Factors affecting phytoplankton distribution and production in the Elephant Island area, Antarctica
During the austral summer of four years, 1990 to 1993, studies on phytoplankton were performed in the Elephant Island area as one component of the US Antarctica Marine Living Resources program. In addition to continuous measurements (temperature, salinity, chlorophyll-a, beam attenuation) made on ship's intake water, a profiling CTD-rosette unit was used to obtain water column characteristics (temperature, salinity, chlorophyll-a, attenuation of solar radiation, beam attenuation) from the surface to 750m depth and also water samples from at least 10 depths for chemical and biological analyses. The sampling grid consisted of an average of 70 stations, all of which were occupied two times each year. The Elephant Island area is a transition zone between the rich coastal areas, where phytoplankton can develop dense blooms, and pelagic waters where the phytoplankton biomass is in general very low. A frontal zone was usually found to the north of Elephant Island and over the continental slope, and high phytoplankton biomass was in general associated with this frontal region. Although the location of this frontal system showed seasonal movement in a north-south direction, it seems to be a consistent feature from year to year. There seems to be considerable year-to-year variability in physical (water temperatures and salinity) and phytoplankton characteristics within the study area, in regard to both distributional patterns in surface waters and to profile characteristics in the upper 100m of the water column. With shallow upper mixed layer depths of less than 50 m, phytoplankton can attain relatively high concentrations. Optimum light conditions for growth occurred when the mixed layer was less than 55% of the euphotic zone. As the area around Elephant Island is characterized by relatively strong and frequent winds, the depth of the upper mixed layer at many stations approached the depth of the euphotic zone, with the result that growth of phytoplankton was light limited.
- Research Organization:
- California Univ., San Diego, La Jolla, CA (United States)
- OSTI ID:
- 7010176
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANTARCTIC OCEAN
PRODUCTIVITY
PHYTOPLANKTON
GROWTH
SPATIAL DISTRIBUTION
BIOLOGICAL RADIATION EFFECTS
NEAR ULTRAVIOLET RADIATION
SEASONAL VARIATIONS
AQUATIC ORGANISMS
BIOLOGICAL EFFECTS
DISTRIBUTION
ELECTROMAGNETIC RADIATION
PLANKTON
PLANTS
RADIATION EFFECTS
RADIATIONS
SEAS
SURFACE WATERS
ULTRAVIOLET RADIATION
VARIATIONS
540310* - Environment
Aquatic- Basic Studies- (1990-)