Michele L. Barnes

Coral reefs in the Anthropocene

Coral reefs support immense biodiversity and provide important ecosystem services to many millions of people. Yet reefs are degrading rapidly in response to numerous anthropogenic drivers. In the coming centuries, reefs will run the gauntlet of climate change, and rising temperatures will transform them into new configurations, unlike anything observed previously by humans. Returning reefs to past configurations is no longer an option. Instead, the global challenge is to steer reefs through the Anthropocene era in a way that maintains their biological functions. Successful navigation of this transition will require radical changes in the science, management and governance of coral reefs.

Social networks and environmental outcomes

Significance Understanding how social dynamics drive outcomes in environmental systems is critical to advancing global sustainability. We link comprehensive data on fishers’ information-sharing networks and observed fishing behaviors to demonstrate that social networks are tied to actions that can directly impact ecological health. Specifically, we find evidence that the propensity for individuals to share information primarily with others most similar to themselves creates segregated networks that impede the diffusion of sustainable behaviors—behaviors that could have mitigated the incidental catch of over 46,000 sharks in a single commercial fishery between 2008 and 2012. Our results suggest having a better understanding of social structures and bolstering effective communication across segregated networks has the potential to contribute toward more sustainable environmental outcomes. Social networks can profoundly affect human behavior, which is the primary force driving environmental change. However, empirical evidence linking microlevel social interactions to large-scale environmental outcomes has remained scarce. Here, we leverage comprehensive data on information-sharing networks among large-scale commercial tuna fishers to examine how social networks relate to shark bycatch, a global environmental issue. We demonstrate that the tendency for fishers to primarily share information within their ethnic group creates segregated networks that are strongly correlated with shark bycatch. However, some fishers share information across ethnic lines, and examinations of their bycatch rates show that network contacts are more strongly related to fishing behaviors than ethnicity. Our findings indicate that social networks are tied to actions that can directly impact marine ecosystems, and that biases toward within-group ties may impede the diffusion of sustainable behaviors. Importantly, our analysis suggests that enhanced communication channels across segregated fisher groups could have prevented the incidental catch of over 46,000 sharks between 2008 and 2012 in a single commercial fishery.

When is brokerage negatively associated with economic benefits? Ethnic diversity, competition, and common-pool resources

Abstract There is a growing body of literature positively linking dimensions of social capital to economic benefits. Yet recent research also points to a potential “dark side” of social capital, where over-embeddedness in networks and the pressures associated with brokerage are hypothesized to constrain actors, having a negative effect on economic outcomes. This dichotomy suggests that context is important, yet the overwhelming majority of existing empirical evidence stems from socially homogenous populations in corporate and organizational settings, limiting a broader understanding of when and how context matters. We advance this discourse to a socially fragmented, ethnically diverse common-pool resource system where information is highly valuable and competition is fierce. Merging several unique datasets from Hawaiis pelagic tuna fishery, we find that network prominence, i.e., being well connected locally, has a significant, positive effect on economic productivity. In contrast, we find that brokerage, defined here as ties that bridge either structurally distinct or ethnically distinct groups, has a significant, negative effect. Taken together, our results provide empirical support to widespread claims of the value of information access in common-pool resource systems, yet suggest that in ethnically diverse, competitive environments, brokers may be penalized for sharing information across social divides. Our results thus contribute to an emerging theory on the fragile nature of brokerage that recognizes its potential perils and the importance of context.

Building adaptive capacity to climate change in tropical coastal communities

To minimize the impacts of climate change on human wellbeing, governments, development agencies, and civil society organizations have made substantial investments in improving people’s capacity to adapt to change. Yet to date, these investments have tended to focus on a very narrow understanding of adaptive capacity. Here, we propose an approach to build adaptive capacity across five domains: the assets that people can draw upon in times of need; the flexibility to change strategies; the ability to organize and act collectively; learning to recognize and respond to change; and the agency to determine whether to change or not.Efforts to improve people’s capacity to adapt to climate change have so far focussed on a relatively narrow understanding of adaptive capacity. In this Perspective, the authors propose an approach to build adaptive capacity across a broader set of domains.

Gravity of human impacts mediates coral reef conservation gains

Significance Marine reserves that prohibit fishing are a critical tool for sustaining coral reef ecosystems, yet it remains unclear how human impacts in surrounding areas affect the capacity of marine reserves to deliver key conservation benefits. Our global study found that only marine reserves in areas of low human impact consistently sustained top predators. Fish biomass inside marine reserves declined along a gradient of human impacts in surrounding areas; however, reserves located where human impacts are moderate had the greatest difference in fish biomass compared with openly fished areas. Reserves in low human-impact areas are required for sustaining ecological functions like high-order predation, but reserves in high-impact areas can provide substantial conservation gains in fish biomass. Coral reefs provide ecosystem goods and services for millions of people in the tropics, but reef conditions are declining worldwide. Effective solutions to the crisis facing coral reefs depend in part on understanding the context under which different types of conservation benefits can be maximized. Our global analysis of nearly 1,800 tropical reefs reveals how the intensity of human impacts in the surrounding seascape, measured as a function of human population size and accessibility to reefs (“gravity”), diminishes the effectiveness of marine reserves at sustaining reef fish biomass and the presence of top predators, even where compliance with reserve rules is high. Critically, fish biomass in high-compliance marine reserves located where human impacts were intensive tended to be less than a quarter that of reserves where human impacts were low. Similarly, the probability of encountering top predators on reefs with high human impacts was close to zero, even in high-compliance marine reserves. However, we find that the relative difference between openly fished sites and reserves (what we refer to as conservation gains) are highest for fish biomass (excluding predators) where human impacts are moderate and for top predators where human impacts are low. Our results illustrate critical ecological trade-offs in meeting key conservation objectives: reserves placed where there are moderate-to-high human impacts can provide substantial conservation gains for fish biomass, yet they are unlikely to support key ecosystem functions like higher-order predation, which is more prevalent in reserve locations with low human impacts.

