Marine observations of carbonate chemistry variability and OA state in Northwest Africa waters (text & video)

OA Week 2021, Africa Hub Session

Dr. Mohammed Idrissi, National Institute of Fisheries Research, Morocco


The Canary Current Large Marine Ecosystem (CCLME) region supply very significant local and international fish resources, based largely on small pelagic fish and artisanal fisheries. Especially on the North West Africa Atlantic Sea, the fishery market contribute to economy of the region bordering this sea and provide an important food and employment to coastal communities. In 2017, the 30-year long EAF Nansen Program (FAO and Norway), began with studies on ocean acidification along the CCLME region. Here, we show the first results ocean acidification state from this new research theme focusing on the North West Africa waters (from Morocco (35°N) to Senegal (12°N). Between May 2017 and December 2019, samples were measured, on this region, onboard the R/V Dr. Fridtjof Nansen for total alkalinity and pH using potentiometric titration and spectrophotometric pH measurements, respectively. The other parameters describing the carbonate chemistry and ocean acidification state were derived from AT and pH, using the CO2SYS calculation program. The survey performed at twenty seven sections perpendicular from the coast (the mesopelagic transect included) with a total of 110 stations in the full water column. We found large variability along the coast, connected to salinity changes, primary production, temperature and biological processes.

Ocean Acidification Week 2021 was sponsored by the following organizations:

(1) GOA-ON, the Global Ocean Acidification Observing Network,

(2) NOAA, the United States National Oceanic & Atmospheric Administration,

(3) IAEA OA-ICC, the International Atomic Energy Agency – Ocean Acidification International Coordination Centre, and

(4) IOC-UNESCO – the Intergovernmental Oceanographic Commission of the United Nations Educational, Scientific and Cultural Organization

For more information, please visit

GOA-ON, YouTube, 24 September 2021. Text and video.

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