Distribution and abundance of Antarctic krill (Euphausia superba) off East Antarctica (80–150°E) during the Austral summer of 1995/1996

Pauly, Tim; Nicol, Stephen; Higginbottom, Ian; Hosie, Graham W.; Kitchener, John A.

doi:10.1016/s0967-0645(00)00032-1

Cited by 70 publications

(26 citation statements)

References 18 publications

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“…As has been observed previously in this region and elsewhere, the size distribution of krill aggregations was strongly dominated by many small, low-biomass aggregations Pauly et al, 2000). The majority of overall biomass, however, was accounted for by the small number of very large aggregations.…”

Section: Krill Distributionsupporting

confidence: 82%

“…Statistical analysis of environmental influences on krill distribution also revealed a consistent negative association with the distance to nearest land. Lascara et al (1999) At the finer scales of 0.5 km acoustic integration intervals, Trathan et al (2003) found no consistent effect of temperature, and instead bathymetry was the only consistent predictor of abundance, with abundance greatest near the shelf-break (similar to the qualitative summertime observations of Ichii et al, 1998 andPauly et al, 2000). Krill in summer may be associated with the shelf break in order to be positioned above CDW, due to the latter being favorable to successful spawning (Hofmann et al, 1992).…”

Section: 42c Environmental Associationsmentioning

confidence: 80%

“…This assumption would lead to overestimates of Antarctic krill biomass in the present study area, at least. In other instances, visual scrutiny and/or some degree of trawling has been employed to distinguish Antarctic krill patches from other sources of volume backscattering such as myctophid fishes (e.g., Sahrhage, 1989;Sprong and Schalk, 1992;Murray et al, 1995;Pauly et al, 2000), but this approach discards a great deal of potential information on the abundance of taxa other than krill.…”

Section: 43c Implications To Acoustic Surveysmentioning

confidence: 99%

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Distribution, patchiness, and behavior of Antarctic zooplankton, assessed using multi-frequency acoustic techniques

Lawson¹

2006

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The physical and biological forces that drive zooplankton distribution and patchiness in an antarctic continental shelf region were examined, with particular emphasis on the Antarctic krill, Euphausia superba. This was accomplished by the application of acoustic, video, and environmental sensors during surveys of the region in and around Marguerite Bay, west of the Antarctic Peninsula, in the falls and winters of 2001 and 2002. An important component of the research involved the development and verification of methods for extracting estimates of ecologically-meaningful quantities from measurements of scattered sound. The distribution of acoustic volume backscattering at the single frequency of 120 kHz was first examined as an index of the overall biomass of zooplankton. Distinct spatial and seasonal patterns were observed that coincided with advective features. Improved parameterization was then achieved for a theoretical model of Antarctic krill target strength, the quantity necessary in scaling measurements of scattered sound to estimates of abundance, through direct measurement of all necessary model parameters for krill sampled in the study region and survey period. Methods were developed for identifying and delineating krill aggregations, allowing the distribution of krill to be distinguished from that of the overall zooplankton community. Additional methods were developed and verified for estimating the length, abundance, and biomass of krill in each acoustically-identified aggregation. These methods were applied to multifrequency acoustic survey data, demonstrating strong seasonal, inter-annual, and spatial variability in the distribution of krill biomass. Highest biomass was consistently associated with regions close to land where temperatures at depth were cool. Finally, the morphology, internal structure, and vertical position of individual krill aggregations were examined. The observed patterns of variability in aggregation characteristics between day and night, regions of high versus low food availability, and in the presence or absence of predators, together reinforced the conclusion that aggregation and diel vertical migration represent strategies to avoid visual predators, while also allowing the krill access to shallowly-distributed food resources. The various findings of this work have important implications to the fields of zooplankton acoustics and Antarctic krill ecology, especially in relation to the interactions of the krill with its predators.

