Spatio-temporal variability of hypoxic events in the Mauritanian upwelling system

Abstract:

Ocean deoxygenation represents one of the most significant alterations currently observed within marine ecosystems. Hypoxic events in the Eastern Boundary Upwelling Ecosystems (EBUE) have been shown to have substantial impacts on ecological and biogeochemical processes. Moreover, it is anticipated that the severity and frequency of oxygen depletion will increase progressively as a result of climate change.

Despite the Mauritanian coast being identified as one of the ‘‘hot spots’’ for coastal hypoxia, it has received less attention compared to other regions such as the Oregon Coast or the Baltic Sea. In this study, we examine a multi-decadal CTD dataset, including measurements of dissolved oxygen, along the north-south latitudinal gradient of the Mauritanian coast.

Climatologies were used to study the spatio-temporal variability (seasonal, interannual) of typical hypoxic events, as well as the less frequent anoxic events, at different depths. Our study reveals both spatial and temporal occurrences of hypoxia across various areas and layers in addition to considerable spatial variation and seasonal fluctuations in the dynamics of dissolved oxygen and temperature.

The outcomes of this study will contribute to a better understanding of this phenomenon and, ultimately, support the sustainable management of fisheries in Mauritania.