STREAM_ISOTOPES_RCVG English utf8 dataset McMurdo Dry Valleys LTER http://mcmlter.org/ 2018-01-24 ISO 19115-2 Geographic Information - North American Profile Metadata - Data with Biological Extensions ISO 19115-2:2009(E) Microbial mat biomass, isotopes, and nutrient ratios sampled over a longitudinal gradient of two McMurdo Dry Valley streams 2018-01-24 publication Tyler Kohler Charles University https://www.cuni.cz/ tyler.j.kohler@gmail.com pointOfContact documentDigital We performed a field survey to assess changes in biomass, nutrient ratios, and isotopic signatures of three different microbial mat types in two glacial meltwater streams in the McMurdo Dry Valleys, Antarctica. Samples were taken in January 2013 from pre-existing transects over Von Guerard Stream and the Relict Channel, and stretched from near the Von Guerard Glacier terminus to the stream outlets at Lake Fryxell. In addition to the three microbial mat types, which included Nostoc (black), Chlorophyte (green), and Oscillatorean (orange) mats, particulate organic matter (POM) was collected from Von Guerard Stream in January 2008 over a full diel cycle in order to determine the origin of material in transport by comparing its elemental and isotopic characteristics with stream mats. Name: Lee F. Stanish Role: associated researcher Name: Daniel Liptzin Role: associated researcher Name: John "Jeb" E. Barrett Role: associated researcher Name: Diane M. McKnight Role: associated researcher Name: Renée F. Brown Role: data manager completed McMurdo Dry Valleys LTER http://mcmlter.org/ organic matter theme LTER Core Areas English ground condition 2007-12-19 2013-01-20 https://mcm.lternet.edu/sites/default/files/data/STREAM_ISOTOPES_RCVG.csv STREAM_ISOTOPES_RCVG eng; US McMurdo Dry Valleys LTER STREAM_ISOTOPES_RCVG Number of Header Lines : 1 Orientation : Column Field Delimiter : , false DATASET_CODE DATASET_CODE STREAM Stream name in the Lake Fryxell Basin, Taylor Valley, Antarctica. DATE_SAMPLED Date samples were collected. Date Time Format: MM/DD/YYYY TIME_SAMPLED Time a sample was taken (for POM only). Expressed in NZST (daylight savings time is observed). Date Time Format: HHMM TRANSECT The established MCM LTER transect that samples were taken from. SAMPLE_TYPE Type of sample. Includes the three mat types (i.e., black, green, orange) as well as POM (particulate organic matter). DISTANCE Distance of a given transect from the Von Guerard Glacier as estimated using Google Earth. D13C Measure of the ratio of 13C:12C in standard delta notation, expressed relative to universal isotope standards (Pee Dee Belemnite) in parts per thousand (per mil). D15N Measure of the ratio of 15N:14N in standard delta notation, expressed relative to universal isotope standards (atmospheric N2) in parts per thousand (per mil). CN Molar ratio of carbon (C) to nitrogen (N). Blank cells indicate missing values. CP Molar ratio of carbon (C) to phosphorus (P). Blank cells indicate missing values. NP Molar ratio of nitrogen (N) to phosphorus (P). Blank cells indicate missing values. AFDM The mass of the mat sample lost following ignition per unit area. CHLA Quantity of measured chlorophyll-a pigment per unit area. AI The ratio of chlorophyll-a to ash-free dry mass. Blank cells indicate missing values. DBF https://mcm.lternet.edu/sites/default/files/data/STREAM_ISOTOPES_RCVG.csv dataset To characterize and compare POM in transport with stream mats, POM samples were retained from an experiment described previously (“drift 1”; Stanish 2011). Briefly, a temporary ‘drift transect’ was established in Von Guerard Stream (-77.613883°, 163.259550°) between two MCM LTER algal monitoring transects (i.e. Von Guerard Middle and Gage; Fig. 1). A plankton net (40 μm mesh) with a 10 μm mesh collection bucket was anchored to the streambed, and POM samples were collected for 2-8 hours at a time over the course of one diel flow cycle over 22-23 January 2008. Trapped material was rinsed into the collection bucket with distilled water, filtered onto pre-combusted GF/F filters, and frozen until analysis. Samples for isotopic and elemental composition were retained from six times periods (times: 21:30, 1:26, 5:17, 9:35, 13:12, and 13:35). Adjacent mats for comparison were sampled at the drift transect on 19 December 2007 (black n=3, orange n=3) and were collected and processed as described below. To test how the distance from the source glacier influences mat elemental and isotopic composition, at least three replicates of black, green, and orange mats