Aquatic Sciences Meeting, Albuquerque 2001

SS37 Linking Dynamic Temporal Processes with Spatial Domains (Spatial and Temporal Connections)

Date: Tuesday, February 13, 2001, Time: 4:15:00 PM

Location: San Miguel

Sharples, J, , Southampton Oceanography Centre, Southampton, United Kingdom, j.sharples@soc.soton.ac.uk

Moore, C, M, Southampton Oceanography Centre, Southampton, United Kingdom, c.moore@soc.soton.ac.uk

Abraham, E, R, National Institute of Water and Atmospheric Research, Wellington, New Zealand, e.abraham@niwa.cri.nz

FUELING AND ERRODING THE SUBSURFACE CHLOROPHYLL MAXIMUM VIA BAROTROPIC AND BAROCLINIC TIDAL ENERGY DISSIPATION

Primary producers within the subsurface chlorophyll maximum (SCM) are dependent on the rate of turbulent diffusion of nutrient down the nitracline, while at the same time risk removal from the SCM via diffusion down the vertical carbon gradient. We have estimated nitrate fluxes into, and carbon fluxes out of, the SCM in two regions, using microstructure measurements of turbulent dissipation and measurements of vertical nitrate and chlorophyll gradients. In a very strongly-stratified water column, with mixing driven by a barotropic tide, turbulent entrainment of carbon into the bottom mixed layer exceeded the potential new production rate controlled by the nitrate flux into the SCM. In a region where mixing was driven by an internal tide, nitrate supply to the SCM was sufficient to sustain the SCM against turbulent removal. Nitrate fluxes in both cases were approximately equal, so the carbon gradient is the pivotal factor in determining the production-removal balance. We suggest that the carbon gradient is controlled by both the stability of the water column, and by the ability of the phytoplankton to adapt to their turbulent environment.

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Aquatic Sciences Meeting, Albuquerque 2001

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