limnchla English utf8 dataset McMurdo Dry Valleys LTER Information Manager im@mcmlter.org pointOfContact 2014-11-04 ISO 19115-2 Geographic Information - North American Profile Metadata - Data with Biological Extensions ISO 19115-2:2009(E) Chlorophyll-a concentrations in discrete water column samples collected from lakes in the McMurdo Dry Valleys, Antarctica (1993-2025, ongoing) 2014-11-04 publication Cristina Takacs-Vesbach University of New Mexico https://www.unm.edu/ cvesbach@unm.edu http://www.vesbachlab.org pointOfContact John Priscu Montana State University http://www.montana.edu/ jpriscu@montana.edu pointOfContact documentDigital An important part of the McMurdo Long Term Ecological Research (LTER) project is monitoring of spatial and temporal patterns, and processes that control primary production in perennial ice-covered lakes. This data package addresses this core area of research by quantifying chlorophyll-a concentrations within specific depths along the water column of several lakes located across the McMurdo Dry Valleys region of Antarctica. Name: Jade Lawrence Role: field technician Name: Renée F. Brown Role: data manager Name: Amy Chiuchiolo Role: former field crew Name: Kathleen A. Welch Role: former lab crew Name: Inigo San Gil Role: former data manager completed McMurdo Dry Valleys LTER Information Manager im@mcmlter.org pointOfContact unknown 2015 - data and metadata migrated to the Drupal Ecological Information Management System at MCM. Inigo San Gil, Ara Kooser and Tina Takacs-Vesbach.    Data from this table was submitted to INSTAAR by John Priscu's team at Montana State University. The raw data files listed under 'file name' are the names of the original files submitted. The 1993/94 and 1994/95 datasets are Microsoft Excel version 6.0 files, and the 1995/96, 1996/97 and 1997/98 datasets are ascii text files. Upon arrival at INSTAAR, the data manager fine-tuned the location codes and limno runs to match those provided in the "locations, dates, codes for lake chemistry, biology samples" file. The file was imported into Microsoft Access on INSTAAR's Unix system, and can currently be found there. The file was then exported in ascii, comma delimited text and MS-DOS text (table layout) on the MCM LTER web site. Both of these files are linked to this web page above. Information for the metadata was obtained from the Metachl9697.rtf file. The file was called up using Microsoft Word version 6.0. Text from this file was used to create this page in html format. organic matter theme LTER Core Areas English Lake Bonney is a saline lake with permanent ice cover at the western end of Taylor Valley in the McMurdo Dry Valleys of Victoria Land, Antarctica. It is 7 kilometres or 4.3 mi long and up to 900 metres or 3,000 ft wide. A narrow channel only 50 metres or 160 ft wide. Lake Bonney at Narrows separates the lake into East Lake Bonney 3.32 square kilometres or 1.28 sq mi and West Lake Bonney, 0.99 square kilometres or 0.38 sq mi. The west lobe is flanked by Taylor glacier. Valley: Taylor Distance to Sea : 25 Maximum Length (km): 4.8 Maximum Width (km): 0.9 Maximum Depth (m): 37 Surface Area (km^2): 3.32 Ice Thickness Average Surface (m): 3 - 4.5 Volume (m^3 * 10^6): 54.7 162.536209106445 162.353210449219 -77.724441528320 -77.697700500488 Lake Bonney is a saline lake with permanent ice cover at the western end of Taylor Valley in the McMurdo Dry Valleys of Victoria Land, Antarctica. It is 7 kilometres or 4.3 mi long and up to 900 metres or 3,000 ft wide. A narrow channel only 50 metres or 160 ft wide. Lake Bonney at Narrows separates the lake into East Lake Bonney 3.32 square kilometres or 1.28 sq mi and West Lake Bonney, 0.99 square kilometres or 0.38 sq mi. Valley: Taylor Distance to Sea : 28 Maximum Length (km): 2.6 Maximum Width (km): 0.9 Maximum Depth (m): 40 Surface Area (km^2): 0.99 Ice Thickness Average Surface (m): 2.8-4.5 Volume (m^3 * 10^6): 10.1 162.354934692383 162.269104003906 -77.727287292480 -77.714805603027 Lake Brownworth is a meltwater lake west of Wright Lower Glacier at the east end of Wright Valley. It was named by the Advisory Committee on Antarctic Names for Frederick S. Brownworth Jr., 162.823226928711 162.718856811523 -77.442016601563 -77.417655944824 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 Lake Hoare occupies a narrower portion of the Taylor Valley, dammed by the Canada Glacier. It would drain almost completely without this dam. There are a number of islands which may be related to an old terminal of Canada Glacier. The lake is fed primarily from direct runoff from the glacier, as well as meltwater streams. (Lake level rose ~1.5 m between 1972 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 : 15 Maximum Length (km): 4.2 Maximum Width (km): 1 Maximum Depth (m): 34 Surface Area (km^2): 1.94 Ice Thickness Average Surface (m): 3.1 - 5.5 Volume (m^3 * 10^6): 17.5 162.935836791992 162.784423828125 -77.639259338379 -77.623085021973 Lake Joyce lies in the Pearse Valley against the Taylor Glacier.  