Ocean ecosystems are shaped by complex interactions between thousands of species, from microscopic organisms near the surface to deep-sea predators thousands of metres below. Understanding how these interconnected communities may respond to climate change and emerging human activities requires approaches that can capture the movement of energy and resources through the entire food web.

Food web models provide a way to explore these connections by representing how organisms interact, how energy moves between different parts of the ecosystem, and how changes in one part of the food web can affect the wider system. By creating a vertically connected model of the ocean, from the surface to the deep seafloor, it becomes possible to investigate how pressures can cascade through marine ecosystems over different timescales.

A key focus is understanding the role of mesopelagic organisms—animals living in the middle layers of the ocean, typically between around 200 and 1,000 metres depth. These communities include fish, squid, and gelatinous organisms that form an important link between surface waters and the deep ocean. Through daily movements between shallow and deeper waters, they transport energy and carbon through the ocean and contribute to the biological carbon pump. However, these organisms are increasingly recognised as potentially vulnerable to future pressures, including climate change and possible future exploitation by mesopelagic fisheries.

The food web model developed in this work will provide a detailed picture of the current state of the North Atlantic Current and Evlanov Sea basin Marine Protected Area (NACES MPA) ecosystem, including interactions between organisms living throughout the water column and on the seafloor. Information on species abundance, diets, energy flows, and ecosystem connections will be combined to understand how the system functions today and identify the conditions needed to maintain a healthy and resilient ocean ecosystem.

Beyond describing the present-day ecosystem, the model will be used to explore how ocean food webs may change under different future scenarios. These scenarios will consider the combined effects of climate change, existing fisheries pressures, and potential emerging activities such as mesopelagic fisheries. By testing different levels of disturbance, the model will help identify when ecosystems may approach critical limits beyond which recovery becomes more difficult.

A central concept in this work is ecosystem stability, which is the ability of an ecosystem to absorb change while continuing to function and recover after disturbance. By identifying indicators of ecosystem health and thresholds of change, it will be possible to define the conditions that allow ocean ecosystems to remain within a safe operating space. This knowledge will support proactive management by identifying risks before irreversible changes occur.

Changes in ocean ecosystems also have important consequences for people. Marine food webs support biodiversity, fisheries, carbon storage, and other benefits that society depends on. Future scenarios will therefore also consider the economic and social implications of ecosystem changes, including potential benefits and costs associated with emerging activities. Particular attention will be given to questions of fairness, including how risks and benefits are distributed between different communities and between present and future generations.

The insights generated will provide a science-based foundation for understanding the consequences of emerging threats and evaluating possible management pathways. By linking ecosystem modelling with economic and social perspectives, this work will support decisions that protect ocean resilience while considering the needs of both current and future generations.

OceanSOS’ work on cumulative and cascading impacts is led by Dr. Rolf Groeneveld at Wageningen University, supported by Dr. Lea-Anne Henry at Mara Consultants Ltd.