Coralligenous habitat in the northern Adriatic Sea: an overview     

Sandra Casellato  Antonio Stefanon 《Marine Ecology》2008,29(3):321-341

The rocky outcrops irregularly scattered in the sandy‐muddy sea bed of the Northern Adriatic, formed by a base rock and a superimposed concretion of vegetal and animal organisms, are considered an infralittoral coralligenous habitat, according to the most recent definition. In the last four decades, research has mainly concentrated on their geology because of the question of the origin of the base rock – very similar to beachrock – which has only recently been attributed to sedimentary cementation induced by methane seeps. Studies on their macrobenthic assemblages have also been published recently, but true comparisons among them are difficult because they mostly refer only to a few selected phyla or to short‐term observations. Very few papers deal with the whole of the animal and plant communities, including all taxonomic groups and the most important environmental variables. On the basis of the literature data concerning several outcrops in the Gulf of Venice, we suggest that the Adriatic reefs differ slightly from the classic deeper coralligenous assemblages around the Mediterranean coast because they have smaller concretions of algae builders. We also suggest that the Northern Adriatic coralligenous reefs are younger than the other reefs occurring in the Mediterranean Sea.  相似文献   

A comparison of economic performance in the fisheries sector: A short- and long-term perspective     

P. Le Floc’h  F. Daurès  C. Brigaudeau  J. Bihel 《Marine Policy》2008

Indicators of the economic performance of fishing vessels are frequently computed in various countries. In this paper, we use different types of information to assess capital value and the economic performance of fishing vessels. On the one hand, field surveys provide technical and financial information on the main components of fishing capital. On the other hand, book values are given in bookkeeping databases. We use both sources of information on fishing capital are used for the same set of vessels, namely the commercial fishing fleet of the French region of Brittany. Based on these two sources, measures of economic performance can be produced for the short term using gross surplus; and for the long term including the cost of capital. The measures of performance obtained are presented and the differences between them are then discussed.  相似文献   

The trade of live crustaceans in Portugal: space for technological improvements     

Barrento  Sara; Marques  Antonio; Pedro  Sonia; Vaz-Pires  Paulo; Nunes  Maria Leonor 《ICES Journal of Marine Science》2008,65(4):551-559

  相似文献   

Basin filling evolution of the central basins of Mallorca since the Pliocene     

Antonio Cap  Celso Garcia 《Basin Research》2019,31(5):948-966

A new compilation of data from 436 drill cores using decompaction and backstripping techniques was used to reconstruct the basin filling history from the Pliocene until the present day in the Palma, Inca and Sa Pobla Basins on the island of Mallorca (Spain). Calcareous rocks dominate the source area and provide a limited amount of clastic input to the basins that has resulted in an average accumulation rate of between 5 and 20 m/Ma during the last 5.3 Ma. Carbonate sediment production dominated the basin filling history during early‐mid Pliocene, but during the Quaternary, the sedimentation processes in the Palma Basin were probably enhanced by an evolution in the drainage network that increased the sediment supply and the accumulated thickness caused by stream capture. However, the maximum sedimentation rate filling the depocentres of the three basins has been decreasing since the Pliocene, showing that not only the catchment transport efficiency but also the relative sea level have been controlling the sediment accumulation in these carbonate basins. The isopach cross‐sections support the idea that a palaeorelief was generated during the Messinian sea level drop and that heterogeneities were filled in from the Pliocene to the Quaternary. We conclude that the central basins of Mallorca were filled heterogeneously due to tectonic and geomorphic processes that controlled sediment transport and production, resulting in different average sedimentation thicknesses that decreased since the Pliocene as the accommodation space became filled and the relative sea level dropped.  相似文献   

A method for checking the quality of geographic metadata based on ISO 19157     

Manuel Antonio Ureña-Cámara  Javier Lacasta  Francisco Javier Ariza-López 《International journal of geographical information science》2019,33(1):1-27

With recent advances in remote sensing, location-based services and other related technologies, the production of geospatial information has exponentially increased in the last decades. Furthermore, to facilitate discovery and efficient access to such information, spatial data infrastructures were promoted and standardized, with a consideration that metadata are essential to describing data and services. Standardization bodies such as the International Organization for Standardization have defined well-known metadata models such as ISO 19115. However, current metadata assets exhibit heterogeneous quality levels because they are created by different producers with different perspectives. To address quality-related concerns, several initiatives attempted to define a common framework and test the suitability of metadata through automatic controls. Nevertheless, these controls are focused on interoperability by testing the format of metadata and a set of controlled elements. In this paper, we propose a methodology of testing the quality of metadata by considering aspects other than interoperability. The proposal adapts ISO 19157 to the metadata case and has been applied to a corpus of the Spanish Spatial Data Infrastructure. The results demonstrate that our quality check helps determine different types of errors for all metadata elements and can be almost completely automated to enhance the significance of metadata.  相似文献   

The Cabo Frio upwelling overrides geographical patterns in the population dynamics of the shrimp Artemesia longinaris Spence Bate, 1888 (Decapoda: Penaeidae)     

Abner Carvalho‐Batista  Joo Alberto Farinelli Pantaleo  Antonio Leo Castilho  Rogrio Caetano da Costa 《Marine Ecology》2019,40(2)