Valley: Pearse  Distance to Sea : 44  Maximum Length (km): 1  Maximum Width (km): 1  Maximum Depth (m): 35  Surface Area (km^2): 0.83  Ice Thickness Average Surface (m): 3.9 - 5.6  Volume (m^3 * 10^6): 4.9 161.662445068359 161.608886718750 -77.726486206055 -77.715972900391 Lake Miers lies in the Miers Valley. Valley: Miers Distance to Sea : 20 Maximum Length (km): 1.5 Maximum Width (km): 0.7 Maximum Depth (m): 21 Surface Area (km^2): 1.3 Ice Thickness Average Surface (m): 3.4 - 6 Volume (m^3 * 10^6): 2.9 163.886840820313 163.812332153320 -78.101478576660 -78.094047546387 A lake with an area of 1 square mile which occupies the north portion of Pyramid Trough, Scott Coast. Named by New Zealand Geographic Board (NZGB) (1994) in association with Pyramid Trough. 162.823226928711 162.718856811523 -77.442016601563 -77.417655944824 Lake Vanda is located in the Wright Valley, adjacent to the Taylor Valley. It is fed primarily by the Onyx River, which has its origin at Lake Brownworth, and ultimately at the Lower Wright Glacier located ~27 km east of the lake. The lake has no outflow. Valley: Wright Distance to Sea : 47 Maximum Length (km): 8 Maximum Width (km): 2 Maximum Depth (m): 75 Surface Area (km^2): 5.2 Ice Thickness Average Surface (m): 2.8 - 4.2 Volume (m^3 * 10^6): 160 161.691970825195 161.391906738281 -77.542304992676 -77.518882751465 ground condition 1993-10-27 2025-01-06 Holm-Hansen, O., C. J. Lorenzen, R. W. Holmes, and J. D. H. Strickland. 1965. Fluorometric determination of chlorophyll. J. Cons. Int. Explor. Mer. 30: 3-15. Strickland, J.D.H. and Parsons. 1977. A practical handbook of seawater analysis. pg. 194. https://mcm.lternet.edu/sites/default/files/data/mcmlter-lake-chla-20251013.csv LIMNO_CHL_A_DEPTH eng; US McMurdo Dry Valleys LTER LIMNO_CHL_A_DEPTH Record Delimiter : \n Number of Header Lines : 1 Number of Footer Lines : 1 Orientation : Column Quote Character : "Field Delimiter : , false DATASET_CODE Code to ID the data table LOCATION NAME Name of lake where measurement was made LOCATION CODE Code for site where measurement was made LIMNO_RUN Code for lake's sampling location and date DATE_TIME Date on which sample was gathered Date Time Format: mm/dd/yyyy DEPTH (m) Distance below ice from which sample was drawn CHL (ug chl-a/l) Chlorophyll a concentration, as averaged from 2 replicates, and measured by Turner Designs Fluorometer CHL COMMENTS Helpful hints about the sample FILE NAME Name of file in which data was submitted DEPTH MASL Depth referred to the Sea level. Distance below Mean Average Sea water level reference from which sample was drawn DBF https://mcm.lternet.edu/sites/default/files/data/mcmlter-lake-chla-20251013.csv dataset The basic method of Holm-Hansen et al. (1965) and Strickland and Parsons (1972), with the modifications noted below, was used to analyze chlorophyll-a samples from the beginning of the LTER dataset in 1993 . Notes on the method and its modifications follow. Lake water samples were collected at specific depths with a five-liter Niskin bottle during normal LTER limnological sampling. Sub-samples were decanted into an amber one-liter Nalgene bottle. Two-100 mL or 200 mL sub-samples were taken from the one-liter amber Nalgene bottle. In a darkened environment, each sample was filtered through a combusted (475C for 4 hours) Whatman 25 mm GF/F using a bell jar apparatus. The filter was folded in half (organic material inside), placed in a glassine envelope, covered with aluminum foil, and frozen immediately for later analysis in McMurdo. The filtrate was collected for nutrient and dissolved organic carbon analyses. All of the following laboratory methods were performed in a darkened environment. In McMurdo, a chlorophyll-a stock concentrate was prepared by dissolving 1 mg of chlorophyll-a standard (Sigma, Anacystic nidulans) in a 100 ml volumetric flask and diluting it to mark with 90% acetone (~10,000 micrograms per liter chlorophyll-a). A Beckman DU-640 UV/vis spectrophotometer was used to determine the actual chlorophyll-a concentration of the stock concentrate and the concentration of the stock dilutions. The absorbance of the stock concentrate was measured at 665 nm and 750 nm (non-acidified readings are denoted by a subscript "o"). The stock concentrate was acidified in the cuvette using 2-4 drops of 3 N HCl. The absorbance after acidification was measured at 665 nm and 750 nm (acidified readings are denoted by a subscript "a"). Chlorophyll-a content was determined using the following equation (Strickland and Parsons 1972; Parsons et al. 1984): Chl-a (micrograms per liter)= [26.7*((ABS665o - ABS665a) - (ABS750o - ABS 750a))*1000]/l where: ABS665o = ABS at 665 nm with no acid ABS665a = ABS at 665 nm plus acid ABS750o = ABS at 750 nm with no acid ABS750a = ABS at 750 nm with acid l = cuvette path length (1 cm) The stock solution was used to prepare six to ten standard dilutions of chlorophyll-a ranging from ~ 1.5 micrograms per liter to 500 micrograms per liter, plus a blank of 90% acetone. 