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Continuous monitoring reveals multiple controls on ecosystem metabolism in a suburban stream.
Citation:
Beaulieu, J. J., C. P. Arango, David A. Balz, AND W. D. Shuster. Continuous monitoring reveals multiple controls on ecosystem metabolism in a suburban stream. FRESHWATER BIOLOGY. John Wiley and Sons, Hoboken, NJ, 58(5):918-937, (2013).
Impact/Purpose:
To inform the public.
Description:
Ecosystem metabolism is an important mechanism for nutrient retention in streams, yet few high studies have investigated temporal patterns in gross primary production (GPP) and ecosystem respiration (ER) using high frequency measurements. This is a potentially important oversight, particularly in urban streams where frequent, but short- duration, storm flows may have a strong influence on ecosystem metabolism. We measured ecosystem metabolism continuously for 23 months in Shepherd Creek, a small urban stream in Cincinnati, OH (USA). Daily GPP was best predicted by a model containing light and its a synergistic interaction between light and with water temperature. Similarly, instantaneous GPP was best predicted by light, but the photosynthesis-irradiance curve exhibited strong counter-clockwise hysteresis throughout the day, which was that was related to differences in water temperature between the morning and afternoon periods. Ecosystem respiration was best predicted by GPP and water temperature. The stream was strongly heterotrophic, with the exception of two days during the 2010 spring algal bloom, and a quantile regression analysis indicated that up to 69% of newly fixed carbon was immediately respired by autotrophic respiration. Inter-annual, seasonal, daily, and hourly variability in ecosystem metabolism was attributed to a combination of light availability, water temperature, storm flow dynamicss, and desiccation. These controlling factors are all affected by human activities in urban streams, suggesting stream ecosystem function is likely to respond in complex ways to changing land use and climatological conditions.
