Table_3_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.

东南太平洋地区的次表层生态系统（深度为50至400米）因采样该偏远区域所面临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棘皮动物群落组成的变异，其中棘皮动物是该地区优势生物群之一。本研究收集了91个采样站点的棘皮动物分类群数据，这些数据来源于历史和近年来的调查（时间范围为1950年至2019年），涵盖了约3,700公里的经度梯度，包括纳兹卡、萨拉·戈梅斯和胡安·费尔南德斯脊。本研究运用了单变量和多变量模型工具来分析底栖动物群落与环境因素之间的关系。研究结果表明，棘皮动物物种丰富度与深度、氧浓度和盐度之间存在显著的正相关关系。棘皮动物群落组成的变化可通过氧浓度、经度和叶绿素a含量进行显著解释。我们在大约101°W和86°W处观察到显著的物种更替，各站点之间的群落组成表现出较大的变异性。这种更替可能反映了物理屏障对扩散（例如，洋流）和生境变化的影响。在复活节岛和德斯文特拉斯岛附近观察到的棘皮动物群落表现出高比例的潜在特有物种和独特的物种组合。本研究首次对东南太平洋次表层棘皮动物群落结构进行了大尺度空间评估。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治理工具。