Aquatic Sciences Meeting, Albuquerque 2001

PC07 Spatial and Temporal Connections

Date: Wednesday, February 14, 2001

Location: Southwest Hall

Edwards, A, M, Bedford Institute of Oceanography, Dartmouth, Canada, andy@caligo.bio.dfo.ca

Platt, T, , Bedford Institute of Oceanography, Dartmouth, Canada, tplatt@is.dal.ca

Wright, D, G, Bedford Institute of Oceanography, Dartmouth, Canada, wrightdg@mar.dfo-mpo.gc.ca

BIOLOGICALLY-INDUCED CIRCULATION --CAN THE BIOLOGY AFFECT THE PHYSICS?

An intriguing question in oceanography concerns the extent to which the biological component of the ocean can influence the physical component. The presence of phytoplankton in a body of water affects the penetration of irradiance through the water column. This influences the temperature and hence the density distribution of the water. If the phytoplankton concentration varies horizontally, then the consequent density distribution will result in a horizontal pressure gradient. In this talk I consider a long band (or strip) of high phytoplankton biomass, flanked on either side by clearer water containing little biomass. By means of a simple model, I present calculations of the velocities induced by the pressure gradients, to show under what conditions the differential heating effects may become significant. Finally, I demonstrate how the induced velocities may act as a mechanism for enhancing the supply of nitrate to near-surface phytoplankton, thereby increasing primary production. This work demonstrates the potential for feedbacks from the biological component of the ecosystem to the physical component.

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Aquatic Sciences Meeting, Albuquerque 2001

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