Feeding and Food Processing in Antarctic Krill (Euphausia superba Dana)

Schmidt, Katrin; Atkinson, Angus

doi:10.1007/978-3-319-29279-3_5

Cited by 59 publications

(42 citation statements)

References 190 publications

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“…Microplankton play a critical role in the WG marine ecosystem. Diatoms, the main drivers of phytoplankton productivity in the Southern Ocean, dominate the microplankton size fraction in net hauls, are easily analyzed by microscopy, and are ideal food for large zooplankton (Schmidt & Atkinson, ; Figure ). They have historically been classified in four ecological groupings within ice‐free waters of the WG: (1) spring forms, (2) spring forms but occurring throughout the year, (3) spring and autumn bloom forms, and (4) spring forms present in the winter and summer/fall species (Hart, , ).…”

Section: Biology I: Phytoplankton Of the Wgmentioning

confidence: 99%

“…Using a feeding basket with a large filtering surface (fine mesh size of 2–3 μm), they efficiently capture nanoplankton and microplankton, particles ranging in size 10–50 μm (Pakhomov et al, ). Even though phytoplankton—in particular diatoms—are the preferred food for krill, protozoans and small copepods are also ingested simultaneously and represent an important supplementary food source year‐round (Schmidt & Atkinson, ; Pakhomov et al, ; Figure ). Krill, like copepods, benefit from eating diatoms, including sea‐ice and planktonic species (Cleary et al, ; Schmidt et al, ).…”

Section: Biology Ii: Food Web Of the Wgmentioning

confidence: 99%

“…Hence, salp fecal pellets could also have a role in recycling organic matter in the upper mesopelagic waters, a process not very well understood (Iversen et al, ). Similarly, krill fecal pellets break up in surface waters, which decreases their sinking rate, thereby facilitating recycling of organic matter and elements in the upper water column (Schmidt & Atkinson, ).…”

Section: Biology Ii: Food Web Of the Wgmentioning

confidence: 99%

See 2 more Smart Citations

The Weddell Gyre, Southern Ocean: Present Knowledge and Future Challenges

Vernet

Geibert

Hoppema

et al. 2019

Reviews of Geophysics

152

168

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The Weddell Gyre (WG) is one of the main oceanographic features of the Southern Ocean south of the Antarctic Circumpolar Current which plays an influential role in global ocean circulation as well as gas exchange with the atmosphere. We review the state‐of‐the art knowledge concerning the WG from an interdisciplinary perspective, uncovering critical aspects needed to understand this system's role in shaping the future evolution of oceanic heat and carbon uptake over the next decades. The main limitations in our knowledge are related to the conditions in this extreme and remote environment, where the polar night, very low air temperatures, and presence of sea ice year‐round hamper field and remotely sensed measurements. We highlight the importance of winter and under‐ice conditions in the southern WG, the role that new technology will play to overcome present‐day sampling limitations, the importance of the WG connectivity to the low‐latitude oceans and atmosphere, and the expected intensification of the WG circulation as the westerly winds intensify. Greater international cooperation is needed to define key sampling locations that can be visited by any research vessel in the region. Existing transects sampled since the 1980s along the Prime Meridian and along an East‐West section at ~62°S should be maintained with regularity to provide answers to the relevant questions. This approach will provide long‐term data to determine trends and will improve representation of processes for regional, Antarctic‐wide, and global modeling efforts—thereby enhancing predictions of the WG in global ocean circulation and climate.