90% acetone was used to dilute the standards. Fo and Fa were obtained for each standard by collecting initial fluorescence data on the Turner 10-AU fluorometer, and then acidifying the standard in the cuvette with 4 drops of 3 N HCl. The cuvette was briefly vortexed before determining Fa. The actual concentrations of the working standards were computed from the spectrophotometrically determined concentration of the stocks. A standard curve of chlorophyll-a concentration vs Fo-Fa was prepared. Each filter was placed into a 20 ml scintillation vial and extracted with 10 ml of 90% acetone. The extract was incubated for ~12 hours under cold (<0C), dark conditions. After incubation, the extract was briefly vortexed and 4 ml dispensed into the cuvette; the cuvette was inserted into the Turner 10-AU fluorometer. After Fo was determined, the sample was acidified with 4 drops of 3 N HCl, vortexed, and Fa was determined. The cuvette was rinsed three times with DI water and three times with 90% acetone to ensure there was no cross contamination of sample or acid between samples. The cuvette exterior was wiped with Kimwipes. The Fo-Fa was determined for each sample and chlorophyll-a concentration (microgram per liter) was calculated by comparison with the standard curve as below: Chlorophyll-a (micrograms per liter) = (((Fo-Fa) - y-intercept)/slope) * (ml extracted/ml filtered) where: Fo-Fa = measured sample fluorescence minus acidified fluorescence y-intercept = fluorescence when Chl-a concentration is zero slope = fluorescence/Chl-a (micrograms per liter) ml extracted = ml of 90% acetone used to extract the Chl-a on the filters ml filtered = ml of actual sample filtered in the field Below is an outline of changes that have occurred to the above chlorophyll-a method over the time frame of the LTER dataset 9697 season The above method was followed with the exception that 90% acetone was replaced with a 1:1 solution of 90% acetone and DMSO. Shoaf and Lium (1976) showed that the absorption spectra of chlorophyll a was identical in 90% acetone and a 1:1 solution of 90% acetone and DMSO. 0506 season The method using a 1:1 solution of 90% acetone and DMSO (Shoaf and Lium, 1976) was followed with the exception that the acidification step was omitted for standards and samples run on the fluorometer. This method (Welschmeyer 1994) was employed to eliminate fluorescence from Chl-b interfering with fluorescence of Chl-a. Besides the lack of acidification, the following configurations were made to the fluorometer as described by Welschmeyer (1994): Lamp: "Blue" F4T40.5B2 (F4T40(1/2)B2) Turner No.10-089. Alternatively, a blue lamp (type 9005)-Turner Designs (No. 10-089) can be used which has identical spectral characteristics. A F4T4D daylight lamp, can provide similar selectivity but with about a 2-fold reduction in sensitivity. Excitation Filter (blue): 436BP10 047 9401; Turner No.10-113 Emission Filter (red): 680BP10 357 9405; Turner No.10-115. NOTE: (The excitation and emission filters should have mirrored side toward the actinic light (ie, facing the direction of incoming light)). 0708 season Midway through the 0708 season a change was made in the Welschmeyer (1994) method where the 1:1 solution of 90% acetone:DMSO in the stock concentrate was replaced with 90% acetone. All other parameters of the method remained unchanged. FRX L1-L5, HOR L1-L5, ELB L1-L4, WLB L1-L4 and VAN L1 were analyzed before the change was made; all other samples were analyzed using the revised method. 0809 season In all steps of the method, the 1:1 solution of 90% acetone:DMSO was replaced with 90% acetone. Citations Holm-Hansen, O., C. J. Lorenzen, R. W. Holmes, and J. D. H. Strickland. 1965. Fluorometric determination of chlorophyll. J. Cons. Int. Explor. Mer. 30: 3-15. Shoaf, W.T. , Lium, B.W. Improved extraction of chlorophyll a and b from algae using dimethyl sulfoxide, 1976. Limnol. Oceanogr. vol. 21. pp 926-928  Strickland, J.D.H. and Parsons. 1977 (1972 ?). Spectrophotometric Determination of Chlorophylls and total Carotenoids. A Practical Handbook of Seawater Analysis Fisheries research Board of Canada, Bulletin. vol. Chapter IV.3. pp185-196 Welschmeyer. Fluorometric Analysis of Chlorophyll a in the Presence of Chlorophyll b and Phaeopigments. 1994. Limnol. Oceanogr. vol. 39. pp1985-1992 Metadata Access Constraints: none Metadata Use Constraints: none annually McMurdo Dry Valleys LTER http://mcmlter.org/ pointOfContact