Relating N and P uptake to metabolism and community structure at different substrata in Augusta Creek, MI

Abstract

Studies have gone to great lengths to explain differences in nutrient uptake rates observed among different streams, while fewer have attempted to explain variations in nutrient uptake seen within a single stream. In order to gain a better understanding of how nutrients are processed at different substrata within a single stream and how that processing relates to community structure, we utilized in situ benthic chambers to measure inorganic nutrient uptake rates and metabolism. In order to accomplish this, we first showed that different substrata were obtained by relating water velocity to substrata type. Then we related inorganic nutrient uptake to abiotic or biotic factors. Finally with measures of metabolism we related these processes to community structure.

Hypothesis: We predicted that autotrophic activity would drive nutrient uptake at cobble sites given that there is more area for large algal community growth on rocks. At sand sites we predicted that heterotrophic activity would dominate net community metabolism given that algal communities were not observable in that habitat.