Dynamics of nutrients and phytoplankton, and fluxes of carbon, nitrogen and silicon in the Antarctic Ocean

Tr�guer, Paul; Jacques, Guy

doi:10.1007/bf00238255

Cited by 239 publications

(97 citation statements)

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“…These rate are 50% or more higher than other modelbased or measured rates of production in the APF, and up to two or more times greater than other estimates in the SIZ (Wefer and Fischer, 1991;Tr! eguer and Jacques, 1992;Qu!…”

mentioning

confidence: 58%

The effect of marginal ice-edge dynamics on production and export in the Southern Ocean along 170°W

Buesseler

Barber

Dickson

et al. 2003

Deep Sea Research Part II: Topical Studies in Oceanography

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We present a synthesis of the rates of gross, new, net and primary production along with particulate organic carbon (POC) flux at 100 m from four cruises along 1701W in the Southern Ocean. Concurrent satellite pigment data, a primary productivity model, and a nitrate mass balance are used to extrapolate daily production estimates in space and time to seasonal and annual rates. From this analysis, we gain a better understanding of the timing, magnitude and impact of the phytoplankton blooms in this region. One of the dominant features with respect to plankton biomass is the association of high chlorophyll levels with the retreat of the sea ice which begins in October just south of the Polar Front. Our primary production model and satellite pigment data suggest higher production and flux levels characterize the marginal ice zone than previous estimates. Elevated rates of new production in ice impacted regions are restricted to relatively short periods following retreat of the ice edge. Export is found to lag the onset of production by up to 1 month. The ratio of POC flux at 100 m to primary production when averaged over the entire season is quite high, increasing from 15% to 25% in the Subantarctic zones to 35-40% near the Polar Front and as high as 50-65% in the southernmost stations, just north of the Ross Sea gyre. Comparisons of phytoplankton community structure and Fe stress indicators suggest that blooms at the Polar Front are initially dominated by large centric diatoms, but are replaced by smaller pennate diatom and non-diatom species as Fe levels decrease. Further south, where Fe levels are never as high and large diatoms are not found, we still observe relatively high biomass and elevated production rates and POC fluxes during the short growing season. r

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mentioning

confidence: 58%

The effect of marginal ice-edge dynamics on production and export in the Southern Ocean along 170°W

Buesseler

Barber

Dickson

et al. 2003

Deep Sea Research Part II: Topical Studies in Oceanography

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“…High phytoplankton concentrations ð41:0 mg m À3 Þ are found below 60 m in the study area (El-Sayed and Weber, 1982;Bianchi et al, 1992;Tre´guer and Jacques, 1992;Smith et al, 1996;Whitehouse et al, 1996). Deep chlorophyll maxima have been observed mostly in the summer/fall in the Scotia Sea (El-Sayed and Weber, 1982), western Antarctic Peninsula (Bianchi et al, 1992;Tre´guer and Jacques, 1992;Smith et al, 1996) and near South Georgia (Whitehouse et al, 1996); they are not observed during winter/spring (El-Sayed and Weber, 1982;Smith et al, 1996).…”

Section: Deep Chlorophyll Maximummentioning

confidence: 86%

“…Deep chlorophyll maxima have been observed mostly in the summer/fall in the Scotia Sea (El-Sayed and Weber, 1982), western Antarctic Peninsula (Bianchi et al, 1992;Tre´guer and Jacques, 1992;Smith et al, 1996) and near South Georgia (Whitehouse et al, 1996); they are not observed during winter/spring (El-Sayed and Weber, 1982;Smith et al, 1996). Due to limited data this feature was not included in this modeling approach, although it may well be one additional food source available to krill in summer.…”

Section: Deep Chlorophyll Maximummentioning

confidence: 99%

Transport of Antarctic krill (Euphausia superba) across the Scotia Sea. Part II: Krill growth and survival

