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PRINCIPAL INVESTIGATOR: KEYWORDS: lake, limnology, thymidine, bacteria, production, Antarctica
ABSTRACT: An important part of the McMurdo Long Term Ecological Research (LTER) is monitoring of
spatial and temporal patterns, and processes that control bacterial production in perennial ice-covered lakes.
This data set quantifies thymidine uptake by bacteria and can be used to estimate bacterial production.
VARIABLES: limno run, location name, location code, date, depth (m),
TDR (nM TDR/day), TDR comments, file name
RESEARCH LOCATION: Samples were collected from the East Lake Bonney, West Lake Bonney, Lake Hoare, and Lake
Fryxell 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. Five-20 mL scintillation vials (3-live treatments,
2-kill treatments) were prepared at each depth for TDR analysis. TDR samples (10 mL)
were taken from the one-liter amber Nalgene bottle and placed in each scintillation
vial. 0.5 mL filtered formalin (0.2µm) was pipetted into each killed treatment vial.
3H Thymidine was pipetted into each vial (final concentration of 20 nM thymidine), first
the live treatments and then the kill treatments. Samples were incubated in the dark at
1-4°C for 20 hours (thymidine incorporation has been shown to be linear for 20 hours
under these conditions, Priscu unpublished). At the end of the incubation period
10 mL of ice cold 10% TCA was added to stop thymidine uptake and precipitate nucleotides.
Vials were stored at 4°C until filtered. Each sample was filtered through a 0.2 µm Nucleopore
polycarbonate membrane filter. Both the scintillation vial and filter tower were rinsed
three times with 5% TCA. Each filter was placed into a new scintillation vial and 15
mL of Cytoscint cocktail was added. Samples were counted with a pre-calibrated (3H) liquid
scintillation counter. Thymidine uptake rate (TDR nM d-1) was calculated using the
following equation:
where DPML is the average dpm for the live treatment, DPMK is the average dpm for the
kill treatment, a is the final concentration of thymidine in each vial (20nM), alpha is
the total dpm added to each vial, and t is the incubation period. The thymidine
uptake rate was adjusted to the ambient lake temperature using the Arrhenius equation:
where Ea is the energy of activation (12,600 cal mol-1, Q10 = 2.2), °CI is the
incubation temperature (°C), °CA is the ambient lake water temperature at specific
depth, and R is a gas constant (1.987 cal mol-1 K-1).
TIMING: Samples were collected from the following sites and dates: CITATIONS:
COMMENTS: The energy of activation was experimentally derived for Lake Bonney
(Priscu, unpublished). If the average of the kill treatment uptake exceeds live treatment
uptake, uptake is reported as zero.
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 25 1 TDR (nM TDR/d) Number Thymidine uptake rate using tritiated thymidine nM TDR/day Null 0 1 0.001 TDR 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 Metatdr9697.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
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
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
15-Jan-1997 17-Jan-1997 12-Jan-1997 9-Jan-1997
1997-1998 8-Nov-1997 11-Nov-1997 15-Nov-1997 18-Nov-1997
20-Dec-1997 22-Dec-1997 26-Dec-1997 29-Dec-1997
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
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
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