Roches de Penmarc'h

Mapis based on the interpretation of various types of data from a number of surveys carried out between 2011-2012 both in the intertidal and subtidal zones. Additionally the seabed « Carte G » from the French hydrographic survey (SHOM) was used in the interpretation process. In the tidal zone the identification was made by interpreting coastal ortho-photographs from BD Ortho (2005 et 2009) and digitising them on scale 1 : 2000ème with further qualification of the polygons based on ground truth data. For the subtidal zone, several data sources from 2011 were available: bathymetric lidar (with sounding density about 1pt*3m-2), side scan sonar (resolution of about 0.2m), underwater video, sediment and fauna samples collected with grabs and trawls. Addtionnally a single beam sounder was running at all times during the transects, which contributing to improve the depth DTM. In the outer rocky circalittoral zone, side scan sonar corridors were surveyed with a coverage of 30-50% depending on places. In the offshore deep circalittoral zone (known as La Grande vasière) where soft sediment is predominant, side scan sonar coverage was reduced to about 5-10%. In these latter two circalittoral zones, interpolation between sonar corridors was supported by SHOM « Carte G » (approx. scale 1:100000) along with a 100m resolution depth DTM. On rocky seabed, exposure at the seabed was described using kinetic energy from a combination of wave and current hydrodynamic models according to the methods described in: http://doi.org/10.13155/49975. Rocky substrate in intertidal and infralittoral zones was derived from the combined interpretation of both the topographic and bathymetric Lidar DTMs and aerial photographs, where permitted by water transparency. Various representations of the DTMs (slope, hillshade) helped delineate rocky outcrops with good reliability. Biological qualification of the substrate polygons was made through taxonomic analysis of benthos samples collected by MNHN in the framework of the project"Ecological assessment of Natura 2000 site - Roches de Penmarc’h".The final habitat classification was a synthesis of the main habitat classifications, namely: Generic habitats from the Habitat Directive (EUR 27), Elementary habitats from the French Cahiers d’habitats, The Rebent classificationand EUNIS level 4 as much as possible.本数据集基于2011-2012年间于潮间带与潮下带开展的多项调查的各类数据解译构建。解译过程中还参考了法国水文海洋局（Service Hydrographique et Océanographique de la Marine, SHOM）编制的"Carte G"海图。潮间带的底质识别依托BD Ortho提供的2005年与2009年海岸正射影像（ortho-photograph）进行解译，以1:2000比例尺完成数字化后，结合地面实测数据对多边形边界进行验证与修正。潮下带则采用2011年的多源调查数据：包括测深激光雷达（bathymetric lidar，测点密度约为3 m²/点）、侧扫声呐（side scan sonar，分辨率约0.2 m）、水下视频影像，以及利用抓斗和拖网采集的沉积物与生物样本。此外，断面调查全程搭载单波束测深仪，用于优化水深数字地形模型（Digital Terrain Model, DTM）。外滨周滨岩质带的侧扫声呐测线覆盖范围依区域不同为30%~50%。位于深水区域的近岸周滨带（即"La Grande vasière"大泥滩区域）以软质沉积物为主，侧扫声呐覆盖范围缩减至约5%~10%。针对后两类周滨带，侧扫声呐测线间的插值解译依托SHOM的"Carte G"海图（比例尺约1:100000）与分辨率为100 m的水深DTM完成。岩质海底的底质暴露程度则依据文献http://doi.org/10.13155/49975中所述方法，结合波浪与海流的水动力模型计算得到的动能进行表征。潮间带与潮下带（infralittoral zone）的岩质基底则通过地形与测深激光雷达DTM结合航空影像解译得到，前提为水域透明度允许观测。各类DTM衍生产品（如坡度、山体阴影）可辅助可靠地圈定岩质露头。底质多边形的生物属性判定则基于法国国家自然历史博物馆（Muséum National d'Histoire Naturelle, MNHN）在"Natura 2000站点——彭马尔克岩石区生态评估"项目框架下采集的底栖生物样本的分类学分析结果。最终的生境分类整合了主流的生境分类体系，包括：欧盟生境指令（Habitat Directive, EUR 27）规定的通用生境、法国《生境手册》（Cahiers d’habitats）中的基础生境、Rebent分类体系，以及尽可能采用的欧洲生境信息标准（European Nature Information System, EUNIS）四级分类。