Fach

Hofmann

Murphy

2006

Deep Sea Research Part I: Oceanographic Research Papers

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A time-dependent, size-structured, physiologically based krill growth model was used in conjunction with a circulation model to test the hypothesis that Antarctic krill (Euphausia superba) populations at South Georgia are sustained by import of individuals from upstream regions. Surface phytoplankton concentrations along the simulated drifter trajectories were extracted from historical Coastal Zone Color Scanner (CZCS) measurements and sea ice biota concentrations were calculated from sea ice concentration and extent extracted along drifter trajectories from Special Sensor Microwave/ Imager measurements. As additional food sources, a time series of heterotrophic food was constructed from historical data, and time series of detritus concentrations were calculated using phytoplankton concentrations extracted from CZCS measurements together with measured particulate organic carbon to chlorophyll a ratios. These food resources along specified drifter trajectories were then input to the krill growth model to determine the size and viability of krill during transport from the source region to South Georgia. The krill growth model simulations showed that no single food source can support continuous growth of krill during the 58-306 days needed for transport to South Georgia. However, under the current assumptions results indicate that combinations of food sources during the transport time enhanced krill survival, with heterotrophic food and detritus being particularly important during periods of low phytoplankton concentrations. The growth model simulations also showed that larval and juvenile krill originating along the western Antarctic Peninsula can grow to 1þ (14-36 mm) and 2þ (26-45 mm) age and size classes observed at South Georgia during the time needed for transport to this region. Krill originating in the Weddell Sea need 20 months for transport, which allows retention in a potentially high food environment, provided by sea ice, for almost 1 year. Krill then complete transport to South Georgia in the following year and larval and juvenile krill grow to 2þ (26-45 mm) and 3þ (35-60 mm) age and size classes during transport. The results of this study show that the successful transport of krill to South Georgia depends on a multitude of factors, such as the location of the spawning area and timing of spawning, food concentrations during transport, predation, and variations in the location of the Southern Antarctic Circumpolar Current Front (SACCF) and in sea ice extent. r

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“…The continental slope is defined by steep, rapidly deepening bathymetry between the shelf and the deep sea (750-3000 m water depth). With regard to Antarctic marine ecosystem types defined by Treguer and Jacques (1992), BS can be attributed to the 'Coastal and Continental Shelf Zone' and the DP to the 'Continental Shelf Edge and Slope', consistent with respective bathymetry, ocean dynamics and water masses (Ducklow et al 2007). …”

Section: Methodsmentioning

confidence: 93%

Horizontal niche partitioning of humpback and fin whales around the West Antarctic Peninsula: evidence from a concurrent whale and krill survey

et al. 2016

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A dedicated aerial cetacean survey was conducted concurrently to a standardised net trawl survey for krill in order to investigate distribution patterns of large whales and different krill species and to investigate relationships of these. Distance sampling data were used to produce density surface models for humpback (Megaptera novaeangliae) and fin whales (Balaenoptera physalus) around the West Antarctic Peninsula (WAP). Abundance for both species was estimated over two strata in the Bransfield Strait and Drake Passage. Distinct distribution patterns suggest horizontal niche partitioning of the two whale species around the WAP, with fin whales aggregating at the shelf edge of the South Shetland Islands in the Drake Passage and humpback whales in the Bransfield Strait. Krill biomass estimated from the concurrent krill survey was used along with CTD data from the same expedition, bathymetric parameters and satellite data on chlorophyll-a and ice concentration to model krill distribution. Comparisons of the predicted distributions of both whale species with the predicted distributions of Euphausia superba, Euphausia crystallorophias and Thysanoessa macrura suggest a complex relationship rather than a straightforward correlation between krill and whales. However, results indicate that fin whales were feeding in an area dominated by T. macrura, while humpback whales were found in areas of higher E. superba biomass. Our results provide abundance estimates for humpback whales and, for the first time, fin whales in the WAP and contribute important information on feeding ecology and habitat use of these two species in the Southern Ocean.

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Dynamics of nutrients and phytoplankton, and fluxes of carbon, nitrogen and silicon in the Antarctic Ocean

Cited by 239 publications

References 0 publications

The effect of marginal ice-edge dynamics on production and export in the Southern Ocean along 170°W

The effect of marginal ice-edge dynamics on production and export in the Southern Ocean along 170°W

Transport of Antarctic krill (Euphausia superba) across the Scotia Sea. Part II: Krill growth and survival

Horizontal niche partitioning of humpback and fin whales around the West Antarctic Peninsula: evidence from a concurrent whale and krill survey

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