Quantifying the squeezing or stretching of fisheries as they adapt to displacement by marine reserves

The designation of no‐take marine reserves involves social and economic concerns due to the resulting displacement of fishing effort, when fishing rights are removed from those who traditionally fished within an area. Displacement can influence the functioning of the fishery and success of the reserve, yet levels of displacement are seldom quantified after reserve implementation and very rarely before that. We devised a simple analytical framework based on set theory to facilitate reserve placement. Implementation of the framework requires maps of fishing grounds, fishing effort, or catch per unit effort for at least 2 years. The framework quantifies the level of conflict that a reserve designation might cause in the fishing sector due to displacement and the opportunities to offset the conflict through fisher spatial mobility (i.e., ability of fishers to fish elsewhere). We also considered how the outputs of the framework can be used to identify targeted management interventions for each fishery. We applied the method in Honduras, where the largest marine protected area in Central America is being placed, for which spatial data on fishing effort were available for 6 fisheries over 3 years. The proposed closure had a greater negative impact on the shrimp and lobster scuba fisheries, which concentrated respectively 28% and 18% of their effort inside the reserve. These fisheries could not accommodate the displacement within existing fishing grounds. Both would be forced to stretch into new fishing grounds, which are available but are of unknown quality. These stakeholders will likely require compensation to offset costly exploratory fishing or to travel to fishing grounds farther away from port.     

A mathematical model of crevice corrosion for buried pipeline with disbonded coatings under cathodic protection

Crevice corrosion occurs in a holiday and disbonded region between coating and pipeline steel. Cathodic protection (CP) is generally recognized as the most effective method for corrosion prevention of pipeline, but its effectiveness may be reduced at defects in a disbonded coating. It is difficult to measure and probe corrosion parameters accurately based on experimental work. Therefore, a mathematical model is necessary to identify the phenomena and mechanisms that contribute to the crevice corrosion process. In this work, a mathematical model was developed to determine the evolution of chemical and electrochemical transient processes of crevice corrosion in NaCl dilute solution, and the effect of cathodic protection and crevice width on corrosion of 20# steel pipeline with disbonded coatings. Results have demonstrated that the extent of crevice corrosion depends on the crevice geometry and could be influenced by the increase of crevice depth and decrease of its width. The oxygen concentrations drop significantly inside a crevice whether CP is applied or not and whether crevice width decreased or not. The pH values and conductivity of crevice solution increase with the time. The research provides a theoretical foundation for cathodic protection of pipelines and establishes an effective corrosion model which can identify the phenomena and mechanisms of the crevice corrosion process. This work could be used to help mitigate the corrosion failure of pipelines to prevent catastrophic accidents in oil, gas and chemical process industries.     

Implications of Macroalgal Isolation by Distance for Networks of Marine Protected Areas

The global extent of macroalgal forests is declining, greatly affecting marine biodiversity at broad scales through the effects macroalgae have on ecosystem processes, habitat provision, and food web support. Networks of marine protected areas comprise one potential tool that may safeguard gene flow among macroalgal populations in the face of increasing population fragmentation caused by pollution, habitat modification, climate change, algal harvesting, trophic cascades, and other anthropogenic stressors. Optimal design of protected area networks requires knowledge of effective dispersal distances for a range of macroalgae. We conducted a global meta‐analysis based on data in the published literature to determine the generality of relation between genetic differentiation and geographic distance among macroalgal populations. We also examined whether spatial genetic variation differed significantly with respect to higher taxon, life history, and habitat characteristics. We found clear evidence of population isolation by distance across a multitude of macroalgal species. Genetic and geographic distance were positively correlated across 49 studies; a modal distance of 50–100 km maintained F_ST < 0.2. This relation was consistent for all algal divisions, life cycles, habitats, and molecular marker classes investigated. Incorporating knowledge of the spatial scales of gene flow into the design of marine protected area networks will help moderate anthropogenic increases in population isolation and inbreeding and contribute to the resilience of macroalgal forests. Implicaciones del Aislamiento por Distancia de Macroalgas para Redes de Áreas Marinas Protegidas     

Combined Effects of Levels of Protection and Environmental Variables at Different Spatial Resolutions on Fish Assemblages in a Marine Protected Area

Abstract: The links between species–environment relations and species’ responses to protection are unclear, but the objectives of marine protected areas (MPAs) are most likely to be achieved when those relations are known and inform MPA design. The components of a species’ habitat vary with the spatial resolution of the area considered. We characterized areas at two resolutions: 250 m² (transect) and approximately 30,000 m² (seascape). We considered three categories of environmental variables: substrate type, bottom complexity, and depth. We sought to determine at which resolution habitat characteristics were a better predictor of abundance and species composition of fishes and whether the relations with environmental variables at either resolution affected species’ responses to protection. Habitat features accounted for a larger proportion of spatial variation in species composition and abundances than differences in protection status. This spatial variation was explained best by habitat characteristics at the seascape level than at the transect level. Species’ responses to protected areas were specific to particular seascape characteristics, primarily depth, and bottom complexity. Our method may be useful for prioritizing marine areas for protection, designing MPAs, and monitoring their effectiveness. It identified areas that provided natural shelter, areas acting as buffer zones, and areas where fish species were most responsive to protection. The identification of such areas is necessary for cost‐effective establishment and monitoring of MPAs.     

