The emerging threat to the coastal urban ecosystems from increased intensity and frequency of weather events is a compelling reason for improving our understanding of the integrity of the existing ecosystem. Resilience of an ecosystem is a critical property that aids recovery and adaptation when subject to intense stress. Quantifying the resilience of an ecological system requires a detailed understanding of the vulnerabilities and interactions within a complex web of interconnected social, technological and economic networks. Through an ecological network analysis of ascendency and redundancy of the flux of energy and material flows, the causal relationships are established through structural equations modeling (SEM) techniques. A model based-on the five factors of driving force (D), pressure (P), state (S), impact (I), and response (R) (DPSIR), recognizes the different roles these factors play in the coastal urban ecological security system of China. Energy and material flows transmission equations of the ecological security network are developed to evaluate the resilience of the ecological security network. The results show that the ecological security network of Chinese coastal cities has a relatively high network occupation rate (A/C = 0.6898), indicating a relatively mature state of the ecological security network of coastal cities with sufficient metabolic capacity and steady status. The low vacancy rate (R/C = 0.3102) shows that the coastal ecological security network lacks flexibility of surplus space. The energy and material flows conversion and dissipation ability in the network are strong: the five factors of DPSIR are highly interdependent, and the ecological security network framework is both steady and mature. However, the resilience of the coastal urban ecosystem against external impacts is weak. It is critical for coastal cities to broaden their planning protocols to introduce more flexible space to increase resilience and guarantee a robust pathway for sustainable development. This study contributes to a rational method for testing the internal causal relationships among DPSIR linkages toward quantifying our understanding of the resilience of a security ecosystem.
Climate change constitutes a new threat to the sustainability of coral ecosystems. The vulnerability of a coral ecosystem to climate-related hazards can greatly increase when it suffers from chronic anthropogenic disturbances (wastewater discharges, eutrophication). These indeed reduce the ability of coral reefs to withstand these hazards (resistance) and their potential to recover their initial condition (resilience) in case of very impacting hazards. Therefore, there is a risk of an amplifier feedback loop snapping in place with an endpoint of a crippling loss of resilience of coral formations and eventually the disappearance of most of them. Reducing such an amplifier feedback loop should be one of the main objectives of the coral coastal management in order to build new human/coral reef societies coviability to face climate change. Reconsidering the strategies of the creation of marine protected areas fits into this framework. This requires a focus on reef connectivity, resistance and resilience of species and species assemblages.
The resilience and recovery dynamics of deep-sea habitats impacted by bottom trawling are poorly known. This paper reports on a fishing impact recovery comparison based on four towed camera surveys over a 15-year period (2001–2015) on a group of small seamounts on the Chatham Rise, east of New Zealand, on which pre-disturbance benthic communities are dominated by thicket-forming scleractinian corals. The six seamounts studied encompass a range of trawl histories, including one with high and persistent levels of trawling throughout the survey period, two with intermittent and intermediate levels of trawling, two which were low/untrawled, and one, ‘Morgue’, which was closed to trawling in 2001, having been heavily trawled up to that point. Still photographs from all surveys were analyzed for the identification and abundance of all visible benthic fauna with effort made to ensure consistency of data among surveys. Because increases in image resolution and quality over time resulted in a persistent trend of increasing abundances, analyses were concentrated on comparisons among seamounts within surveys and how these relationships changed with time. The abundance, species richness, and diversity of benthic communities were higher on low/untrawled seamounts than on those that had been trawled. Multivariate community structure showed similar patterns at each survey point, the low/untrawled seamounts being strongly dissimilar to the persistently trawled seamount, with the others ranged between these extremes, broadly in accordance with their cumulative trawl histories. Community structure on the persistently trawled seamount was less variable than on the other seamounts throughout the study period, possibly because of regular ‘re-setting’ of the community by disturbance from trawling. Although there was some variability in results between whole seamount and summit sector analyses, in general communities on Morgue remained similar to those on the persistently trawled seamount, showing little indication of steps toward recovery to its pre-disturbance state following its closure. These results indicate low resilience of benthic communities on the seamounts to the effects of bottom trawling.
Coral reef managers currently face the challenge of mitigating global stressors by enhancing local ecological resilience in a changing climate. Effective herbivore management is one tool that managers can use in order to maintain resilience in the midst of severe and frequent bleaching events. One recommended approach is to establish networks of herbivore management areas (HMAs), which prohibit the take of herbivorous reef fishes. However, there is a need to develop design principles to guide planning and implementation of these HMAs as a resilience-building tool. We refine available guidance from fully protected marine protected area (MPA) networks and developed a set of 11 biophysical design principles specifically for HMAs. We then provide a case study of how to apply these principles using the main Hawaiian Islands. We address site-specific considerations in terms of protecting habitats, including ecologically critical areas, incorporating connectivity, and addressing climate and local threats. This synthesis integrates core marine spatial planning concepts with resilience-based management and provides actionable guidance on the design of HMAs. When combined with social considerations, these principles will support spatial planning in Hawai‘i and could guide the future design of HMA networks globally.
