Fast and easy method for seagrass monitoring: application of acoustic telemetry to precision mapping of Posidonia oceanica beds     

Descamp P  Holon F  Ballesta L  Guilbert A  Guillot M  Boissery P  Raimondino V  Deter J 《Marine pollution bulletin》2011,62(2):284-292

Posidonia oceanica is an endemic seagrass from the Mediterranean Sea. It is an indicator of water quality and of the ecological state of coastal ecosystems. The aim of this paper is to test acoustic telemetry for monitoring the position of P. oceanica meadow limits with varied types. After evaluating the accuracy of the system, we present results from a spatiotemporal survey of P. oceanica meadows on nine sites located on the French coast. The method has been demonstrated to be highly efficient for high precision underwater mapping regardless of meadow type, with 1 cm accuracy for a distance of 40 m between the base and the pointer. A temporal survey led at Cerbere-Banyuls shows a weak global progression of 4 m² (progression of 26 m² - regression of 22 m²) between 2006 and 2010. Finally, we discuss the cost and efficiency of this method, and wether it should be generalized for further studies.  相似文献   

地质钻探铝合金钻杆材料研制及室内试验研究   总被引：20，自引：0，他引：20  

梁健 《地质与勘探》2011,47(2):304-308

与钢钻杆相比,铝合金钻杆具有比强度高、刚度低、耐腐蚀性好等优点,在实施钻探工程作业时,可增加现有钻探设备钻进能力,减少钻机动力消耗,降低钻探施工难度,减轻工人劳动强度.开展地质钻探铝合金钻杆研究,对提高我国难进入地区地质调查钻探工程效率、推动地质钻探科学技术进步以及节能降耗工作具有重大现实意义.本文介绍了7E04铝合金...  相似文献   

Estimating global discards and their potential reduction for the Galician fishing fleet (NW Spain)     

Ian Vázquez-Rowe  M Teresa MoreiraGumersindo Feijoo 《Marine Policy》2011

This study presents the first comprehensive estimation of discard amounts in the Galician fishing fleet, in order to provide an integral view of this increasing environmental problem at a regional scale. Subsequently, a series of improvement actions relating to discard minimization are suggested with the goal of enhancing the performance of the Galician fishing fleet through discard minimization. Discard estimates were constructed individually for the different Galician fisheries by aggregating primary data obtained from a total of 89 fishing vessels and secondary data for those fleets that were not directly sampled. Results showed that roughly 60,250 t of marine organisms were discarded by the Galician fleet in 2008, representing 16.9% of the total capture. Moreover, an important percentage of these discards were linked mainly to trawling vessels and to a lesser extent, to certain long lining fisheries. Therefore, improved management measures in target stocks should take into account the fact that alternative fishing gears other than trawl nets may reduce the amount of discards for certain species. This estimation may improve the assessment of stocks and help to quantify the damage that discards may have on wild ecosystems.  相似文献   

Responses of the fishing sector to transitional constraints: From reactive to proactive change,Yucatan fisheries in Mexico     

Carmen Pedroza  Silvia Salas 《Marine Policy》2011

Most fisheries management studies have concentrated on understanding resource dynamics and have paid less attention to understanding the dynamics of those who use the resources. This situation limits the knowledge about the fisheries system as a whole and specifically about the viability of management schemes. It is vital to understand how the actors within the fishing sector (fishing firm owners/managers, fishers, fisheries managers, and traders) may respond to changes in fishing resources trends, market dynamics, and fisheries policies before they are implemented. These issues are explored in this paper by applying a longitudinal analysis of the Yucatan Mexico's fishing industry. The analysis is presented within the framework of the theory of change and coping strategies. The study primarily involved interviews during 2008 with the main owners of companies in the fishing industry and with fisheries managers and other stakeholders. Time-series catch data on the main fishing resources are also reviewed to evaluate changes across three historical periods and describe how the actors have perceived and responded to those changes. Given conditions of uncertainty in resource availability, changes in market demand and changes in institutional arrangements, the viability of traditional business and resource management practices are discussed. The analysis presents different kind of triggers that have modified the conditions of the fishing sector and had had impacts on the socio-economic–ecological system in which fisheries are embedded. The need for adaptive strategies in the whole chain of the fisheries business and resource management is stressed, given the current changes and conditions of fisheries. The discussion states a series of actions that could improve the relationships between business practices and fisheries management.  相似文献   

