Water masses and 200 m relative geostrophic circulation in the western Bransfield Strait region

Niller, Pearn P.; Amos, Anthony F.; Hu, Jian Hwa

doi:10.1016/0198-0149(91)90091-s

Cited by 124 publications

(55 citation statements)

References 3 publications

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“…The water characteristics of the deep water found in Wilhelmina Bay were the same as the modified UCDW found in the Gerlache Strait (Niiler et al 1991, Hofmann et al 1996. The temperature reached 0.3°C in both the inner and outer parts of the bay (Figs.…”

Section: Hydrography and Circulationmentioning

confidence: 49%

Austral fall−winter transition of mesozooplankton assemblages and krill aggregations in an embayment west of the Antarctic Peninsula

Espinasse¹,

Zhou²,

Zhu³

et al. 2012

Mar. Ecol. Prog. Ser.

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To assess krill aggregations and humpback whale Megaptera novaeangliae foraging behavior, spatial and temporal relationships between Antarctic krill Euphausia superba and zooplankton taxonomic groups were studied during an interdisciplinary cruise conducted in May and June 2009 within Wilhelmina Bay on the western side of the Antarctic Peninsula. A vesselmounted acoustic Doppler current profiler (ADCP) and a calibrated EK-60 echo sounder were used to assess circulation patterns and krill distributions in the bay, and a multiple opening and closing net (with 333 µm mesh) and environmental sensing system (MOCNESS) was used to collect live samples of mesozooplankton and krill for taxonomic composition analysis. The results from this field study complement a previous one that examined an anticyclonic bay-scale circulation of Antarctic krill. This super-aggregation of krill covered ~100 km 2 , had a concentration of 1000s of individuals m -2 and was associated with more than 306 humpback whales present in Wilhelmina Bay. Our results from the mesozooplankton study revealed that krill continuously conducted diel vertical migrations and formed aggregations in the inner bay, while the chlorophyll concentration at the surface decreased from 2.2 to 0.6 g C m −2 due to the decrease of daylight, and zooplankton concentrations increased from 0.5 to 1.5 g C m −2 probably from advective influx. Most zooplankton were distributed below 200 m while krill fed in the upper 150 m. The spatial and temporal correlations between krill and small-to medium-sized mesozooplankton imply that krill may become omnivorous when there is a lack of phytoplankton in the late austral fall. Though both phytoplankton and zooplankton biomasses contributed only small fractions of the daily ration needed for krill metabolism in Wilhelmina Bay, it is not clear what caused krill to aggregate on such a large scale, as this led to high mortality as a result of starvation and predation by whales and other top predators.

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Section: Hydrography and Circulationmentioning

confidence: 49%

Austral fall−winter transition of mesozooplankton assemblages and krill aggregations in an embayment west of the Antarctic Peninsula

Espinasse¹,

Zhou²,

Zhu³

et al. 2012

Mar. Ecol. Prog. Ser.

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“…In addition, studies have shown mesoscale variability associated with the flow on the continental shelf west of the Antarctic Peninsula (Stein, 1992), in Bransfield Strait (Niiler et al, 1991), and in Drake Passage (Joyce and Patterson, 1977;Peterson et al, 1982;Bryden, 1983;Hofmann and Whitworth, 1985;Klinck, 1985;Gille and Kelly, 1996;Moore et al, 1999). Frontal eddies found in the Drake Passage are usually observed to be 30-40 km in horizontal scale (Joyce and Patterson, 1977) and need an average time of 14 days to move through a region (Bryden and Pillsbury, 1977).…”

Section: Introductionmentioning

confidence: 99%

Transport of Antarctic krill (Euphausia superba) across the Scotia Sea. Part I: Circulation and particle tracking simulations