were taken from the three established Von Guerard transects (descriptions in McKnight et al. 1998; GPS coordinates in Kohler et al. 2015). Samples were collected from Von Guerard Gage on 14 January 2013, and from the Middle and Upper transects on 15 January 2013. To achieve a higher resolution in longitudinal patterns, duplicate (and occasionally triplicate) samples of black and orange mats were also taken along 7 of the established Relict Channel transects (McKnight et al. 2007) and the Harnish Stream gage on 20 January 2013. For both streams, sampling was executed by lifting mats from substrata with a spatula, and cores were taken with a brass cork borer (#13, 227 mm2). For each mat type, cores were taken for elemental and isotopic composition (C:N:P stoichiometry, and δ13C and δ15N isotopes) and biomass as ash-free dry mass (AFDM) and chlorophyll-a (chla) if sufficient material was available. Samples were dewatered onto Whatman® GF/F filters, wrapped in foil, and frozen at the field camp for later analysis. Transect distances from Von Guerard Glacier were approximated with Google Earth©. Biomass (as AFDM and chla) was determined as in Kohler et al. (2015). Briefly, chla was measured by extracting samples in 90% buffered acetone for 24 hours (Welschmeyer 1994) and analyzed on a Turner Designs 10-AU field fluorometer. AFDM subsamples were dried at 55ºC for 24 h (or until a constant mass was achieved), weighed, burned at 450ºC for 4 h and reweighed, then rewetted and dried to determine mass loss caused by hydration of sediments (Steinman et al. 1996). An autotrophic index (AI) was created by dividing chla values by their corresponding AFDM. All biomass analyses were performed in Crary Laboratory at McMurdo Station. The C:N:P and isotope subsamples were dried at 50-55 ºC and ground to a powder. Carbonates were removed from the C:N aliquot by fumigation (Hedges and Stern 1984) to prevent loss of acid-soluble carbon that may occur with rinsing. Percent C and N content was measured using a CE 1500 Elemental Analyzer, and δ13C and δ15N isotope ratios were obtained with Finnigan-MAT Delta Plus XL mass spectrometer at the University of California Berkeley Center for Stable Isotope Biogeochemistry. The %P aliquot was combusted in a muffle furnace at 500 ºC for 1 h, digested with 1N HCl, and analyzed as orthophosphate (Murphy and Riley 1962) with a Lachat QuikChem 8500 Flow Injection Analyzer at the Kiowa Lab, University of Colorado. A spinach standard (#1570a) was analyzed every ~10 samples to ensure method accuracy and digestion success. Resulting values were converted to molar C:N:P ratios. Hedges, J.I., and J.H. Stern. 1984. Carbon and nitrogen determinations of carbonate containing solids. Limnol. Oceanogr. 29: 657-663,  doi: 10.4319/lo.1984.29.3.0657 Kohler, T.J., L.F. Stanish, S.W. Crisp, J.C. Koch, D. Liptzin, J.L. Baeseman, and D.M. McKnight. 2015. Life in the main channel: long-term hydrologic control of microbial mat abundance in McMurdo Dry Valley streams, Antarctica. Ecosystems 18: 310-327, doi:10.1007/s10021-014-9829-6 McKnight, D.M., A.S. Alger, C.M. Tate, G. Shupe, and S. Spaulding. 1998. Longitudinal patterns in algal abundance and species distribution in meltwater streams in Taylor Valley, Southern Victoria Land, Antarctica, p. 109–127. In J.C. Priscu, [ed.], Ecosystem Dynamics in a Polar Desert: The McMurdo Dry Valleys, Antarctica, Antarctic Research Series Vol. 72, American Geophysical Union. McKnight, D.M., C.M. Tate, E.D. Andrews, D.K. Niyogi, K. Cozzetto, K. Welch, W.B. Lyons, and D.G. Capone. 2007. Reactivation of a cryptobiotic stream ecosystem in the McMurdo Dry Valleys, Antarctica: A long-term geomorphological experiment. Geomorphology 89: 186-204. Murphy, J., and J.P. Riley. 1962. A modified single solution method for determination of phosphate in natural waters. Anal. Chim. Acta. 26: 31-36. Stanish L.F. 2011. Ecological controls on stream diatom communities in the McMurdo Dry Valleys, Antarctica. Ph.D. thesis. Univ. of Colorado. Steinman, A., Lamberti, G.A., and Leavitt, P.R. 1996. Biomass and pigments of benthic algae. In Hauer, F.R., and Lamberti, G.A., Eds. Methods in stream ecology. 2nd ed. San Diego, CA: Academic Press, 357-379. Welschmeyer, N.A. 1994. Fluorometric analysis of chlorophyll a in the presence of chlorophyll b and pheopigments, Limnol. Oceanog. 39: 1985–1992. doi: 10.4319/lo.1994.39.8.1985 Metadata Access Constraints: none Metadata Use Constraints: none annually McMurdo Dry Valleys LTER http://mcmlter.org/ pointOfContact