutrient cycling. We studied drought-isolated pools in Kings Creek on Konza Prairie Biological Station, Kansas, USA on two dates in July. We utilized recirculating chambers filled with 15NH4+-enriched stream water to estimate N remineralization, uptake, and nitrification associated with biofilms. On the first sampling date, rates of remineralization averaged 1.46 mmol-N/m2/hr (SE=0.04) and uptake averaged 0.69 mmol-N/m2/hr (SE=0.13). On the second sampling date, rates of remineralization averaged 0.46 mmol-N/m2/hr (SE=0.04) and uptake averaged 1.44 mmol-N/m2/hr (SE=0.23). O’ Brien et al. 2008, collected NH4+ uptake and remineralization rates in Kings Creek during normal flow. Remineralization averaged 0.03 mmol-N/m2/hr (SE=0.03) and uptake averaged 0.01 mmol-N/m2/hr (SE=0.01). Generally, remineralization and uptake rates during drought were higher than results taken during normal flow. As pools dried, nutrients became more concentrated in the water resulting in high background NH4 levels, consistent with our hypothesized increased remineralization rates.
Molly Fisher (Co-Presenter/Co-Author), Simpson College , firstname.lastname@example.org;
James Guinnip (Primary Presenter/Author), Kansas State University, email@example.com;
Walter Dodds (Co-Presenter/Co-Author), Kansas State University, firstname.lastname@example.org;