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991.
敏感区诊断是适应性观测的关键问题,集合变换卡尔曼方法(EnsembleTransformKalmanFilter,ETKF)是目前主要的诊断方法之一。将集合变换卡尔曼方法应用于海洋环境适应性观测,根据ROMS海洋模式数据构建海表温度集合预报,以黑潮流域宫古海峡附近海域为验证区进行敏感区诊断计算,分析不同间隔时间条件下敏感区分布情况,结合模拟系统观测试验验证在敏感区进行适应性观测对预报质量的提升效果。结果表明,在诊断所得敏感区内添加观测能够提升预报质量;随时间间隔增大,敏感区向上游区域平移且预报质量提升效果减小;与在验证区整体添加观测相比,敏感区观测对预报质量提升效果基本相同并且观测成本明显减少。 相似文献
992.
Spatio‐temporal variation in density and size structure of the endangered sea cucumber Isostichopus fuscus in Huatulco National Park,Mexico 下载免费PDF全文
The brown sea cucumber Isostichopus fuscus (Ludwig, 1875) has been subjected to strong fishing pressure and is currently considered an endangered species by the IUCN Red List of Threatened Species. Spatial and temporal variations in density were analysed and population parameters of I. fuscus were estimated in three localities of the Southern Mexican Pacific. Density was estimated using circular transects covering a 300 m2 area in each locality. Body length and weight were also measured. The mean density was 0.018 ± 0.013 individuals·m?2, and was statistically significantly lower during summer. The mean length and weight were 22.4 ± 3.8 cm and 396 ± 130 g, respectively, and statistically significant differences were found among localities. The weight–length relationship was W = 0.28·L1.32 and the mean relative condition index (Kn) = 1.04 ± 0.31. The von Bertalanffy growth equation was Lt = 38.7·(1–exp(?0.4·t)). The lowest values of length, weight and age were found at Dos Hermanas, suggesting that this locality could be favorable for the settlement of larvae and recruitment and growth of juveniles. The present study is the second to estimate densities of I. fuscus and the first one to publish data on size structure and growth for the population at Bahias de Huatulco. The densities were so low in the three sampled localities that none of them would be able to support a fishery, even under a sustainable management scheme. The information collected in the present study could be helpful for management programs of the Huatulco National Park, as all the data used for these currently come mainly from the populations of I. fuscus in the Gulf of California. 相似文献
993.
《Marine Policy》2017
With over 30 years’ experience of managing Marine Protected Areas (MPAs), China has established more than 250 MPAs in its coastal and marine areas, but the overall management effectiveness is unimpressive [46]. Recently, China has made commitments to expand the MPA coverage in its waters ([7,52,53]) and develop an “ecological barrier” along the coast by connecting MPAs and islands by 2020 (The State Council 2015). In this context, this study reviews major challenges in current MPA practices in China, including the lack of systematic and scientific approaches, inadequate laws and regulations, ineffective governance mechanisms, conflicts between conservation and exploitation, limited funding, and inadequate monitoring programs. Four scenarios for developing China's MPA networks are developed and analyzed based on a literature review of experience in the United States, Canada, Australia, New Zealand, the European Union and the Philippines, as well as a set of interviews with Chinese MPA experts. These scenarios include: 1) creating a national system with an inventory of MPAs, 2) developing social networks, 3) developing regional ecological networks, and 4) developing a national representative network. The first two scenarios focus on the enhancement of the governance system through connecting individual MPAs as a social, institutional, and learning network, which could provide opportunities for creating an ecologically coherent network, while the latter two emphasized ecological connectivity and representativeness. Given different focuses, they can be applied at different stages of implementation and combinations of scenarios can be used depending on China's needs. 相似文献
994.