The transformation of coral reefs has profound implications for millions of people. However, the interactive effects of changing reefs and fishing remain poorly resolved. We combine underwater surveys (271 000 fishes), catch data (18 000 fishes), and household surveys (351 households) to evaluate how reef fishes and fishers in Moorea, French Polynesia responded to a landscape-scale loss of coral caused by sequential disturbances (a crown-of-thorns sea star outbreak followed by a category 4 cyclone). Although local communities were aware of the disturbances, less than 20% of households reported altering what fishes they caught or ate. This contrasts with substantial changes in the taxonomic composition in the catch data that mirrored changes in fish communities observed on the reef. Our findings highlight that resource users and scientists may have very different interpretations of what constitutes ‘change’ in these highly dynamic social–ecological systems, with broad implications for successful co-management of coral reef fisheries.
Ecological theory predicts that ecosystems with multiple basins of attraction can get locked in an undesired state, which has profound ecological and management implications. Despite their significance, alternative attractors have proven to be challenging to detect and characterize in natural communities. On coral reefs, it has been hypothesized that persistent coral-to-macroalgae “phase shifts” that can result from overfishing of herbivores and/or nutrient enrichment may reflect a regime shift to an alternate attractor, but, to date, the evidence has been equivocal. Our field experiments in Moorea, French Polynesia, revealed the following: (i) hysteresis existed in the herbivory–macroalgae relationship, creating the potential for coral–macroalgae bistability at some levels of herbivory, and (ii) macroalgae were an alternative attractor under prevailing conditions in the lagoon but not on the fore reef, where ambient herbivory fell outside the experimentally delineated region of hysteresis. These findings help explain the different community responses to disturbances between lagoon and fore reef habitats of Moorea over the past several decades and reinforce the idea that reversing an undesired shift on coral reefs can be difficult. Our experimental framework represents a powerful diagnostic tool to probe for multiple attractors in ecological systems and, as such, can inform management strategies needed to maintain critical ecosystem functions in the face of escalating stresses.
Ecological trade-offs due to different perturbations are here quantified by comparing direct impacts and net effects using fishing pressures on marine ecosystems as controlled perturbations. Results highlight that trade-offs emerge in majority of cases when evaluated through multispecies models and are independent from model complexity. Trade-offs showed a dome-shaped relationship with direct impact thus supporting the theory of positive effects of intermediate levels of disturbance. Moreover, trade-off intensity resulted to be related to the capability of the system to react to perturbation, i.e., to ecosystem resilience. Overall the work shows the benefit of complex system analysis that permits the emerging ecological trade-offs which are neglected in simpler single species analyses.
Resilience underpins the sustainability of both ecological and social systems. Extensive loss of reef corals following recent mass bleaching events have challenged the notion that support of system resilience is a viable reef management strategy. While resilience-based management (RBM) cannot prevent the damaging effects of major disturbances, such as mass bleaching events, it can support natural processes that promote resistance and recovery. Here, we review the potential of RBM to help sustain coral reefs in the 21st century. We explore the scope for supporting resilience through existing management approaches and emerging technologies and discuss their opportunities and limitations in a changing climate. We argue that for RBM to be effective in a changing world, reef management strategies need to involve both existing and new interventions that together reduce stress, support the fitness of populations and species, and help people and economies to adapt to a highly altered ecosystem.
To cope with fisheries unsustainability, the Mexican government has recently promoted strategies of public participation to support decision making. This type of strategy is important in the Huave Lagunar System (HLS) in the Isthmus of Tehuantepec, Oaxaca, where fishers have historically maintained close ethnobiological interactions with their natural resources. This chapter describes the pre-Hispanic fishery system of San Francisco del Mar Pueblo Viejo under the premise that self-government practices in HLS favor the pursuit of social resilience, the ability of a self-organizing system to return to its original state after being disturbed by extreme events. The design of a Fisheries and Climate Planning Agenda that includes strategies considering key aspects of social diversity presents itself as an opportunity to facilitate the reach of social support for decision making, an essential step toward supporting a realistic panorama of sustainability for the sector.
This chapter synthesizes more than two decades of interdisciplinary scholarship by the coauthors related to fishing families and coastal communities. Amid the contemporary narrative of increasing coastal storms, erosion, and other physical hazards associated with climate and related coastal hazards facing coastal communities, we find myriad ways that Oregon fishing families and communities adapt to changes and continually demonstrate cultural and community resilience. Fishing families have exhibited their resilience through transformations in family roles, changes in the makeup of the fleet (graying), and never-ending management and resource shifts. This process of adapting to change has been a thread in our research, from one of our first collaborative projects, Adapting to Change: Fishing Businesses, Families, Communities, and Regions (1995) to our current project, The Old(er) Men of the Sea: Graying of the Fishing Industry and Its Impact on Local Community Resiliency. Our work illustrates an ever-present culture of adaptation that serves as the anchor of resilience in coastal Oregon.