Phytoplankton production and biomass at frontal zones in the Atlantic sector of the Southern Ocean

Laubscher, R. K.; Perissinotto, Renzo; McQuaid, Christopher D.

doi:10.1007/bf00233138

Cited by 188 publications

(97 citation statements)

References 50 publications

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“…However, the low phaeopigment concentrations (0.24 mg m-3, 1 3 % of the TPP), and the coincidence of high chl a concentrations with distinctly depleted nutrient levels, suggest active growth. Laubscher et al (1993) reported a close association between chlorophyll and silicate concentrations in the vicinity of the PF, and that the main controlling factor of phytoplankton growth appeared to be the spatial covariance between silicate levels and water column stability. They commented that of all the macronutrients only silicate may be present at limiting concentrations north of the PF, and that productivity may be favoured at the southern edge of the PF where higher concentrations are available.…”

Section: The Polar Front Bloommentioning

confidence: 86%

Substantial open-ocean phytoplankton blooms to the north of South Georgia, South Atlantic, during summer

Whitehouse¹,

Priddle²,

Trathan³

et al. 1996

Mar. Ecol. Prog. Ser.

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Substantial open-ocean phytoplankton blooms in the Antarctic Zone to the northwest of South Georgia, South Atlantic are described. Chlorophyll a , nutrient and physical oceanography data, collected between 2 and 5 January 1994 and again 1 mo later between 2 and 4 February along a 450 km transect comprising 14 stations, are presented. The transect crossed the Subantarct~c and the Polar Front During the January transect survey, in 2 locations to the south of the Polar Front, average surface mixed-layer chlorophyll a concentrations were >8 and > l 3 mg m-.', and were associated wlth silicate, nitrate and phosphate depletions (<2.0, < l 1.0 and 1.0 mm01 m-"respectively), and nitrite and ammonium enhancement (>0.3 and >1.4 mm01 m-3 respectively). O n e of the phytoplankton blooms was associated wlth the nearby Polar Front, but the origin of a bloom further south, well w~t h l n the Antarctic Zone, was not clear. Phytoplankton production predicted by nutrient drawdown was far greater than the observed biomass on both surveys. If a common Antarctic Zone origin is accepted for the southern bloom, a dechne in biomass of -2.7 m01 C m-2 occurred in the upper 50 m of the water column between the 2 surveys, which cannot be accounted for by zooplankton grazlng. If the bloom had originated in Subantarctic water advected to the south of the Polar Front, in~tial nutrient concentrat~ons would have been lower and consequently predicted production was closer to the observed biomass values. Nevertheless, the area may be one of intense but local carbon export.

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Section: The Polar Front Bloommentioning

confidence: 86%

Substantial open-ocean phytoplankton blooms to the north of South Georgia, South Atlantic, during summer

Whitehouse¹,

Priddle²,

Trathan³

et al. 1996

Mar. Ecol. Prog. Ser.

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“…Whereas this seems to be correct for coastal regions, primary production in oceanic areas of the Southern Ocean seems to be closely linked to the occurrence of fronts (Laubscher et al 1993;Smetacek et al 1997). In the area of this investigation both presumptions are important, since it is both a frontal region and in close proximity to the coast and edge of the ice shelf, respectively.…”

Section: Introductionmentioning

confidence: 97%

Phytoplankton dynamics in relation to hydrography, nutrients and zooplankton at the onset of sea ice formation in the eastern Weddell Sea (Antarctica)