《Marine Policy》2017
The biodiversity of East to Southeast (E–SE) Asian waters is rapidly declining because of anthropogenic effects ranging from local environmental pressures to global warming. To improve marine biodiversity, the Aichi Biodiversity Targets were adopted in 2010. The recommendation of the Subsidiary Body on Scientific, Technical and Technological Advice (SBSTTA), encourages application of the ecologically or biologically significant area (EBSA) process to identify areas for conservation. However, there are few examples of the use of EBSA criteria to evaluate entire oceans. In this article, seven criteria are numerically evaluated to identify important marine areas (EBSA candidates) in the E–SE Asia region. The discussion includes 1) the possibility of EBSA criteria quantification throughout the E–SE Asia oceans and the suitability of the indices selected; 2) optimal integration methods for criteria, and the relationships between the criteria and data robustness and completeness; and; 3) a comparison of the EBSA candidates identified and existing registered areas for the purpose of conservation, such as marine protected areas (MPAs). Most of the EBSA criteria could be quantitatively evaluated throughout the Asia-Pacific region. However, three criteria in particular showed a substantial lack of data. Our methodological comparison showed that complementarity analysis performed better than summation because it considered criteria that were evaluated only in limited areas. Most of the difference between present-day registered areas and our results for EBSAs resulted from a lack of data and differences in philosophy for the selection of indices. 相似文献
995.
Spatial difference and mechanisms of influence of geo-economy in the border areas of China 总被引:2,自引:0,他引:2
Border areas are both important territorial security barriers and portals to the outside world. Considering the complicated geopolitical environment of China’s inland borders, analysis of the current status and mechanisms of influence of geo-economy in border areas is of great significance. Namely, this analysis is important towards leveraging traditional advantages to accelerate China’s development in border and minority areas. Based on a comprehensive analysis, our study constructed a framework to analyze the geo-economy in border areas, and also introduced three indexes: local economy, export-oriented economy and local development. In addition, our study systematically described geo-economic evolution in the border areas of China. We also analyzed the mechanism of geo-economic spatial differentiation in these border areas by using geographical detectors. Our results indicated that the level of geo-economic influence in border areas has grown steadily with significant spatial differentiation. The absolute geo-economic dominance of Northeast China gradually declines over time. Areas with geo-economic advantages are highly dispersed, showing a spatial polarization pattern with several polar nuclei including Mudanjiang city (Northeast China), Baotou city (Inner Mongolia), Bortala Mongol Autonomous Prefecture (Xinjiang), Dehong Dai and Jingpo Autonomous Prefecture and the city of Chongzuo (Yunnan-Guangxi area). Geo-economics in border area is mainly influenced by national policies, the development level of neighboring countries, as well as the desire of these countries to cooperate with China in bilateral trade. Favorable policies, traffic, cultural proximity and other factors also impact the geo-economics of border areas significantly. The Inner Mongolia and Tibet areas are mainly influenced by neighboring countries, while Northeast China and Xinjiang are mainly affected by Chinese policies; the Yunnan-Guangxi area is influenced by a combination of these factors. At the end of the study, we provide our recommendations for developing policies that further geo-economic advantages in complex geopolitical environments and in areas with varied development. 相似文献
996.
基于USLE和GIS的水土流失敏感性空间分析——以河北太行山区为例 总被引:6,自引:0,他引:6
以USLE方程为理论指导,遥感影像为主要数据源,基于ArcGIS 进行水土流失敏感性空间分析。选择降雨侵蚀力、土地利用类型、坡度、植被覆盖度等影响因子构建水土流失敏感性评价指标体系,在考虑不同因子影响作用大小的情况下,运用空间分析的方法按标准将水土流失敏感性分为五级;并以河北太行山区为例进行研究,利用危险性指数表征研究区水土流失敏感性大小,分析研究区在不同地理背景下的水土流失敏感区的空间分布特征。研究表明:河北太行山区的水土流失敏感性危险性指数为3.97;空间上水土流失敏感性分等级呈现明显的条带状分布;中度敏感区所占面积比例最大,为39.2%;整体水土流失敏感性中度偏重。 相似文献
997.
连片特困区的贫困是特殊的区域性贫困,减贫与发展的关键在于形成区域自我发展能力。了解连片特困区自我发展能力的现状、制约因素和时空演变规律就显得十分重要。本研究基于中观的视角,将区域自我发展能力理解为产业能力、市场能力、空间能力和软实力四个维度耦合的复杂系统,通过构建多指标综合测算方法,测算了连片特困区的典型代表武陵山片区2005、2008 和2011 年各县市的自我发展能力,并对其时空演变特征与趋势进行了分析。结果表明:① 武陵山片区自我发展能力整体偏低且发展不平衡;② 空间能力和软实力是制约武陵山片区自我发展能力提升的两块短板;③ 2005-2011 年间,武陵山片区自我发展能力各维度间的一致性逐渐增强,自我发展能力内部结构更为合理;④ 武陵山片区自我发展能力空间上呈“东南部相对下降,北部整体上升”的趋势,并且产业能力、市场能力、空间能力和软实力均有自身明显的演变趋势。 相似文献
998.
