British
Antarctic Survey,
High Cross,
version 13.9.01 uksoglobec1
Background
In order to achieve an understanding of
ecosystems sufficient to predict how they might respond to change, their major
interactions need to be identified and examined. To make this objective
tractable, GLOBEC has selected “keystone” species for study. Within the
Southern Ocean, Antarctic krill (Euphausia superba) is an obvious target species. It has an
enormous biomass, which not only supports commercial
fisheries and a wide range of other higher predators, but also has impacts on planktonic components of the system. Krill have a broad
Southern Ocean distribution, encompassing areas of seasonal sea ice cover and
permanently open water regions. Climate driven changes in ocean circulation or
winter sea ice will affect the dynamics and distributions of krill populations.
Thus it is important to gain a mechanistic understanding of these interactions
in order to predict the responses of krill-based food webs to variation and
secular change in the environment. SO GLOBEC focuses on the study of key, but
poorly known processes dictating krill survival. Such processes include the
role of sea ice in their over-wintering success, or their growth and
development during dispersal in the Antarctic Circumpolar Current.
Within the Antarctic Circumpolar
Current are oceanic fronts, which may dictate the survival during dispersal of
krill. These fronts are rapid current jets, which can disperse populations far
from their source regions, enhance gene flow across large areas and help
repopulate depleted regions. Some fronts are also zones of enhanced primary
productivity; rich feeding grounds for krill. However, a major question, as yet
unresolved, is the importance of these fronts in providing the phytoplankton
blooms essential for krill survival and reproduction in the ice-free months. A
front of major potential importance to krill is the Southern Antarctic
Circumpolar Current Front (SACCF), as it forms an approximate northern boundary
of their distribution. However, its relationship with the seasonal sea ice zone
and its role in krill dispersal are presently unclear. The proximity of this
front to the
Although krill are a central focus of SO GLOBEC,
it recognises the need for a multidisciplinary approach to understand the
biological and physical processes governing their survival (SO GLOBEC objectives).
The interactions between krill and their food, competitors and predators
dictate growth and mortality. They also dictate behaviour, for example
schooling and diel vertical migration, which in turn
link with the 3D flow field to determine larger scale distribution. As part of
its DYNAMOE
programme, the British Antarctic Survey is conducting a major
interdisciplinary study of the role of oceanic fronts in dictating krill growth
and survival in the
The
1) How important are
oceanic fronts in controlling the growth and development of krill?
2) How important are oceanic fronts in
determining the dispersal and survival of krill?
British Antarctic Survey
International Whaling Commission