军绿有机涂层和金属漆涂层全浸泡下的腐蚀行为对比研究

目的针对车辆装备长期在高盐雾、高湿热、高日照等恶劣的气候环境下使用,会受到腐蚀影响的现状,探究现役军用有机涂层防护性能。方法采用电化学阻抗谱技术研究军绿有机涂层和金属漆涂层在3.5%NaCl溶液中的腐蚀电化学行为,分析这两种涂层在浸泡期间的电化学阻抗谱特征,通过拟合等效电路得到涂层电阻R_c和涂层电容C_c,并用这两个电化学参数评价军绿有机涂层和金属漆涂层的耐蚀性能。结果军绿有机涂层抗腐蚀介质渗透能力很强,而金属漆涂层抗腐蚀介质渗透能力稍弱。结论两种涂层都表现出很好的防护性能,且金属漆涂层在腐蚀后期的防护性能要优于军绿有机涂层。     

海洋环境下ZL115-T5铸铝合金/C41500海军黄铜腐蚀行为研究

目的研究海军某型装备壳体结构材料在海洋环境下的腐蚀行为及规律。方法根据折算出的实验室加速腐蚀试验环境谱,开展了ZL115-T5铸铝合金试验件、ZL115-T5铸铝合金/C41500海军黄铜接触试验件、模拟实际涂抹黄油试验件以及模拟维护涂抹缓蚀剂试验件的实验室加速腐蚀试验。结果得到了该型铝合金在不同服役年限及服役状态下的腐蚀形貌、质量、平均腐蚀深度以及腐蚀损伤度变化规律。结论该型合金在不同服役状态下的腐蚀行为呈现差异化,ZL115-T5铸铝合金与C41500海军黄铜偶合接触会加速铸铝合金的腐蚀,黄油能够在一定程度上抑制电偶腐蚀,但效果并不明显。缓蚀剂能够延缓海洋环境下ZL115-T5铸铝合金腐蚀,其中THFS-10软膜缓蚀剂以及THFS-15长效硬膜缓蚀剂效果较好。     

富营养化淡水中黑色金属试样腐蚀加速的微生物学机制研究

目的探究黑色金属在污染淡水中后期腐蚀加速规律的生物学机制。方法采用高通量测序分析A3钢在富营养化水体和清洁水体中腐蚀产物内微生物的种群结构,并结合元素分析和XPS分析。结果获得了A3钢的腐蚀产物内微生物的门水平物种分布柱状图、OTU估计数统计表、OTU韦恩图、硫酸盐还原菌各属的相对丰度、微生物属水平热图等数据。结论在富营养化水体中,硫酸盐还原菌呈现更显著的水平,造成金属的硫化腐蚀更为严重,验证了黑色金属在富营养化污染淡水水体中后期腐蚀速率反转加速的现象。     

三种流速下高强钢与微弧氧化钛电偶腐蚀研究

目的研究三种流速下微弧氧化钛和高强钢的电偶腐蚀行为。方法在面积比为1:1情况下进行1,3,7 m/s流速下的电化学测试和电偶腐蚀试验研究。结果随着流速的增大,偶合电流、总腐蚀速率和电偶腐蚀速率增大。当流速为7 m/s时,高强钢总腐蚀速率和电偶腐蚀速率分别达到8.64 mm/a和0.39 mm/a,与静态相比分别增大146倍和15.6倍,与1 m/s流速下相比分别增大8.6倍和5倍。结论在面积比为1:1时,冲刷腐蚀速率远大于电偶腐蚀速率。     

某型机襟翼舱下壁板蒙皮腐蚀原因分析与修理措施研究

目的研究某型机襟翼舱下壁板蒙皮产生腐蚀损伤的原因,分析腐蚀危害性,制定腐蚀修补方案,提出后续腐蚀防护与控制的建议措施。方法首先现场仔细检查结构的腐蚀状况,然后分别从结构设计与选材、服役环境分析、腐蚀产物分析3个方面研究结构腐蚀产生的成因,并且针对性地制定腐蚀部位的补强修理方案。结果在襟翼舱局部高温湿热环境下形成的内部冷凝水,夹杂大气环境中的Cl~-污染侵袭,导致壁板蒙皮材料LY12铝合金产生了晶间剥落腐蚀。结论老龄飞机机体结构腐蚀成因复杂多样,准确界定腐蚀原因是制定腐蚀防护与控制措施的关键。     

热带海洋大气环境下X70管线钢的缝隙腐蚀行为研究

目的研究X70管线钢在热带海洋大气实海环境下的缝隙腐蚀行为。方法在距离湛江东海岛海岸50m和200 m处分别搭建楔型缝隙模型,安装大气环境Cl-收集装置和自动气象监测站。结果距离海岸越近,风速越大,大气中Cl-沉降速率也越大,X70管线钢缝隙腐蚀越严重。X70管线钢在距离海岸50 m处发生缝隙腐蚀的最大缝宽约为0.96 mm,200 m处最大缝宽约为3.75 mm,50 m处缝隙腐蚀更严重。结论缝隙腐蚀区域形成了氧浓差电池,同时随着缝隙液中Cl-向缝隙内迁移,发生闭塞区电池自催化过程,在二者共同作用下,缝隙腐蚀区域较非缝隙腐蚀区域腐蚀更严重。