基于稳定同位素和贝叶斯模型的引黄灌区地下水硝酸盐污染源解析

地下水硝酸盐（NO₃^-）污染已经成为全球严重的水环境问题之一,由于饮用水中高含量NO₃^-会转化成亚硝酸盐而增加各种疾病和癌症风险,其来源的确定对于NO₃^-污染的预防和控制非常重要。本文以黄河下游第二大灌区——潘庄灌区为例,首次采用NO₃^-的氮氧稳定同位素结合贝叶斯模型追溯地下水NO₃^-的来源并量化各种来源的贡献比例。结果表明,地下水NO₃^-含量分布在0.1~197.0 mg·L^-1,平均值为34.2 mg·L^-1。与《生活饮用水卫生标准》中规定的地下水NO₃^-最大含量[20 mg（N）·L^-1,相当于NO₃^-含量90 mg·L^-1]相比,有10%的样品NO₃^-含量超标。井深<30 m、30~60 m和>60 m的地下水NO₃^-平均含量分别为25.9 mg·L^-1、39.7 mg·L^-1和20.1 mg·L^-1。空间上,宁津县、武城县、平原县和禹城市有大片区域地下水NO₃^-含量较高。地下水NO₃^-的δ¹⁵N组成范围为0.72‰~23.93‰,平均值为11.62‰;δ¹⁸O组成范围为0.49‰~22.50‰,平均值为8.46‰。同位素结果表明粪便和污水、农业化肥是地下水中NO₃^-的主要污染来源。这反映了人类活动是引起地下水NO₃^-污染的主要原因。贝叶斯模型结果显示,粪便和污水对潘庄灌区地下水中NO₃^-平均贡献率高达56.2%,化肥的平均贡献率为19.3%,大气降水和土壤的平均贡献率分别为6.2%和12.3%。由于污水、粪便和化肥是地下水中NO₃^-的主要来源,为保护和改善研究区地下水水质,建议加强污水管道建设,强化畜禽粪便的管理以及提高化肥利用效率。     

Population impacts of endangered short-tailed albatross bycatch in the Alaskan trawl fishery

We conduct a decision analysis that explores the effects of trawl-related fishery mortality on achieving the population recovery goals for the US federally-endangered short-tailed albatross (Phoebastria albatrus), proposed by the US Fish and Wildlife Service. A population model is constructed and its parameters estimated using data on counts of the numbers of albatross chicks and eggs at Torishima Island, Japan, where 83% of the world’s population of this species is found. Bayesian inference is used to assign probabilities to alternative plausible rates of fishing mortality and as the basis for population projections with different levels of trawl mortality to determine their effects on achieving the population recovery goals. The analyses of the impact of trawl mortality on the Torishima short-tailed albatross population suggests that exceeding the current expected incidental take in the Alaskan groundfish trawl fishery, two in any 5-year period, by as much as a factor of 10 would have little impact on when the proposed recovery goals for the species are achieved. A quantitative approach that addresses uncertainty, such as that outlined in this study, could aid the process to evaluate allowable limits in light of species recovery goals by addressing both take limits and recovery goals within the same framework.     

Validation of the indirect fluorescent antibody and the complement fixation tests for the diagnosis of Theileria equi

The indirect fluorescent antibody (IFA) test for Theileria equi was evaluated to assess test's suitability for the serological diagnosis of equine piroplasmosis, to provide performance parameters for the purpose of test validation, and to compare it with the complement fixation (CF) test. Using a protocol that included Evan's blue, the specificity of the IFA test was estimated at 99.0% for T. equi by the classical method of analysis, and 96.6% by the Bayesian method. The use of Evan's blue in the test protocol increased test specificity and contributed to an excellent test agreement between two collaborating laboratories (kappa = 0.96). Using Bayesian analysis, the sensitivity estimate for the IFA test was 89.2%. The CF test sensitivity and specificity estimates for T. equi were 63.1 and 96.4%, respectively, as determined by Bayesian analysis. The IFA test was more sensitive than the CF test but the specificity estimates were similar.     