《Marine Policy》2015
MPAs and stakeholder education are marine conservation cornerstones, but data to assess adherence to regulations and the success of educational methods are missing. Local MPAs have been established to protect inter-tidal mudflats and shore users from bait collection which is a contentious worldwide issue. Video cameras monitored activity and confirmed if collectors adhered to the rules at three UK sites with different MPA systems. An educational approach (a voluntary code leaflet) was also assessed through stakeholder discussion and observation. Fareham Creek and Dell Quay supported a considerable number of collectors with none observed at Pagham Harbour. At Fareham Creek bait dug areas were evident in discrete patches in unprotected and protected areas, but observed collectors mainly used the latter. The failure to exclude collectors is due to the lack of enforcement. At Dell Quay virtually all dug areas were outside protected areas and was confirmed by the camera footage. Success is attributed to regular on-the-ground ‘unofficial’ enforcement by the managing NGO. Of the retailers, 75% had heard of the code and the majority stated they followed it. However, none of the 26 collectors observed followed a key rule (e.g. backfilling holes). Local marine conservation is relatively cheap and can be effective, but only if: management matches the actual pressure; scientific evaluation for all components (including education) is integrated from the beginning; adequate site enforcement is included; education methods are active, two-way and sustained. 相似文献
999.
《African Journal of Marine Science》2013,35(3):639-642
The first documented recapture of a South African-tagged juvenile blue shark Prionace glauca off Uruguay lends weight to the hypothesis of a single blue shark population in the South Atlantic. The presence of neonate blue sharks with umbilical scars and females with post-parturition scars, as well as the high frequency of small juveniles in research longline catches, confirm the existence of a parturition and nursery area off South Africa. The final positions of three tagged sharks suggest that large-scale movement patterns in the South Atlantic are a mirror image of movements in the North Atlantic, with sharks using the north-westerly Benguela Drift to migrate into the tropics and ultimately across into South American waters. The confirmed existence of a parturition and nursery area off the south coast of South Africa and the movement of sharks into both adjacent ocean basins suggest that the southern African blue sharks are part of a single stock that straddles the South Atlantic and Indian oceans, and possibly the entire Southern Hemisphere. 相似文献
1000.
Reproductive biology of horse mackerel Trachurus capensis and Trachurus trecae in Namibia and Angola
《African Journal of Marine Science》2013,35(2):141-150
Harvest control measures for Namibia and Angola are defined using reference points for spawning biomass, which requires knowledge of spawning potential and dynamics of fishery stocks. The reproductive biology of two species of horse mackerel, Trachurus capensis and Trachurus trecae, in these waters was investigated for spawning distribution in time and space. Samples were collected during two scientific cruises conducted in February and July/August 2007 off the coast of Namibia and Angola. A total of 396 fish ovaries was examined to determine the spawning dynamics of the two species. The ovaries were histologically analysed and their oocyte distributions mapped. The length (TL)–weight relationships of the two species differed significantly. The observed development of oocyte recruitment and absence of a hiatus in the oocyte distribution indicated that these species are indeterminate spawners. Analyses of the data from the NatMIRC database (2001–2004) indicated annual changes in gonadosomatic index (GSI) for T. capensis at different latitudes, but these changes were small. GSI also fluctuated between years and areas, but there were no clear spatial or temporal trends, with averages ≤4.0% at all stations. The GSI of both species was not indicative of the histologically determined development of gonad maturity. Oocyte maturation for T. capensis indicated that smaller and younger fish spawn first. Batch fecundity (F) for T. trecae was best described by F = 4 986 TL (cm) – 99 645 (r 2 = 0.83). This study provided the first analyses of oocyte development in time and space for the two species in the region. 相似文献