phytplkt English utf8 dataset McMurdo Dry Valleys LTER http://mcmlter.org/ 2014-11-04 ISO 19115-2 Geographic Information - North American Profile Metadata - Data with Biological Extensions ISO 19115-2:2009(E) Summer Phytoplankton Densities 1992-2001 2014-11-04 publication Diane McKnight University of Colorado Boulder http://www.colorado.edu/ diane.mcknight@colorado.edu pointOfContact documentDigital   Phytoplankton were collected over four austral summers (1991-92 through1994-95) to examine seasonal and annual fluctuation in species composition and biovolume in Lakes Fryxell, Hoare, West Lake Bonney, and East Lake Bonney. All of these lakes are perennially ice-covered lakes located in the Dry Valleys of South Victoria Land, Antarctica.        The phytoplankton consisted primarily of cryptophyte and chlorophyte flagellates, and filamentous cyanobacteria. Some common taxa were vertically stratified (Oscillatoria limnetica, Phormidium angustissimum, Pyramimonas sp., Oscillatoria sp.), while others showed no distinct vertical stratification (Chlamydomonas subcaudata, Cryptomonas sp.). The stratification of the phytoplankton reflects the gradients of nutrients and light, and the stability of the water column. Name: Inigo San Gil Role: data manager completed McMurdo Dry Valleys LTER http://mcmlter.org/ unknown metadata enhanced in 2016 - san gil population dynamics theme LTER Core Areas English The Lake Fryxell basin is formed by a moraine depression in a wider portion of the Taylor Valley. It has a number of moraine islands and shallower areas, as well as several relatively well developed deltas. The lake is fed by at least 10 meltwater streams with a total drainage catchment of 230 km2. The lake is dammed to the southwest by the Canada Glacier and is topographically closed. It is perennially ice covered; during summer months, an ice-free moat generally forms around much of the lake margin. Lake levels have risen ~2 m between 1971 and 1996. There are no surface outflows; the only known water loss is through ice ablation (evaporation, sublimation and physical scouring). Valley: Taylor Distance to Sea : 9 Maximum Length (km): 5.8 Maximum Width (km): 2.1 Maximum Depth (m): 20 Surface Area (km^2): 7.08 Ice Thickness Average Surface (m): 3.3 - 4.5 Volume (m^3 * 10^6): 25.2 163.259582519531 163.048782348633 -77.622711181641 -77.597076416016 ground condition 1992-01-01 2001-12-31 https://mcm.lternet.edu/sites/default/files/LIMNO_PHYTO_DENSITY_SUMMER.csv LIMNO_PHYTO_DENSITY_SUMMER eng; US McMurdo Dry Valleys LTER LIMNO_PHYTO_DENSITY_SUMMER Record Delimiter : \n Number of Header Lines : 28 Number of Footer Lines : 1 Orientation : Column Quote Character : "Field Delimiter : , false DATASET_CODE Code to ID the data table LIMNO_RUN Code for lake's sampling location and date LOCATION NAME Name of lake where measurement was made LOCATION CODE Code for site where measurement was made DATE_TIME Date on which sample was gathered Date Time Format: mm/dd/yyyy DEPTH (m) Distance below ice from which sample was drawn PHYLUM None SPECIES None DENSITY (cells/mL) Density (cells/mL) FILE NAME Name of file in which data was submitted DEPTH MASL Depth referred to the Sea level. DBF https://mcm.lternet.edu/sites/default/files/LIMNO_PHYTO_DENSITY_SUMMER.csv dataset  Discrete samples for phytoplankton enumeration were collected from the oxygenated portion of the water column (below the bottom of the ice to a depth of 10 m) at 0.5 m intervals. Sampling was done primarily between the hours of 14:00 and 20:00 (during the austral summer, the illuminated period is 24 h/day) by either peristaltic pump or Kemmerer bottle. Samples were collected in 1 l bottles and preserved immediately with Lugon's solution (American Public Health Association, 1985). Identification and counts were made with an inverted microscope by the method of Utermohl (1958). At least 100 individuals of the most numerous algae were counted per sample at 100x magnification. The total number of individuals counted was dependent on the number of taxa, but ranged between 200 and 500. Counting error ranged between 13 and 26%, depending on species. Algal species identifications were made using Geitler (1932), Seaburg et al. (1979) and Prescott (1962). Cell volumes were estimated for dominant taxa by measuring cell dimensions of 50-100 individuals and using closest geometric formulas of additional dates and depths to determine changes in cell volume over time. For rare taxa, volume estimates were made from fewer cell measurements.         Primary productivity was measured using the method of Strickland and Parsons (1972). In situ 24 h incubations were made in triplicate 300 ml light and duplicate 300 ml dark bottles with Na14CO3 (3 uCi per 300 ml, New England Nuclear). Following 24 h incubation, samples were well shaken and filtered through Whatman GF/F filters in the dark. The filters were placed in scintillation vials and acidified with 1 ml of 5% acetic acid in methanol to remove [C14 carbonates. The [C14] fixed by biological activity was determined in Aquasol (New England Nuclear) by liquid scintillation.          Samples for nitrate and orthophosphate were frozen within several hours of collection, later filtered through 0.45 um Nucleopore filters and analyzed by air-segmented continuous-flow absorption spectrophotometry (Alpkem RFA-300) (Antweiler et al., 1993). Chlorophyll extractions were made in 95% ethanol (Jesperson and Christoffersen, 1987) and measured in a Turner Designs Model 10 Fluorometer. Metadata Access Constraints: none Metadata Use Constraints: none annually McMurdo Dry Valleys LTER http://mcmlter.org/ pointOfContact