Long-term decline in krill stock and increase in salps within the Southern Ocean

  title={Long-term decline in krill stock and increase in salps within the Southern Ocean},
  author={Angus Atkinson and Volker Siegel and Evgeny A. Pakhomov and Peter Rothery},
Antarctic krill (Euphausia superba) and salps (mainly Salpa thompsoni) are major grazers in the Southern Ocean, and krill support commercial fisheries. Their density distributions have been described in the period 1926–51, while recent localized studies suggest short-term changes. To examine spatial and temporal changes over larger scales, we have combined all available scientific net sampling data from 1926 to 2003. This database shows that the productive southwest Atlantic sector contains >50… 
Long-Term Relationships between the Marine Environment, Krill and Salps in the Southern Ocean
It was demonstrated that krill abundance was greater in years with lower sea water temperature, greater sea-ice extent and higher nutrient concentration, while salps showed the opposite pattern.
Oceanic circumpolar habitats of Antarctic krill
The unusual circumpolar distribution of krill reflects a balance between advection, migration, top–down and bottom–up processes, and the retention ofKrill in moderately productive oceanic habitats is a key factor in their high total production.
Modelling the life cycle of Salpa thompsoni
Restricted regions of enhanced growth of Antarctic krill in the circumpolar Southern Ocean
It is demonstrated that projections of impacts of future change need to account for spatial and seasonal variability of key ecological processes within ocean ecosystems.
Latitudinal variations in Salpa thompsoni reproductive fitness
Salpa thompsoni is a major grazer that plays a significant and disproportionate role in the Southern Ocean biogeochemical cycle. It occurs in higher numbers in the warmer mid‐latitude waters of the
Overwinter habitat selection by Antarctic krill under varying sea-ice conditions: implications for top predators and fishery management
Climate change will affect Antarctic krill Euphausia superba, krill-dependent predators, and fisheries in the Southern Ocean as areas typically covered by sea ice become ice-free in some winters.
Krill (Euphausia superba) distribution contracts southward during rapid regional warming
High-latitude ecosystems are among the fastest warming on the planet1. Polar species may be sensitive to warming and ice loss, but data are scarce and evidence is conflicting2–4. Here, we show that,


Effects of sea-ice extent and krill or salp dominance on the Antarctic food web
Data from 1995 and 1996 are provided that support hypothesized relationships between krill, salps and region-wide sea-ice conditions and suggest that decreased krill availability may affect the levels of their vertebrate predators.
Episodic recruitment in Antarctic krill Euphausia superba in the Palmer LTER study region
The recruitment index was positively correlated with the absolute value of a seasonal El Nino/Southern Oscillation (ENSO) index, with strongest recruitment during the neutral or moderate periods of ENSO.
Ocean circulation off east Antarctica affects ecosystem structure and sea-ice extent
It is proposed that along this coastline ocean circulation determines both the sea-ice conditions and the level of biological productivity at all trophic levels as well as the scales of local surveys and global observations.
Primary production in Southern Ocean waters
The Southern Ocean forms a link between major ocean basins, is the site of deep and intermediate water ventilation, and is one of the few areas where macronutrients are underutilized by
Ecological importance of the Southern Boundary of the Antarctic Circumpolar Current
The association of primary production, Krill, and whales with the Southern Boundary, suggests that it provides predictably productive foraging for many species, and is of critical importance to the function of the Southern Ocean ecosystem.
Seasonal and Regional Variation in the Pelagial and its Relationship to the Life History Cycle of Krill
The earlier concept of Antarctic pelagic seasonality has changed drastically. We now know that the characteristic pelagic community resembles the oligotrophic communities of warm, nutrient-depleted
Krill transport in the Scotia Sea and environs
Historical observations of the large-scale flow and frontal structure of the Antarctic Circumpolar Current in the Scotia Sea region were combined with the wind-induced surface Ekman transport to
Environmental response of upper trophic-level predators reveals a system change in an Antarctic marine ecosystem
  • K. Reid, J. Croxall
  • Environmental Science
    Proceedings of the Royal Society of London. Series B: Biological Sciences
  • 2001
The effects of underlying changes in the system on the krill population structure have been amplified by predatorinduced mortality, resulting in breeding predators now regularly operating close to the limit of krill availability.