Feeding and energy budgets of larval Antarctic krill Euphausia superba in summer

Meyer, Bettina; Atkinson, Angus; Blume, Bodo; Bathmann, Ulrich

doi:10.3354/meps257167

Cited by 50 publications

(37 citation statements)

References 31 publications

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“…Body length, elemental composition and growth The high inter-annual variability in phytoplankton concentration in the water column during summer and autumn, and the sea ice dynamics and micro algal biomass in winter and spring pack ice, has an important impact on the condition and hence development of larval krill Meyer et al 2002bMeyer et al , 2003Meyer et al , 2009. Seasonal variations in body length and dry mass are very similar in larvae from diVerent regions (Fig.…”

Section: Physiological Condition Of Larvae In Diverent Seasons and Rementioning

confidence: 84%

“…Larvae show no signiWcant diVerences in metabolic activity, measured as respiration rates, between summer and autumn, ranging from 0.7 to 1.4 l O 2 mg DW h ¡1 (Ikeda 1981;Meyer et al 2002aMeyer et al , b, 2003Meyer et al , 2009, whereas in winter, the respiration rates are only half of those in summer (Frazer et al 2002a;Meyer et al 2009). The respiration rates of freshly caught larvae from mid-winter are comparable with rates of furcilia from late summer and autumn starved for 1 week (Fig.…”

Section: Metabolic and Feeding Activitymentioning

confidence: 99%

“…10a) and feeding activities (Fig. 10b) when exposed to increasing food concentrations (Meyer et al 2002b(Meyer et al , 2003(Meyer et al , 2009. Winter larvae can have a daily food intake up to 500 g C l ¡1 (Fig.…”

Section: Wap (Marguerite Bay Daly 2004)mentioning

confidence: 99%

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The overwintering of Antarctic krill, Euphausia superba, from an ecophysiological perspective

2011

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A major aim of this review is to determine which physiological functions are adopted by adults and larvae to survive the winter season with low food supply and their relative importance. A second aim is to clarify the extent to which seasonal variation in larval and adult krill physiology is mediated by environmental factors with a strong seasonality, such as food supply or day light. Experimental studies on adult krill have demonstrated that speciWc physiological adaptations during autumn and winter, such as reduced metabolic rates and feeding activity, are not caused simply by the scarcity of food, as was previously assumed. These adaptations appear to be inXuenced by the local light regime. The physiological functions that larval krill adopt during winter (reduced metabolism, delayed development, lipid utilisation, and variable growth rates) are, in contrast to the adults, under direct control by the available food supply. During winter, the adults often seem to have little association with sea ice (at least until early spring). The larvae, however, feed within sea ice but mainly on the grazers of the ice algal community rather than on the algae themselves. In this respect, a miss-match in timing of the occurrence of the last phytoplankton blooms in autumn and the start of the sea ice formation, as has been increasingly observed in the west Antarctic Peninsula (WAP) region, will impact larval krill development during winter in terms of food supply and consequently the krill stock in this region.

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Section: Physiological Condition Of Larvae In Diverent Seasons and Rementioning

confidence: 84%

Section: Metabolic and Feeding Activitymentioning

confidence: 99%

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The overwintering of Antarctic krill, Euphausia superba, from an ecophysiological perspective

2011

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“…Larval krill abundance was estimated from the amount of larvae caught by the 1 m 2 net with 350 μ m mesh size. For evaluating the condition of larvae in terms of feeding activity (indicated by the digestive gland size), growth rate and stomach content, larvae were sampled in the OW and the MIZ with a RMT or a Bongo net 42 , whereas in the PIZ, larvae were sampled by scientific divers using the plankton pump system MASMA (MAnguera SubMArina) 9 . MASMA consists of a motor-driven centrifugal pump filtering seawater through a zooplankton net with 200 μ m mesh size into a 2 l cod end, which was located inside an airtight container.…”

