Review: the energetic value of zooplankton and nekton species of the Southern Ocean

Schaafsma, Fokje; Cherel, Yves; Flores, Hauke; Franeker, J.A. van; Lea, Mary‐Anne; Raymond, Ben; Putte, Anton P. Van de

doi:10.1007/s00227-018-3386-z

Cited by 68 publications

(42 citation statements)

References 205 publications

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“…Fishes are the second most important food source, after krill, for higher trophic predators, in particular the energy‐rich pelagic myctophids and the Antarctic silver fish Pleuragramma antarcticum (Barrera‐Oro, ; Schaafsma et al, ; Figure ). Neutrally buoyant P. antarcticum constitutes >90% of abundance and biomass of midwater fishes in coastal waters, playing an important role in the food web (Donnelly & Torres, ; Hubold, ; Hubold & Tomo, ).…”

Section: Biology Ii: Food Web Of the Wgmentioning

confidence: 99%

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

Vernet

Geibert

Hoppema

et al. 2019

Reviews of Geophysics

144

147

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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 Ii: Food Web Of the Wgmentioning

confidence: 99%

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

Vernet

Geibert

Hoppema

et al. 2019

Reviews of Geophysics

144

147

View full text Add to dashboard Cite

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“…Our study further highlights that populations of the larger, krill consuming myctophids, particularly E. antarctica, G. nicholsi, and G. braueri, may also be impacted concurrently by sustained reductions of krill in their diet. Although it is possible that such species could survive periods of krill shortages by increasing their intake of other prey taxa, particularly copepods and small euphausiids, these food sources are unlikely to yield the same calorific content as krill per unit effort of foraging (Schaafsma et al, 2018). These myctophids may therefore be unable to meet their metabolic demands as efficiently through such a dietary shift and, consequently, they could be subjected to starvation stresses and increased population depletion.…”

Section: Impact Of Ocean-warming On Food Web Dynamicsmentioning

confidence: 99%

Myctophid Fish (Family Myctophidae) Are Central Consumers in the Food Web of the Scotia Sea (Southern Ocean)

et al. 2019

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Myctophids are the most abundant and diverse mesopelagic fishes in the Southern Ocean. They are a conduit of energy between primary consumers and higher marine predators, and between the surface layers and the mesopelagic depths. However, there remain major uncertainties about their ecology, particularly regarding their role in Southern Ocean food webs in waters south of the Antarctic Polar Front, which are often regarded as dominated by Antarctic krill. Limited data on the feeding ecology of myctophids has made it difficult to assess the importance of myctophids as consumers of krill and how they fit in the traditional view of a krill-dominated system (diatom-krillhigher predator). We provide a new assessment of the role of myctophids in Southern Ocean food webs using information from recent trophodynamic studies of myctophids conducted in the Scotia Sea, one of the most productive regions of the Southern Ocean and a region that sustains both major populations of higher predators (sea birds, seals, whales) and important commercial fisheries (krill, toothfish, and mackerel icefish). Collectively, these data show that myctophids have a central role in Southern Ocean food webs as both predators and prey. Large myctophid species are prevalent consumers of krill throughout their distributional range and in different seasons in the Scotia Sea. Moreover, best estimates of both myctophid and higher predator consumption of krill to date indicate that large myctophids are the greatest predators of krill in this region, consuming almost as much krill as do all other vertebrates. Nevertheless, there are several smaller myctophid species that do not eat krill, instead consuming copepods and other small euphausiids. Myctophids therefore link primary producers to higher predators through both krill-dependent and krill-independent trophic pathways, emphasizing their importance in regional food webs. Consequently, trophic pathways involving large myctophids are unlikely to be exempt from the direct consequences of projected redistribution and/or reduction in krill population biomass under scenarios of ocean-warming, whilst trophic pathways involving small myctophids may be more resilient to such effects and become increasingly important to higher trophic levels. Further studies are required to determine the extent to which myctophids can maintain food web stability and sustain higher predator populations Frontiers in Marine Science | www.frontiersin.org 1 September 2019 | Volume 6 | Article 530 Saunders et al. Trophodynamics of Scotia Sea Myctophidsduring periods of prolonged reductions in krill abundance. Including knowledge of the role of myctophids in Southern Ocean food webs will be important for developing robust projections of the impacts of future change to inform decision making for conservation and management.

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“…Risso's dolphins switched dynamically and seamlessly from being more generalist predators to specialists, frequently over the course of a single 5− 10 min dive. Risso's dolphins were never found in patches of crustaceans, which have the lowest energy density of the available prey groups (Benoit-Bird 2004, Schaafsma et al 2018, although they were equally abundant as fish patches. Risso's dolphins' relative prey selectivity between squid and fish changed with depth.…”

Section: I Imentioning

confidence: 99%