Abstract: Recognition is growing that fisheries must be both ecologically and commercially sustainable. The bioeconomic models proposed herein constitute an analytic framework capable of integrating the ethics and Societal values associated with fisheries preservation. Specifically, we focus on the normalized optimal (equilibrium) fish population, z*, a dimensionless variable representing biomass as a proportion of environmental capacity. We model z* as a function of (a) the dimensionless "bionomic growth ratio", γ, which is the ratio of the discount rate to the intrinsic population growth rate, and (b) the preservation coefficient, Ω, which is the ratio of the preservation value (a measure of Society's value for the stock) to price, assuming that the population growth rate and intrinsic growth rate are fixed. It is shown that increasing Ω significantly impacts z*, particularly for moderate values of γ (2 γ 4). Finally, stochastic population models are used to analyze the risk of a fish stock collapse due to harvesting pressures. The bioeconomic models and simulations herein described improve the accuracy and reliability of maximum sustainable yield management. 相似文献
Primary purposes for catchment management are to establish a cost-effective allocation and use of its water resources and
to most effectively apply measures to protect the quantity and quality of the water produced by the catchment. For the latter
purpose, diffuse sources of contamination are the greatest difficulty. Diffuse (or non-point source) water pollution poses
challenges for public policy and requires innovative management approaches. Solutions ultimately require behavioural change
and a broad societal response, and must be flexible and adaptive to stochastic catchment conditions and to long-term trends.
Internationally, new models of governance for difficult land and water resource management problems are developing. This paper
reviews the characteristics of ‘wicked’ environmental management problems and the specific policy challenges posed by diffuse
water pollution. A framework for action is derived and compared to the activities and outcomes of water protection in the
New York City watershed. Successes to date in this case indicate that because land management and diffuse sources of pollution
have a local basis, protection of water at source necessitates the fostering of local instruments for an adaptive and twin-track
strategy of applied research and stakeholder deliberation, supported by multi-level partnerships and an enabling regulatory
environment. Although long running, evidence from this case alone is insufficient to establish whether potential trade-offs
between water protection and the economic vitality of catchment communities can be fully resolved. 相似文献
The Devils Lake Emergency Outlet Diversion conflict is systematically studied from a strategic viewpoint using the Graph Model for Conflict Resolution in order to obtain insights about the resolution of this nagging international dispute. By modelling the conflict for the situation existing as of July 2005, just before the project began operation, the dispute is put into proper perspective and, subsequently, a stability analysis is carried out to obtain potential resolutions or equilibria. The results of a sensitivity analysis accurately predict the deal which actually took place when Canada and the American state of North Dakota reached a negotiated settlement. Finally, suggestions are put forward for improving the Boundary Waters Treaty of 1909 between Canada and the United States. 相似文献
The 2010 Deepwater Horizon (DWH) oil spill exposed common bottlenose dolphins (Tursiops truncatus) in Barataria Bay, Louisiana to heavy oiling that caused increased mortality and chronic disease and impaired reproduction in surviving dolphins. We conducted photographic surveys and veterinary assessments in the decade following the spill. We assigned a prognostic score (good, fair, guarded, poor, or grave) for each dolphin to provide a single integrated indicator of overall health, and we examined temporal trends in prognostic scores. We used expert elicitation to quantify the implications of trends for the proportion of the dolphins that would recover within their lifetime. We integrated expert elicitation, along with other new information, in a population dynamics model to predict the effects of observed health trends on demography. We compared the resulting population trajectory with that predicted under baseline (no spill) conditions. Disease conditions persisted and have recently worsened in dolphins that were presumably exposed to DWH oil: 78% of those assessed in 2018 had a guarded, poor, or grave prognosis. Dolphins born after the spill were in better health. We estimated that the population declined by 45% (95% CI 14–74) relative to baseline and will take 35 years (95% CI 18–67) to recover to 95% of baseline numbers. The sum of annual differences between baseline and injured population sizes (i.e., the lost cetacean years) was 30,993 (95% CI 6607–94,148). The population is currently at a minimum point in its recovery trajectory and is vulnerable to emerging threats, including planned ecosystem restoration efforts that are likely to be detrimental to the dolphins’ survival. Our modeling framework demonstrates an approach for integrating different sources and types of data, highlights the utility of expert elicitation for indeterminable input parameters, and emphasizes the importance of considering and monitoring long-term health of long-lived species subject to environmental disasters. Article impact statement: Oil spills can have long-term consequences for the health of long-lived species; thus, effective restoration and monitoring are needed. 相似文献
This study was conducted to improve the ability of indigenous New Zealand white-rot fungi to remove pentachlorophenol (PCP) from contaminated field soil. The effects of different bioaugmentation conditions on PCP removal and extracellular enzyme expression were measured in the laboratory. The conditions were fungal growth substrate and co-substrate composition, culture age, and Tween 80 addition to the contaminated soil. The fungi used were Trametes versicolor isolate HR131 and Trametes sp. isolate HR577. Maximum PCP removal was 70% after 7 wk from a 1043 mg kg(-1) PCP-contaminated soil inoculated with an 11-d-old fungal culture of T. versicolor isolate HR131. There was minimal production of undesirable pentachloroanisole by the fungi. Tween 80 addition had no affect on PCP removal. Poplar sawdust was more suitable as a fungal growth substrate and a co-substrate amendment for PCP removal and extracellular enzyme expression than the locally available pine and fir sawdust. Pentachlorophenol removal was not necessarily correlated with extracellular enzyme expression. The research results demonstrate that PCP biodegradation was affected by inoculum culture age, by the presence of a co-substrate amendment, and by growth substrate composition after white-rot fungal bioaugmentation into PCP-contaminated field soils. 相似文献
利用种群模型评价农药暴露时间序列的方法与现有常用的风险评价方法进行了比较。美国环境保护局农药项目办公室(The US Environmental Protection Agency’s Office of Pesticide Programs)在近30年对水生生物农药日暴露值建立了模型,但并未对这些信息进行充分的利用。我们利用糠虾(Americamysis bahia)毒性数据和种群数量统计数据推演了毒代动力学一毒效动力学(Toxicokinetic-Toxicodynamic, Tk-Td)与一系列矩阵种群模型联用的数值。糠虾是一种沿岸浅海底的小型甲壳动物,通常用于常规毒性测试中。我们展示了这种联用方法如何仅用现有的标准常规毒性数据来优化已有的风险评价方法。我们创建了几种暴露场景,每种场景在基于生物的传统方法中有着相同的初始风险表征特征,而种群模型方法中则显示出不同的风险水平。这种TK-TD与种群模型联用的方法可以对不同的急性和慢性毒性数据的场景区分出不同的风险水平,而传统的风险评价方法则做不到。这种联用方法在风险评价方面独具优势,特别是针对污染物的暴露浓度随时间变化的情况。
精选自Glen Thursby, Keith Sappington, Matthew Etterson. Coupling Toxicokinetic-Toxicodynamic (Tk-Td) and Population Models for Assessing Aquatic Ecological Risks to Time-Varying Pesticide Exposures. Environmental Toxicology and Chemistry,2018,37:2633-2644.
详情请见 https://doi.org/10.1002/etc.4224 相似文献