Reduced Epifluorescence Microscopy Water Column Samples from R/V Tangaroa TAN1810 in the Chatham Rise (Subtropical and Sub-Antarctic waters off of New Zealand) from October to November 2018 (Salp Food Web Ecology project)

The structure of the phytoplankton community is crucially important to pelagic food webs, biogeochemical processes. and carbon (C) cycle. This study quantifies C-based size spectra, phytoplankton community composition across subtropical and subantarctic waters east of New Zealand. Depth-resolved water column samples were analyzed using epifluorescence microscopy at 15 different sampling locations. Samples were analyzed for biomass and abundance of microplankton (>20 µm), nanoplankton (2-20 µm) and picoplankton (<2 µm) and diatoms. Our results suggest that the subtropical waters are dominated by nanoplankton (35.2 ± 4.6 µg C/L). Offshore subantarctic waters were dominated by picoplankton (24.7 ± 2.1 µg C/L) while microplankton dominated in coastal subantarctic waters (21.7 ± 2.2 µg C/L). Overall, our study helps provide important insights into the structure of phytoplankton communities, their biomass distribution and their contribution to carbon sequestration in the subtropical and subantarctic waters east of New Zealand, highlighting the dominance of nanoplankton in subtropical waters and picoplankton in offshore subantarctic waters.浮游植物群落（phytoplankton community）结构对远洋食物网（pelagic food webs）、生物地球化学过程以及碳（C）循环均具有至关重要的意义。本研究针对新西兰东部亚热带与亚南极海域的浮游植物群落组成及基于碳的粒径谱展开量化分析。研究采集了15个不同采样站位的分层水柱样品，并采用落射荧光显微镜（epifluorescence microscopy）开展分析。本次分析测定了微型浮游植物（microplankton，>20 μm）、小型浮游植物（nanoplankton，2~20 μm）、超微型浮游植物（picoplankton，<2 μm）以及硅藻（diatoms）的生物量与丰度。研究结果显示，亚热带海域以小型浮游植物占主导，其生物量为35.2±4.6 μg C/L。亚南极外海海域以超微型浮游植物占主导（24.7±2.1 μg C/L），而亚南极近岸海域则以微型浮游植物占主导（21.7±2.2 μg C/L）。总体而言，本研究为新西兰东部亚热带与亚南极海域的浮游植物群落结构、生物量分布及其在碳封存（carbon sequestration）中的作用提供了重要见解，并明确了亚热带海域以小型浮游植物为主、亚南极外海海域以超微型浮游植物为主的分布特征。