Ecologically or Biologically Significant Marine Areas - Regional Subsets - Predicted Seamount locations

Seamounts and knolls are "undersea mountains", the former rising more than 1000 m from the seafloor. These features provide important habitats for aquatic predators, demersal deep-sea fish and benthic invertebrates. However most seamounts have not been surveyed and their numbers and locations are not well known. Previous efforts to locate and quantify seamounts have used relatively coarse bathymetry grids. Here we use global bathymetric data at 30 arc-sec resolution to identify seamounts and knolls. We identify 33,452 seamounts and 138,412 knolls, representing the largest global set of identified seamounts and knolls to date. We compare estimated seamount numbers, locations, and depths with validation sets of seamount data from New Zealand and Azores. This comparison indicates the method we apply finds 94% of seamounts, but may overestimate seamount numbers along ridges and in areas where faulting and seafloor spreading creates highly complex topography. The seamounts and knolls identified herein are significantly geographically biased towards areas surveyed with ship-based soundings. As only 6.5% of the ocean floor has been surveyed with soundings it is likely that new seamounts will be uncovered as surveying improves. Seamount habitats constitute approximately 4.7% of the ocean floor, whilst knolls cover 16.3%. Regional distribution of these features is examined, and we find a disproportionate number of productive knolls, with a summit depth of o 1.5 km, located in the Southern Ocean. Less than 2% of seamounts are within marine protected areas and the majority of these are located within exclusive economic zones with few on the High Seas. The database of seamounts and knolls resulting from this study will be a useful resource for researchers and conservation planners.

The data was collected to support the Western South Pacific Regional Workshop to facilitate the description of Ecologically or Biologically Significant Marine Areas (EBSA) UNEP/CBD/SBSTTA/16/INF/6

海山（seamount）与海丘（knoll）均属于“海底山脉”，其中海山指从海底隆起高度超过1000米的海底地形。此类地貌为水生捕食者、底栖深海鱼类与底栖无脊椎动物提供了关键栖息地。然而，绝大多数海山尚未被系统勘测，其实际数量与分布位置均未明确。过往针对海山的定位与量化研究，多采用分辨率相对较低的水深地形（bathymetry）网格。本研究采用30角秒分辨率的全球水深地形数据，开展海山与海丘的识别工作。本次研究共识别出33452座海山与138412座海丘，是迄今为止全球规模最大的已公开海山与海丘数据集。研究团队将本次估算得到的海山数量、位置与水深数据，与新西兰及亚速尔群岛的海山验证数据集进行对比，结果显示本研究采用的识别方法可检出94%的现有海山，但在断层活动与海底扩张形成复杂地形的海脊沿线区域，该方法可能会高估海山的实际数量。本次研究识别的海山与海丘在地理分布上显著偏向于已开展船载测深的海域。鉴于全球仅6.5%的洋底完成过测深作业，因此随着勘测技术的进步，未来仍可能发现大量新的海山。海山栖息地总面积约占全球洋底的4.7%，而海丘则覆盖16.3%的全球洋底。研究团队对这些地貌的区域分布特征进行了分析，发现南大洋区域存在大量顶深不超过1.5公里的高产海丘。仅有不到2%的海山位于海洋保护区内，且其中绝大多数位于专属经济区，公海区域内的海山保护区寥寥无几。本研究构建的海山与海丘数据库，将为科研人员与海洋保护规划者提供极具价值的研究资源。

本数据集的采集工作旨在支持西南太平洋区域研讨会，助力《生态或生物重要海洋区域（Ecologically or Biologically Significant Marine Areas, EBSA）》相关工作，相关文件编号为UNEP/CBD/SBSTTA/16/INF/6。