Bayes and diagnostic testing

Interpretation of the result of a diagnostic test depends not only on the actual test result(s) but also on information external to this result, namely the test's sensitivity and specificity. This external information (also called prior information) must be combined with the data to yield the so-called updated, posterior estimates of the true prevalence and the test characteristics. The Bayesian approach offers a natural, intuitive framework in which to carry out this estimation process. The influence of the prior information on the final result may not be ignored. Guidance for the choice of prior information not in conflict with the data can be obtained from a set of statistics and indices (DIC, p(D), Bayes-p).     

基于贝叶斯分析的干热河谷区橙子林冠层蒸腾耗水模拟

需耗水机制是进行农田/果园水分管理和调控的基础。本文聚焦蒸腾耗水机制,基于贝叶斯参数估计方法对比了不同Jarvis-Stewart模型配置对干热河谷区橙子林蒸腾耗水量的模拟效果,探索了Jarvis-Stewart模型在影响因子交互效应较强条件下蒸腾耗水模拟中的适用性。结果表明,考虑不同影响因子及其限制函数会对模拟效果产生较大影响,其中考虑土壤含水率和叶面积指数对模拟效果改善作用明显,而引入饱和水汽压差和气温则不同程度地降低模拟精度;考虑的影响因子越多,模型结构越复杂,模拟效果不一定越好;筛选出的最佳模型结构基本实现了橙子林蒸腾耗水的可靠模拟,但模拟效果仍有明显改进空间,因此,应综合考虑模型复杂程度、模拟精度及不确定性等,进一步探究适宜的模型结构。研究可为果园节水灌溉技术体系建立和水分管理优化提供科学依据,也能为耗水模型的进一步发展和完善提供理论支撑。     

基于贝叶斯方法的东、黄海鲐资源评估及管理策略风险分析

运用基于贝叶斯的剩余产量模型,对东、黄海鲐资源进行评估,确定了当前鲐资源开发利用状态,估算了在不同收获率水平下未来5年鲐资源量和年总可捕捞量,分析了管理策略实施后鲐资源崩溃的风险。结果表明,2006年东、黄海鲐正遭受过度捕捞,但其资源量并未处于过度捕捞状态。决策分析表明,收获率为0.3是最适预防性的管理策略,在该策略下,鲐平均资源量将从2006年的451千吨将增加到2011年的871千吨,2011年资源量恢复到BMSY的概率为0.48,而过度捕捞的概率为0。     

Dissolved oxygen controls summer habitat of Clear Lake Hitch (Lavinia exilicauda chi), an imperilled potamodromous cyprinid

Clear Lake Hitch is an imperilled minnow endemic to Clear Lake, Lake County, California, United States listed as threatened under the California Endangered Species Act (ESA) and a candidate for listing under the United States ESA. It exhibits a potamodromous life cycle whereby adults, which reach up to 6 + years in age and over 350 mm in length, migrate into Clear Lake's ephemeral tributaries briefly during spring to spawn. Conservation and management of Clear Lake Hitch is inhibited, in part, by a lack of information on the lacustrine habitat of nonbreeding individuals within Clear Lake. To address this problem, we sampled Clear Lake Hitch with gill nets in a stratified random sampling design to determine the distribution and habitat associations in early summer 2017 and 2018. We identified abundance-habitat relationships for juveniles and adults using Bayesian zero-inflated negative binomial generalised linear mixed modelling. Results indicated that dissolved oxygen concentration was the most important habitat feature measured; juveniles and adults were substantially more abundant in normoxic (≥2 mg/l) than in hypoxic (<2 mg/l) habitat. Both also exhibited weak positive relationships with chlorophyll fluorescence, suggesting relatively productive habitats may support higher numbers of Clear Lake Hitch. Spatially, juveniles were most abundant in nearshore habitats while adults were ubiquitous, indicating an ontogenetic habitat expansion that may be associated with a resource availability-predation risk trade-off. Management actions undertaken to improve hypoxia problems in Clear Lake would also improve Clear Lake Hitch habitat.     

