The Mesozoic is punctuated by several extreme episodes of oxygen drawdown in the ocean, known as Oceanic Anoxic Events (OAE). Beside these discrete events, little is however known about longer-term oxygen level fluctuations and their controls. A high-resolution dataset of Rare Earth Elements (REE) content in carbonate deposited in the Vocontian Basin (SE France) has allowed to survey the evolution of the Cerium anomaly (Ce/Ce*) during part of the Early Cretaceous (latest Hauterivian – early Aptian). This ratio is used as a proxy for the degree of oceanic oxygenation. The Cerium anomaly is compared to the coeval evolution of relative sea level, organic-rich occurrences, and nutrient level proxies, in order to infer a cause-and-consequence relationship between these parameters and the evolution in sea-water oxygenation. The long-term evolution of the Cerium anomaly shows that northwestern Tethyan water masses have evolved from less oxygenated during the latest Hauterivian – early Barremian interval to more oxygenated during the late Barremian – earliest Aptian time, before being strongly oxygen –depleted during the early Aptian OAE 1a time interval. This trend is correlated with both the long-term trend in nutrient levels, as well as with the frequency of organic-rich layers within the rock record. On a medium-term scale (sub-stage level), there is a good correlation between the Cerium anomaly and tectono-eustatism (as deduced by the Mn content of the basinal carbonate and sequence stratigraphic observation on surrounding shallow-water areas). This suggests that sea-level changes, by altering ocean stratification and currents, as well as modulating the amount of nutrient delivered from the continent, exert control on oceanic oxygenation via changes in primary productivity.