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1.
In recent years conservationist NGOs, policy makers, and scientists in the tropics have expressed a fascination with marine protected areas for simultaneously achieving conservation goals and economic development. Despite their popularity, MPAs often encounter serious implementation challenges due to, at least to some extent, our limited understanding of MPA processes as influenced by neoliberal ideology and practice. By resituating MPAs in debates of neoliberal conservation, this study aims to examine social and economic changes that MPAs bring about in fishing communities. Taking a fishing village in the Philippines as a case study, it shows technocratic solution seeking led to further marginalization of small-scale fishers through unequal distribution of benefits and burdens. Here it is argued that MPAs are prone to exclusionist processes of redefining the value and legitimate users of marine resources, which further limits the opportunities for small-scale fishers to participate meaningfully in resource governance.  相似文献   

2.
Recently there has been increased interest in the use of Marine Protected Areas (MPAs) as tools for the conservation of marine habitats and species. This has resulted in the declaration of many MPAs around the world. Despite this activity there have been few tests of hypotheses about the design criteria for selection and management of these areas, resulting in a haphazard and ad hoc selection of protected areas, with conflicting and inconsistent terminology and objectives. The application of appropriately tested scientific information to the design of MPAs will increase the likelihood of success in the future.To 1st January 1992, 267 MPAs had been declared in Australia, covering a total area of ca 400 019 km2. The history of their declaration has been sporadic and uneven. Conflicts over State and Federal legislation and, within states, conflicts over jurisdiction among agencies caused by overlapping responsibilities, have at times slowed the declaration of MPAs. In this paper, the history of MPAs in Australia is used as a case study to discuss the problems, both biological and administrative, of declaring MPAs.  相似文献   

3.
Marine protected areas (MPAs) are increasingly being recognized as an alternative management tool for conserving marine resources and ecosystems. By integrating organism dispersal rates, ecosystem interactions and fishing effort dynamics, ECOSPACE, a spatially explicit ecosystem-based modeling tool, allowed us to compare the ecological consequences of alternative MPA zoning policies within the proposed Gwaii Haanas National Marine Conservation Area, located off the west coast of British Columbia, Canada. The desired effects of MPAs include higher fishery yields, the conservation of biodiversity, and/or the preservation of intact ecosystems. However, ECOSPACE predicts that when MPAs are small, species interactions and movements may make these objectives difficult to achieve. ECOSPACE suggests that the effects of MPAs are reduced at their boundaries where fishing effort is predicted to concentrate. Furthermore, top predators may become more abundant within MPAs, which could lead to a depression of their prey species and a subsequent increase of species at even lower trophic levels. Trophic cascade patterns and density gradients across boundaries are nontrivial departures from our simple expectations of how MPAs protect areas and will force us to reconsider what constitutes effective conservation. Our ECOSPACE model indicates that the establishment of multi-use buffer zones may help alleviate these realistic but worrisome ecological predictions. When coupled with an overall reduction in harvest pressure, ECOSPACE suggests that a MPA with a large core `no-take' zone and large buffer will result in the greatest increase in organism biomass. The use of marine zoning may be an effective management tactic to reduce social conflict and conserve marine ecosystems.  相似文献   

4.
Models provide useful insights into conservation and resource management issues and solutions. Their use to date has highlighted conditions under which no-take marine protected areas (MPAs) may help us to achieve the goals of ecosystem-based management by reducing pressures, and where they might fail to achieve desired goals. For example, static reserve designs are unlikely to achieve desired objectives when applied to mobile species or when compromised by climate-related ecosystem restructuring and range shifts. Modelling tools allow planners to explore a range of options, such as basing MPAs on the presence of dynamic oceanic features, and to evaluate the potential future impacts of alternative interventions compared with ‘no-action’ counterfactuals, under a range of environmental and development scenarios. The modelling environment allows the analyst to test if indicators and management strategies are robust to uncertainties in how the ecosystem (and the broader human–ecosystem combination) operates, including the direct and indirect ecological effects of protection. Moreover, modelling results can be presented at multiple spatial and temporal scales, and relative to ecological, economic and social objectives. This helps to reveal potential ‘surprises'', such as regime shifts, trophic cascades and bottlenecks in human responses. Using illustrative examples, this paper briefly covers the history of the use of simulation models for evaluating MPA options, and discusses their utility and limitations for informing protected area management in the marine realm.  相似文献   

5.
The concept of sustainability, an abstract one by its nature, has been given a mathematical representation through the use of Fisher information as a measure. It is used to propose the sustainability hypotheses for dynamical systems, which has paved the way to achieve sustainable development through externally enforced control schemes. For natural systems, this refers to the task of ecosystem management, which is complicated due the lack of clear objectives. This work attempts to incorporate the idea of sustainability in ecosystem management. The natural regulation of ecosystems suggests two possible control options, top-down control and bottom-up control. A comparison of these two control philosophies is made on generic food chain models using the objectives derived from the sustainability hypotheses. Optimal control theory is used to derive the control profiles to handle the complex nature of the models and the objectives. The results indicate a strong relationship between the hypotheses and the dynamic behavior of the models, supporting the use of Fisher information as a measure. As regards to ecosystem management, it has been observed that top-down control is more aggressive but can result in instability, while bottom-up control is guaranteed to give a stable and improved dynamic response. The results also indicate that bottom-up control is a better option to affect shifts in the dynamic regimes of a system, which may be required to recover the system from a natural disaster like the hurricane Katrina.  相似文献   

6.
It is argued that multiscale approaches are necessary for an explanatory modeling of biological systems. A first step, besides common to the multiscale modeling of physical and living systems, is a bottom-up integration based on the notions of effective parameters and minimal models. Top-down effects can be accounted for in terms of effective constraints and inputs. Biological systems are essentially characterized by an entanglement of bottom-up and top-down influences following from their evolutionary history. A self-consistent multiscale scheme is proposed to capture the ensuing circular causality. Its differences with standard mean-field self-consistent equations and slow-fast decompositions are discussed. As such, this scheme offers a way to unravel the multilevel architecture of living systems and their regulation. Two examples, genome functions and biofilms, are detailed.  相似文献   

7.
The ups and downs of trophic control in continental shelf ecosystems   总被引:1,自引:0,他引:1  
Traditionally, marine ecosystem structure was thought to be determined by phytoplankton dynamics. However, an integrated view on the relative roles of top-down (consumer-driven) and bottom-up (resource-driven) forcing in large-scale, exploited marine ecosystems is emerging. Long time series of scientific survey data, underpinning the management of commercially exploited species such as cod, are being used to diagnose mechanisms that could affect the composition and relative abundance of species in marine food webs. By assembling published data from studies in exploited North Atlantic ecosystems, we found pronounced geographical variation in top-down and bottom-up trophic forcing. The data suggest that ecosystem susceptibility to top-down control and their resiliency to exploitation are related to species richness and oceanic temperature conditions. Such knowledge could be used to produce ecosystem guidelines to regulate and manage fisheries in a sustainable fashion.  相似文献   

8.
The paper reviews the main findings of rocky shore and subtidal nearshore experimental marine ecology (EME) in cold and temperate marine ecosystems during the past four decades. It analyzes the role of EME in coastal management and conservation. The historical development of strategies for managing single or multispecies fisheries are reviewed. The published results show over-exploitation and depletion of more than 60% of the fish stocks and a lack of connection between the management of fisheries and results derived from experimental marine ecology. This is mainly due to: (a) the different temporal and spatial scale at which most marine ecologists and fishery managers operate; (b) the lack of long-term fishery monitoring and adaptive techniques for management; and (c) limitations in the design of experiments on fisheries. Large-scale oceanic perturbations, due to combinations of excessive resource exploitation and environmental variability coupled with present trends in management approaches are discussed. Modern approaches and tools for management of fisheries, such as Adaptive Management (AM), Territorial User Rights in Fisheries (TURFs), Individual Transferrable Quotas and Non-Transferrable Quotas (ITQs, INTQs) are discussed in the context of small-scale fisheries and EME. Published views on limits of applied ecological research with regards to management of fisheries are discussed. Linkages between EME, marine conservation and the establishment of Marine Protected Areas (MPAs) and experimental exclusions of humans are highlighted. Results derived from MPAs, such as: (a) species or community trophic cascades, and (b) the role of key-stone species and species interaction strengths, are discussed. It is concluded that the role of EME in conservation has been greater than has been the case in management of fisheries. The potential to link EME, conservation and the management of fisheries is exemplified through the proposed establishment in Chile of a connected network of Scientific Reserves, MPAs and TURFs sites. The final conclusion is that to cross-fertilize EME, conservation and management, there are three main challenges: (1) to end the traditional view of approaching the management of fisheries and marine conservation as contradictory/antagonizing issues; (2) to improve communications between experimental marine ecology and the management of fisheries through the implementation of experimentation and adaptive management; (3) to improve linkages between marine conservation, the management of fisheries and social sciences.  相似文献   

9.
The ability of marine protected areas (MPAs) to provide protection from indirect stressors, via increased resilience afforded by decreased impact from direct stressors, remains an important and unresolved question about the role MPAs can play in broader conservation and resource management goals. Over a five-year period, we evaluated coral and fish community responses inside and outside three MPAs within the Roviana Lagoon system in Solomon Islands, where sedimentation pressure from upland logging is substantial. We found little evidence that MPAs decrease impact or improve conditions and instead found some potential declines in fish abundance. We also documented modest to high levels of poaching during this period. Where compliance with management is poor, and indirect stressors play a dominant role in determining ecosystem condition, as appears to be the case in Roviana Lagoon, MPAs may provide little management benefit.  相似文献   

10.
Over the past 40 years there have been marked shifts in arable farmland management that are widely believed to have had a considerable impact on flowering plants and invertebrates and the small mammals and birds that rely upon them. It is not yet possible to predict the dynamics of plants and invertebrates either with past or future changes in farmland management. This study investigates whether a basic invertebrate classification, formed of broad trophic groups, can be used to describe interactions between invertebrates and their resource plants and evaluate management impacts for genetically modified, herbicide-tolerant (GMHT) and conventional herbicide management in both spring- and winter-sown oilseed rape. It is argued that the analyses validate trophic-based approaches for describing the dynamics of invertebrates in farmland and that linear models might be used to describe the changes in invertebrate trophic group abundance in farmland when driven by primary producer abundance or biomass and interactions between invertebrates themselves. The analyses indicate that invertebrate dynamics under GMHT management are not unique, but similar to conventional management occurring over different resource ranges, and that dynamics differed considerably between spring- and winter-sown oilseed rape. Thus, herbicide management was of much lower impact on trophic relationships than sowing date. Results indicate that invertebrate dynamics in oilseed rape are regulated by a combination of top-down and bottom-up trophic processes.  相似文献   

11.
Recent arguments for conventional fisheries management approaches (CFMAs) and against no-take marine protected areas (NTMPAs) are reviewed, i.e. CFMAs are more effective, density-dependent factors will lead to reduced fish stock production in and around NTMPAs, rights-based approaches in combination with CFMAs will be more effective, and natural refuges from fishing already exist. It is concluded that these are largely valid but only from a fisheries management perspective. The arguments of proponents of NTMPAs and those of proponents of CFMAs are considered as contrasting storylines, the divergences between which are based on two key factors: different objectives and different science. In relation to different objectives, it is concluded that the arguments against NTMPAs based on their lack of fisheries management benefits must be considered as only applying to the secondary resource conservation objectives of such designations and not to the primary marine biodiversity conservation objectives. On this basis it is argued that it is counter-productive for NTMPAs to be ‘sold’ on a win–win basis, including their potential to deliver fisheries management benefits, as this detracts from their marine biodiversity conservation objectives and leaves such calls open to arguments that CFMAs are better able to deliver fisheries management objectives. In relation to different science, it is concluded that criticisms of NTMPAs and support for CFMAs implicitly resist the shift from Mode 1 (reductive, intra-disciplinary) to Mode 2 (holistic, trans-disciplinary) science that is inherent in calls for NTMPAs as part of an ecosystem approach. Mode 2 science attempts to accommodate both uncertainty and wider societal values and preferences, and it is argued that arguments for NTMPAs should be more explicitly focussed on this potential. It is difficult, if not impossible and inappropriate, to extend the reductive approach inherent in CFMA analyses to encompass the broader ethical and scientific concerns for the health of marine ecosystems and their component populations and habitats that arguments for NTMPAs reflect. NTMPA proponents might focus on stressing that arguments against such designations and in favour of CFMAs do not encompass such valid concerns, therefore they tell only half of the story.
P. J. S. JonesEmail:
  相似文献   

12.
Designing marine protected areas for migrating fish stocks   总被引:1,自引:0,他引:1  
This paper extends an earlier analysis and presents an investigation of how migration rates affect the performance of various types of management regimes with respect to economic yield and conservation benefits. Particular emphasis is placed on evaluating the geometric design of marine protected areas (MPAs). Earlier results have shown that MPAs are only likely to provide significant benefits when they are used in conjunction with direct catch or effort controls, unless they are quite large and cover most of the resource in question. Conversely, catch and effort controls are far more effective when protected areas are included in the management regime as a buffer against uncertainty. Dispersal of reproduction (recruitment) to other areas is an important expected benefit of protected areas, but such dispersal increases the variability of the effects of the area protection. If fishing mortality rates outside of the protected area are not controlled then dispersal can result in nullifying some of the benefits of the protected area. Similarly, adult migration increases the variability in the results when an area is protected and critically depends upon an overall control of fishing mortality outside the area. For both dispersal and migration separately or in combination, however, there are clear benefits to using MPAs in conjunction with catch or effort controls. These benefits are expressed in terms of long-term yield and recovery probabilities. In addition, short-term yield declines relatively slowly with increasing area protected. Design of the protected areas is seen to be important since using contiguous areas provide greater protection against overfishing than protected areas in isolation.  相似文献   

13.
This study provides insight into the importance of top carnivores (top-down control) and nutrient inputs (bottom-up control) in structuring food chains in a terrestrial grassland system. Qualitative predictions about food chain structure are generated using 4 simple models, each differing in assumptions about some key component in the population dynamics of the herbivore trophic level. The four model systems can be classified broadly into two groups (1) those that assume plant resource intake by herbivores is limited by search rate and handling time as described by classic Lotka-Volterra models; and (2) those that assume plant resource intake by herbivores is limited externally by the supply rate of resources as described by alternatives to Lotka-Volterra formulations. The first class of models tends to ascribe greater importance to top-down control of food chain structure whereas the second class places greater weight on bottom-up control. I evaluated the model predictions using experimentally assembled grassland food chains in which I manipulated nutrient inputs and carnivore (wolf spider) abundance to determine the degree of top-down and bottom-up control of grassland plants and herbivores (grasshoppers). The experimental results were most consistent with predictions of the second class of models implying a predominance of bottom-up control of food chain structure.  相似文献   

14.
Coral reefs and associated fish populations have experienced rapid decline in the Caribbean region and marine protected areas (MPAs) have been widely implemented to address this decline. The performance of no-take MPAs (i.e., marine reserves) for protecting and rebuilding fish populations is influenced by the movement of animals within and across their boundaries. Very little is known about Caribbean reef fish movements creating a critical knowledge gap that can impede effective MPA design, performance and evaluation. Using miniature implanted acoustic transmitters and a fixed acoustic receiver array, we address three key questions: How far can reef fish move? Does connectivity exist between adjacent MPAs? Does existing MPA size match the spatial scale of reef fish movements? We show that many reef fishes are capable of traveling far greater distances and in shorter duration than was previously known. Across the Puerto Rican Shelf, more than half of our 163 tagged fish (18 species of 10 families) moved distances greater than 1 km with three fish moving more than 10 km in a single day and a quarter spending time outside of MPAs. We provide direct evidence of ecological connectivity across a network of MPAs, including estimated movements of more than 40 km connecting a nearshore MPA with a shelf-edge spawning aggregation. Most tagged fish showed high fidelity to MPAs, but also spent time outside MPAs, potentially contributing to spillover. Three-quarters of our fish were capable of traveling distances that would take them beyond the protection offered by at least 40–64% of the existing eastern Caribbean MPAs. We recommend that key species movement patterns be used to inform and evaluate MPA functionality and design, particularly size and shape. A re-scaling of our perception of Caribbean reef fish mobility and habitat use is imperative, with important implications for ecology and management effectiveness.  相似文献   

15.
Incorporating warming disturbances into the design of marine protected areas (MPAs) is fundamental to developing appropriate conservation actions that confer coral reef resilience. We propose an MPA design approach that includes spatially- and temporally-varying sea-surface temperature (SST) data, integrating both observed (1985–2009) and projected (2010–2099) time-series. We derived indices of acute (time under reduced ecosystem function following short-term events) and chronic thermal stress (rate of warming) and combined them to delineate thermal-stress regimes. Coral reefs located on the Brazilian coast were used as a case study because they are considered a conservation priority in the southwestern Atlantic Ocean. We show that all coral reef areas in Brazil have experienced and are projected to continue to experience chronic warming, while acute events are expected to increase in frequency and intensity. We formulated quantitative conservation objectives for regimes of thermal stress. Based on these objectives, we then evaluated if/how they are achieved in existing Brazilian MPAs and identified priority areas where additional protection would reinforce resilience. Our results show that, although the current system of MPAs incorporates locations within some of our thermal-stress regimes, historical and future thermal refugia along the central coast are completely unprotected. Our approach is applicable to other marine ecosystems and adds to previous marine planning for climate change in two ways: (i) by demonstrating how to spatially configure MPAs that meet conservation objectives for warming disturbance using spatially- and temporally-explicit data; and (ii) by strategically allocating different forms of spatial management (MPA types) intended to mitigate warming impacts and also enhance future resistance to climate warming.  相似文献   

16.
Anthropogenic impacts are increasingly affecting the world''s oceans. Networks of marine protected areas (MPAs) provide an option for increasing the ecological and economic benefits often provided by single MPAs. It is vital to empirically assess the effects of MPA networks and to prioritize the monitoring data necessary to explain those effects. We summarize the types of MPA networks based on their intended management outcomes and illustrate a framework for evaluating whether a connectivity network is providing an outcome greater than the sum of individual MPA effects. We use an analysis of an MPA network in Hawai''i to compare networked MPAs to non-networked MPAs to demonstrate results consistent with a network effect. We assert that planning processes for MPA networks should identify their intended outcomes while also employing coupled field monitoring-simulation modeling approaches, a powerful way to prioritize the most relevant monitoring data for empirically assessing MPA network performance.  相似文献   

17.
Concepts and issues in marine ecosystem management   总被引:2,自引:0,他引:2  
Ecosystem management means different things to different people, but the underlying concept is similar to that of the long-standing ethic of conservation. Current interest in marine ecosystem management stems from concerns about overexploitation of world fisheries and the perceived need for broader perspectives in fisheries management. A central scientific question is whether the effects of harvesting (top down) or changes in the physical environment (bottom up) are responsible for major changes in abundance.Historically, ecology, fisheries biology, oceanography, fisheries management and the fishing industry have gone somewhat separate ways. Since the 1980s, increasing attention has been given to multispecies aspects of fisheries, the linkages between oceanography and fish abundance and more holistic approaches to fisheries management.Sorting out the causes and effects of fluctuations in fish abundance is complicated by the lack of reliability of fisheries statistics. Discards, dishonesty and the inherent logistic difficulties of collecting statistics all combine to confuse interpretation. The overcapacity of fishing fleets and their unrestricted use are widely recognized as a contributing cause to overfishing and declines in fish stocks in many parts of the world.Ecosystem management, as shorthand for more holistic approaches to resource management, is, from a fisheries management perspective, centred on multispecies interactions in the context of a variable physical and chemical environment. Broader perspectives include social, economic and political elements which are best considered pragmatically as a part of the context of fisheries management.Objectives in marine ecosystem management are varied. From a biological perspective, an underlying principle of management is commonly assumed to be a sustained yield of products for human consumption. Whether that should be taken to mean that the yield should always be of the same products is less certain. Fishing commonly changes the relative abundance of species of fishes. Thus, a biological objective should specify the species mix that is desired.Concern for the maintenance of global diversity has generated a substantial literature on threatened and endangered species. In general, it has not been considered likely that marine fish species could be rendered extinct and greatest attention has been given to marine mammals, sea birds and sea turtles. The provision of marine parks and sanctuary areas are obvious first steps in providing a measure of protection, at least for the less widely ranging species.Related to the current concepts of ecosystem management are expressions such as ecosystem health and ecosystem integrity which are given a wide range of different meanings, none of which are readily translated into operational language for resource management. These and similar expressions are best assessed as rhetorical devices. The essential components of ecosystem management are sustainable yield, maintenance of biodiversity and protection from the effects of pollution and habitat degradation.Theory for marine ecosystem management has a long history in fisheries and ecological literature. Ecological models such as Lotka-Volterra equations, ECOPATH, trophic cascades and chaos theory do not give practical guidance for management. Fleet interaction and multispecies virtual population analysis models hold more promise for fisheries managers.Alaska provides particular opportunities for developing new concepts in fisheries management. Statistics of catch are good, stock assessments are at the state-of-the-art level and management has been prudent. Debate is active on the causes of substantial changes in abundance of many species including marine mammals, because substantial changes in the fisheries have been accompanied by major changes in oceanographic conditions.As elsewhere, the resultant changes may be a consequence of top-down and bottom-up effects. The bottom part is beyond human control, and ecosystem management is centred on managing the top-down or fisheries component in the context of special measures of protection for particular species.Whether that is a realistic goal depends in part on how much special protection is to be afforded to which species. Marine mammals, for example, are given high priority for special protection, but like fisheries they too may have significant roles in shaping the structure of marine ecosystems. Eventually, ecosystem management must come to grips with the question of how much protection of particular species is desirable in achieving optimal use of living marine resources.  相似文献   

18.
19.
The dependence of long-term fishery yields on primary productivity, largely based on cross-system comparisons and without reference to the potential dynamic character of this relationship, has long been considered strong evidence for bottom-up control in marine systems. We examined time series of intensive empirical observations from nine heavily exploited regions in the western North Atlantic and find evidence of spatial variance of trophic control. Top-down control dominated in northern areas, the dynamics evolved from bottom-up to top-down in an intermediate region, and bottom-up control governed the southern areas. A simplified, trophic control diagram was developed accounting for top-down and bottom-up forcing within a larger region whose base state dynamics are bottom-up and can accommodate time-varying dynamics. Species diversity and ocean temperature co-varied, being relatively high in southern areas and lower in the north, mirroring the shifting pattern of trophic control. A combination of compensatory population dynamics and accelerated demographic rates in southern areas seems to account for the greater stability of the predator species complex in this region.  相似文献   

20.
Marine conservation programs in Oceania are increasingly turning to precautionary and adaptive management, particularly approaches which emphasize local participation and customary management. Although the application of community-based natural resource management is widespread in the region, the full integration of local knowledge and practices into the design, implementation, and monitoring of community-based conservation programs has been limited. There is also little empirical data to show whether or not community-based conservation projects are meeting their stated objectives. This paper summarizes an integrated method for selecting Marine Protected Area (MPA) sites and presents empirical evidence that illustrates how an MPA that was largely conceived using indigenous ecological knowledge and existing sea tenure governance (i.e., customary management practices), as part of a regional precautionary and adaptive community-based management plan, is showing signs of biological and social success. More generally, the paper shows how hybrid natural and social research approaches in tandem with customary management for designing MPAs can protect coral reefs in Oceania.  相似文献   

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