Development and testing of a Bayesian population model for the bigeye thresher shark,Alopias superciliosus,in an area subset of the western North Pacific

A Bayesian population modelling tool integrating separable virtual population analysis, per‐recruit models and age‐structured demographic analysis was developed for the bigeye thresher Alopias superciliosus (Lowe) population in an area subset of the western North Pacific. The mortality rates for years 1989–2016 were estimated, various biological reference points and associated risks of decline were also estimated, and alternative harvest strategies for the stock were evaluated. Estimates of the posterior mean of fishing mortality for bigeye thresher shark suggest fishing pressure has been high in recent years (2011–2016). The estimated population growth rate (λ) (without fishing) obtained from age‐structured demographic model was relatively low (λ = 1.01 per year; 95% confidence intervals of 1.00 and 1.03 per year). Risk analyses revealed that only low levels of fishing pressure (10% of the current fishing pressure) over a wide range of ages could maintain a relatively low risk of population decline for bigeye threshers. Sensitivity testing indicated that the model is robust to prior specification. The developed framework could be used as an assessment tool to evaluate the risk of decline for other widely distributed pelagic shark species where insufficient catch and effort data are available.     

Balancing resource protection and fishing activity: The case of the European hake in the northern Iberian Peninsula

One of the fundamental aims of the Ecosystem Approach to Fisheries Management is to ensure the long‐term sustainability of the fishery by protecting key life‐cycle habitats, such as recruitment areas. In this study, we apply a hurdle Bayesian hierarchical spatio‐temporal model that describes the abundance of European hake (Merluccius merluccius) recruits in the northern continental shelf of the Iberian Peninsula. Our findings clearly show four persistent nurseries, the main one being located along the continental shelf of the Artabrian gulf (off La Coruña). The preferential habitats identified for the hake recruits are areas within a bathymetric range of 120–200 m, with 15–16°C of Sea Surface Temperature, a Chl‐a concentration of 0.8–1.2 mg/m³ and low values of seabed rugosity (unconsolidated substrates). Searching for a compromise with fisheries, we also assess the degree of overlap of the main nursery areas with two fisheries footprints, a local one using Vessel Monitoring System data of trawl fishery of Marín, and a global one using Automatic Identification System data of different type of trawlers (bottom otter, beam and midwater trawls). The two fisheries footprints present different degree of overlapping in distinct areas, highlight the need of specific fleet‐adapted management rules in order to protect juvenile stages. We discuss that understanding the distributional patterns associated with key life stages, such as recruitment, and their interaction with fishing activities, is essential for applying appropriate spatial management measures and improving fishery sustainability.     

Difficulties associated with modeling growth in the Atlantic angel shark (Squatina dumeril)

Several methods were used in an attempt to develop an age and growth model for the Atlantic angel shark (Squatina dumeril). Band counts from vertebral sections, which were fit to the traditional von Bertalanffy growth equation, the Gompertz growth equation, and the two-parameter von Bertalanffy growth equation, did not produce realistic parameter estimates. Additionally, a length-based Bayesian model was applied to fishery-independent length–frequency data, and a full Bayesian model was fitted to length-at-age data to estimate parameters for von Bertalanffy growth equation. Both the length-based and full Bayesian models failed to converge; the length–frequency data showed high bimodality unrelated to season, year, or other factors, and band counts were not predictable by length. Vertebral band counts were not valid for ageing Atlantic angel sharks, and length-based methods, which require normally distributed length–frequencies, were not appropriate for this data set. This study represents the first attempt at modeling age and growth for this species and provides research guidelines for future research initiatives.