Large-Scale Fluctuations in Distribution and Abundance of Krill — A Discussion of Possible Causes

Priddle, J.; Croxall, John P.; Everson, Inigo; Heywood, R. B.; Murphy, Eugene J.; Prince, P. A.; Sear, Chris

doi:10.1007/978-3-642-73724-4_14

Cited by 123 publications

(119 citation statements)

References 26 publications

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“…Although the diet of elephant seals is principally composed of cephalopods and fishes (Slip 1995) and although such prey in the Southern Ocean are scarce, it is probable that krill is a major food source for many species in the Antarctic ecosystem, including those that southern elephant seals consume (Rodhouse 1989). As for krill (Priddle et al 1988), oceanographic features are likely to control the distribution of cephalopods (Piatkowski et al 1991;Rodhouse et al 1992) and fishes (Claireaux et al 1995). Close to the Antarctic continent, several elephant seals targeted the sea floor of the Antarctic shelf, particularly in areas with the coldest bottom waters.…”

Section: Discussionmentioning

confidence: 99%

Successful foraging zones of southern elephant seals from the Kerguelen Islands in relation to oceanographic conditions

Bailleul

Charrassin²,

Monestiez

et al. 2007

Phil. Trans. R. Soc. B

120

115

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Southern elephant seals, Mirounga leonina, undertake large-scale oceanic movements to access favourable foraging areas. Successful foraging areas of elephant seals from the Kerguelen Islands are investigated here in relation to oceanographic parameters. Movements and diving activity of the seals as well as oceanographic data were collected through a new generation of satellite relayed devices measuring and transmitting locations, pressure, temperature and salinity. For the first time, we have associated foraging behaviour, determined by high increased sinuosity in tracks, and dive density (i.e. number of dives performed per kilometre covered), and changes in body condition, determined by variations in drift rate obtained from drift dives, to identify the oceanographic conditions of successful foraging zones for this species. Two main sectors, one close to the Antarctic continent and the other along the Polar Front (PF), where both foraging activity and body condition increase, seem to be of particular interest for the seals. Within these regions, some seals tended to focus their foraging activity on zones with particular temperature signatures. Along the Antarctic continent, some seals targeted colder waters on the sea bottom during benthic dives, while at the PF the favourable zones tended to be warmer. The possible negative effect of colder waters in Antarctic on the swimming performances of potential fish or squid prey could explain the behaviour of elephant seals in these zones, while warmer waters within the PF could correspond to the optimal conditions for potential myctophid prey of elephant seals.

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Section: Discussionmentioning

confidence: 99%

Successful foraging zones of southern elephant seals from the Kerguelen Islands in relation to oceanographic conditions

Bailleul

Charrassin²,

Monestiez

et al. 2007

Phil. Trans. R. Soc. B

120

115

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“…If such a shift in the SACCF occurs about a month after spawning time, the effect may be that very few krill reach South Georgia and the population abundance is reduced. This type of variability may contribute to the strong fluctuations in krill abundance reported for waters around South Georgia (Heywood et al, 1985;Priddle et al, 1988).…”

Section: Key Processes Controlling Krill Transportmentioning

confidence: 99%

“…The thin line represents the 2000-m isobath. The areas of consistent Antarctic krill spawning, as identified in Marr (1962) Transport of krill from these regions to South Georgia is thought to be accomplished by largescale ocean currents (Priddle et al, 1988;Witek et al, 1988;Murphy et al, 2004b).…”

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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“…Further north, with a longer time series, the frequency of high recruitment years has not been as repetitive (Siegel and Loeb, 1995;Siegel, 2005), although there is a rough correspondence between successful recruitment years between the two regions 800 km apart (Siegel et al, 2003;Ducklow et al, 2007). However, with several possible reproductive summers, Antarctic krill would not need successful recruitment every year, and models suggest that several years of low to zero recruitment would not preclude recovery of the stock (Priddle et al, 1988).…”

Section: Critical Periodsmentioning

confidence: 99%

Life Under Antarctic Pack Ice: A Krill Perspective

Quetin¹,

Ross²

2009

Smithsonian at the Poles : Contributions to International Polar Year Science

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Large-Scale Fluctuations in Distribution and Abundance of Krill — A Discussion of Possible Causes

Cited by 123 publications

References 26 publications

Successful foraging zones of southern elephant seals from the Kerguelen Islands in relation to oceanographic conditions

Successful foraging zones of southern elephant seals from the Kerguelen Islands in relation to oceanographic conditions

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

Life Under Antarctic Pack Ice: A Krill Perspective

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