EDI Staging Environment
In August 2007, the Lake Sunapee Protective Association (LSPA) deployed a buoy in Lake Sunapee, NH with a meteorological station, dissolved oxygen sensor at 1 m, and a string of thermistor water temperature sensors collecting data every 10 minutes. For this dataset, the Lake Sunapee buoy was located at a location near Loon Island all year (August 2007–December 2008) including during the winter.
We used high-frequency dissolved oxygen, photosynthetically active radiation (PAR), wind speed, and water temperature profile data to estimate daily rates of gross primary production, respiration, and net ecosystem production as metrics of ecosystem metabolism and carbon cycling. This dataset included under-ice data, and we compared seasonal changes in ecosystem metabolism rates for an entire lake year from the start of fall mixing in 2007 through the end of summer stratification in 2008. Under-ice and mixing periods are infrequently sampled due to logistical challenges and assumptions of low biological activity, resulting in limited understanding of the contribution of winter epilimnetic metabolism to annual carbon cycling. Using a continuous year of high-frequency dissolved oxygen data, we found that on average, under-ice net ecosystem production (NEP) was negative, in contrast to positive NEP for the spring and summer periods. Importantly, under-ice respiration was 2.4 times higher than summer respiration. Gross primary production was low but not absent under ice and increased during the last under-ice phase. Including winter metabolism estimates flipped annual NEP from autotrophy to heterotrophy, highlighting the importance of estimating metabolism year-round.
Our methods for the data analysis are described in Brentrup et al. (In revision at LO Letters) and were similar to Richardson et al. (2016) with some modifications described in the methods. This dataset also includes derived thermocline depth calculations from the water temperature thermistor data on the Lake Sunapee buoy to convert epilimnetic metabolism data in volumetric units to areal units for the water column. We also collected daily total precipitation and snow depth data from the Newport, NH NOAA NCDC weather station, as well as wind speed, PAR, and water temperature data from the Lake Sunapee buoy for the same time period. This dataset also includes derived Schmidt stability calculations from the water temperature thermistor data on the Lake Sunapee buoy. We used these data to test for significant environmental correlates with the ecosystem metabolism metrics during the under-ice, summer stratification, and full lake year periods.
All datasets have been QAQC’d to remove obviously errant readings, highly suspicious readings and artifacts of buoy maintenance.
EDI is a collaboration between the University of New Mexico and the University of Wisconsin – Madison, Center for Limnology:
