The Role of Pre-Existing Disturbances in the Effect of Marine Reserves on Coastal Ecosystems: A Modelling Approach

We have used an end-to-end ecosystem model to explore responses over 30 years to coastal no-take reserves covering up to 6% of the fifty thousand square kilometres of continental shelf and slope off the coast of New South Wales (Australia). The model is based on the Atlantis framework, which includes a deterministic, spatially resolved three-dimensional biophysical model that tracks nutrient flows through key biological groups, as well as extraction by a range of fisheries. The model results support previous empirical studies in finding clear benefits of reserves to top predators such as sharks and rays throughout the region, while also showing how many of their major prey groups (including commercial species) experienced significant declines. It was found that the net impact of marine reserves was dependent on the pre-existing levels of disturbance (i.e. fishing pressure), and to a lesser extent on the size of the marine reserves. The high fishing scenario resulted in a strongly perturbed system, where the introduction of marine reserves had clear and mostly direct effects on biomass and functional biodiversity. However, under the lower fishing pressure scenario, the introduction of marine reserves caused both direct positive effects, mainly on shark groups, and indirect negative effects through trophic cascades. Our study illustrates the need to carefully align the design and implementation of marine reserves with policy and management objectives. Trade-offs may exist not only between fisheries and conservation objectives, but also among conservation objectives.     

Marine reserves with ecological uncertainty

To help manage the fluctuations inherent in fish populations scientists have argued for both an ecosystem approach to management and the greater use of marine reserves. Support for reserves includes empirical evidence that they can raise the spawning biomass and mean size of exploited populations, increase the abundance of species and, relative to reference sites, raise population density, biomass, fish size and diversity. By contrast, fishers often oppose the establishment and expansion of marine reserves and claim that reserves provide few, if any, economic payoffs. Using a stochastic optimal control model with two forms of ecological uncertainty we demonstrate that reserves create a resilience effect that allows for the population to recover faster, and can also raise the harvest immediately following a negative shock. The tradeoff of a larger reserve is a reduced harvest in the absence of a negative shock such that a reserve will never encompass the entire population if the goal is to maximize the economic returns from harvesting, and fishing is profitable. Under a wide range of parameter values with ecological uncertainty, and in the ‘worst case’ scenario for a reserve, we show that a marine reserve can increase the economic payoff to fishers even when the harvested population is not initially overexploited, harvesting is economically optimal and the population is persistent. Moreover, we show that the benefits of a reserve cannot be achieved by existing effort or output controls. Our results demonstrate that, in many cases, there is no tradeoff between the economic payoff of fishers and ecological benefits when a reserve is established at equal to, or less than, its optimum size.     

Application of marine reserves to reef fisheries management

Abstract Establishing permanent ‘no-take’ marine reserves, areas where fishing and all other extractive activities are prohibited, is an attractive but under-utilized tool for fisheries management. Marine reserves could potentially deal with many fishery problems that are not effectively addressed by other traditional management measures; they also offer numerous social, economic, and scientific benefits not directly related to fisheries. Limited but growing research has shown beneficial biological and economic effects of marine reserves on fisheries. More research is needed, especially at larger scales, to determine the ideal marine reserve size, number and location necessary to optimize fisheries productivity and resource conservation. Sufficient evidence is available to justify the expanded use of marine reserves in an adaptive approach to fisheries management.     

海洋保护地社区多元化生计与生态系统服务的依赖关系

海洋保护地在主要承担典型海洋生态系统、珍稀濒危物种、重要自然资源自然遗迹和人文资源有效保护的同时,兼具生态功能维持、资源可持续利用与社区经济持续发展等多重任务,普遍面临着生态保护与社区生计发展间的依赖-冲突关系,探究社区生计与生态系统服务间的依赖关系,对实现海洋保护地与社区协调发展具有重要意义。基于山东长岛海洋保护地的415户社区居民的调研数据,运用可持续生计分析框架和生态系统服务依赖度模型,分析社区居民的生计资本和生态系统服务依赖度(IDES) 的特征,进一步结合多元回归模型探究生计资本对 IDES 的影响。结果表明:(1)社区居民生计资本得分呈现出由渔业主导型向务工主导型、旅游主导型、渔业兼业型递增的总趋势,且不同类型社区居民的生计资本结构具有较大差异;(2)渔业兼业型和旅游主导型社区居民从生态系统获取的收益显著高于其它居民,IDES总指数由大到小排序依次为渔业主导型、旅游主导型、渔业兼业型、务工主导型,且渔业主导型生计的供给服务依赖度显著高于其他类型,文化服务依赖度最低;(3)生计资本对不同类型居民的供给、文化服务依赖度的影响存在差异,海上养殖规模、渔业作业范围、接受政府技能培训次数、生态补偿政策、社会组织参与程度、旅游扶持政策惠及程度等指标是平衡居民生态系统服务依赖结构的关键。基于此,从不同类型居民以及当地政府多个角度提出提高长岛海洋保护地社区居民生计资本水平,优化生态系统服务依赖结构的建议,以期为实现海洋保护地与社区的协调发展提供参考借鉴。     

江苏近海生态系统服务价值评估

海洋生态系统服务是人类从海洋生态系统中获得的效益,对沿海地区社会经济具有重要的支撑作用。采用国家标准《海洋生态资本评估技术导则》的方法,评估了江苏省管辖海域的生态系统服务价值,并揭示了其空间分布特征。江苏近海海域面积1.18万km2,2008年提供的生态系统服务总价值为426.02亿元,供给服务、文化服务、调节服务和支持服务价值分别为226.38亿元,186.61亿元,12.68亿元和0.34亿元;3个沿海地市比较,盐城近海生态系统服务价值最高,为184.55亿元;其次是连云港近海,为155.58亿元;南通近海最低,为85.89亿元。江苏近海生态系统服务价值空间分布密度平均为361.91万元/km2,从近岸到远海总体呈逐渐降低趋势,高值区主要分布在滨海旅游区和海洋保护区,中值区出现在养殖区,其它海域的服务价值则较低。江苏近海生态系统服务利用属于供给服务和文化服务共同主导的综合开发利用型,连云港近海属于文化服务主导的开发利用型,盐城近海属于供给服务和文化服务共同主导的综合开发利用型,南通近海则属于供给服务主导的开发利用型。建议在江苏近海开展离岸养殖工程,以提高近海供给服务价值;在盐城,特别是南通近岸海域开发海洋公园、渔家乐和其他亲水性旅游活动以提高文化服务价值。     

Rapid Effects of Marine Reserves via Larval Dispersal

Marine reserves have been advocated worldwide as conservation and fishery management tools. It is argued that they can protect ecosystems and also benefit fisheries via density-dependent spillover of adults and enhanced larval dispersal into fishing areas. However, while evidence has shown that marine reserves can meet conservation targets, their effects on fisheries are less understood. In particular, the basic question of if and over what temporal and spatial scales reserves can benefit fished populations via larval dispersal remains unanswered. We tested predictions of a larval transport model for a marine reserve network in the Gulf of California, Mexico, via field oceanography and repeated density counts of recently settled juvenile commercial mollusks before and after reserve establishment. We show that local retention of larvae within a reserve network can take place with enhanced, but spatially-explicit, recruitment to local fisheries. Enhancement occurred rapidly (2 yrs), with up to a three-fold increase in density of juveniles found in fished areas at the downstream edge of the reserve network, but other fishing areas within the network were unaffected. These findings were consistent with our model predictions. Our findings underscore the potential benefits of protecting larval sources and show that enhancement in recruitment can be manifested rapidly. However, benefits can be markedly variable within a local seascape. Hence, effects of marine reserve networks, positive or negative, may be overlooked when only focusing on overall responses and not considering finer spatially-explicit responses within a reserve network and its adjacent fishing grounds. Our results therefore call for future research on marine reserves that addresses this variability in order to help frame appropriate scenarios for the spatial management scales of interest.     

