Acceptance and utilization of LTER data requires that:
FILE NAME: PRINCIPAL INVESTIGATOR: OTHERS:
KEYWORDS: lake, limnology, phytoplankton, density, phylum
ABSTRACT: Phytoplankton were collected over four austral summers (1991-92
through 1994-95) to examine seasonal and annual fluctuation in species
composition and biovolume in Lakes Fryxell, Hoare, West Lake Bonney, and East
Lake Bonney. All of these lakes are perennially ice-covered lakes located in the
Dry Valleys of South Victoria Land, Antarctica. The phytoplankton consisted primarily of
cryptophyte and chlorophyte flagellates, and filamentous cyanobacteria. Some common
taxa were vertically stratified (Oscillatoria limnetica, Phormidium angustissimum,
Pyramimonas sp., Oscillatoria sp.), while others showed no distinct vertical
stratification (Chlamydomonas subcaudata, Cryptomonas sp.). The stratification of
the phytoplankton reflects the gradients of nutrients and light, and the stability
of the water column.
VARIABLES: limno run, location name, location code, date, depth (m), phylum,
species, density (cells/mL), file name
RESEARCH LOCATION: Lake Fryxell, Lake Bonney and Lake Hoare are all
located in Taylor Valley, South Victoria Land, Antarctica. Lake Fryxell (77 37'S, 163 07'E)
is at an elevation of 16 m above sea level. It has an area of 7 km2 and a maximum
depth of 19 m. The perennial ice cover has a thickness of ~4.5 m. Sampling was
conducted at a center station, where the depth was 18.5 m. Lake Bonney is roughly
6.0 kilometers in length and up tp 900 meters wide. It is comprised of a larger
east basin and a smaller west basin. Samples were gathered from both basins. The
east lobe has a perennial ice cover thickness of ~3.8 m; the west lobe has a perennial
ice cover thickness of ~3.7 m. Lake Hoare occupies a narrower portion of the valley,
is dammed by the Canada Glacier, and would drain almost completely without this dam.
It is roughly 4.2 kilometers long and up to 1100 meters wide. There are a number
of islands which may be related to an old terminal moraine of Canada Glacier. The
perennial ice cover thickness is ~4.0 m.
METHODS: Discrete samples for phytoplankton enumeration were collected from the
oxygenated portion of the water column (below the bottom of the ice to a depth
of 10 m) at 0.5 m intervals. Sampling was done primarily between the hours of 14:00 and
20:00 (during the austral summer, the illuminated period is 24 h/day) by either peristaltic
pump or Kemmerer bottle. Samples were collected in 1 l bottles and preserved
immediately with Lugon's solution (American Public Health Association, 1985).
Identification and counts were made with an inverted microscope by the method of
Utermohl (1958). At least 100 individuals of the most numerous algae were
counted per sample at 100x magnification. The total number of individuals
counted was dependent on the number of taxa, but ranged between 200 and 500.
Counting error ranged between 13 and 26%, depending on species. Algal species
identifications were made using Geitler (1932), Seaburg et al. (1979) and
Prescott (1962). Cell volumes were estimated for dominant taxa by measuring
cell dimensions of 50-100 individuals and using closest geometric formulas of
additional dates and depths to determine changes in cell volume over time. For
rare taxa, volume estimates were made from fewer cell measurements.
Primary productivity was measured using the method of Strickland and Parsons
(1972). In situ 24 h incubations were made in triplicate 300 ml light and
duplicate 300 ml dark bottles with Na14CO3 (3 uCi per 300 ml, New England Nuclear).
Following 24 h incubation, samples were well shaken and filtered through Whatman
GF/F filters in the dark. The filters were placed in scintillation vials and
acidified with 1 ml of 5% acetic acid in methanol to remove [C14] carbonates.
The [C14] fixed by biological activity was determined in Aquasol (New England
Nuclear) by liquid scintillation.
Samples for nitrate and orthophosphate were frozen within several hours of
collection, later filtered through 0.45 um Nucleopore filters and analyzed by
air-segmented continuous-flow absorption spectrophotometry (Alpkem RFA-300)
(Antweiler et al., 1993). Chlorophyll extractions were made in 95% ethanol
(Jesperson and Christoffersen, 1987) and measured in a Turner Designs Model 10
Fluorometer.
TIMING: Samples were gathered from the following locations and dates: CITATIONS: Spaulding, Sarah A, Diane M. McKnight, Richard L. Smith and Richard Dufford.
1994. Phytoplankton population dynamics in perennially ice-covered Lake
Fryxell, Antarctica. Journal of Plankton Research. Vol.16 no.5 pp.527-541.
COMMENTS:
STATUS: Public Access (Type 1).
VARIABLE DESCRIPTION: LOG:
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.
VARIABLE TYPE UNITS MISSING VALUE INDICATOR MINIMUM MAXIMUM PRECISION
Location String None Required entry n/a n/a n/a
Latitude String DD-MM-SS South Required entry n/a n/a n/a
Longitude String DDD-MM-SS East Required entry n/a n/a n/a
Description String None Null n/a n/a n/a