Table_2_Environmental Drivers of Mesophotic Echinoderm Assemblages of the Southeastern Pacific Ocean.xlsx

Mesophotic ecosystems (50–400 m depth) of the southeastern Pacific have rarely been studied because of the logistical challenges in sampling across this remote zone. This study assessed how oxygen concentrations and other environmental predictors explain variation in echinoderm assemblages at these mesophotic systems, where this group is among the predominant fauna. We compiled data on echinoderm taxa at 91 sampling stations, from historical and recent surveys (between 1950 and 2019), covering a longitudinal gradient of approximately 3,700 km along with the Nazca, Salas y Gómez, and Juan Fernández ridges. Uni- and multivariate model-based tools were applied to analyze the patterns of benthic fauna in relation to environmental factors. Our results indicate a significant positive relationship between echinoderm species richness and depth, oxygen, and salinity. Changes in echinoderm community composition were significantly explained by oxygen, longitude, and chlorophyll-a. We observed notable species turnovers at ∼101 and ∼86°W, where assemblages tend to be more variable across stations. This turnover possibly reflects the effects of physical barriers to dispersion (e.g., currents) and habitat changes. Echinoderm assemblages observed around Easter and Desventuradas Islands presented a high occurrence of potentially endemic taxa and distinct species assemblages. This study is the first to assess the structure of mesophotic echinoderm assemblages of the southeastern Pacific Ocean along a large spatial scale. The information reported here could help design appropriate management tools for the vast, recently created, marine protected areas in the southeastern Pacific.

东南太平洋的次表层生态系统（深度50–400米）因采样该偏远区域的物流挑战而鲜有研究。本研究旨在评估氧浓度及其他环境预测因子如何解释这些次表层系统中海百合类群组成的变异，该类群是其中主要的生物群落之一。我们收集了91个采样站点的海百合物种数据，这些数据来自1950年至2019年的历史和近期调查，涵盖了约3700公里的经度梯度，以及纳兹卡、萨拉亚戈梅斯和胡安费尔南德斯脊。我们应用了基于单一和多元模型的分析工具，以分析底栖动物群与环境因素之间的关系。我们的结果表明，海百合物种丰富度与深度、氧浓度和盐度之间存在显著的正相关关系。海百合群落组成的改变可被氧浓度、经度和叶绿素-a显著解释。我们在大约101°W和86°W处观察到显著的物种更替，在这些区域，各站点之间的组合多样性较高。这种更替可能反映了物理障碍对扩散（例如，洋流）和栖息地变化的影响。在复活节岛和德斯文图拉斯岛周围观察到的海百合组合呈现了高比例的潜在特有物种和独特的物种组合。本研究首次评估了东南太平洋次表层海百合组合的空间结构。所报告的信息有助于为东南太平洋广阔的新近设立的海洋保护区设计适当的管理工具。