Humboldt Current

Upwelling brings nutrients to the surface, which support phytoplankton and ultimately increase biological productivity.

The system's high productivity supports other important fishery resources as well as marine mammals (eared seals and cetaceans) and seabirds.

Periodically, the upwelling that drives the system's productivity is disrupted by the El Niño-Southern Oscillation (ENSO) event, often with large social and economic impacts.

Marine air is cooled by the current and thus is not conducive to generating precipitation (although clouds and fog are produced).

[1] Variability in this system is driven by latitudinal shifts between the Intertropical Convergent Zone and the trade winds in the north.

Shifts within the South Pacific High at mid-latitudes, as well as cyclonic storms and movement of the Southern Westerlies southward also contribute to system changes.

[1] The Humboldt current, occupying the upper ocean, flows equatorward carrying fresh, cold Sub-Antarctic surface water northward, along the outskirts of the subtropical gyre.

[1] Off the coast of central Chile, there is a coastal transition zone (CTZ), which is characterized by high eddy kinetic energy.

[1] This lack of ventilation is the primary driver of an intense oxygen minimum zone (OMZ) which is formed in the sub-surface to intermediate depths.

In the north, the EUC ventilates the OMZ, and in the south the PCU advects low oxygen waters southward towards northern Chile.

[3] Coastal upwelling is the main factor contributing to the high biological productivity of the Humboldt current.

The current hosts a wide range of organisms including multiple species of plankton, mollusks, sea urchins, crustaceans, fish, and marine mammals.

This is due to the moderate upwelling, which causes lower turbulence, as well as a weakened Ekman drift offshore.

These two species experience population shifts related to climate changes and environmental events such as El Niño.

[1] The productivity of the Humboldt Current System is strongly affected by El Niño and La Niña events.

[1] During an El Niño event, the thermocline and upper region of the OMZ deepen to greater than 600 m. This causes a loss of nitrogen and decrease in export of carbon.

[1] During El Niño events, fish abundance and distribution are significantly affected, often leading to stock crashes and cascading social and economic impacts.

These events have led to sequential changes, where sardines and anchovies have replaced each other periodically as the dominant species in the ecosystem.