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Section: Krill Distributionsupporting

confidence: 82%

Section: 42c Environmental Associationsmentioning

confidence: 80%

Section: 43c Implications To Acoustic Surveysmentioning

confidence: 99%

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Distribution, patchiness, and behavior of Antarctic zooplankton, assessed using multi-frequency acoustic techniques

Lawson¹

2006

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“…The distribution and abundance of krill Euphausia superba and other zooplankton in the Mawson region is patchy and highly variable over short temporal and small spatial scales in summer (Hosie et al 1988, Hosie et al 1997, Pauly et al 2000. Although some local foraging took place, the penguins in this study concentrated much of their guard and crèche stage foraging activity along the continental shelf break where E. superba aggregate in greatest concentrations (Higginbottom et al 1988, Hosie et al 1988, and large krill predominate in summer (Lascara et al 1999, Salihoglu et al 2001.…”

Section: Foraging Ranges During Breeding and Environmental Constraintsmentioning

confidence: 79%

Environmental conditions and life history constraints determine foraging range in breeding Adélie penguins

Clarke¹,

Emmerson²,

Otáhal³

2006

Mar. Ecol. Prog. Ser.

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Foraging movements of Adélie penguins are constrained both by environmental conditions (e.g. sea ice cover) and life history factors (e.g. regular offspring provisioning). We describe within season changes in foraging range, trip duration and body condition of Adélie penguins nesting at Béchervaise Island, East Antarctica, in the context of these constraints. Penguins were satellite tracked over multiple seasons during the incubation, guard, crèche and pre-moult phases of their annual cycle. They ranged farthest during incubation when sea ice was extensive and shortest during the guard stage when chicks were small and sea ice limited in extent. Prior to their annual moult the birds foraged hundreds of kilometres to the west and east of their breeding sites. A recurrent polynya facilitated access to the sea early in the season when ice cover was extensive. Kernel analyses showed that penguins foraged most intensively close to the colony, along submarine canyons and at the continental shelf break. Increases in foraging range, as the chick rearing period progressed, were consistent with changing energy requirements of adults and chicks and likely intraspecific competition. Whilst provisioning their offspring, penguins adopted a variable combination of time minimising and food maximising foraging behaviour in which choice of foraging rule was determined largely by adult body condition.

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“…Within the Weddell Gyre, the ASF and CC act to precondition shelf waters for the formation of Antarctic Bottom Water (Fahrbach et al 1992), melt the underside of ice shelves (Fahrbach et al 1994), and transport Antarctic krill and nutrients (Pauly et al 2000). Near the tip of the Antarctic Peninsula, though, the ASF and CC encounter complex topography and come into confluence with the ACC in the region over and surrounding the South Scotia Ridge known as the Weddell Scotia Confluence (Patterson and Sievers 1980).…”

Section: Introductionmentioning

confidence: 99%

Surface Circulation at the Tip of the Antarctic Peninsula from Drifters

Thompson

Heywood

Thorpe

et al. 2009

Journal of Physical Oceanography

113

126

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An array of 40 surface drifters, drogued at 15-m depth, was deployed in February 2007 to the east of the tip of the Antarctic Peninsula as part of the Antarctic Drifter Experiment: Links to Isobaths and Ecosystems (ADELIE) project. Data obtained from these drifters and from a select number of local historical drifters provide the most detailed observations to date of the surface circulation in the northwestern Weddell Sea. The Antarctic Slope Front (ASF), characterized by a ∼20 cm s−1 current following the 1000-m isobath, is the dominant feature east of the peninsula. The slope front bifurcates when it encounters the South Scotia Ridge with the drifters following one of three paths. Drifters (i) are carried westward into Bransfield Strait; (ii) follow the 1000-m isobath to the east along the southern edge of the South Scotia Ridge; or (iii) become entrained in a large-standing eddy over the South Scotia Ridge. Drifters are strongly steered by contours of f /h (Coriolis frequency/depth) as shown by calculations of the first two moments of displacement in both geographic coordinates and coordinates locally aligned with contours of f /h. An eddy-mean decomposition of the drifter velocities indicates that shear in the mean flow makes the dominant contribution to dispersion in the along-f /h direction, but eddy processes are more important in dispersing particles across contours of f /h. The results of the ADELIE study suggest that the circulation near the tip of the Antarctic Peninsula may influence ecosystem dynamics in the Southern Ocean through Antarctic krill transport and the export of nutrients.

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Distribution and abundance of Antarctic krill (Euphausia superba) off East Antarctica (80–150°E) during the Austral summer of 1995/1996

Cited by 70 publications

References 18 publications

Distribution, patchiness, and behavior of Antarctic zooplankton, assessed using multi-frequency acoustic techniques

Distribution, patchiness, and behavior of Antarctic zooplankton, assessed using multi-frequency acoustic techniques

Environmental conditions and life history constraints determine foraging range in breeding Adélie penguins

Surface Circulation at the Tip of the Antarctic Peninsula from Drifters

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