(Table S1) Relative abundances of coccolithophore taxa in surface sediment samples from the Equatorial and Southeastern Pacific

This study aims to contribute to a more detailed knowledge of the biogeography of coccolithophores in the Equatorial and Southeastern Pacific Ocean. Census data of fossil coccoliths are presented in a suite of core-top sediment samples from 15°N to 50.6°S and from 71°W to 93°W. Following standard preparation of smear slides, a total of 19 taxa are recognized in light microscopy and their relative abundances are determined for 134 surface sediment samples. Considering the multivariate character of oceanic conditions and their effects on phytoplankton, a Factor Analysis was performed and three factors were retained. Factor 1, dominated by Florisphaera profunda and Gephyrocapsa oceanica, includes samples located under warm water masses and indicates the occurrence of calcite dissolution in the water column in the area offshore Chile. Factor 2 is related to cold, low-salinity surface-water masses from the Chilean upwelling, and is dominated by Emiliania huxleyi, Gephyrocapsa sp. < 3 µm, Coccolithus pelagicus and Gephyrocapsa muellerae. Factor 3 is linked to more saline, coastal upwelling areas where Calcidiscus leptoporus and Helicosphaera carteri are the dominant species.

本研究旨在增进对赤道及东南太平洋海域颗石藻（coccolithophores）生物地理学的精细化认知。本研究提供了15°N至50.6°S、71°W至93°W范围内一系列岩芯表层沉积物样品的化石颗石（coccoliths）普查数据。经标准涂片玻片（smear slides）制备流程后，通过光学显微镜（light microscopy）共鉴定出19个类群，并对134个表层沉积物样品的类群相对丰度进行了定量测定。考虑到海洋环境条件的多变量特征及其对浮游植物（phytoplankton）的影响，本研究开展了因子分析（Factor Analysis），最终保留3个主因子。因子1以深水颗石藻（Florisphaera profunda）和大洋桥石藻（Gephyrocapsa oceanica）为优势类群，对应暖水团覆盖区域，指示智利近岸海域水柱中存在方解石溶解（calcite dissolution）现象。因子2与智利上升流（upwelling）区的低温低盐表层水团相关，优势类群包括艾氏球石藻（Emiliania huxleyi）、粒径小于3μm的桥石藻未定种（Gephyrocapsa sp. < 3 µm）、海生球石藻（Coccolithus pelagicus）以及穆勒桥石藻（Gephyrocapsa muellerae）。因子3与盐度更高的沿岸上升流区相关，优势类群为细孔球石藻（Calcidiscus leptoporus）和卡特螺旋球石藻（Helicosphaera carteri）。