Mapping the economic costs and benefits of conservation

Resources for biodiversity conservation are severely limited, requiring strategic investment. Understanding both the economic benefits and costs of conserving ecosystems will help to allocate scarce dollars most efficiently. However, although cost-benefit analyses are common in many areas of policy, they are not typically used in conservation planning. We conducted a spatial evaluation of the costs and benefits of conservation for a landscape in the Atlantic forests of Paraguay. We considered five ecosystem services (i.e., sustainable bushmeat harvest, sustainable timber harvest, bioprospecting for pharmaceutical products, existence value, and carbon storage in aboveground biomass) and compared them to estimates of the opportunity costs of conservation. We found a high degree of spatial variability in both costs and benefits over this relatively small (~3,000 km²) landscape. Benefits exceeded costs in some areas, with carbon storage dominating the ecosystem service values and swamping opportunity costs. Other benefits associated with conservation were more modest and exceeded costs only in protected areas and indigenous reserves. We used this cost-benefit information to show that one potential corridor between two large forest patches had net benefits that were three times greater than two otherwise similar alternatives. Spatial cost-benefit analysis can powerfully inform conservation planning, even though the availability of relevant data may be limited, as was the case in our study area. It can help us understand the synergies between biodiversity conservation and economic development when the two are indeed aligned and to clearly understand the trade-offs when they are not.     

Density dependence and the economic efficacy of marine reserves

Predictions on the efficacy of marine reserves for benefiting fisheries differ in large part due to considerations of models of either intra- or inter-cohort population density regulating fish recruitment. Here, I consider both processes acting on recruitment and show using a bioeconomic model how for many fisheries density dependent recruitment dynamics interact with harvest costs to influence fishery profit with reserves. Reserves consolidate fishing effort, favoring fisheries that can profitably harvest low-density stocks of species where adult density mediates recruitment. Conversely, proportion coastline in reserves that maximizes profit, and relative improvement in profit from reserves over conventional management, decline with increasing harvest costs and the relative importance of intra-cohort density dependence. Reserves never increase profit when harvest cost is high, regardless of density dependent recruitment dynamics. I quantitatively synthesize diverse results in the literature, show disproportionate effects on the economic performance of reserves from considering only inter- or intra-cohort density dependence, and highlight fish population and fishery dynamics predicted to be complementary to reserve management. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

海州湾生态系统服务价值评估

参照千年生态系统评估的分类体系,并考虑污染等因素引起生态系统服务的退化,评估了海州湾生态系统的潜在和实际服务价值.结果表明,2005年海州湾的潜在服务价值为16.64×108元,平均单位面积海域的服务价值为1.90× 106元/km2.潜在服务价值中,供给服务、文化服务和调节服务分别占53.39％,35.48％和10.84％.考虑赤潮、食品中累积的污染物超标以及温室气体排放等因素造成的生态服务质量和数量的退化,2005年海州湾生态系统提供的实际服务价值为14.08×108元,平均单位面积海域的服务价值为1.61×106元/km2.实际服务价值中,供给服务、文化服务和调节服务分别占48.32％,41.94％和9.74％.海水富营养化和污染等因素导致的生态服务价值降低2.56× 108元,影响最大的是食品供给和气候调节服务.     

污染湖泊生态系统服务净价值评估——以滇池为例

水污染是我国湖泊生态系统面临的主要环境问题,评估污染条件下湖泊生态系统服务价值对认识和恢复污染湖泊生态功能具有重要意义。针对当前湖泊生态系统服务价值评估方法中未体现水污染负面影响的问题,在传统生态系统服务功能价值评估框架的基础上,将水污染造成的经济损失内化到生态系统服务功能价值中,提出了针对污染湖泊的生态系统服务功能价值评估方法。应用该方法核算了滇池生态系统服务净价值。结果表明:2006—2015年滇池年均生态系统服务功能价值为386.55亿元/a,水污染改变了滇池的价值结构,供水价值丧失,气候调节、旅游和蓄水等成为滇池生态系统服务功能价值的主体;滇池水污染对流域内外经济社会发展造成的损失达到15.23亿元/a,主要经济损失体现在生态补水费用和蓝藻去除费用;综合湖泊生态系统服务的正向价值和水污染的负向损失,滇池的净生态系统服务价值为371.33亿元/a,占流域GDP的11.7%。将水污染损失纳入湖泊生态系统服务功能价值评估中增强了评价结果的合理性,能够更加真实地反映湖泊生态系统对人类经济社会发展的综合影响。     

Marine reserves can enhance ecological resilience

The goals of ecosystem‐based management (EBM) include protecting ecological resilience, the magnitude of a perturbation that a community can withstand and remain in a given state. As a tool to achieve this goal, no‐take marine reserves may enhance resilience by protecting source populations or reduce it by concentrating fishing in harvested areas. Here, we test whether spatial management with marine reserves can increase ecological resilience compared to non‐spatial (conventional) management using a dynamic model of a simplified fish community with structured predation and competition that causes alternative stable states. Relative to non‐spatial management, reserves increase the resilience of the desired (predator‐dominated) equilibrium state in both stochastic and deterministic environments, especially under intensive fishing. As a result, spatial management also increases the feasibility of restoring degraded (competitor‐dominated) systems, particularly if combined with culling of competitors or stock enhancement of adult predators.     

53 A Seaweed's perspective on marine reserves

In response to major changes in coastal ecosystems in recent decades, a number of governmental agencies around the world are establishing marine reserves – areas where removal of animals or plants is prohibited. Although marine reserves are touted as an ecosystem based approach to management of marine resources, the vast majority of attention on reserve design and impact focuses solely on fish. Although a few species of algae are commercially harvested, most are not. As a result, they will receive little direct benefit from protection by reserves aside from habitat protection. From the perspective of a seaweed, the primary impacts of marine reserves will therefore be indirect through species interactions. We examine the rapidly growing theoretical and empirical literature on marine reserves to anticipate the likely responses of seaweeds to exclusion of fishing. The key issues that emerge are: the trophic level of prior fishing and the dispersal scales of seaweeds relative to their competitors and consumers. The latter issue is poorly understood and poses a key challenge to phycologists if we are to effectively incorporate seaweeds into future marine reserve design.     

Using marine reserves to estimate fishing mortality

The proportion of a fish stock that is killed by fishing activity is often calculated as the catch divided by the estimated stock biomass. However, stock biomass is notoriously difficult to estimate reliably, and moreover, the catch may be uncertain or misreported and does not include losses due to discarding. In all too many fisheries, these difficulties have lead to underestimates of total fishing mortality and the commercial demise of the fishery. No‐take marine reserves eliminate fishing mortality from within their boundaries and, for species that exhibit seasonal migratory behaviour, comparison of reserves with fished areas can provide direct estimates of the proportion killed by fishing. For an important exploited species in New Zealand, seasonal changes in density of sub‐legal fish at three marine reserves were similar in both reserve and adjacent non‐reserve areas. However, this result did not hold for legal‐size fish, and the difference in seasonal change between reserved and non‐reserved areas was used to obtain direct estimates of the total localized fishing mortality in the non‐reserve area over 6‐month periods. Estimates of the percentage of legal‐size fish killed by fishing ranged from 70 to 96%. These results demonstrate an unanticipated practical benefit from marine reserves that goes beyond their ecological role.     

On the Optimal Size of Marine Reserves

The excessive and unsustainable exploitation of our marine resources has led to the promotion of marine reserves as a fisheries management tool. Marine reserves, areas in which fishing is restricted or prohibited, can offer opportunities for the recovery of exploited stock and fishery enhancement. This study examines the impact of the creation of marine protected areas, from both economic and biological perspectives. The consequences of reserve establishment on the long-run equilibrium fish biomass and fishery catch levels are evaluated. We include reserve size as control variable to maximize catch at equilibrium. A continuous time model is used to simulate the effects of reserve size on fishing catch. Fish movements between the sites is assumed to take place at a faster time scale than the variation of the stock and the change of the fleet size. We take advantage of these two time scales to derive a reduced model governing the dynamics of the total fish stock and the fishing effort. Simulation results suggest that the establishment of a protected marine reserve will always lead to an increase in total fish biomass, an optimal size of a marine reserve can achieve to maximize the catch at equilibrium.     

Ecosystem Services in Conservation Planning: Targeted Benefits vs. Co-Benefits or Costs?

There is growing support for characterizing ecosystem services in order to link conservation and human well-being. However, few studies have explicitly included ecosystem services within systematic conservation planning, and those that have follow two fundamentally different approaches: ecosystem services as intrinsically-important targeted benefits vs. substitutable co-benefits. We present a first comparison of these two approaches in a case study in the Central Interior of British Columbia. We calculated and mapped economic values for carbon storage, timber production, and recreational angling using a geographical information system (GIS). These 'marginal' values represent the difference in service-provision between conservation and managed forestry as land uses. We compared two approaches to including ecosystem services in the site-selection software Marxan: as Targeted Benefits, and as Co-Benefits/Costs (in Marxan's cost function); we also compared these approaches with a Hybrid approach (carbon and angling as targeted benefits, timber as an opportunity cost). For this analysis, the Co-Benefit/Cost approach yielded a less costly reserve network than the Hybrid approach (1.6% cheaper). Including timber harvest as an opportunity cost in the cost function resulted in a reserve network that achieved targets equivalently, but at 15% lower total cost. We found counter-intuitive results for conservation: conservation-compatible services (carbon, angling) were positively correlated with each other and biodiversity, whereas the conservation-incompatible service (timber) was negatively correlated with all other networks. Our findings suggest that including ecosystem services within a conservation plan may be most cost-effective when they are represented as substitutable co-benefits/costs, rather than as targeted benefits. By explicitly valuing the costs and benefits associated with services, we may be able to achieve meaningful biodiversity conservation at lower cost and with greater co-benefits.     

Management Strategy Evaluation Applied to Coral Reef Ecosystems in Support of Ecosystem-Based Management

Ecosystem modelling is increasingly used to explore ecosystem-level effects of changing environmental conditions and management actions. For coral reefs there has been increasing interest in recent decades in the use of ecosystem models for evaluating the effects of fishing and the efficacy of marine protected areas. However, ecosystem models that integrate physical forcings, biogeochemical and ecological dynamics, and human induced perturbations are still underdeveloped. We applied an ecosystem model (Atlantis) to the coral reef ecosystem of Guam using a suite of management scenarios prioritized in consultation with local resource managers to review the effects of each scenario on performance measures related to the ecosystem, the reef-fish fishery (e.g., fish landings) and coral habitat. Comparing tradeoffs across the selected scenarios showed that each scenario performed best for at least one of the selected performance indicators. The integrated ‘full regulation’ scenario outperformed other scenarios with four out of the six performance metrics at the cost of reef-fish landings. This model application quantifies the socio-ecological costs and benefits of alternative management scenarios. When the effects of climate change were taken into account, several scenarios performed equally well, but none prevented a collapse in coral biomass over the next few decades assuming a business-as-usual greenhouse gas emissions scenario.     

Rapid Assessment of Ecosystem Services Provided by Two Mineral Extraction Sites Restored for Nature Conservation in an Agricultural Landscape in Eastern England

Despite growing recognition that mineral sites restored for nature conservation can enhance local biodiversity, the wider societal benefits provided by this type of restoration relative to alternative options are not well understood. This study addresses this research gap by quantifying differences in ecosystem services provision under two common mineral site after-uses: nature conservation and agriculture. Using a combination of site-specific primary field data, benefits transfer and modelling, we show that for our sites restoration for nature conservation provides a more diverse array of ecosystem services than would be delivered under an agricultural restoration scenario. We also explore the effects of addressing different conservation targets, which we find alter the provision of ecosystem services on a service-specific basis. Highly species-focused intervention areas are associated with increased carbon storage and livestock grazing provision, whereas non-intervention areas are important for carbon sequestration, fishing, recreation and flood risk mitigation. The results of this study highlight the wider societal importance of restored mineral sites and may help conservation managers and planners to develop future restoration strategies that provide benefits for both biodiversity and human well-being.     

Increased Disease Calls for a Cost-Benefits Review of Marine Reserves

Marine reserves (or No-Take Zones) are implemented to protect species and habitats, with the aim of restoring a balanced ecosystem. Although the benefits of marine reserves are commonly monitored, there is a lack of insight into the potential detriments of such highly protected waters. High population densities attained within reserves may induce negative impacts such as unfavourable trophic cascades and disease outbreaks. Hence, we investigated the health of lobster populations in the UK’s Marine Conservation Zone (MCZ) at Lundy Island. Comparisons were made between the fished, Refuge Zone (RZ) and the un-fished, No-Take Zone (NTZ; marine reserve). We show ostensibly positive effects such as increased lobster abundance and size within the NTZ; however, we also demonstrate apparent negative effects such as increased injury and shell disease. Our findings suggest that robust cost-benefit analyses of marine reserves could improve marine reserve efficacy and subsequent management strategies.     

Declining reliance on marine resources in remote South Pacific societies: ecological versus socio-economic drivers

Degraded coral reef ecosystems yield limited goods and services, which is expected to have significant socio-economic impacts on isolated tropical island communities with strong reliance on coral reefs. This study investigates socio-economic changes, specifically in fresh fish consumption and fishing activities, associated with environmental degradation at five fishing grounds (qoliqoli) in the Lau Islands (Fiji). Semi-structured interviews with fishers and senior household members revealed that the importance of fishing was low relative to other occupations, and consumption of fresh fish has declined over the last decade. Reduced fishing and choice of fresh fish is largely attributable to an increased need to derive income as well as new income-generating opportunities. A possible consequence of reduced reliance on marine resources was limited awareness of recent environmental degradation caused by climate-induced coral bleaching and outbreaks of coral-feeding crown-of-thorns starfish. Limited use and reduced awareness of the local marine environment in the short term may erode social memory and local ecological knowledge, reducing opportunities to fall back on marine resources. This may also compromise long-term economic and social stability. Conversely, low reliance on marine resources may confer greater flexibility to adapt to future ecological change in the marine environment. Importantly, changes in fish consumption and exploitation of marine resources were linked to socio-economic factors rather than a consequence of recent degradation of marine environments. Greater knowledge of the dynamics driving change in marine resource use is necessary to understand how societies respond to ecological and socio-economic change, and to identify opportunities for adaptive sustainable ecosystem management.     

The Role of Eelgrass in Marine Community Interactions and Ecosystem Services: Results from Ecosystem-Scale Food Web Models

Eelgrass beds provide valuable refuge, foraging, and spawning habitat for many marine species, including valued species such as Pacific salmon (Oncorhynchus spp.), Pacific herring (Clupea pallasi), and Dungeness crab (Metacarcinus magister). We used dynamic simulations in a food web model of central Puget Sound, Washington, USA developed in the Ecopath with Ecosim software, to examine how the marine community may respond to changes in coverage of native eelgrass (Zostera marina), and how these modeled responses can be assessed using an ecosystem services framework, expressing these services with economic currencies in some cases and biological proxies in others. Increased eelgrass coverage was most associated with increases in commercial and recreational fishing with some small decreases in one non-market activity, bird watching. When we considered ecosystem service categories that are aggregations of individual groups of species, we saw little evidence of strong tradeoffs among marine resources; that is, increasing eelgrass coverage was essentially either positive or neutral for all services we examined, although we did not examine terrestrial activities (for example, land use) that affect eelgrass coverage. Within particular service categories, however, we found cases where the responses to changes in eelgrass of individual groups of species that provide the same type of ecosystem service differed both in the magnitude and in the direction of change. This emphasizes the care that should be taken in combining multiple examples of a particular type of ecosystem service into an aggregate measure of that service.