High Seas Marine Protected Areas: Benthic environmental conservation priorities from a GIS analysis of global ocean biophysical data

In order to design a representative network of high seas marine protected areas (MPAs), an acceptable scheme is required to classify the benthic bioregions of the oceans. Given the lack of sufficient biological information to accomplish this task, we used a multivariate statistical method with 6 biophysical variables (depth, seabed slope, sediment thickness, primary production, bottom water dissolved oxygen and bottom temperature) to objectively classify the ocean floor into 11 different categories, comprised of 53,713 separate polygons, that we have termed "seascapes". Validation of the seascape classification was carried out by comparing the seascapes with an existing map of seafloor geomorphology, and by GIS analysis of the number of separate polygons and perimeter/area ratio. We conclude that seascapes, derived using a multivariate statistical approach, are biophysically meaningful subdivisions of the ocean floor and can be expected to contain different biological associations, in as much as different geomorphological units do the same. Our study illustrates how the identification of potential sites for high seas marine protected areas can be accomplished by GIS analysis of seafloor geomorphic and seascape classification maps. Using this approach, maps of seascape and geomorphic heterogeneity were generated in which heterogeneity hot-spots identify themselves as MPA candidates. The use of computer-aided mapping tools removes subjectivity in the MPA design process and provides greater confidence to stakeholders that an unbiased result has been achieved.

为构建具有代表性的公海海洋保护区（Marine Protected Areas, MPAs）网络，需建立一套可行的分类方案以对大洋底栖生物区进行划分。鉴于现有生物学信息不足以完成该划分工作，本研究采用包含6项生物物理变量（水深、海底坡度、沉积物厚度、初级生产力、底层水溶解氧及底层水温）的多元统计方法，将大洋底客观划分为11个类别，共计包含53713个独立多边形，我们将其命名为‘海洋景观（seascapes）’。

本研究通过将海洋景观分类结果与现有海底地貌图进行对比，并借助地理信息系统（Geographic Information System, GIS）分析独立多边形数量与周长面积比，完成了海洋景观分类的验证。研究表明，通过多元统计方法得到的海洋景观是具备生物物理意义的大洋底划分单元，正如不同地貌单元一般，不同海洋景观内部也可孕育出各异的生物群落。

本研究展示了如何通过对海底地貌与海洋景观分类图开展地理信息系统分析，筛选出潜在的公海海洋保护区选址。借助该方法，本研究生成了海洋景观与地貌异质性分布图，其中异质性热点区域可直接作为海洋保护区候选点位。采用计算机辅助制图工具可消除海洋保护区设计流程中的主观性，让利益相关方更确信研究得到了客观公正的结果。