About This Project

During severe low-oxygen events, rock lobsters can walk out of the ocean. Building on ocean glider observations of a 2026 South African walkout, we will test whether a Living Threshold integrating oxygen and temperature better predicts historical walkouts than oxygen alone. An extended 2027 glider deployment in hypoxic Walvis Bay, Namibia, combined with regional modelling, will test how these thresholds develop across the West African margin.

Ask the Scientists

What is the context of this research?

Severe low-oxygen events occur throughout the Benguela upwelling system, sometimes triggering lobster walkouts, fish kills and major ecosystem impacts. Yet hypoxia is usually defined using a fixed oxygen threshold, even though an animal’s oxygen requirements change also with temperature. In February 2026, our gliders captured temperature and oxygen before and during a major lobster walkout in Elands Bay, South Africa, allowing us to explore a lobster-specific Metabolic Index as a Living Threshold at unprecedent spatio-temporal resolution. We will now expand from this event across space and time: hindcasting historical events with regional models and extending a 2027 glider deployment in Walvis Bay, Namibia, to observe how physiologically stressful habitat develops. Together, these observations and models will explore Living Thresholds across the wider West African margin.

What is the significance of this project?

A threshold is useful only if crossing it tells us something biologically meaningful. Fixed oxygen thresholds are simple, but identical oxygen levels can affect animals differently depending on temperature and physiology. Living Thresholds offer a way to connect changing ocean conditions directly to biological stress. Lobster walkouts provide a clear observed response to test this idea, while Walvis Bay offers a contrasting natural laboratory where extreme hypoxia affects multiple marine species. By combining autonomous observations with regional modelling, we can test whether biologically informed thresholds outperform oxygen alone, and understand where, when and why they are crossed. Improving our ability to predict these events could translate oxygen loss into ecological risk across one of the world’s major upwelling systems, with direct relevance for fisheries and coastal communities affected by walkouts and fish kills.

What are the goals of the project?

We will test whether Living Thresholds identify biologically dangerous hypoxia better than oxygen alone. First, we will combine historical lobster walkout records from South Africa's Department of Forestry, Fisheries and the Environment (DFFE), satellite and atmospheric reanalysis data, and Princeton University ocean hindcast model, developed and evaluated through WAM, to test the lobster Metabolic Index beyond the 2026 Elands Bay event. Second, we will extend the planned three-month 2027 WAM glider deployment in Walvis Bay, Namibia, by 1 to 2 months, collecting over 3,000 additional vertical profiles. These observations will track the onset, persistence and variability of extreme hypoxia and identify when physiological thresholds are crossed. Finally, we will use the ocean hindcast model to examine the oceanographic processes driving threshold crossings and assess their wider relevance along the West African margin.