Algae Primary Productivity in Reactivated Channel


As part of the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, water was diverted to a relict stream channel in order to reactivate the streamflow. The purpose of this experiment was to quantify the time scales of response to the arrival of water after many years of dessication. This data set includes results from light and dark incubations of algae to calculate net and gross primary productivity of algal communities from the Relict Channel in the Fryxell basin.

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Within each transect, algal mats were visually identified as either orange, red, black, or green. Not all types of algal mats were found within every transect. Algal samples were collected using a cork borer, placed in either light or dark vials, and incubated in the stream for 3 to 8 hours during sunny conditions. Primary productivity was measured as the change in oxygen concentration in the vial using an oxygen electrode. Net primary productivity (NPP, light bottles) and community respiration (CR, dark bottles) were calculated as follows: NPP or CR (ug C/cm2/hr)=((change in mg O2/L x v) x 0.375 C/O2 x 1000 ug/mg)/area/hours incubated, where O2/L = change in oxygen concentration, v = volume of vial (liters), C/O2 = atom/atom conversion of oxygen to carbon, area = area of cork borer (cm2).

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Data and metadata moved to DEIMS in 2015, to enhance LTER services Data from this table was initially included in the raw data files specified under the variable for 'file name'. These are Microsoft Excel version 6.0 files and can be found in the McMurdo LTER data manager's home directory on INSTAAR's Unix system. Once submitted to INSTAAR, the data manager combined all of the Relict Channel files that included information on primary production, and removed any variables that had no direct influence on the primary productivity of a given algal / incubation type. The resulting file is represented in the "relcprpr.dat" file used on the web page.


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