et al. 2005

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The quantitative and qualitative distribution of phytoplankton was investigated along five NorthSouth transects in the eastern Weddell Sea during the transition from late autumn to winter. Relationships with the regional hydrography, progressing sea ice coverage, nutrient distribution and zooplankton are discussed and compared with data from other seasons. To the north of the Antarctic Slope Front (ASF) a remnant temperature minimum layer was found above the primary pycnocline throughout summer. Surface waters had not entirely acquired typical winter characteristics. While temperature was already in the winter range, this was not the case for salinity. Highest biomass of phytoplankton, with the exception of the first transect, was found in the region adjoining the ASF to the north. Absolute chlorophyll a (Chl a) concentrations dropped from 0.35 to 0.19 lg l À1 . Nutrient pools exhibited a replenishing tendency. Ammonium concentrations were high (0.75-2 lmol l À1 ), indicating extensive heterotrophic activity. The phytoplankton in the ASF region was dominated by nanoflagellates, particularly Phaeocystis spp.. North of the ASF the abundance of diatoms increased, with Fragilariopsis spp., F. cylindrus and Thalassiosira spp. dominating. Community structure varied both due to hydrographical conditions and the advancing ice edge. The phytoplankton assemblage formed during late autumn were very similar to the ones found in early spring. A POC/PON ratio close to Redfield, decreasing POC concentration and a high phaeophytin/ Chl a ratio, as well as a high abundance of mesozooplankton indicated that a strong grazing pressure was exerted on the phytoplankton community. A comparison between primary production (PP) in the water column and the sea ice showed a shift of the major portion of PP into the ice during the period of investigation.

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“…Phytoplankton blooms associated with the PF are typically dominated by larger diatom species (Lutjeharms et al, 1985;Laubscher et al, 1993;Dafner and Mordosova, 1994;Jochem et al, 1995;de Baar et al, 1995;Smetacek et al, 1997;Brown and Landry, 2001). Smaller phytoplankton species experience strong grazing pressure by microzooplankton.…”

Section: Introductionmentioning

confidence: 99%

Surface chlorophyll concentrations in relation to the Antarctic Polar Front: seasonal and spatial patterns from satellite observations

Moore

Abbott

2002

Journal of Marine Systems

150

118

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Satellite ocean color data from the Sea Viewing Wide Field of View Sensor (SeaWiFS) are used to investigate phytoplankton bloom dynamics at the Antarctic Polar Front (PF). Satellite sea surface temperature (SST) data are used to map the location of the PF at weekly timescales. Elevated chlorophyll within the PF often appears as a narrow band that occupies only a portion of the SST gradient across the PF. Phytoplankton blooms within the PF occur most frequently during the month of December and are unevenly distributed within the Southern Ocean. Elevated chlorophyll concentrations at the PF are most frequently observed where the current is interacting with large topographic features.Mesoscale physical processes, including meander-induced upwelling and increased eddy mixing, where the PF encounters large topographic features likely leads to increased nutrient flux to surface waters in these regions. The highest mean chlorophyll values associated with the PF occur where the front comes into contact with relatively shallow waters along the North Scotia Ridge and at Kerguelen Plateau. Iron input from sedimentary sources likely plays an important role in these regions.Over seasonal timescales it appears likely that light-limitation prevents phytoplankton blooms at the PF during winter and spring months. PF blooms are observed most commonly during December when surface radiation peaks and mixed layer depths are rapidly shoaling. Even during December, when the light regime would seem to be favorable, PF blooms are largely restricted to regions where enhanced nutrient fluxes to surface waters due to frontal dynamics are likely. During late summer, nutrient limitation due to depletion of iron and possibly silicate largely prevent blooms at the PF. In the fall, deepening mixed layers would provide some relief from nutrient limitation but likely lead again to light-limitation of growth rates and the prevention of blooms. D

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Phytoplankton production and biomass at frontal zones in the Atlantic sector of the Southern Ocean

Cited by 188 publications

References 50 publications

Substantial open-ocean phytoplankton blooms to the north of South Georgia, South Atlantic, during summer

Substantial open-ocean phytoplankton blooms to the north of South Georgia, South Atlantic, during summer

Phytoplankton dynamics in relation to hydrography, nutrients and zooplankton at the onset of sea ice formation in the eastern Weddell Sea (Antarctica)

Surface chlorophyll concentrations in relation to the Antarctic Polar Front: seasonal and spatial patterns from satellite observations

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