Deoxygenation and the impact on ocean biogeochemistry in the Santa Barbara Channel, and the broader implication for deoxygenation policy

Deoxygenation occurs along coastal environments and open ocean that affects ocean biogeochemistry and marine species. The causes of deoxygenation are multifaceted and can be influenced by various physical and biogeochemical properties in the ocean. The California Current System experiences deoxygenation along its coast and continental shelf, and effects sub-basins like the Santa Barbara Channel (SBC), located in the Southern California Bight. Here, oxygen concentrations can become hypoxic and anoxic, influencing the release of trace metals like iron from the sediment and the formation of sulfur-oxidizing bacteria mats in response to sulfide production in the sediment. Quantifying the impacts that deoxygenation has in the Santa Barbara Channel, will provide insights into ocean biogeochemistry locally, and in the California Current System more generally, along with guidance for broader ocean policies to advance regulations to combat ocean deoxygenation. In this dissertation, I will use data from two research expedition on R/V Atlantis in 2019 and 2023 to the Santa Barbara Channel and its basin, to quantify how benthic Fe flux affects phytoplankton growth along with the spatial and temporal distribution of oxygen in the basin; and extrapolate the impact of hypoxia and anoxia on basin-wide benthic Fe flux. Lastly, I developed a framework to determine the factors that can contribute to the implementation of deoxygenation policy into the Biodiversity Beyond National Jurisdiction Treaty. Since deoxygenation can affect marine biodiversity, fisheries management, and blue economies, it is important to determine the social-human environmental factors for governance and management as it relates to deoxygenation. Chapter 2. To investigate the influence of benthic Fe release from the oxygen-deficient deep basin on surface phytoplankton production, we combined benthic Fe flux measurements with numerical simulations using the Regional Ocean Model System coupled to the Biogeochemica