South region of the gulf of California large marine ecosystem upwelling, fluxes of CO₂ and nutrients

The Gulf of California Large Marine Ecosystem (LME) is one of the most productive and biologically rich marine ecosystems in the world with a high rate of endemic species. The combination of high biological productivity and biological richness characterizing the region is the result of its unique geology and geography, shaping strong currents and tides that generate the upwelling of cool, nutrient-rich waters. These waters support an extremely high abundance of plankton that in turn is the basis of a complex food web sustaining a diversity of fish, birds, and marine mammals. As Mexico's most important fishery region, the Gulf of California provides seafood to locals and for export to other countries. In addition, manifold coastal lagoons, coastal marine sea-beds, mangrove forests, and 922 islands are important reproductive, nesting and nursing sites for hundreds of resident and migratory bird species. However, even when several oceanographic processes that confer a high productivity to the Gulf of California LME have been documented, there is very little field work to monitor these phenomena, such as coastal upwelling in the southern region, as well as the spatial and temporal variability in nutrient concentrations, the effect of exchange with coastal systems and the role of the Gulf of California as a sink or exporter of carbon dioxide (CO₂), for example, in winter the region of the Grandes Islas, there are a source of CO₂ to the atmosphere (pCO₂ >580 µatm). On this, the records show that in the last 250 years the concentrations of atmospheric CO₂ in the world have increased and it has been reported that the ocean daily fixed 2.2 metric tons of CO₂, this content has changed from 280 µatm before the industrial revolution to 407 µatm in recent times. In the Gulf of California, studies conducted on carbon dioxide (air-ocean flow, dissolved inorganic carbon, total alkalinity) are scarce, and suggest a net flow CO₂ from coastal waters into the atmosphere mainly in the region of the Grandes Islas, caused by the intense vertical mixing. In the absence of time-series data on the processes occurring in the southern part of the Gulf, it is necessary to start continuous records of temperature, salinity, dissolved oxygen, pH vertical structure and the measurements of dissolved inorganic carbon, total alkalinity and nutrients to improve understanding of the biogeochemical structure of the water column and possible exchanges with the coast.