COS 93-5 - Feedbacks between ecosystem state and human behavior determine coral reef resilience

Friday, August 12, 2016: 9:20 AM
Palm B, Ft Lauderdale Convention Center
Andrew Rassweiler, Department of Biological Science, Florida State University, Tallahassee, FL, Matthew Lauer, Department of Anthropology, San Diego State Univeristy, San Diego, CA and Sally Holbrook, Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA

Disturbance and recovery are natural features of ecosystems, but in many systems the trajectories of recovery from disturbance have been radically altered by human activity.  Although the effects of human activity on ecosystem resilience and recovery have been studied extensively, human activity is typically treated as an external driver, rather than as a dynamic component of the system. This is true for coral reef systems, with an increasing number of coral reefs worldwide being shown to undergo persistent transitions from coral-dominated to macroalgae-dominated community states.  Fishing on herbivores contributes to reduced reef resilience, as lower herbivory can make it easier for macroalgae to become established after disturbances that result in landscape-scale loss of coral. Despite the acknowledged importance of fishing, relatively little attention has been paid to the potential for feedbacks between ecosystem state and fisher behavior, in part because it requires deep collaboration between social and natural scientists. Here we explore how dynamic feedbacks between human behavior and ecosystem state affect recovery from disturbance in coral reefs in Moorea, French Polynesia.  We couple methods from environmental anthropology with spatially explicit ecological models to explore these feedbacks between small-scale fisheries and coral reefs.


Our anthropological work  has revealed  how aspects of ecological state such as the abundance of macroalgae affect people’s preference for fishing in particular lagoon habitats. We incorporate these habitat preferences into a spatially explicit bio-economic model of ecological dynamics and fishing in Moorea’s lagoons, and  show that feedbacks between spatial fishing behavior and ecological state can have critical effects on coral reef resilience. When fishers avoid macroalgae-dominated patches, this behavior consistently leads to more coherence across the reef-scape. However, this coherence results in sharply divergent outcomes depending on the scale of disturbance.  For modest disturbances, the behavior can promote recovery of coral, increasing resilience, but for more severe disturbances it can accelerate coral decline, creating fragility at the landscape scale.  The effects of these feedbacks with human behavior also depend on the details of fisher mobility, particularly the spatial scales over which they make decisions about where to fish. These results emphasize that resilience and other properties of coral reefs cannot be understood without considering humans as a dynamic part of the system.