Mesophotic coral ecosystems (MCEs; ~30–150 m depth) are among the most biologically diverse and least protected ecosystems in the world's oceans. However, discussions regarding the conservation of these unique ecosystems are scarce. To address this issue, we identified the features of MCEs that demonstrate they should be considered as a global conservation priority. Some MCEs are characterized by their well-preserved and unique seascapes; their narrow environmental tolerance and high vulnerability to anthropogenic effects; and their slow recovery and reduced reproductive performance. The unique biodiversity of MCEs includes depth-adapted specialist species and new species, most of which are threatened or important fishery resources. MCEs also provide refuge against human stressors, valuable ecosystem services, and ecological connectivity. MCEs generally meet the criteria to be classified as Ecologically and Biologically Significant Marine Areas under the Convention on Biological Diversity. However, we highlight that many MCEs worldwide are threatened and not yet adequately protected by fishery regulations, marine protected areas, or considered in marine spatial planning. Establishing MCEs as a global conservation priority requires the designation of national, international, transnational, public, and private policies.

中生珊瑚生态系统（MCE；深度约30-150 m）是世界上生物多样性最丰富，保护最少的生态系统之一。但是，关于保护这些独特生态系统的讨论很少。为了解决这个问题，我们确定了MCE的特征，这些特征表明应将MCE视为全球保护的重点。一些MCE的特点是保存完好的独特的海景。它们对环境的耐受力狭窄，对人为影响的脆弱性高；它们的恢复缓慢，生殖能力下降。MCE独特的生物多样性包括深度适应的专业物种和新物种，其中大多数是受威胁的或重要的渔业资源。MCE还为人类压力源，有价值的生态系统服务和生态连通性提供了避难所。MCE通常符合被《生物多样性公约》归类为具有生态和生物意义的海洋区域的标准。但是，我们强调指出，全世界许多MCE都受到威胁，尚未受到渔业法规，海洋保护区的充分保护，或者尚未在海洋空间规划中加以考虑。将MCE确立为全球保护重点需要指定国家，国际，跨国，公共和私人政策。