Joshua P. DarlingRuth C. HeindelJoel G. SingleyAnna J. BergstromDiane M. McKnight 2020-09-24 tabular digitial data McMurdo Dry Valleys LTER McMurdo Dry Valleys LTER 10.6073/pasta/21650245acdf99704b4571b887fdeb2a https://mcm.lternet.edu/content/hyporheic-diatom-community-assemblages-von-guerard-stream-taylor-valley-mcmurdo-dry-valleys In this data package, we present diatom community assemblages from hyporheic sediments collected in January 2019 from six transects across Von Guerard Stream, Taylor Valley, Antarctica. These samples were collected to address questions about the retention and processing of particulate organic matter in the hyporheic zone of McMurdo Dry Valley streams. The six transects were located at pools, riffles, and meanders (three of each geomorphology type) along Von Guerard Stream and extended across the stream channel to the edges of the wetted zone, ranging from 6.6 to 13.6 m in length. At each sampling location, we collected subsurface sediment sample that was preserved in formalin directly after sample collection. We characterized diatom assemblages by counting a total of 300 diatom valves from each preserved diatom sample. This data package is associated with a complementary data package that contains hyporheic sediment chemistry for the same samples. 2019-01-10 ground condition As needed Transect type is "meander." Coordinates provided by Ruth Heindel on 24 September 2020. 163.255683000000 163.255683000000 -77.610933000000 -77.610933000000 Transect type is "meander." Coordinates provided by Ruth Heindel on 24 September 2020. 163.296560000000 163.296560000000 -77.620117000000 -77.620117000000 Transect type is "pool." Coordinates provided by Ruth Heindel on 24 September 2020. 163.282600000000 163.282600000000 -77.618700000000 -77.618700000000 Transect type is "pool." Coordinates provided by Ruth Heindel on 24 September 2020. 163.293367000000 163.293367000000 -77.619867000000 -77.619867000000 Transect type is "riffle." Coordinates provided by Ruth Heindel on 24 September 2020. 163.256000000000 163.256000000000 -77.611083000000 -77.611083000000 Transect type is "riffle." Coordinates provided by Ruth Heindel on 24 September 2020. 163.280733000000 163.280733000000 -77.618467000000 -77.618467000000 LTER Core Areas population dynamics None <cntperp> <cntper>McMurdo Dry Valleys LTER Information Manager</cntper> </cntperp> <cntemail>im@mcmlter.org</cntemail> Name: Braeden Lukkari Role: lab technician Name: Renée F. Brown Role: data manager Not Applicable Not Applicable Field and/or Lab Methods Field MethodsDuring January 2019, we collected hyporheic sediments nine transects across pools, meanders, and riffles along Von Guerard Stream in Taylor Valley, Antarctica. Each transect was composed of five sampling sites at different lateral positions across the stream channel: two sampling sites were located at the margins of the visible wetted zone, one sampling site was directly under the thalweg, and two sampling sites were located halfway between the wetted margin and the thalweg. Transects ranged from 6.6 m to 13.6 m in total length across the stream channel. At each sampling site, we removed the surface sediment and mat material in order to focus our sampling on the underlying hyporheic sediments. To characterize the diatom assemblages, we collected a sample in a plastic scintillation vial that was preserved in formalin directly after sample collection. Laboratory AnalysesDiatom assemblages were characterized at six of the nine transects (two transects for pool, meander, and riffle) by counting a total of 300 diatom valves from preserved samples. First, a subset of sediment was transferred to 50 mL centrifuge tubes. We cleaned samples of organic content by digesting with hydrogen peroxide (30 mL of 30% H2O2) for 48 hours at 100ºC. After digestions were complete, samples were repeatedly rinsed with distilled water until a neutral pH was reached. We isolated diatoms from sand grains and other mineral aggregates through repeated resuspension and centrifugation to carefully retain the diatoms in the supernatant. Aliquots of supernatant were dried on coverslips and mounted to glass microscope slides using a highly refractive adhesive (Zrax, W. P. Dailey, Philadelphia, USA). We counted diatoms at 1250x magnification on an Olympus BX50 DIC microscope and identified taxa using descriptions listed in the Antarctic Freshwater Diatoms Database. Fragmented diatom frustules were identified to the highest taxon-level possible (mostly genus level). All relative abundance composition data was standardized to the total number of diatom valves counted per sample.   