Fisheries privatization,social transitions,and well-being in Kodiak,Alaska     

《Marine Policy》2015

Scholars and fishermen alike view the privatization of fishing rights as a fundamental driver of social change in fishing communities. This article presents the results of a mixed-methods ethnographic study in Kodiak, Alaska, exploring how fisheries privatization processes remake fishery systems. Findings from this study suggest that a diverse range of fishery participants share core values about the social dimensions of fishery systems. Support or opposition to past privatization processes tended to be articulated in reference to how these core values (e.g., hard work, opportunity, and fairness) were perceived to have been strengthened or eroded by such processes. Data from this study suggest that while still widespread in the Kodiak fishing community, core social values in fishing may be changing as a result of privatization processes. Although ethnographic and survey data showed a range of perspectives on the effects of privatization on fishing and the Kodiak community, study participants tended to talk about privatization as a significant change that had divisive, negative impacts in the community. Crew members and the next generation of fishermen were identified as disproportionately affected by privatization processes. Ethnographic data detail important shifts in the power, status, and livelihoods of crew members. Nearly all Kodiak fishery participants interviewed expressed concern about the future of fisheries access in the community for the next generation, in large part because of the substantial financial barriers to entry generated by privatization of fisheries access. Many discussed the need for more entry-level opportunities necessary for access in all fisheries.  相似文献   

国内外旋转导向钻井系统导向原理          下载免费PDF全文

雷静  杨甘生  梁涛  胡驰 《探矿工程》2012,39(9):53-58

旋转导向钻井技术是目前世界上最具代表性和先进性的钻井技术,该技术的核心是旋转自动导向系统。总结了国内外旋转导向钻井系统的发展概况,对各系统的导向机构工作原理进行了对比分析,并就旋转导向钻井系统未来的发展和完善提出了看法。  相似文献   

国内太阳数据VO化初步方案   总被引：1，自引：0，他引：1  

林钢华 《天文研究与技术》2004,1(3):210-215

随着太阳物理研究的深入、观测仪器的发展、观测数据的积累，促使人们去思考这样的问题：利用全世界不同时间、地点、波段的太阳相关数据、历史数据去对很多悬而未解的科学问题寻求答案，同时使研究者容易的去检索这些数据，进行分析，这就是虚拟太阳天文台要解决的问题，也是为什么虚拟太阳天文台项目得到了全世界有关天文台、研究所和大学的积极响应和运作。本文介绍了国内应如何面对虚拟天文台的发展及国内太阳数据VO化初步方案。  相似文献   

Artisanal fishing in Andalusia (II): Safety and working conditions policy     

F. Piniella  J.P. Novalbos  P.J. Nogueroles 《Marine Policy》2008,32(4):551-558

In an earlier paper, we presented a statistical study dealing comprehensively with the so-called “artisanal fleet”, with data on the typology of vessels and on the extractive effort. In this paper, we focus our research on safety and working conditions.Although numerous factors are known that can directly influence the health of the sailor or fisherman, and that are present one way or another in both the fishing and merchant fleets, it is necessary to address in particular the problem of coastal fishermens’ health in order to identify areas of health and safety that need to be improved. The results of this analysis, among other aspects, identify the injuries associated with machinery, tools, nets and protection devices, the health status, the life styles and the working conditions.  相似文献   

基于GIS的精细化格点预报平台设计与实现——以青岛市为例   总被引：1，自引：0，他引：1  

宁方志  季民  陈许霞 《测绘与空间地理信息》2017,40(5)

针对目前天气预报发展需求,本文提出了精细化格点天气预报。不同于传统的站点天气预报,精细化格点预报平台是进行图像交互及编辑订正的平台,核心功能模块包括格点数据下载及解析、可视化显示、图形编辑订正和预报产品输出。目前,精细化天气预报平台已经应用于青岛市海洋气象服务平台,经过不断地改进,预报精度由原先的9 km提高到了现在的3 km,实现了青岛地区的24 h气象预报以及数据订正,减少了气象服务人员的工作量。  相似文献   

Analysis of pedestrian behaviors through non-invasive Bluetooth monitoring     

《Applied geography (Sevenoaks, England)》2017

This paper presents a novel framework to analyze pedestrians' behavioral patterns throughout shopping environments in the historical center of Barcelona, Spain. We employ a Bluetooth detection technique to capture a large-scale dataset of pedestrians' behavior over a one-month period, including during a key sales period. We focused on comparing particular behaviors before, during, and after the discount sales by analyzing this large-scale dataset, which is different but complementary to the conventionally used small-scale samples. Our results uncover pedestrians actively exploring a wider area of the district during a discount period compared to weekdays, giving rise to strong underlying mobility patterns.  相似文献