Local management actions can increase coral resilience to thermally-induced bleaching

Recent large-scale analyses suggest that local management actions may not protect coral reefs from climate change, yet most local threat-reduction strategies have not been tested experimentally. We show that removing coral predators is a common local action used by managers across the world, and that removing the corallivorous snail Coralliophila abbreviata from Caribbean brain corals (Pseudodiploria and Diploria species) before a major warming event increased coral resilience by reducing bleaching severity (resistance) and post-bleaching tissue mortality (recovery). Our results highlight the need for increased evaluation and identification of local interventions that improve coral reef resilience.Experimental removal of corallivorous snails from corals in the Caribbean Sea shows that this local management action can improve coral resilience to severe warming through reducing bleaching severity and post-bleaching tissue mortality.

Social–Ecological Network Approaches in Interdisciplinary Research: A Response to Bohan et al. and Dee et al.

[Extract] In two recent articles, Bohan et al. [1] and Dee et al. [2] develop conceptual arguments for the benefits of applying an interdisciplinary social–ecological network approach to the study of human–nature systems in general, and ecosystem services in particular. We agree. Network approaches can account for the interdependencies between complex human and ecological dynamics that underpin many important environmental problems (e.g., [3]). As such, their use has been advocated by several others as a fruitful way to bridge across the natural and social sciences in the development of new theories, frameworks, and tools for environmental problem-solving [4]. We emphasize here that conceptual thinking around social–ecological network sciences is now sufficiently mature to extend beyond the conceptual and look across disciplines to further develop actionable interdisciplinary research. To demonstrate this, we showcase a selection of past efforts and highlight an integrated social–ecological network approach that has already been applied empirically across a range of human–nature contexts. This is intended not only to complement Bohan et al. [1] and Dee et al. [2] but also to serve as a call for research on social–ecological networks to connect more with the existing interdisciplinary literature in the field.

Theorizing the Social Structural Foundations of Adaptation and Transformation in Social-Ecological Systems

Social networks are frequently cited as vital for facilitating successful adaptation and transformation in linked social-ecological systems to overcome pressing resource management challenges. Yet confusion remains over the precise nature of adaptation versus transformation, and the specific social network structures that facilitate these processes. Here we adopt a network perspective to theorize a continuum of structural capacities in social-ecological systems that set the stage for effective adaptation and transformation. We begin by drawing on the resilience literature and the multilayered action situation to link processes of change in social-ecological systems to decision making across multiple layers of rules underpinning societal organization. We then present a framework that hypotheses seven specific social-ecological network configurations that lay the structural foundation necessary for facilitating adaptation and transformation, given the type and magnitude of human action required. A key contribution of the framework is explicit consideration of how social networks relate to ecological structures and the particular environmental problem at hand. Of the seven configurations identified, three are linked to capacities conducive for adaptation and three to transformation, while one is hypothesized to be important for facilitating both processes. We discuss how our theoretical framework can be applied in practice by highlighting existing empirical examples from related environmental governance contexts. Further extension of our hypotheses, particularly as more data become available, can ultimately help guide the design of institutional arrangements more effective at dealing with change.

The social structural foundations of adaptation and transformation in social-ecological systems

Social networks are frequently cited as vital for facilitating successful adaptation and transformation in linked social-ecological systems to overcome pressing resource management challenges. Yet confusion remains over the precise nature of adaptation vs. transformation and the specific social network structures that facilitate these processes. Here, we adopt a network perspective to theorize a continuum of structural capacities in social-ecological systems that set the stage for effective adaptation and transformation. We begin by drawing on the resilience literature and the multilayered action situation to link processes of change in social-ecological systems to decision making across multiple layers of rules underpinning societal organization. We then present a framework that hypothesizes seven specific social-ecological network configurations that lay the structural foundation necessary for facilitating adaptation and transformation, given the type and magnitude of human action required. A key contribution of the framework is explicit consideration of how social networks relate to ecological structures and the particular environmental problem at hand. Of the seven configurations identified, three are linked to capacities conducive to adaptation and three to transformation, and one is hypothesized to be important for facilitating both processes. We discuss how our theoretical framework can be applied in practice by highlighting existing empirical examples from related environmental governance contexts. Further extension of our hypotheses, particularly as more data become available, can ultimately help guide the design of institutional arrangements to be more effective at dealing with change.

The pleasure of pursuit: recreational hunters in rural Southwest China exhibit low exit rates in response to declining catch

Hunting is one of the greatest threats to tropical vertebrates. Examining why people hunt is crucial to identifying policy levers to prevent excessive hunting. Overhunting is particularly relevant in Southeast Asia, where a high proportion of mammals and birds are globally threatened. We interviewed hunters in Southwest China to examine their social behavior, motivations, and responses to changes in wildlife abundance. Respondents viewed hunting as a form of recreation, not as an economic livelihood, and reported that they would not stop hunting in response to marked declines in expected catch. Even in scenarios where the expected catch was limited to minimal quantities of small, low-price songbirds, up to 36.7% of respondents said they would still continue to hunt. Recreational hunting may be a prominent driver for continued hunting in increasingly defaunated landscapes; this motivation for hunting and its implications for the ecological consequences of hunting have been understudied relative to subsistence and profit hunting. The combination of a preference for larger over smaller game, reluctance to quit hunting, and weak enforcement of laws may lead to hunting-down-the-web outcomes in Southwest China.