Section: Nature Ecology and Evolutionmentioning

confidence: 99%

The winter pack-ice zone provides a sheltered but food-poor habitat for larval Antarctic krill

et al. 2017

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A ntarctic krill Euphausia superba, a key species in Southern Ocean food webs 1 , plays a central role in ecosystem processes and community dynamics of apex predators, and is the target of a commercial fishery 2 . Krill spawn in late spring and their larvae develop during summer, autumn and under the ice in winter to emerge as juveniles in the following spring. The newly spawned eggs sink from the surface to up to 1,000 m depth where they hatch and the developing larvae actively swim upwards to feed in the upper water column 1 . Larval Antarctic krill have low lipid reserves, which are insufficient to support long periods of starvation. Therefore, winter, when primary production is minimal, is assumed to be a critical bottleneck for larval krill development and hence recruitment to the adult population 3,4 . Present hypotheses suggest that high algal biomass in winter sea ice enhances larval krill winter-feeding conditions and growth [5][6][7][8] . This implies that larvae have access to this high algal biomass within the sea ice. However, recent observations 9,10 indicate that the linkage between sea ice and krill recruitment success is not as direct as has been suggested. The timing of ice-edge advance and annual ice-season duration is highly variable, and does not necessarily show a clear link to krill recruitment in the following year ( Supplementary Figs. 1 and 2). Along the Antarctic Peninsula, adult krill have a five to six year population cycle with oscillations in biomass exceeding an order of magnitude 9 . According to bioenergetics models, part of the variability is due to interannual variation in reproductive output 11 as well as autumn blooms that may govern the possible overwinter survival rate of larvae 11,12 . In the Bransfield Strait, three krill winter surveys have shown that krill abundance is an order of magnitude higher than in summer, regardless of concurrent sea-ice conditions 10 A dominant Antarctic ecological paradigm suggests that winter sea ice is generally the main feeding ground for krill larvae. Observations from our winter cruise to the southwest Atlantic sector of the Southern Ocean contradict this view and present the first evidence that the pack-ice zone is a food-poor habitat for larval development. In contrast, the more open marginal ice zone provides a more favourable food environment for high larval krill growth rates. We found that complex under-ice habitats are, however, vital for larval krill when water column productivity is limited by light, by providing structures that offer protection from predators and to collect organic material released from the ice. The larvae feed on this sparse ice-associated food during the day. After sunset, they migrate into the water below the ice (upper 20 m) and drift away from the ice areas where they have previously fed. Model analyses indicate that this behaviour increases both food uptake in a patchy food environment and the likelihood of overwinter transport to areas where feeding conditions are more favourable in spring.

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“…Studies on krill larval ecology are limited (e.g. Ross and Quetin 1989;Daly 1990;Meyer et al 2002;Meyer and Oettle 2005) but important since the survival rates during the early life stages ultimately determines the population size of krill. Eggs hatch and develop through several embryonic stages to larval krill during summer.…”

Section: Introductionmentioning

confidence: 99%

Structural changes in the digestive glands of larval Antarctic krill (Euphausia superba) during starvation

et al. 2009

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The eVects of starvation on ultrastructure of digestive gland cells were studied in furcilia larvae of Antarctic krill (Euphausia superba: hereafter krill). Under laboratory conditions, larvae were starved for 0, 5, 10, 15, 20 and 25 days, and their R-cells were investigated by transmission electron microscope. R-cells are thought to play a role in the storage and absorption of nutrients. In fed larvae, numerous mitochondria scattered homogenously, and densely packed microvilli were observed on the apical surface of R-cells. After 5 days of starvation, mitochondria were swollen and were found concentrated in the apical region in R-cells. A decrease in cell volume and an increase in thickness of the basal lamina with many irregular infoldings were observed after 10-15 days of starvation. Lipid droplets were rarely found in the R-cells regardless of whether larvae had been fed or starved suggesting an inability to store lipid. Without the ability to store energy in the form of lipid, survival would be dependant on sourcing continuous food until maturation.

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Feeding and energy budgets of larval Antarctic krill Euphausia superba in summer

Cited by 50 publications

References 31 publications

The overwintering of Antarctic krill, Euphausia superba, from an ecophysiological perspective

The overwintering of Antarctic krill, Euphausia superba, from an ecophysiological perspective

The winter pack-ice zone provides a sheltered but food-poor habitat for larval Antarctic krill

Structural changes in the digestive glands of larval Antarctic krill (Euphausia superba) during starvation

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