Summer vs Winter Phytoplankton Presence 1989-1991



Using automated overwinter sampling devices, we collected preserved phytoplankton samples from multiple depths in Lake Fryxell, a permanently ice-covered lake in southern Victoria Land, Antarctica. Photosynthetic algae were maintained in a stable water column throughout winter darkness. The algal taxa overwintered in different ways in a species-specific manner. Typical vegetative cells were the most abundant form for all species found in the water column. Populations of one chlorophyte, Stichococcus sp., were observed in winter, but the species was absent in both summers. Two cryptophyte species were more abundant in winter than in summer. We interpret the increase in algal population size as evidence of heterotrophic growth in winter and of mixotrophic behavior throughout the year. For two chlorophyte species, some portion of the population had a distinctive morphology, for example, many Chlamydomonas subcaudata Wille. formed akinetes, whereas many Chlorella sp. contained a large amount of starch or other storage material. During winter, vegetative cells of the most abundant cyanobacterial species, Phormidium angustissimum West et West, occurred at the depth of the summer maximum and at depths below the oxycline. The presence of P. angustissimum below the oxycline may have resulted from the accumulation of settling cells at a depth with a greater density. In contrast to the settling of P. angustissimum, the general absence of the other algal species below the oxycline in winter indicated that these species were not influenced by overwinter settling.

Date Range: 

January 1, 1989 to December 31, 1991
Data Citation
Mcknight, D.M. 2014. Summer vs Winter Phytoplankton Presence 1989-1991. Environmental Data Initiative. DOI: 10.6073/pasta/e9d17c42840bc30988a18d14b3e4d3a7. Dataset accessed 12 June 2021.


formerly known as phytprsn. Find details here about the measurements metadata - units used, codes, etc.

Variables (click to expand): 

  • Label:
  • Definition: Table Identifier
  • Type: Nominal
  • Missing values: None specified
  • Label: Phylum
  • Definition: Phylum for the specimens observed
  • Type: Code list
  • Codes:
    • Bacillariophyta = Bacillariophyta
    • Chlorophyta = Chlorophyta
    • Chrysophyta = Chrysophyta
    • Cyanophyta = Cyanophyta
    • Cryptophyta = Cryptophyta
  • Missing values: None specified
  • Label:
  • Definition: Species of the organism
  • Type: Nominal
  • Missing values: None specified
  • Label:
  • Definition: The place or location where samples were taken. In this case, it is on Lake Fryxell.
  • Type: Nominal
  • Missing values: None specified
Time Period
  • Label:
  • Definition: The time period when the organism presence was monitored
  • Type: Code list
  • Codes:
    • Winter 1989 = The austral winter of 1989
    • Summer 1990 = The austral summer of 1990
    • Winter 1990 = The austral winter of 1990
    • Summer 1991 = The austral summer of 1991
  • Missing values: None specified
  • Label:
  • Definition: boolean presence, a 0 indicates the organism was not detected at the time period, a 1 indicates the organism presence detected.
  • Type: Code list
  • Codes:
    • FALSE = absent
    • TRUE = present
  • Missing values: None specified


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