Coastal upwelling off Peru: Low Oxygen, Low PH, High Variability

Chair: Yuri Artioli

Graco Michelle (1), Avy Bernales (1), Carhuapoma Wilson (1, 2), Diana Alvites (2), Beaufort Luc (3), David Correa (1)

1 DGIOCC, Instituto del Mar del Perú IMARPE, Callao, 22, Perú
2 CEREGE Université Aix- Marseille. Aix., France
3 University Peruana Cayetano Heredia (UPCH), Lima, Perú

Background
The Coastal Upwelling off Perú, one of the most productive ecosystems in the world, is considered a hot spot for the scientific community, because of the extensive and intensive Oxygen Minimum Zone (ZMO), the low pH, its role as a source of CO2 and N2O and one of the strongest interannual signals of variability such as El Niño. Considering the complex relationships between environmental factors, biotic components and variability it was necessary develop an integrated study with different disciplines and approaches in order to get a better understanding of how this ecosystem works and the feedbacks between its different components.

Methods
Since 2013, at IMARPE, we perform a national project with international partners to investigate the upwelling of Peru from the sediments to the atmosphere. We perform with a bimonthly resolution a sampling in the central area of Peru, Callao (12°C) from the coast to 50 mn, in order to characterize the physical, chemical and the biological component.

Findings
Here, we will present recent results associated with the last El Niño event 2014-2015 in the variability of the OMZ and pH off Callao and the strong impact in the chemistry and the phytoplankton communities. The data indicate a strong presence of the nanoplankton community and coccolitophorids with different degrees of calcification in a coastal open-ocean gradient of physical conditions, oxygen, N/P ratio and pH.

Conclusions
We confirm that the upwelling ecosystems is a window for insights in the context of the climate change and is necessary the review of some paradigms.