During March 1998 we studied in situ bio-optical parameters along a north-south transect (142? ¿E) between 42¿ and 55? ¿S. Surface chorophyll a (chl a) reflected mixed layer chl a concentrations and showed a general decrease with increasing latitude. Changes in chl a concentration often coincided with physical boundaries, and differences in fluorescence yield and photoadaption by the phytoplankton were observed north and south of the Subantarctic Front. In this region chromophoric dissolved organic matter (CDOM) absorption, generally exceeded phytoplankton pigment absorption at 443 nm. Satellite-derived chl a, using the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) OC4 algorithm, generally underestimated the in situ chl a concentration except in areas of low chl a (<0.15 mg m-3) where the SeaWiFS algorithm was found to overestimate in situ chl a. ¿ 2001 American Geophysical Union