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PRINCIPAL INVESTIGATOR: KEYWORDS: lake, limnology, respiration, electron transport system, ETS, Antarctica
ABSTRACT: An important part of the McMurdo Long Term Ecological Research (LTER) is monitoring of
spatial and temporal patterns, and processes that control net primary production (carbon dynamics) in
perennial ice-covered lakes. One of the primary losses of carbon fixed by phytoplankton is through
respiration, directly by the phytoplankton themselves and secondarily through the metabolic contributions of
heterotrophic organisms such as bacterioplankton and protozoa. The coupling of low metabolic activity and
supersaturated gases in the water column prohibits a direct measurement of respiration. Therefore, we
measure the respiratory electron transport system (ETS) activity which drives oxidative phosphorylation, and
hence oxygen consumption in all aerobic organisms (Packard 1985). This data set addresses this core area of
research and estimates a community-wide respiration rate at specific depths in McMurdo Dry Valley lakes.
VARIABLES: limno run, location name, location code, date, depth (m),
ETS (µmol O2 L-1 hr-1), ETS comments,
respiration (µmol O2 L-1 hr-1), respiration 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. The two-one liter clear Nalgene
bottles were used for the ETS experiment. Depending on the lake and depth at
which each analysis was performed, 1000-2000 mL of lake water was filtered through a
Whatman 47 mm GF/F filter. The filter was folded in half (organic material inside),
placed in a glassine envelope, and stored at 0°C until analysis (<30 min). In an
ice bath, the filter was combined with 3 mL of homogenization buffer and homogenized
for 90 seconds with a glass/teflon tissue grinder. The mixture was decanted into a cone
centrifuge tube; it was centrifuged in the cold for 3 minutes, vortexed for 30 seconds,
and centrifuged for another 15 minutes. 0.5 mL of the extract was pipetted
supernatant into three 1-cm quartz cuvettes (2 replicate, 1 control) and placed
in an ice bath. The control sample was boiled for 10 minutes and cooled in an
ice bath. 1.5 mL of substrate solution and 0.5 mL of INT
solution was added to each cuvette, vortexed for 30 seconds, and incubated at 1-4°C for one hour. The
reaction was terminated in the cuvette with 0.5 mL of termination solution. The
absorbance was measured at 490 nm with a spectrophotometer. Light absorption by the sample
is directly proportional to the moles of electrons transferred through the
electron transport system (ETS). Community ETS (µmol O2 L-1 hr-1) was calculated
using the following equation:
where AbsR is the average absorbance of the replicate samples, AbsC is the
absorbance of the control sample, a is ratio of the volume of homogenization
buffer to the volume of lake water filtered, b is the ratio of the final volume
of reaction mixture in each cuvette to the volume of extract supernatant, c is
the extinction coefficient for formazan (31.8 Abs cm-1 µmol O2-1), and t is the
incubation period. Community ETS was adjusted to ambient lake temperature using
the Arrhenius equation:
where Ea is the energy of activation (15,000 cal mol-1, Q10 = 2.66), °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).
A first order relationship exists between ETS activity and respiratory capacity in aquatic microorganisms (e.g.,
Kenner and Ahmed 1975, Christiansen et al. 1980). Our studies have revealed that 44% and 56% of measured ETS
activity is from bacterioplankton and phytoplankton, respectively, in Lake Bonney (Takacs and Priscu, unpublished
data). Using these relationships, in concert with published respiration:ETS ratios (Packard 1985), we derived a
community respiration:ETS ratio of 0.61 for the water column of Lake Bonney. Individual respiration:ETS ratios for
bacteria and phytoplankton were computed as 0.513 and 0.097, respectively.
TIMING: Samples were collected from the following sites and dates: CITATIONS: Ahmed, S. I., and R. A. Kenner. 1977. A study of in vitro electron transport activity in marine
phytoplankton as a function of temperature. Journal of Phycology 13: 116-121.
Christiansen, J.P., T.G. Owens, A.H. Devol, and T. Packard. 1980. Respiration physiological state in
marine bacteria. Marine Biology 55: 267-276.
Kenner, R. A., and S. I. Ahmed. 1975. Measurements of electron transport
activities in marine environments. Marine Biology 33: 119-127.
Packard, T.T. 1985. Measurement of electron transport activity in microplankton. Advances in Aquatic
Microbiology 3: 207-261.
Priscu, J.C., and C.R. Goldman. 1984. The effect of temperature on photosynthetic and respiratory
electron transport system activity in the shallow and deep-living phytoplankton of a subalpine lake.
Freshwater Biology 14:143-155.
COMMENTS: Energy of activation is an average of values ranging from 9300-16000 cal mol-1
(Ahmed and Kenner, 1977), and is supported by an experimentally derived value of 9720 cal mol-1 in Lake
Bonney (Priscu, unpublished). If the absorbance of the kill sample is greater than the average of the
live samples, ETS 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 ETS (µmol O2 L-1 hr-1) Number Community Respiration Rate quantified by the Electron Transport System µmol oxygen / liter / hour Null 0 1 0.001 ETS 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, which are stored in the /data1/data/lakes/lakebio/ directory on
INSTAAR's Unix system. 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) to present 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 Metaets9697.rtf and Metaets9798.rtf files. The files
were called up using Microsoft Word version 6.0. Text from these files 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
none