Algae Ash-Free Dry Mass 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 table contains data showing the ash-free dry mass represented by algal type (brown-colored, red-colored, orange-colored, or green-colored, filamentous, sand, rock or moss) and incubation type (light, dark, or none) for 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 t ransect. A maximum of five algal samples of each color were collected from each transect using a #13 cork borer (diameter = 17 mm, area = 227 square mm). Algal samples were preserved in 10% formalin for laboratory identifications. A maximum of five additional algal samples of each color were collected for ash-free dry mass analyses. Moss samples were also collected using the same method as for algae samples. Samples for ash-free dry mass measurements were filtered through GF/C glass fiber filters and frozen. The samples were dried (100 degrees C) for 24 hours, weighed, ashed (450 degrees C) for 4 hours, rehydrated with water, dried for 24 hours, and reweighed.


Data from this table was initially included in the raw data files specified under the variable for 'file name'. These are Microsoft Excel version 5.0 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 for "ash-free dry mass", and removed any variables that had no direct influence on it. The resulting file is represented in the "afdmrlc.dat" file used on the web page. In October 1998, the data manager reviewed the values provided for location, and found that there was a lack of consistency among Relict Channel datasets that should contain corresponding location values. It was desirable to match locations from this dataset with those represented in the sampling points (eg. latitude, longitude, elevation, location name). Dev Niyogi and Mike Gooseff provided assistance in translating location values, as well as in specifying coordinates for the Relict Channel sample points. As a result, the following records had the original location name replaced with a location code: Relict channel site #1 RC1 Relic channel site #2 RC2 Relict channel site #2 RC2 Relic channel site #3 RC3 Relict channel site #3 RC3 Relic channel site #4 RC4 Relict channel site #4 RC4 Relict channel site #5 RC5 Relict channel site #6 RC6 Relict channel site #7 RC7.


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