Fach

Klinck

2006

Deep Sea Research Part I: Oceanographic Research Papers

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The Harvard Ocean Prediction System (HOPS) is configured to simulate the circulation of the Scotia Sea and environs. This is part of a study designed to test the hypothesis that Antarctic krill (Euphausia superba) populations at South Georgia in the eastern Scotia Sea are sustained by import of individuals from upstream regions, such as the western Antarctic Peninsula. Comparison of the simulated circulation fields obtained from HOPS with observations showed good agreement. The surface circulation, particularly through the Drake Passage and across the Scotia Sea, matches observations, with its northeastward flow characterized by three high-speed fronts. Also, the Weddell Sea and the Brazil Current, and their associated transports match observations. In addition, mesoscale variability, an important component of the flow in this region, is found in the simulated circulation and the model is overall well suited to model krill transport. Drifter simulations conducted with HOPS showed that krill spawned in areas coinciding with known krill spawning sites along the west Antarctic Peninsula continental shelf can be entrained into the Southern Antarctic Circumpolar Current Front (SACCF). They are transported across the Scotia Sea to South Georgia in 10 months or less. Drifters originating on the continental shelf of the Weddell Sea can reach South Georgia as well; however, transport from this region averages about 20 months. Additional simulations show that such transport is sensitive to changes in wind stress and the location of the SACCF. The results of this study show that krill populations along the Antarctic Peninsula and the Weddell Sea are possible source populations that can provide krill to the South Georgia population. However, successful transport of krill to South Georgia is shown to depend on a multitude of factors, such as the location of the spawning area and timing of spawning, and variations in the location of the SACCF. Therefore, this study provides insight into which environmental factors control the successful transport of krill across the Scotia Sea and with it a better understanding of krill distribution in the region. r

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“…This is a slope front that is located along the southern South Shetland Island slope and that separates TBW from the waters on the shelf of the archipelago (García et al 1994). There is a baroclinic jet associated with this slope front, which is known as the Bransfield Current (BC) (Niiler et al 1991, Zhou et al 2002, Zhou et al 2006, and which circulates northeastwards along the southern South Shetland Island slope. Zhou et al (2006) suggested that this current could be viewed as a narrow western boundary current where a southwestward windinduced flow would return northeastwards as a consequence of the blockage in the topography.…”

Section: Introductionmentioning

confidence: 99%

Distribution of meroplankton communities in the Bransfield Strait, Antarctica

Vázquez¹,

Ameneiro²,

Putzeys³

et al. 2007

Mar. Ecol. Prog. Ser.

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The spatial distribution of meroplankton in Bransfield Strait, Antarctica, and its relationships with hydrographical conditions are described. Biological sampling was carried out with BIONESS sampling gear at 19 stations and at 5 depths between 10 and 300 m. The main hydrographic features were a shallow hydrographic front in the southern part of the strait that separates Transitional Zonal Water with Bellingshausen influence (TBW) from Transitional Zonal Water with Weddell influence (TWW) and a slope front, the so-called Bransfield front, along the South Shetland Islands Slope (SSI). A northeastward baroclinic jet known as the Bransfield Current (BC) originates from this slope front. The meroplankton community was very diverse and included 12 types of larvae, dominated by polychaete and echinoderm larvae. The meroplankton were more abundant closer to the SSI in the BC and decreased in number towards the Antarctic Peninsula. Polychaete larvae were found close to both shores but mainly close to the SSI in TBW; they were very sparse in the central basin, appeared again below 100 m depth in TWW, and increased in abundance in upper layers at stations between the hydrographic front and the Antarctic Peninsula, in TWW. By contrast, echinoderm larvae mainly occupied the central basin and were always associated with the upper 100 m in TBW, just above the polychaete larvae; they were almost absent from TWW. In summary, meroplanktonic larval exhibit a strong dependence on water masses, depth, and fronts.

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Water masses and 200 m relative geostrophic circulation in the western Bransfield Strait region

Cited by 124 publications

References 3 publications

Austral fall−winter transition of mesozooplankton assemblages and krill aggregations in an embayment west of the Antarctic Peninsula

Austral fall−winter transition of mesozooplankton assemblages and krill aggregations in an embayment west of the Antarctic Peninsula

Transport of Antarctic krill (Euphausia superba) across the Scotia Sea. Part I: Circulation and particle tracking simulations

Distribution of meroplankton communities in the Bransfield Strait, Antarctica

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