stream ecology

Algal microbial mat biomass measurements from the McMurdo Dry Valleys and Cape Royds, Antarctica (1994-2019, ongoing)


As part of the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, a systematic sampling program has been undertaken to monitor the glacial meltwater streams in that region. This dataset contains microbial biomass concentrations found in algal mats located in streams throughout the McMurdo Dry Valleys as well as in ponds of the nearby Cape Royds. Microbial mat biomass has been collected as part of the McMurdo LTER since the 1993-1994 field season and measured as ash-free dry mass (AFDM) and chlorophyll-a (Chl-a).

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Algal mats were sampled along transects established by the MCMLTER in early to mid-January as in Alger et al. (1997), and mats were identified as either orange, black, green or red in color. Mats were collected using a brass cork borer (1.7 cm diameter) and placed into Whirlpack® bags containing stream water. In the laboratory, samples were de-watered on pre-combusted Whatman GF/C filters, wrapped in foil, and stored at -20°C. Prior to the year 2000, Chl-a samples were extracted in buffered acetone and analyzed spectrophotometrically using the trichromatic method. After 2000, Chl-a was extracted in buffered acetone and analyzed using a Turner Designs 10-AU field fluorometer. Both methods have been shown to produce comparable Chl-a results (Lorenzen and Jeffrey 1980). For AFDM analysis, samples were dried at 100°C for 24 h, weighed, burned at 450°C for 4 h and re-weighed, and then re-wetted and dried to determine mass loss due to hydration of sediments. Both Chl-a and AFDM analyses were performed at Crary Laboratory in McMurdo Station.


The original iterations of the 'stream microbial biomass' data file were created by Tyler Kohler, Lee Stanish and Diane McKnight, and submitted to Inigo San Gil (the data manager) at the Institute of Arctic and Alpine Research (INSTAAR). For proper standardization in the database, the data was massaged into the fields strmgageid, collection date, etc. Entered in the database using Toad 4 Oracle from Dell inc (formerly own by Quest inc.)


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