Omnivorous feeding behavior of the Antarctic krill Euphausia superba

Price, Holly J.; Boyd, Kenneth R.; Boyd, Carl M.

doi:10.1007/bf00391246

Cited by 126 publications

(93 citation statements)

References 37 publications

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“…However, the krill were large relative to their food, and microscopic examination of uneaten diatoms and copepods in grazed and control containers showed very few damaged cells. This is supported by experiments with live cells at high concentrations (Price et al 1988;Atkinson and Snÿ-der 1997), from which we conclude that sloppy feeding was not a problem.…”

Section: Resultssupporting

confidence: 71%

“…The alternating food-no food regime was maintained for 2 weeks to enable acclimation to this regime. Zooplankton tend to eat faster after short-term starvation (Mackas and Burns 1986;Kremer and Kremer 1988), and pulsed feeding on a day-to-day frequency may not be unnatural for krill (Price et al 1988). Excretion was measured for the 24-h period ϳ2 h after they were allowed to feed, when it would likely have been at its highest daily rate.…”

Section: Excretion In Relation To Feeding-mentioning

confidence: 99%

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Ammonium excretion by Antarctic krill Euphausia superba at South Georgia

Atkinson

Whitehouse

2000

Limnology & Oceanography

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Excretion by Antarctic krill Euphausia superba (hereafter ''krill'') is measured typically in small containers of filtered seawater for 12-24 h, which may cause a reduction of swimming, feeding, and metabolism. If the maximum published excretion rates are realistic, krill would be a major source of regenerated nitrogen in the South Georgia area because of their high biomass there. Because literature values are variable, depending on season, feeding history and the experimental set-up, our aim was to measure both a mean and an upper value of krill excretion rate at South Georgia. Experiments were on juvenile krill during October-November 1997 and January 1998. Freshly caught animals excreted 1.6-2.8 nmol ammonium mg Ϫ1 dry mass h Ϫ1; within the fivefold range of summer literature values for equivalent-sized krill. Maximum rates were determined on acclimated krill in large containers during alternating 1-d periods with and without food. During the feeding periods in saturating food concentrations, the mean daily ration was ϳ32% of body carbon d Ϫ1 and excretion was 210% (October-November) and 280% (January) of the values for freshly caught krill. This equates to a maximum loss of ϳ2% of body nitrogen d Ϫ1 . Excretion rates decreased during the 1-d periods without food, and rates during the feeding periods were ϳ30% higher than in those without food. This suggests that the lack of feeding in traditional experiments leads to roughly 30% underestimates of excretion rate. These results help to set some limits on ammonium production rates of South Georgia krill over regional scales. Our calculations suggest that the role of krill in this varies between habitats to the west of the island (insignificant) and those in the east (significant).

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Section: Resultssupporting

confidence: 71%

Section: Excretion In Relation To Feeding-mentioning

confidence: 99%

Ammonium excretion by Antarctic krill Euphausia superba at South Georgia

Atkinson

Whitehouse

2000

Limnology & Oceanography

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“…Feeding rates for the Antarctic krill Euphausia superba were much higher in 50 1 tanks compared to 5 l containers (Price et al 1988). Increasing density of krill also negatively affected filtration rates (Morris et al 1983).…”

Section: Discussion Of Methodsmentioning

confidence: 95%

“…Euphausiids, particularly E. pacifica, are relatively large, abundant members of the plankton in the Southern California Bight (Brooks & MuILin 1983). Many speci.es of euphausiids are omnivorous and exhibit plasticity in feeding mode, being able to filterfeed, using 'compression filtration' or to feed raptorially on zooplankton (Hamner 1988, Price et al 1988. Some species, such as E. pacifica, vertically migrate from depth to the surface each night to feed (Bnnton 1967) and have the potential to decrease the abundance of large, rapidly sinking particles in the ep~pelagic zone.…”

Section: Introductionmentioning

confidence: 99%

Feeding by the euphausiid Euphausia pacifica and the copepod Calanus pacificus on marine snow

Dilling¹,

Wilson²,

Steinberg³

et al. 1998

Mar. Ecol. Prog. Ser.

138

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ABSTRACT. Consumption and assi~mlation rates of marine zooplankton feeding on large, abundant aggregates, known as marine snow, were measured for the first time. Two common zooplankton species, the euphausiid Euphausia pacifica and the copepod Calanuspacificus, consumed diverse types of field-collected marine snow, including diatom flocs, abandoned larvacean houses, and dinoflagellate aggregates, regardless of their composition, C:N ratio, age, or the availability of alternate dispersed food. Ingest~on rates of aggregates by E. pacifica increased with Increasing marine snow concentration, although in situ concentrations of aggregates were not sufficient to elic~t a maximum ingestion rate Ingestion rates of aggregates by E. pacifica at higher aggregate concentrations were from 9 to 15 pg C euphausiid-' h-'. Assimilation efficiencies of euphausiids grazing on marine snow were 83 % (dinoflagellate snow) and 64 to 75% (diatom/larvacean house snow) These results indicate that marine snow can be an ~mportant food source for marine zooplankton and that consumption of large aggregates 1s likely to play a role in the cycling of carbon and the structure of food webs In the pelagic zone of the ocean.

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“…As ®lter feeders, krill feed mainly on phytoplankton. Primary production in Antarctic waters is, however, characterized by high seasonal and spatial variation (El-Sayed and Taguchi 1981;ElSayed and Weber 1982) and, potentially, E. superba can also change to carnivorous feeding at low phytoplankton densities or during the Antarctic winter (Price et al 1988;Lancraft et al 1991;Huntley et al 1994;Atkinson and SnyÈ der 1997;Pakhomov et al 1997). Krill are able to graze on patchy food sources very e ciently (Hamner et al 1983).…”

Section: Introductionmentioning

confidence: 99%

A laboratory study on digestive processes in the Antarctic krill, Euphausia superba , with special regard to chitinolytic enzymes

Saborowski

Búchholz

1999

Polar Biology

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Feeding experiments of 9, 14 and 20 days duration were carried out on the Antarctic krill, Euphausia superba. Two groups were fed with the chitinous diatom Cyclotella cryptica and the non-chitinous green algae Dunaliella bioculata, respectively. A control group remained unfed. The time courses of the activities of endo-and exochitinase in the stomach and the midgut gland were compared with those of the digestive enzymes protease, cellulase (1,4-b-D-glucanase) and laminarinase (1,3-b-D-glucanase). Speci®c activities of all enzymes were higher in the stomach than in the midgut gland. Characteristic time courses of activity were evident after 4 days. In starved animals, enzyme activities decreased to a minimum after 4 days and recovered within 14 days to initial values. In the stomach, the activities of endo-and exochitinase increased when krill were fed on Cyclotella. For animals fed with Dunaliella, activities stayed constant or decreased slightly. The results con®rm chitinases as digestive enzymes and, therefore, the capability of krill to utilize various food sources.

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Omnivorous feeding behavior of the Antarctic krill Euphausia superba

Cited by 126 publications

References 37 publications

Ammonium excretion by Antarctic krill Euphausia superba at South Georgia

Ammonium excretion by Antarctic krill Euphausia superba at South Georgia

Feeding by the euphausiid Euphausia pacifica and the copepod Calanus pacificus on marine snow

A laboratory study on digestive processes in the Antarctic krill, Euphausia superba , with special regard to chitinolytic enzymes

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