Field MethodsDuring January 2019, we collected hyporheic sediments nine transects across pools, meanders, and riffles along Von Guerard Stream in Taylor Valley, Antarctica. Each transect was composed of five sampling sites at different lateral positions across the stream channel: two sampling sites were located at the margins of the visible wetted zone, one sampling site was directly under the thalweg, and two sampling sites were located halfway between the wetted margin and the thalweg. Transects ranged from 6.6 m to 13.6 m in total length across the stream channel. At each sampling site, we removed the surface sediment and mat material in order to focus our sampling on the underlying hyporheic sediments. To characterize the diatom assemblages, we collected a sample in a plastic scintillation vial that was preserved in formalin directly after sample collection.Laboratory AnalysesDiatom assemblages were characterized at six of the nine transects (two transects for pool, meander, and riffle) by counting a total of 300 diatom valves from preserved samples. First, a subset of sediment was transferred to 50 mL centrifuge tubes. We cleaned samples of organic content by digesting with hydrogen peroxide (30 mL of 30% H2O2) for 48 hours at 100ºC. After digestions were complete, samples were repeatedly rinsed with distilled water until a neutral pH was reached. We isolated diatoms from sand grains and other mineral aggregates through repeated resuspension and centrifugation to carefully retain the diatoms in the supernatant. Aliquots of supernatant were dried on coverslips and mounted to glass microscope slides using a highly refractive adhesive (Zrax, W. P. Dailey, Philadelphia, USA). We counted diatoms at 1250x magnification on an Olympus BX50 DIC microscope and identified taxa using descriptions listed in the Antarctic Freshwater Diatoms Database. Fragmented diatom frustules were identified to the highest taxon-level possible (mostly genus level). All relative abundance composition data was standardized to the total number of diatom valves counted per sample.   unknown Hyporheic zone sediment diatoms Dataset code Internal dataset code. The data provider Internal dataset code. Stream name Name of the stream where sample was collected. The data provider Name of the stream where sample was collected. Sample date Date samples were collected. The data provider calendar date/time MM/DD/YYYY gregorian calendar Sample identifier Unique sample identifier that contains the geomorphology type, the transect number, and the lateral position. Sample identifiers are based on location, e.g., P1-3 refers to a sample collected from pool transect number 1 (upper transect) and at position 3 of 5 across the transect. The data provider M meander The data provider P pool The data provider R riffle The data provider Transect identifier Transect identifier. Transects are numbered from north to south. The data provider M meander The data provider P pool The data provider R riffle The data provider Geomorphic classification Geomorphic classification type of the sample/transect location. The data provider Geomorphic classification type of the sample/transect location. Lateral position Lateral position of the sample across the transect. The data provider 1 margin of the wetted zone (inside bank for meanders) The data provider 2 intermediate The data provider 3 stream thalweg The data provider 4 intermediate The data provider 5 margin of the wetted zone (outside bank for meanders) The data provider Taxon identifier Taxon identifier relates observed species to current (as of August 2020) taxonomy updated to the Antarctic Freshwater Diatoms Database: http://huey.colorado.edu/diatoms/taxa/index.php The data provider Taxon identifier relates observed species to current (as of August 2020) taxonomy updated to the Antarctic Freshwater Diatoms Database: http://huey.colorado.edu/diatoms/taxa/index.php Species Genus and specific epithet of species using taxonomy current as of August 2020. The data provider Genus and specific epithet of species using taxonomy current as of August 2020. Relative abundance Qualitative, percent relative abundance for each species in each sample. The data provider percent McMurdo Dry Valleys LTER The data distributor shall not be liable for innacuracies in the content http 1 0 1 column , https://mcm.lternet.edu/sites/default/files/data/HZSEDS_DIATOMS_0.csv None 2020-09-24 2020-09-24 McMurdo Dry Valleys LTER http://mcmlter.org/ Biological Data Profile of the Content Standards for Digital Geospatial Metadata devised by the Federal Geographic Data Committee. Drupal Ecological information Management Systems, version D7, Biological Data Profile module