Widespread rocky reef occurrence in the central English Channel and the implications for predictive habitat mapping   总被引：1，自引：1，他引：0  

Markus Diesing  Roger Coggan  Koen Vanstaen 《Estuarine, Coastal and Shelf Science》2009,83(4):647-658

Reefs are one of the marine habitats listed in Annex I of the European Union's Habitats Directive, which aims to establish a coherent European ecological network of Special Areas of Conservation. EU Member States are required to prepare and propose a national list of sites for evaluation under the scheme, but currently the occurrence of reefs in the United Kingdom's nearshore and offshore areas is not well documented. Here we report on our search for rocky reefs in the central English Channel, which unexpectedly revealed an extensive reef system covering an area of 1100 km². Prior to our work, it was generally perceived that the seabed in this area comprised mostly gravel, with a few isolated rock outcrops.Our approach to determining the location, extent and character of these reefs incorporated broad, medium and fine-scale analyses over a 3200 km² area of seabed, using single- and multi-beam acoustic data, ground-truthed by underwater video and stills imagery. A benthic terrain model was developed in ArcGIS to map topographic features at the broad and medium scales. Biotope assignments were made at the fine scale through detailed analysis of video footage obtained from 30 sampling stations. The study area has a complex geological history and lies at the centre of a major bedload-parting zone. Together, these strongly influence the seabed character and the distribution of biotopes. An integrated assessment of the physical and biological features was used to map the study area to level 4 of the EUNIS habitat classification system.Similar physical conditions exist in other areas of the UK continental shelf, raising the prospect of predicting where other rocky reef systems might occur. In the absence of a co-ordinated national seabed survey programme, such predictions, coupled with interpretation of existing single-beam bathymetry data, can help prioritise areas where limited survey resources could be most effectively deployed.  相似文献   

The contribution of trace elements from seawater to chimneys： a case study of the native sulfur chimneys in the sea area off Kueishantao, northeast of Taiwan Island     

刘长华  汪小妹  靳新娣  曾志刚  陈镇东 《中国海洋湖沼学报》2009,27(1):162-171

Hydrothermal fluid containing abundant matter erupts from seafloor, meets ambient cold seawater and forms chimneys. So the main matter origins of chimneys are seawater and matter which are taken by hydrothermal fluid from deep reservoir. However, because of seawater’s little contribution to the forming of chimneys, it is usually covered by the abundant matter which is taken by hydrothermal fluid. Therefore, chimneys formed in ordinary deep seawater hydrothermal activity, containing complex elements, cannot ...  相似文献   

双探针型海底热流计数据解算模型选取   总被引：2，自引：0，他引：2       下载免费PDF全文

杨小秋  施小斌  许鹤华  徐行  李官保  郭兴伟  罗贤虎 《热带海洋学报》2009,28(4):28-34

选取适合于双探针型海底热流计数据解算的简化模型,是双探针型海底热流计结构优化的理论基础,对提高海底热流数据解算精度具有重要意义。本文基于脉冲式双探针海底工作的有限元数值模型,对双探针的脉冲加热时间、体生热率、热物性、长度及半径等因素在双探针脉冲法的3个线热源简化模型中所引起的模型误差作了详细的分析和讨论,并以模型误差最小为原则选取简化模型。结果表明：1）脉冲加热有限长线热源（PFLS: pulsed finite line source）模型是双探针脉冲法中较为实用的简化模型,它可消除加热时间和探针长度对介质热物性参数求解的影响;2）在PFLS模型下,探针热导率对待测介质热物性测量的影响可以忽略;而探针间距越大、半径越小及其体积比热容与待测介质越接近,则所求介质热物性的模型误差就越小;在保证温度传感器能有效记录到温度变化的前提下,探针脉冲功率的大小基本不影响介质热物性求解的模型误差。  相似文献   

立体测绘型双翼民用无人机航空摄影系统的实现与应用     

吴云东  张强 《测绘学院学报》2009,(3)

按照领域专用、性价匹配的思想,设计并实现了一套满足小区域大比例尺地形图立体测绘要求的无人机航空摄影系统。该系统以双翼无人机为遥感平台,以数字相机为传感器,配置3轴稳定云台,直接获得数字航空影像,具有自主飞行、低空作业、无需机站支持、起降距离短、滑翔性能好等特点。系统包括双翼无人机、飞行自动控制与安全、CCD数字相机、稳定云台、空地无线通讯、地面站和数据处理等7个子系统。分别介绍了系统的总体结构和各子系统的技术状况;分析和比较了系统的GSD、像点移位、基高比等关键参数在保证成像质量和成图精度方面的合理性;报告和展示了系统在广州新客站、丹江口文物考古测量工程的试验情况和部分成果;最后对系统的改进提出了建议。  相似文献   

发展我国海底取样技术的几点设想   总被引：13，自引：0，他引：13       下载免费PDF全文

段新胜  鄢泰宁陈劲 顾湘 《地质与勘探》2003,39(2):69-73

论述了进行海底取样的意义和目的，介绍了国外研制的各种海底取样器工作原理及应用特点，提出了发展我国海底取样技术的几点设想。  相似文献   

卡罗琳M4平顶海山区地貌特征与地质过程研究          下载免费PDF全文

刘喆昊  张建兴  王冰  刘玉斌  杜梦迪  栾振东 《海洋与湖沼》2023,54(2):351-361

卡罗琳M4平顶海山位于卡罗琳海脊与马里亚纳海沟交界处,对其地貌与地质过程的研究有利于深入理解地球动力及环境背景与该地区海山演化的关系。基于“科学”号实测的全覆盖多波束水深数据与“发现”号遥控无人潜水器(remote operated vehicle, ROV)多次下潜获取的近海底影像资料,描述了卡罗琳M4平顶海山及附近区域的地形地貌特征,并对影响海山演化的主要地质过程进行了分析。线性喷发中心等火山地貌指示了研究区内沿线性喷口的裂隙式喷发活动。“C”字型的弯曲形态与陡崖说明山顶平台边缘经历过多次崩塌与破坏,滑坡痕与沉积块体/碎屑组成了块体搬运体系,并在中下段斜坡转变为浊流形成冲沟与水道。M4海山顶部还发育有较为完整的残留环礁地貌,其被淹没的机制可能是由于上升流输入的丰富营养物质影响了底栖环境的光照,从而抑制了珊瑚生长。  相似文献