From external shocks to internal propagation within agri-food systems: a socio-metabolic perspective of the animal sector on an isolated tropical island

Insular agri-food systems face significant challenges due to their exposure to external shocks via trade dependencies, geographic isolation, and constrained land and natural resources. This study proposes a novel socio-metabolic analytical framework and applies it to investigate how external shocks propagate within the animal product supply systems (APSS) of La Reunion Island, a French overseas department. By conceptualizing APSS as a metabolic network, we analyze characteristics that influence three vulnerability factors: exposure, sensitivity, and incapacity to cope. To analyze shock propagation dynamics, this paper introduces the distinction between cascading and domino effects: cascading effects trace the sectors and stages impacted, while domino effects highlight how the nature of disruptions evolves as they spread. Using a mixed-methods approach, we map flow dynamics and identify critical interaction nodes susceptible to convey shock propagation clusters. Drawing on stakeholder insights, our empirical findings from disruptions during the COVID-19 pandemic, the Russo-Ukrainian war, and other events reveal the interplay of different cascading and domino effects influencing the availability, accessibility and stability of animal-based products. Our findings underscore a paradox: while import-dependent local APSS are highly exposed and present vulnerabilities to external shocks, they also buffer impacts on the food supply by ensuring some degree of autonomy. The results offer insights into the systemic vulnerabilities of insular agri-food systems and provide a framework for analyzing shock propagation in complex food supply networks.