Upwelling areas are among the most productive ecosystems on the planet, influencing the biology of marine organisms. This study investigated the population dynamics of the shrimp Artemesia longinaris in two regions in southeastern Brazil, one inside (Macaé—Rio de Janeiro State) and one outside (Ubatuba—State of São Paulo) the Cabo Frio upwelling area. The aim was to verify the influence of the upwelling phenomenon on the abundance, growth, longevity, size of sexual maturity, and reproductive period of the species. In total, 188,902 individuals were captured at Macaé and 3,461 at Ubatuba. Individuals captured at Macaé showed larger maximum size, higher longevity, and slower growth rate, besides reaching sexual maturity at larger sizes than at Ubatuba. Continuous reproduction was observed in both regions, with juvenile recruitment peaks in spring and summer. Local conditions observed at Macaé were influenced by the Cabo Frio upwelling zone, characterized by productive and cooler waters that are around 20°C during most of the year. The upwelling phenomenon is probably the main factor influencing the population parameters studied here, changing the geographic patterns previously observed for the variation of these parameters in A. longinaris.  相似文献   

ALMA observations of the circumstellar envelope around EP Aqr     

Pham Thi Tuyet Nhung  Do Thi Hoai  Pham Tuan-Anh  Thibaut Le Bertre  Pierre Darriulat  Pham Ngoc Diep  Nguyen Thi Phuong  Nguyen Thi Thao  Jan Martin Winters 《天文和天体物理学研究(英文版)》2019,(3):97-110

Atacama Large Millimetre/sub-millimetre Array(ALMA) observations of CO(1–0) and CO(2–1) emissions from the circumstellar envelope of the asymptotic giant branch(AGB) star EP Aqr have been made with four times better spatial resolution than previously available. They are analysed with emphasis on the de-projection in space of the effective emissivity and flux of matter using as input a prescribed configuration of the velocity field, assumed to be radial. The data are found to display an intrinsic axisymmetry with respect to an axis making a small angle with respect to the line of sight. A broad range of wind configurations, from prolate(bipolar) to oblate(equatorial) has been studied and found to be accompanied by significant equatorial emission. Qualitatively, the effective emissivity is enhanced near the equator to produce the central narrow component observed in the Doppler velocity spectra and its dependence on star latitude generally follows that of the wind velocity with the exception of an omni-present depression near the poles. In particular, large equatorial expansion velocities produce a flared disc or a ring of effective emissivity and mass loss. The effect on the determination of the orientation of the star axis of radial velocity gradients, and possibly competing rotation and expansion in the equatorial disc, is discussed. In general,the flux of matter is found to reach a broad maximum at distances of the order of 500 AU from the star.Arguments are given that may be used to favour one wind velocity distribution over another. As a result of the improved quality of the data, a deeper understanding of the constraints imposed on morphology and kinematics has been obtained.  相似文献   

CNS+GNSS+INS船载高精度实时定位定姿算法改进研究   总被引：2，自引：1，他引：1  

程风  李海霞  常乐  王力  牛小骥 《测绘通报》2019,(5):30-34

天文导航(CNS)、卫星导航(GNSS)和惯性导航(INS) 3种系统组合可提供高精度的定位定姿结果。实际工程中因INS长时间误差累积,以及系统硬件传输存在不可忽略的时间延迟,导致INS提供给CNS的预报粗姿态误差较大,恶劣海况下难以保障快速搜星,造成天文导航可靠性下降、姿态测量精度较低的问题。为此,本文提出了一种CNS+GNSS+INS高精度信息融合实时定位定姿框架,引入了等角速度外推措施,有效地解决了惯导信息延迟问题。通过高精度转台模拟恶劣海况下载体大角速度摇摆,验证了本文提出的改进算法的有效性。试验结果表明,该算法架构简单,性能可靠,显著提高了恶劣环境下星敏感器的快速、准确搜星能力,保障了三组合姿态测量的精度和可用性。  相似文献   

动载作用下混凝土细观损伤的CT图像分割和灰度共生矩阵特征值研究          下载免费PDF全文

丁卫华  朱琳  黄力  张乐  秦俊绒  李爱国 《CT理论与应用研究》2021,30(2):170-182

动载作用下混凝土随应力变化的系列CT图像完整地记录了混凝土内部破损过程,在CT图像中能直接观察到细观裂纹时混凝土往往已发生宏观破坏,挖掘混凝土材料损伤的细观信息是混凝土细观力学分析的核心.本文基于混凝土单轴动态压缩CT试验,获得不同应力阶段的横断面CT图像,分别应用图像分割技术和灰度共生矩阵法提取孔隙率和4个特征值,研...  相似文献   

中国大陆强震孕育深处的变形模式     

陈棋福  李乐  姜金钟 《地震地磁观测与研究》2021,42(2):99-100

地震预测面临着地球内部的"不可入性"和大地震"非频发性"的问题,是极具挑战性且尚待解决的世界性科学难题之一(陈运泰,2009) .地震活动是断裂活动的直接体现,精定位的震源深度客观反映了断裂深部发生地震滑动变形的起始位置.断裂深部发生的慢滑动和重复地震等对揭示断裂深部行为具有重要的指示意义(Harris,2017).在...  相似文献