By relating observed changes to the pressures suffered, the Marine Strategy Framework Directive intends to better control the factors of environmental degradation and to manage their consequences in European waters. Several descriptors are defined within the framework of the MFSD and in particular descriptor 1 relating to the biological diversity of the seabed and descriptor 6 relating to the seabed integrity (i.e. the quality of their structures and functions). For each descriptor, indicators and threshold values must be defined and a novel conceptual approach to define and detect seabed integrity thresholds is proposed here. Bottom trawling being the main source of shelf continental disturbance, it is important to evaluate its impact on benthic habitat. The goal of this study is to propose a methodology to determine “Good Ecological Status” threshold values for each habitat type present in three contrasted MFSD sub-region (North Sea, English Channel and Mediterranean Sea). Trawling impacts are dependent of the spatial and temporal distribution of the fishing effort, fishing gears, intensity of natural disturbances and habitat types. Benthic community structures present in these areas were studied using by-catch non-commercial benthic invertebrates data collected during French scientific bottom trawl surveys. Swept area ratios derived from VMS data were used to quantify the intensity of fishery induced abrasion on the seabed. A modeling approach was used to determine abrasion threshold values on each EUNIS level 4 habitat. The values, beyond which trawling has an adverse effect on benthic communities, have been determined for each habitat. This made it possible to assess and map the ecological status of each of the habitats and to determine the percentage of each habitat impacted by trawling. The method proposed here to evaluate the impact of trawling on benthic communities highlighted that the vast majority of the investigated sub-regions were adversely impacted or lost as a result of seabed impacting trawling.

通过将观察到的变化与所承受的压力联系起来，《海洋战略框架指令》旨在更好地控制环境退化的因素并管理其在欧洲水域中的后果。在MFSD框架内定义了几个描述符，尤其是与海底生物多样性有关的描述符1和与海床完整性（即其结构和功能的质量）有关的描述符6。对于每个描述符，必须定义指标和阈值，并在此提出一种定义和检测海底完整性阈值的新颖概念方法。底拖网捕捞是陆架大陆性扰动的主要来源，重要的是评估其对底栖生境的影响。这项研究的目的是提出一种方法，以确定存在差异的三个MFSD子区域（北海，英吉利海峡和地中海）中每种生境类型的“良好生态状况”阈值。拖网捕鱼的影响取决于捕捞努力的时空分布，渔具，自然干扰的强度和栖息地的类型。使用法国科学海底拖网调查期间收集的兼捕非商业底栖无脊椎动物数据，研究了这些地区存在的底栖动物群落结构。从VMS数据得出的扫描面积比用于量化渔业在海底引起的磨损强度。使用一种建模方法来确定每个EUNIS 4级栖息地的磨损阈值。价值，对于每个栖息地，已经确定拖网对底栖生物有不利影响。这样就可以评估和绘制每个栖息地的生态状况，并确定拖网影响每个栖息地的百分比。这里提出的评估拖网对底栖生物影响的方法强调指出，由于海床影响拖网，绝大多数被调查的次区域受到不利影响或损失。