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Microbial Ecoenzymatic Stoichiometry as an Indicator of Nutrient Limitation in US Streams and Rivers
Citation:
HILL, B. H., C. M. ELONEN, L. R. SEIFERT, AND A. A. MAY. Microbial Ecoenzymatic Stoichiometry as an Indicator of Nutrient Limitation in US Streams and Rivers . Presented at American Society of Limnology and Oceanography/ North American Benthological Society Joint Meeting, Santa Fe, NM, June 06 - 10, 2010.
Impact/Purpose:
To compare microbial ecoenzymatic activity at 2122 randomly-selected stream and river sites across the conterminous United States.
Description:
We compared microbial ecoenzymatic activity at 2122 randomly-selected stream and river sites across the conterminous US. The sites were evenly distributed between wadeable and non-wadeable streams and rivers. Sites were aggregated into nine larger physiographic provinces for statistical analyses and reporting. We also sampled 233 least-disturbed (reference) sites in order to set ecoenzymatic activity expectations for C, N and P acquisition. Microbial biomass stoichiometry is expected to be 60C:7N:1P, and this ratio should be reflected in the ratios of glycosidase, peptidase, and phosphatase activities. We demonstrate relative N-limitation in 7-33% of the total assessed stream and river length; P-limitation in 35-59% of stream and river length; and no limitation in 26-47% of stream and river length. Ecoenzymatic stoichiometry indicated that the majority of streams (56-70% of total stream length) are not balanced in their C, N, and P acquisition, further suggesting relative nutrient limitation. The ratio of phenol oxidase to glycosidase activity indicated a prevalence of recalcitrant C in 14-34% of stream and river length. There were no differences between streams and rivers in nutrient limitation and stoichiometric balance.