Primary productivity observations in the eastern tropical Pacific off Cabo Corrientes, Mexico

Abstract

The in situ primary productivity (PP) and phytoplankton biomass (chlorophyll a concentration, Chla) of the Cabo Corrientes region, in the eastern tropical Pacific off Mexico, were studied using data from three oceanographic cruises (May and November 2002, and June 2003). The coastal region (<60 km) was found to be affected by coastal upwelling, causing phytoplankton biomass and production rates in this region to be up to two times higher than at the offshore stations. The highest surface Chla values were registered in May 2002 (>2 mg m–3), when the mean PP was 361 mgC m–2 d–1. The highest PP values were recorded in June 2003, with a mean value of 447 mgC m–2 d–1, and the lowest in November 2002, with a mean value of 200 mgC m–2 d–1. Satellite ocean color images, supported by our field data, suggest that the area off Cabo Corrientes can be characterized by three periods: (1) a relatively intense upwelling period, with high Chla and PP (spring); (2) an upwelling relaxation period, when the highest PP values of the year were recorded (late spring-early summer); and (3) a summer-fall period, with strong stratification and lowest Chla and PP values. The high PP registered for the region off Cabo Corrientes during the spring season leads us to conclude that this is an area of high fertility, similar to other rich regions in the Pacific Ocean off Mexico.

Oceanographic conditions and marine mammals: identifying a potential relationship in the coastal region of the Mexican Central Pacific

“…4). These results coincide with those reported by López-Sandoval et al (2009), who characterized this period as productive because that is when maximum values of primary productivity and Chl-a occur, and it is also when sunlight and oceanographic conditions are favorable for phytoplankton growth.…”

“…2 and 4), which had previously been reported as the main fertilizing processes propagating near the continental shelf (200 m) in this region of the MCP (Salas et al 2006, Pantoja et al 2012. The MDS could have resulted in the lifting/sinking (~20 m) of isotherms, allowing cold-water intrusion towards the surface, as has been described by some authors (e.g., Torres-Orozco et al 2005, Salas et al 2006, López-Sandoval et al 2009). Although gyres could not be clearly identified by AVISO data within the study area (due to the 1/3° data resolution); however, the SST and Chl-a satellite data were useful to identified some of these structures that have been described during the entire year.…”

“…The influence of the CC has been reported in this area by several authors (Fiedler & Talley 2006, Lavín et al 2006b, López-Sandoval et al 2009). The SST images and geostrophic currents indicated several MDS, mainly cyclonic gyres (Figs.…”

“…2a-d) is the occurrence of upwelling events such as those that have been reported near Cabo Corrientes during the winter-spring period (Filonov et al 2000, Torres-Orozco et al 2005, Kessler 2006, López-Sandoval et al 2009). The NOAA upwelling index 5 for this period suggests an upwelling event, with cold water being transported by winds and marine currents from the northwest, as has been described by Fiedler & Talley (2006).…”

“…However, few studies have described the interaction between marine mammals and their environment in coastal and tropical areas such as the MCP region, where oceanographic parameters vary seasonally due to anthropogenic and continental influences as well as to the presence of storms (Salas et al 2006). This particular zone is located within a dynamic transition zone that generates variability in physico-chemical parameters and the increase of the region´s primary productivity (Galicia-Pérez et al 2006, Kessler 2006, López-Sandoval et al 2009). …”