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Section: Biology I: Phytoplankton Of the Wgmentioning

confidence: 99%

Section: Biology Ii: Food Web Of the Wgmentioning

confidence: 99%

Section: Biology Ii: Food Web Of the Wgmentioning

confidence: 99%

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The Weddell Gyre, Southern Ocean: Present Knowledge and Future Challenges

Vernet

Geibert

Hoppema

et al. 2019

Reviews of Geophysics

152

168

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“…The processes discussed above in combination with horizontal mixing and advection could also contribute to the large spatial extent and longevity of blooms in open waters of the Southern Ocean. The role of fecal material from other important species of the Southern Ocean in maintaining biological stocks via iron recycling, such as krill, whales and other marine mammals, has received increasing attention (Nicol et al, 2010;Ratnarajah et al, 2014;Schmidt and Atkinson, 2016;Smetacek and Nicol, 2005;Tovar-Sanchez et al, 2007). During LO-HAFEX, the presence of krill and salps (and their fecal pellets) was negligible when compared to copepod numbers (M. Iversen, data not published).…”

Section: Implications For Iron Cycling and Its Study In The Southern mentioning

confidence: 99%

Iron partitioning during LOHAFEX: Copepod grazing as a major driver for iron recycling in the Southern Ocean

et al. 2017

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100-150 m, the accumulation of LFe 48h in the upper 80 m after the second fertilization and provided the iron required for the maintenance of the LOHAFEX bloom for many weeks. Our results provide the first quantitative evidence of the major ecological relevance of copepods and their fecal products in the cycling of iron in silicate depleted areas of the Southern Ocean. Index terms 4807 Chemical speciation and complexation 0414 Biogeochemical cycles, processes, and modeling 0461 Metals 0489 Trace element cycling

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“…For example, Polito et al () indicate that spatial or temporal variation krill δ 13 C and δ 15 N values in this dataset were best explained by similar variation in the size of krill around the South Shetland Islands and between years. Krill δ 15 N values in the study region ranged from 1.7‰ to 5.4‰ and increased with standard length, indicative of a higher trophic‐level diet as krill grow larger (Polito et al ; Schmidt and Atkinson ). Furthermore, the range in krill δ 15 N values with body size observed in our study is similar in magnitude to spatial differences in mean krill δ 15 N values seen around the Southern Ocean (1.0‰ to 6.2‰; reviewed by Polito et al []).…”

Section: Discussionmentioning

confidence: 99%

Intraspecific variation in a dominant prey species can bias marine predator dietary estimates derived from stable isotope analysis

Polito

Trivelpiece

Reiss

et al. 2019

Limnology & Ocean Methods

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It is often assumed that variation in consumer stable isotope values (δ15N and δ13C) reflect shifts in diet between isotopically distinct prey species. However, an alternate hypothesis is that such variation could be as a result of spatial, temporal, or ontogenetic variation in the stable isotope values of a key prey species that propagate up marine food chains. In the Southern Ocean, Antarctic krill (Euphausia superba) occupy a key position, linking primary production to secondary consumers including fish, squid, seabirds, and marine mammals. As such Antarctic krill represent an ideal prey species to test the critical assumptions behind what has become a common method of dietary analysis in marine predators. Similar to previous studies, we found that stable isotope values of Antarctic krill exhibit significant intraspecific variation associated with both ontogenetic (size) and oceanographic factors (chlorophyll a concentration). Our modeling results showed that intraspecific variation in the stable isotope values of Antarctic krill has the potential to force mean isotope values of krill predators by as much as 2.4‰, independent of changes in the species composition of diet. Our findings indicate that intraspecific variation in the stable isotope values of a single, dominate prey species, such as Antarctic krill, has the potential to bias both absolute and relative estimates of marine predator diets using stable isotope mixing models. Therefore, caution is warranted to avoid spatial, temporal, and ontogenetic mismatches between the stable isotope values of prey sources used in mixing models and the actual stable isotope values of prey consumed by marine predators.

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Feeding and Food Processing in Antarctic Krill (Euphausia superba Dana)

Cited by 59 publications

References 190 publications

The Weddell Gyre, Southern Ocean: Present Knowledge and Future Challenges

The Weddell Gyre, Southern Ocean: Present Knowledge and Future Challenges

Iron partitioning during LOHAFEX: Copepod grazing as a major driver for iron recycling in the Southern Ocean

Intraspecific variation in a dominant prey species can bias marine predator dietary estimates derived from stable isotope analysis

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