Phytoplankton biomass, P-I relationships and primary production in the Weddell Sea, Antarctica, during the austral autumn

Dower, K. M.; Lucas, Michael I.; Phillips, Ronald C.; Dieckmann, Gerhard; Robinson, David L.

doi:10.1007/bf01876828

“…Incorporation of phytoplankton into newly formed grease ice did occur, since higher Chl a values than in the adjacent water column were found in six grease ice samples (Chl a conc. " x ¼ 0:66 lgl À1 sd= ±0.17) (Dower et al 1996).…”

Section: Nutrients and Biological Parametersmentioning

confidence: 99%

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

Krell

¹

,

Schnack-Schiel

²

,

Thomas

³

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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“…Data on the light regime were obtained from Dower et al (1996). To follow the large-scale development of sea ice cover, sea ice concentration data obtained from the National Snow and Ice Data Center (1992) were used.…”

Section: Methodsmentioning

confidence: 99%

“…This results in a maximum areal primary production in closed pack ice of 24 mgC m À2 d À1 Gleitz and Thomas (1993). Assuming that primary production in the open water declines within the observed range by Dower et al (1996) this loss can at least be partially compensated by primary production in the ice. Thus, this region may be able to sustain a primary production capacity of up to 40 mgC m À2 d À1 far into late autumn despite decreasing light conditions.…”

Section: Zooplanktonmentioning

confidence: 99%

“…Dower et al (1996) calculated primary production rates of 15.6 -41.5 mgC m À2 d À1 in the same area integrated down to the critical depth. This can be assumed to be a very conservative estimate, since they used a photocompensation irradiance of 5 lmol m À2 s À1 , whereas values of 1 lmol m À2 s À1 or even less are more appropriate (Mock and Kroon 2002).…”

Section: Zooplanktonmentioning

confidence: 99%

See 1 more Smart Citation

Population changes of Antarctic fur seals at Nyrøysa, Bouvetøya

Hofmeyr

¹

,

Krafft

²

,

Kirkman

³

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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“…The organic matter can, in some locations, accumulate as green mats on the seabed (Gutt et al, 1998;Smith and DeMaster, 2008;C.R. Smith et al, 2012), providing a high quality food supply for benthos during the autumn and winter months (Mincks et al, 2005;Isla et al, 2006b) when the pelagic input of organic matter to the benthic realm is negligible (Wefer and Fischer, 1991;Dower et al, 1996;Palanques et al, 2002;Isla et al, 2006b). During this time, the benthos continues to feed and metabolize (Barnes and Clarke, 1995;McClintic et al, 2008), at least in part due to the near-bottom currents that resuspend and redistribute material (Gardner et Winds and currents advect suspended particles from surface production for great distances (hundreds of km), determining the place where pelagic organic matter will reach the benthic realm (Dunbar et al, 1998;Diekmann and Kuhn, 1999;Isla et al, 2004;Holland and Kwok, 2012).…”

Section: Impacts Of Advection On the Antarctic Benthosmentioning

confidence: 99%

Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

Hunt

¹

,

Drinkwater

²

,

Arrigo

³

et al. 2016

Progress in Oceanography

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a b s t r a c tWe compare and contrast the ecological impacts of atmospheric and oceanic circulation patterns on polar and sub-polar marine ecosystems. Circulation patterns differ strikingly between the north and south. Meridional circulation in the north provides connections between the sub-Arctic and Arctic despite the presence of encircling continental landmasses, whereas annular circulation patterns in the south tend to isolate Antarctic surface waters from those in the north. These differences influence fundamental aspects of the polar ecosystems from the amount, thickness and duration of sea ice, to the types of organisms, and the ecology of zooplankton, fish, seabirds and marine mammals. Meridional flows in both the North Pacific and the North Atlantic oceans transport heat, nutrients, and plankton northward into the Chukchi Sea, the Barents Sea, and the seas off the west coast of Greenland. In the North Atlantic, the advected heat warms the waters of the southern Barents Sea and, with advected nutrients and plankton, supports immense biomasses of fish, seabirds and marine mammals. On the Pacific side of the Arctic, cold waters flowing northward across the northern Bering and Chukchi seas during winter and spring limit the ability of boreal fish species to take advantage of high seasonal production there. Southward flow of cold Arctic waters into sub-Arctic regions of the North Atlantic occurs mainly through Fram Strait with less through the Barents Sea and the Canadian Archipelago. In the Pacific, the transport of Arctic waters and plankton southward through Bering Strait is minimal.In the Southern Ocean, the Antarctic Circumpolar Current and its associated fronts are barriers to the southward dispersal of plankton and pelagic fishes from sub-Antarctic waters, with the consequent evolution of Antarctic zooplankton and fish species largely occurring in isolation from those to the north. The Antarctic Circumpolar Current also disperses biota throughout the Southern Ocean, and as a result, the biota tends to be similar within a given broad latitudinal band. South of the Southern Boundary of the ACC, there is a large-scale divergence that brings nutrient-rich water to the surface. This divergence, along with more localized upwelling regions and deep vertical convection in winter, generates elevated nutrient levels throughout the Antarctic at the end of austral winter. However, such elevated nutrient levels do not support elevated phytoplankton productivity through the entire Southern Ocean, as iron concentrations are rapidly removed to limiting levels by spring blooms in deep waters. However, coastal http://dx

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Phytoplankton biomass, P-I relationships and primary production in the Weddell Sea, Antarctica, during the austral autumn

Cited by 9 publications

References 57 publications

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

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

Population changes of Antarctic fur seals at Nyrøysa, Bouvetøya

Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

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