Aggregation and vertical migration behavior of Euphausia superba

Zhou, Meng; Dorland, Ryan D.

doi:10.1016/j.dsr2.2004.07.009

Cited by 95 publications

(85 citation statements)

References 42 publications

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“…Because lunge feeding involves the intermittent engulfment of discrete volumes of prey-laden water at depth, decreased efficiency will necessitate more foraging time to meet energetic demands (Goldbogen et al 2007). Dense krill patches that are deep during the day typically migrate towards the sea surface at night and disperse into lower density (Zhou & Dorland 2004). Rorquals that target deep, dense krill aggregations will track their diel migration; lunge-feeding effort at depth gradually decreases at dusk and then progressively increases at dawn .…”

Section: Resultsmentioning

confidence: 99%

Skull and buccal cavity allometry increase mass-specific engulfment capacity in fin whales

2009

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Rorqual whales (Balaenopteridae) represent not only some of the largest animals of all time, but also exhibit a wide range in intraspecific and interspecific body size. Balaenopterids are characterized by their extreme lunge-feeding behaviour, a dynamic process that involves the engulfment of a large volume of prey-laden water at a high energetic cost. To investigate the consequences of scale and morphology on lunge-feeding performance, we determined allometric equations for fin whale body dimensions and engulfment capacity. Our analysis demonstrates that larger fin whales have larger skulls and larger buccal cavities relative to body size. Together, these data suggest that engulfment volume is also allometric, increasing with body length as L 3:5 body . The positive allometry of the skull is accompanied by negative allometry in the tail region. The relative shortening of the tail may represent a trade-off for investing all growth-related resources in the anterior region of the body. Although enhanced engulfment volume will increase foraging efficiency, the work (energy) required to accelerate the engulfed water mass during engulfment will be relatively higher in larger rorquals. If the mass-specific energetic cost of a lunge increases with body size, it will have major consequences for rorqual foraging ecology and evolution.

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Section: Resultsmentioning

confidence: 99%

Skull and buccal cavity allometry increase mass-specific engulfment capacity in fin whales

2009

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“…A large and persistent gyre has also been observed over the northern portion of the study region (Figure 4.1b;Smith et al, 1999;Klinck et al, 2004), which may serve to retain planktonic organisms. Smaller gyres have been observed in more coastal reaches of the region, with similar potential effects on retention Zhou and Dorland, 2004). A coastal current flows towards the southwest, which may serve to advect zooplankton into or out of the study region .…”

Section: Southern Ocean Global Ecosystems Dynamics (So Globec) Programentioning

confidence: 91%

“…Even in this depth range, since the position of the ship in relation to time of day was effectively random, any diel changes in vertical position should simply introduce random error into the acoustic measurements. Diel vertical migration of some component of the zooplankton community undoubtedly does occur (e.g., Zhou and Dorland (2004) observed distinct diel vertical migrations by individual euphausiid aggregations), but it seems that the influence of such migrations on our large-scale analyses of overall zooplankton volume backscattering is minor.…”

Section: Potential Limitations Of the Acoustic Techniquementioning

confidence: 98%

“…It is also possible that the canyons and regions of variable bathymetry present in these coastal regions provide a refuge from currents that otherwise would advect the krill from the region. Meso-scale eddies were present in these coastal waters during both years Zhou and Dorland 2004), potentially enhancing retention of krill or its planktonic prey. Alternately, contrary to the general understanding that krill spawn along and beyond the continental shelf break (reviewed in Siegel, 2005), Brinton (1991) suggested on the basis of patterns in the distribution of larval krill in the western Bransfield Strait that some krill, particularly small adults, may spawn in the deep basins in coastal reaches of the continental shelf.…”

Section: 42c Environmental Associationsmentioning

confidence: 99%

“…Physical processes may also play a role, however, and Zhou and Dorland (2004) suggest that horizontal current shear and strain limit the horizontal extent of krill aggregations. Most studies examining the relationship of krill and higher predators have concentrated on the question of how the distribution and population size of land-based and diving predators relates to that of the krill (Alonzo and Mangel, 2001).…”

Section: Acknowledgmentsmentioning

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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Impacts of Climate Change on the Southern Ocean

Mintenbeck

2017

Climate Change Impacts on Fisheries and Aquaculture

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Aggregation and vertical migration behavior of Euphausia superba

Cited by 95 publications

References 42 publications

Skull and buccal cavity allometry increase mass-specific engulfment capacity in fin whales

Skull and buccal cavity allometry increase mass-specific engulfment capacity in fin whales

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

Impacts of Climate Change on the Southern Ocean

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