Intra-annual upwelling patterns and its linkage with primary production in the euphotic zone (24.5°N) of Southern Baja California coast

Abstract The continental shelf of Southern Baja California has been scarcely researched south of 25°N despite it being oceanographically necessary to gain a better understanding of the north-eastern Pacific transitional zone between middle and tropical latitudes. Therefore, the intra-annual patterns of the upwelling cycle and primary production were studied in a monitoring station (24.5°N, 112.1°W; 85 m depth) from August 2008 to December 2011. Monthly, thermohaline vertical profiles were recorded and seawater sampled at 100, 33, 10, 3 and 1% irradiance depth levels. Dissolved oxygen, nutrients and chlorophyll -a concentrations and net primary production (NPP, remote sensed and in situ) were determined. Two half-yearly recurrent periods (P  −2  d −1 in the triennium 2009–2011. Although the influence of La-Nina event was observed during the warm period of 2010 and the cold period of 2011, this change did not significantly affect NPP (P