467
ern Mediterranean, the upward transport of nutrient-rich subsurface waters induced by
frontal mesoscale upwelling is usually thought as responsible for the fertilization of the
euphotic layer and for the further enhanced phytoplankton concentrations which are measured in the vicinity of those fronts (Prieur, 1986; Tinton) et aI., 1988). The biological
implications of mesoscale distortions in the Balearic front were investigated by Pinot et
al. (1995c). The study focused on an eddy ffront system observed in the Channel of Ibiza
during November 1990 and the ageostrophic motion was again computed from the omega
equation. Substantial upward velocities (5 m/ day) were found at the cold side of the
front and within the adjacent cyclonic eddy. The maximum vertical transport was found
coincident with an upward doming of the nitrocline and with chlorophyll maxima, Figure
8a and b. These results establish the relevance of vertical transport in accounting for the
fertilization and high biomass concentrations observed within fronts.
19
20
21
22
2J
24
25
26
27
x (km)
Figure 8a: West-east cross section of vertical velocity (10**-5 m/s) in the Channel of lbiza in
November 1990 (from Pinot et al. , 1995c).