Acceptance and utilization of LTER data requires that:
FILE NAME: PRINCIPAL INVESTIGATOR: OTHERS: KEYWORDS: lake, flagellate, nanoflagellate, heterotrophic, phototrophic, bacteria, ciliate, Antarctica, limnology, microzooplankton
ABSTRACT: In conjunction with the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, lakes
were monitored for microzooplankton by a team based out of the University of Nottingham (led by Johanna Laybourn-Parry). This dataset
shows numbers of ciliates, bacteria, heterotrophic nanoflagellates, and phototrophic nanoflagellates found at various depths in Lake
Fryxell.
VARIABLES: location, date, depth, #ciliates, #Askenasia, #S_Monodinium, #L_Monodinium,
#Strombidium, #Vorticella, #Bursaria, #Sphaerophyra, #bacteria, #HNAN, #PNAN
RESEARCH LOCATION: Lake Fryxell (77°37' S, 163°07' E) has an area of 7
km2 and a maximum depth of 19 m. The average depth is 9 m and therefore the
lake has an extensive littoral zone (above a depth of 9 m) where microbial mats are
abundant. The lake is chemically stratified with an oxic zone extending down to 9.5 m. A
distinct oxycline is present between 7.5 and 9.5 m below which the waters are anoxic. The
lake is permanently stratified. The upper waters are low in nutrients
(NH4+, NO2-, NO3-, and
PO4-) but ammonium and soluble reactive phosphorus increase below
the oxycline. Thus the upper waters experience a combination of low temperatures,
nutrient limitation and highly attenuated light because of ice cover.
METHODS: Water was collected using either a Kemmerer bottle or a Van Dorn
sampler lowered through a hole in the 4-m-thick ice with a Jiffy-drill in January 1992
and in January 1994 at a center station (depth 18.5 m). Samples were taken at 1-m
intervals down to 12 m into the anoxic zone. In 1992, 250-ml subsamples were fixed in
Lugol's iodine for the analysis of ciliates, and other aliquots fixed in glutaraldehyde
for bacterial counts. In 1994, 1.1-l samples were fixed in buffered glutaraldehyde for
protozoological and bacterial analysis. These were kept refrigerated in the dark and
flown to Australia or New Zealand for immediate analysis. Both fixatives are regarded
as reliable for protistan analysis provided samples are analysed within a few months of
collection. However, in our experience while Lugol's iodine is considered best for
preserving abundance, it does cause more cell distortion of some species than
glutaraldehyde, which gives better preservation of ciliates in freshwater samples. One
liter of water from each depth was preserved in Lugol's iodine for phytoplankton counts.
Temperature was measured with a (YSI) Yellow Springs Instruments 54 meter and probe, and
conductivity with a Radiometer Conductivity meter.
Ten milliliters of the buffered glutaraldehyde-fixed material was stained with DAPI, and
filtered onto a 0.2-µm black polycarbonate filter, and bacterial numbers were counted
under epifluorescence microscopy using UV excitation. Fifty milliliters was stained with
DAPI, filtered onto 1.0-µm polycarbonate filters and viewed under epifluorescence
microscopy using both blue and UV filters to determine heterotrophic and autotrophic
flagellate abundances. The larger protozooplankton in each 1-l sample of
glutaraldehyde-fixed water were concentrated by settling, stained with bromophenol blue
and counted in Sedgewick-Rafter counting chambers under DIC microscopy at x320. Detailed
analysis was undertaken under higher magnification using both DIC and phase microscopy.
For phytoplankton analysis between 5 and 50 ml was subsampled. These phytoplankton were
settled and enumerated using the inverted microscope method of Utermohl.
TIMING: Samples were gathered in January 1992 and January 1994.
CITATIONS: Laybourn-Parry, Johanna, Mark R. James, Diane M.
McKnight, John Priscu, Sarah A. Spaulding, and Russell Shiel. 1997. The
microbial plankton of Lake Fryxell, southern Victoria Land, Antarctica during
the summers of 1992 and 1994. Polar Biology. 17: 54-61.
COMMENTS:
STATUS: Restricted Access (Type IV).
VARIABLE DESCRIPTION:
VARIABLE TYPE DESCRIPTION UNITS MISSING VALUE INDICATOR MINIMUM MAXIMUM PRECISION Location Text Name of lake where measurement was made none Required entry n/a n/a n/a Date Date Date on which sample was gathered mmm-yyyy Required entry Jan-1992 Jan-1999 mm Depth (m) Number Depth at which sample was drawn from lake meters Required entry 1 12 1 #Ciliates Number Number of ciliates counted/liter of lake water # / liter Required entry n/a n/a n/a #Askenasia Number Number of Askenasia organisms counted/liter of lake water # / liter Required entry 0 n/a 1 #S_Monodinium Number Number of S_Monodinium organisms counted/liter of lake water # / liter Required entry 0 n/a 1 #L_Monodinium Number Number of L_Monodinium organisms counted/liter of lake water # / liter Required entry 0 n/a 1 #Strombidium Number Number of Strombidium organisms counted/liter of lake water # / liter Required entry 0 n/a 1 #Vorticella Number Number of Vorticella organisms counted/liter of lake water # / liter Required entry 0 n/a 1 #Bursaria Number Number of Bursaria organisms counted/liter of lake water # / liter Required entry 0 n/a 1 #Sphaerophyra Number Number of Sphaerophyra organisms counted/liter of lake water # / liter Required entry 0 n/a 1 #Bacteria Number Number of bacteria x 108 counted/liter of lake water # x 108/ liter Required entry 0 n/a 1 #HNAN Number Number of heterotrophic nanoflagellates x 105 counted/liter of lake water # x 105/ liter Required entry 0 n/a 1 #PNAN Number Number of phototrophic nanoflagellates x 105 counted/liter of lake water # x 105/ liter Required entry 0 n/a 1 LOG: Data for this file was submitted by Johanna Laybourn-Parry to
the data manager at INSTAAR on October 21, 1998. Files were sent via e-mail as well
as a hard copy. The original version of the file is stored on the Unix system in
"/data1/data/lakes/plankton/laybourn-parry/Fryxell". Upon arrival at INSTAAR, the
data manager reformatted the file to present it in a relational mode. This
was done using Microsoft Access. It was then exported in comma delimited ascii and
MS-DOS text format to present on the web. Links to these files are provided above.
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.