Diel vertical migration of euphausiids and their contribution to the vertical flux of carbon in the northern Benguela Upwelling System off Namibia


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Thorsten.Werner [ at ] awi.de

Abstract

In the highly productive northern Benguela Upwelling System (nBUS), euphausiids can dominate the zooplankton community and may contribute substantially to the vertical flux of carbon. The predominant vertical transport of carbon produced by phytoplankton in the upper water layers of the ocean to deeper layers takes place by sinking of particulate organic carbon (POC). Several processes mediated by the zooplankton community can either enhance or limit the vertical carbon flux and regulate the efficiency of the biological carbon pump. Main biological pathways by which carbon is exported to deeper water layers are the active transport of carbon by vertical migration of pelagic animals, such as krill, and the passive transport of faecal pellets. A conceptual model will be introduced, combining diel vertical migration (DVM) patterns of dominant krill species, with environmental parameters such as temperature, food availability and with physiological constraints such as species-specific respiration rates, which may explain seasonal adaptations of DVM to changes in water temperature, oxygen and food availability. Energetic considerations based on the DVM model showed that temperature acted as the controlling and limiting factor with food abundance further modifying the vertical positioning of krill species. Variable spatial and temporal distributions of krill will lead to seasonal and regional differences in the export of carbon to deeper water layers. We will show how the different krill species contribute to the downward transport of carbon by vertical migration, and assess its importance relative to other vertical carbon fluxes in the nBUS.



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Conference (Talk)
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Not peer-reviewed
Publication Status
Published
Event Details
15th Southern African Marine Science Symposium - Waves of Change, 15 Jul 2014 - 18 Jul 2014, Stellenbosch, South Africa.
Eprint ID
36021
Cite as
Werner, T. and Buchholz, F. (2014): Diel vertical migration of euphausiids and their contribution to the vertical flux of carbon in the northern Benguela Upwelling System off Namibia , 15th Southern African Marine Science Symposium - Waves of Change, Stellenbosch, South Africa, 15 July 2014 - 18 July 2014 .


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