Seabed foraging by Antarctic krill: Implications for stock assessment, bentho‐pelagic coupling, and the vertical transfer of iron

By K. Schmidt, A. Atkinson, S. Steigenberger, S. Fielding, Margaret C. M. Lindsay, D. Pond, Geraint A. Tarling, T. Klevjer, C. Allen, S. Nicol and 1 more. 2011

219 citations recorded by the source corpus.

A compilation of more than 30 studies shows that adult Antarctic krill (Euphausia superba) may frequent benthic habitats year‐round, in shelf as well as oceanic waters and throughout their circumpolar range. Net and acoustic data from the Scotia Sea show that in summer 2‐20% of the population reside at depths between 200 and 2000 m, and that large aggregations can form above the seabed. Local differences in the vertical distribution of krill indicate that reduced feeding success in surface waters, either due to predator encounter or food shortage, might initiate such deep migrations and results in benthic feeding. Fatty acid and microscopic analyses of stomach content confirm two different foraging habitats for Antarctic krill: the upper ocean, where fresh phytoplankton is the main food source, and deeper water or the seabed, where detritus and copepods are consumed. Krill caught in upper waters retain signals of benthic feeding, suggesting frequent and dynamic exchange between surface and seabed. Krill contained up to 260 nmol iron per stomach when returning from seabed feeding. About 5% of this iron is labile, i.e., potentially available to phytoplankton. Due to their large biomass, frequent benthic feeding, and acidic digestion of particulate iron, krill might facilitate an input of new iron to Southern Ocean surface waters. Deep migrations and foraging at the seabed are significant parts of krill ecology, and the vertical fluxes involved in this behavior are important for the coupling of benthic and pelagic food webs and their elemental repositories.

Subfields: Global and Planetary Change, Nature and Landscape Conservation, Oceanography

View Paper: https://www.semanticscholar.org/paper/eb273d08e6857557541d979f814f71e15836b056

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Global and Planetary Change

1. A. Atkinson
2. B. Meyer
3. V. Siegel
4. K. Schmidt
5. P. Trathan
6. S. Hill
7. D. Pond
8. J. Watkins

In Nature and Landscape Conservation

1. B. Meyer
2. A. Atkinson
3. K. Schmidt
4. J. Watkins
5. D. Pond
6. V. Siegel
7. S. Hill
8. P. Trathan

In Oceanography

1. P. Trathan
2. V. Siegel
3. Bruno Danis
4. C. Broyer
5. E. Murphy
6. B. Meyer
7. S. Hill
8. A. Atkinson

Citations in the corpus

• The Importance of Krill Predation in the Southern Ocean (2016, background): “…studies have shown that krill feed on the benthos year round throughout Antarctica, with an estimated ~20% of the stock deeper than 200 m at any one time (Schmidt et al. 2011), although others (see chapter 2, Siegel and Watkins 2016) suggest that the percentage below 200 m may only be around 5%.”
• Distribution, Biomass and Demography of Antarctic Krill, Euphausia superba (2016, background): “They also may also show a diel vertical migration which may be strong or absent (Hamner and Hamner 2000; Siegel 2005), and may even use the bottom as a habitat (Kawaguchi et al. 1986; Gutt and Siegel 1994; Schmidt et al. 2011).”
• Biogeographic Atlas of the Southern Ocean (2014, background): “…pelagic life in the open Antarctic Ocean, Antarctic krill feed on any preys items, including protists (Schmidt et al. 2006), but the diet may shift preferentially to copepods (Granelli et al. 1993, Mayzaud et al. 1998), and even to the micro-fauna of the sea-bed sediment (Schmidt et al. 2011).”
• Variable food absorption by Antarctic krill: Relationships between diet, egestion rate and the composition and sinking rates of their fecal pellets (2012, background): “This may reflect further unmeasured factors, such as the highly variable silicification of diatoms and the uptake of dense lithogenic sediment during benthic feeding excursions (Schmidt et al., 2011).”
• The overwintering of Antarctic krill, Euphausia superba, from an ecophysiological perspective (2011, background): “A recent study found adult krill near the seaXoor in many regions and during all seasons in the Southern Ocean, indicating the ability to utilise benthic detritus to supplement diet throughout the year (Schmidt et al. 2011a).”
• Overwinter habitat selection by Antarctic krill under varying sea-ice conditions: implications for top predators and fishery management (2017, background): “Additionally, recent effort has focused on the importance of deep-ocean (>1500 m) benthic environments as overwintering habitats (Atkinson et al. 2009, Schmidt et al. 2011) that might harbor a large fraction of krill during winter.”
• Krill, climate, and contrasting future scenarios for Arctic and Antarctic fisheries (2014, background): “…abundance estimates consider Antarctic krill as an epipelagic organism, while more recent studies indicate an additional stock component of up to 20% distributed in deep waters and along bottom, representing unaccounted biomass in the stock assessments (Gutt and Siegel, 1994; Schmidt et al., 2011).”
• Feeding and overwintering of Antarctic krill across its major habitats: The role of sea ice cover, water depth, and phytoplankton abundance (2014, background): “Together, their intensive grazing and excretion can affect local nutrient cycles and phytoplankton dynamics (Smetacek et al. 2004; Schmidt et al. 2011); therefore, krill are considered ‘‘engineers’’ of ecosystem structure and function.”