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Flexibility and constraints in life histories Project

Flexibility and constraints in life histories is a component project of Discovery 2010: integrating Southern Ocean ecosystems into the Earth System science research programme, part of the British Antarctic Survey research strategy Global Science in an Antarctic Context (GSAC) 2005–2009


Project leader: Geraint Tarling
Work package leader (zooplankton): Rachael Shreeve
Work package leader (nekton): Martin Collins
Work package leader (higher predators): Richard Phillips


FLEXICON is investigating the life-cycles of some of the world's most durable and abundant organisms that are vital to the Earth's systems. Marine organism in the Southern Ocean must endure one of the most extreme environments on the planet, with sea-temperatures often below freezing and summers that sometimes last just a few weeks. They must also adapt to the Antarctic Circumpolar Current, the world's strongest ocean current, as well as an ice sheet that can expand and contract hundreds of kilometres each day. Despite this, some of largest biomasses and abundances of organisms occur there and their high productivity makes the Southern Ocean an important carbon sink, crucial to the regulation of the Earth's climate.

FLEXICON seeks to understand what characteristics make Southern Ocean organisms succeed or fail in this extreme and variable environment. In particular, it is examining the flexibility and constraints in the physiology and behaviour of organisms that allow them to complete their life-cycles successfully. Key to its approach is the identification of CRITICAL STAGES, those stages that are particularly vulnerable to environmental change. Measuring the response of these stages to potential extremes helps us understand how these species may respond to any future climatic shifts.

FLEXICON will examine key species at all trophic levels, from copepods and krill, through mesopelagic and commercial fish, to albatrosses, penguins and seals. Its approach will be firstly, to build models of the life-cycles of key organisms through using best available information in databases and publications. These models will then help in the design of field campaigns that will measure important missing parameters and provide data for testing model predictions. The final refined models will have the capacity to predict the response of key species to future environmental scenarios, such as changes to ice-extent, sea-temperature, primary productivity and food availability.

FLEXICON is a core part of the DISCOVERY 2010 programme and intimately linked with the other DISCOVERY 2010 projects. It will provide FOODWEBS with base-line parameters, such as the timing and extent of the seasonality in the abundances of key species. CEMI will use FLEXICON's parameterisation of the krill life-cycle in its circumpolar distributional models. The improved understanding of the life-cycles of commercially exploited species, such as krill, mackerel icefish and Patagonian toothfish will be important inputs into the OEM project. FLEXICON will generate information that will be useful to other BAS core programmes, such as BIOFLAME (krill genetics) and COMPLEXITY (foraging and swarming behaviours). It will also be an intellectual- and data-provider to international bodies such as CCAMLR, EUROCEANS, ICED, GLOBEC/IMBER and IPY.

Within DISCOVERY 2010, FLEXICON will facilitate the following key tasks:

  • Life-cycles and distribution of Southern Ocean calanoid copepods: The ultimate aim of this task is to develop a circumpolar view of the stage-distribution of two key Southern ocean calanoid copepod species, Calanoides acutus and Rhincalanus gigas. The first stage will be to develop simple functions that relate the condition factor of animals to environmental variables such as temperature and food availability. These model organisms will then be integrated into flow fields, and also linked to environmental conditions in order to predict areas of high and low developmental viability and regionality in optimal life-cycle phenotypes.
  • Seal and penguin demography and consumption: This will determine the short-term demographic consequences of environmental variability in penguin and seal populations around the Scotia Sea. It will be centred on the development of demographic models that will, subsequently, provide base-line parameters for food web models. In particular, it will provide a means of examining the consequences of demographic shifts to higher predator consumption levels.
  • Albatrosses and Petrels: This task will determine levels of juvenile mortality in wandering, black-browed and grey-headed albatrosses. Also, it will compare breeding period dynamics in Northern and Southern Giant petrels and their sensitivity to environmental variability. The work will deploy devices incorporating some of the latest advances in satellite tracking technology and results will be analysed with state of the art GIS softwares. Findings will have direct relevance to ecological measures taken to conserve these threatened species.
  • Dynamics of krill life-cyles, populations and distributions (in collaboration with CEMI): This task will work towards developing a Scotia Sea model in which advection and distribution of krill is coupled to environmental conditions and growth. The model will be initialised with length-frequency data from CCAMLR 2000 survey, the DISCOVERY reports and BAS sources such as the JR82 cruise. It will be forced with outputs of the OCCAM model and satellite derived environmental data (temperature and Chla). Animals will grow according to the functional responses developed by Atkinson et al. (2006) and Tarling et al. (2006). Predictions will be validated against net and predator data of length frequencies at various locations around the Scotia Sea. This approach will be a test-bed for the development of a fully coupled life-cycle model at a circumpolar scale.