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PRINCIPAL INVESTIGATOR: KEYWORDS: lake, limnology, primary production, chlorophyll-a, Antarctica
ABSTRACT: 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 set addresses this core area of research and quantifies chlorophyll-a concentrations at specific
depths in McMurdo Dry Valley lakes.
VARIABLES: limno run, location name, location code, date, depth (m),
Chl-a (µg L-1), Chl-a comments, file name
RESEARCH LOCATION: Samples were collected from the East Lake Bonney, West Lake Bonney, Lake Hoare, Lake
Fryxell, Lake Joyce, and Lake Miers limnological sampling stations, located in the McMurdo Dry Valleys of Antarctica. Descriptions of these lakes
can be found in the McMurdo Dry Valley Lake
Descriptions file.
METHODS: Lake water samples were collected at specific depths with a
five-liter Niskin bottle during normal LTER limnological sampling. Sub-samples were
decanted into three-1 L Nalgene bottles (2-light and 1-amber), two-500 mL amber Nalgene
bottles, three-150 mL borosilicate glass bottles, two-20 mL scintillation vials, and
one-30 mL serum vial. Two-100 mL sub-samples were taken from the one-liter amber Nalgene
bottle. In a darkened environment, each sample was filtered through a combusted (475°C 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.
In McMurdo, chlorophyll-a standards were prepared by dissolving 1 mg of chlorophyll-a in a
100 ml volumetric flask and diluting it to mark with a 1:1 solution of 90% acetone and DMSO.
A Beckman DU-640 UV/vis spectrophotometer was used to determine the actual stock
concentration. The absorbance of the stock solution was determined at l=665 nm and l=750 nm;
The corrected initial absorbance was calculated (665o = Abs.665 - Abs.750). The
stock solution was acidified in the cuvette using 4 drops of 3 N HCl and analyzed again. The
absorbance after acidification was used at l=665 nm and l=750 nm to determine 665a (665a = Abs.665 -
Abs.750). Chlorophyll-a content was determined by the following equation:
where v = extract volume, V = volume of water filtered, and L is the pathlength of the
cuvette. The stock solution was used to prepare six standard solutions of chlorophyll-a
ranging from ~ 0.0015 µg ml-1 to 0.150 µg ml-1. Fo and Fa were obtained for each standard by
collecting initial fluorescence data, and then acidifying the standard in the cuvette with 4
drops of 3 N HCl. The cuvette was briefly vortexed before determining Fa.
Each filter was placed into a 20 ml scintillation vial and extracted with 10 ml of 1:1 solution
of 90% acetone and DMSO. The extract was incubated for ~12 hours under cold (<0°C), dark
conditions. After incubation, 4 ml of extract was briefly vortexed & 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
between samples. The cuvette exterior was wiped with Kimwipes. The Fo-Fa was determined for each
sample and chlorophyll-a concentration was calculated using the standard curve.
TIMING: Samples were collected from the following sites and dates:
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.
Strickland, J.D.H. and Parsons. 1977. A practical handbook of seawater analysis. pg. 194.
COMMENTS: Chlorophyll-a values reported in this file are the means of two replicate
samples taken at each depth.
STATUS: Public Access (Type 1).
VARIABLE DESCRIPTION:
VARIABLE TYPE DESCRIPTION UNITS MISSING VALUE INDICATOR MINIMUM MAXIMUM PRECISION Limno Run Text Code for lake's sampling location and date none Required entry n/a n/a n/a Location Name Text Name of lake where measurement was made none Required entry n/a n/a n/a Location Code Text Code for site where measurement was made none Required entry n/a n/a n/a Date Date Date on which sample was gathered mm/dd/yy Required entry 01/01/93 12/31/99 dd Depth (m) Number Distance below ice from which sample was drawn meters Required entry 1 60 1 CHL (µg chl a/l) Number Chlorophyll a concentration, as averaged from 2 replicates, and measured by Turner Designs Fluorometer µg Chlorophyll-a/liter Null -1 25 0.001 CHL Comments Text Helpful hints about the sample Null n/a n/a n/a File Name Text Name of file in which data was submitted Null n/a n/a n/a LOG: 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.
NOTE: Data contained in these files has been subjected to quality
control standards imposed by the investigator. The user of this data
should be aware that, while efforts have been taken to ensure that these
data are of the highest quality, there is no guarantee of perfection
for the data contained herein and the possibility of errors exists. If
you encounter questionable data, please contact the MCM LTER data manager
(; (303)492-4639) so that the data can be
corrected or qualified. Thus, these data may be modified and future
data will be appended.
Season East Bonney West Bonney Hoare Fryxell Joyce Miers Trough
1993-1994 27-Oct-1993 29-Oct-1993 6-Nov-1993 16-Nov-1993
10-Nov-1993 12-Nov-1993
24-Nov-1993 26-Nov-1993 1-Dec-1993 7-Dec-1993
7-Dec-1993 9-Dec-1993
21-Dec-1993 23-Dec-1993 30-Dec-1993 7-Jan-1994
19-Jan-1994 18-Jan-1994
1994-1995 2-Nov-1994 5-Nov-1994 10-Nov-1994 14-Nov-1994
23-Nov-1994 25-Nov-1994 30-Nov-1994 4-Dec-1994
17-Dec-1994 19-Dec-1994 24-Dec-1994 30-Dec-1994
10-Jan-1995 12-Jan-1995 20-Jan-1995 17-Jan-1995
1995-1996 19-Sep-1995 21-Sep-1995 7-Sep-1995 14-Sep-1995
14-Sep-1995
6-Oct-1995 4-Oct-1995 25-Sep-1995 28-Sep-1995
17-Oct-1995 19-Oct-1995 10-Oct-1995 14-Oct-1995
2-Dec-1995 5-Dec-1995 21-Nov-1995 26-Nov-1995
1-Jan-1996 4-Jan-1996 23-Dec-1995 27-Dec-1995
1996-1997 3-Nov-1996 1-Nov-1996 8-Nov-1996 26-Oct-1996
24-Nov-1996 26-Nov-1996 2-Dec-1996 19-Nov-1996 5-Dec-1996 10-Dec-1996
15-Jan-1997 17-Jan-1997 12-Jan-1997 9-Jan-1997
1997-1998 31-Oct-1997 2-Nov-1997
8-Nov-1997 11-Nov-1997 7-Nov-1997 12-Nov-1997
15-Nov-1997 18-Nov-1997
1-Dec-1997 26-Nov-1997 28-Nov-1997
8-Dec-1997 3-Dec-1997 10-Dec-1997 5-Dec-1997 9-Dec-1997 5-Dec-1997
12-Dec-1997 16-Dec-1997
20-Dec-1997 22-Dec-1997 26-Dec-1997 29-Dec-1997
6-Jan-1998 8-Jan-1998
17-Jan-1998 20-Jan-1998
26-Jan-1998
1998-1999 9-Nov-1998 11-Nov-1998 3-Nov-1998 28-Oct-1998
6-Dec-1998 9-Dec-1998 1-Dec-1998 23-Nov-1998
30-Dec-1998 1-Jan-1999 26-Dec-1998 20-Dec-1998 23-Dec-1998
1999-2000 6-Nov-1999 11-Nov-1999 17-Nov-1999 30-Oct-1999
3-Dec-1999 5-Dec-1999 12-Dec-1999 27-Nov-1999
28-Dec-1999 30-Dec-1999 4-Jan-2000 23-Dec-1999
none
none