Subtidal and Intertidal Seagrass Beds

<div style='text-align:Left;font-size:12pt'><p style='margin:0 0 0 0;'><span><span>The subtidal polygons were digitised around survey data in which Zostera marina (subtidal seagrass) beds were identified from dive and towed camera surveys. The boundary was digitised according to SAC guidance using the minimum number of vectors/lines and staying as close as possible to the feature of interest, but including a boundary of approximately 2.5 times the maximum depth (for navigation purposes). Further survey work is planned to provide more ground truthing points in Ballyhenry Bay and a second seagrass bed was identified in Castleward bay but its extent was not mapped.</span></span></p><p><p style='margin:0 0 0 0;'><span><span>The digitised polygons encompassing intertidal seagrass (Zostera subgroup zosterella noltei) mapped using high spec GPS data-logger (TRIMBLE) on foot and when possible by Hovercraft provided by the Environment Protection Agency (EPA) in the Republic of Ireland. This work was done by the Marine Monitoring and Assessment Team and was repeated over a number of years to detect change in area, density or number of species however this layer only shows the latest data. MMAT have added that due to health and safety reasons the Larne Lough and Carlingford Lough surveys are not complete, and all the seagrass in these areas was not mapped. They will be prioritised this year and it is hoped that the remaining areas will be surveyed using a drone and/or hovercraft in 2020.</span></span></p><p><p><p style='font-size:16ptmargin:7 0 7 0;'><span /></p><p style='font-weight:bold;margin:7 0 7 0;'><span /></p></div>潮下带多边形（subtidal polygons）基于相关调查数据进行描边数字化，该调查通过潜水及拖曳式摄像调查识别出了鳗草（Zostera marina）潮下海草床。其边界依据特别保护区（Special Area of Conservation，SAC）指南进行数字化，采用最少数量的矢量/线要素，尽可能贴近目标地物，但为满足航行需求，边界范围设置为约2.5倍最大水深。目前已规划开展进一步调查工作，以在巴利亨利湾（Ballyhenry Bay）获取更多地面验证点；另在卡斯尔沃德湾（Castleward bay）发现了一处海草床，但尚未绘制其分布范围。 潮间带海草（intertidal seagrass）的数字化多边形覆盖了矮大叶藻类群（Zostera subgroup zosterella noltei），其测绘工作通过徒步携带高精度GPS数据记录仪（TRIMBLE）完成，并在可行时使用爱尔兰共和国环境保护署（EPA）提供的气垫船开展作业。此项工作由海洋监测与评估团队（Marine Monitoring and Assessment Team，MMAT）实施，并在多年间重复开展以监测海草床的面积、密度或物种数量变化，但本图层仅展示最新调查数据。MMAT补充说明，受健康与安全因素限制，拉恩湾（Larne Lough）与卡林福德湖（Carlingford Lough）的调查尚未完成，该区域内的所有海草均未完成测绘。本年度将优先推进这两处区域的调查工作，预计2020年将使用无人机和/或气垫船完成剩余区域的测绘。