Shock events are, by definition, rare, but they can have devastating consequences for systems. This is especially the case for socio-ecological dynamics given inherent links and nonlinear feedbacks. Yet, we do not have a lot of ecological theory on how shock events affect socio-ecological systems. We use Caribbean coral reef fisheries as a case study to investigate these issues. Coral reef fisheries are an ideal case study as there is often time series data available, the linkages between the social and ecological components of the system are clear, and they are frequently exposed to different types of disturbance events. In particular, the system we consider is often exposed to hurricanes and bleaching events. Past work of these systems has incorporated multi-trophic dynamics and linked these dynamics to the social system via fishing. We extend this previous work to build a framework to incorporate shocks into these socio-ecological models. Specifically, we use a series of five differential equations to model algal turf, macroalgae, coral, parrotfish, and human opinion on conservation. We incorporate shocks as temporary increases in coral or parrotfish mortality.
Results/Conclusions
Here we show that shock events can dramatically alter the dynamics of a socio-ecological system. Without shocks, all state variables go to an equilibrium point with coral cover eventually approaching zero after several decades. We find that shock events can quickly shift the system into an unfavorable alternative stable state. However, we also identify situations where the degradation of coral habitat via a shock event can paradoxically rescue a coral reef because of feedback from the social dynamics. Specifically, a mild shock event spurs action in the community to close the area to fishing and protect the coral reef. This is not possible for larger shock events or if they are too frequent. Our work provides a foundation for additional studies on shocks and socio-ecological dynamics for both coral reef communities and other systems. Our work also highlights how management of coral reef fisheries changes in the face of disturbances. Specifically, without including feedback loops with social dynamics, managers may make incorrect management decisions. More detailed and realistic versions of our models could be used to directly inform policy for specific systems.
