Shell dissolution state of the thecosome pteropod Limacina helicina antarctica during Polarstern cruise PS111 (ANT-XXXIII/2)

At high latitudes, thecosome pteropods (marine pelagic mollusks) can dominate zooplankton communities and are important food web components. Due to their calcium carbonate shell made of aragonite, they significantly contribute to ocean carbon flux and are particularly vulnerable to ocean acidification. Aragonite undersaturation (Ωar < 1) events are projected to rapidly increase in frequency and duration in the Antarctic Weddell Sea by 2050 due to uptake of increasing amounts of anthropogenic CO2. This potentially perils thecosomes by inducing shell dissolution. The project aim was to describe the importance of thecosome pteropods in terms of their biomass contribution relative to that of other mesozooplankton groups in the Weddell Sea pelagic ecosystem and to describe the current shell dissolution state of thecosome pteropods in relation to prevailing ocean carbonate chemistry conditions as a benchmark for possible future monitoring of ongoing ocean change processes. This dataset includes the shell dissolution assessment performed on scanning electron microscopy (SEM) pictures of individual thecosome pteropod specimen of the species Limacina helicina antarctica. It also includes accompanying overview pictures of the pteropods taken prior to SEM analysis with a stereomicroscope. Total dissolution severity was assessed based on the occurrence of three severity types of dissolution (Type I, Type II, Type III) on the surface of the protoconch and first two whorls of the individual shells. Along with the dataset individual SEM pictures of each shell (overview and close-ups of the 2nd whorl, 1st whorl and the protoconch) are provided. Individual Pteropods were usually collected from 500–0 m depth during PS111 at the eastern Weddell Sea Shelf and the Filchner-Ronne ice shelf.

在高纬度地区，有壳翼足类（thecosome pteropods，海洋中上层软体动物）可主导浮游动物群落，是食物网的重要组成部分。由于其外壳由文石（aragonite）构成的碳酸钙组成，它们对海洋碳通量具有显著贡献，且对海洋酸化尤为敏感。文石不饱和（Ωar <1）事件的频率和持续时间预计将因人为二氧化碳（CO₂）吸收量增加而在2050年前于南极威德尔海迅速上升，这可能通过诱导外壳溶解危及有壳翼足类。本项目旨在阐明有壳翼足类的生物量贡献相对于威德尔海中层生态系统中其他中型浮游动物群（mesozooplankton groups）的重要性，并描述其当前外壳溶解状态与主导海洋碳酸盐化学条件（carbonate chemistry conditions）的关系，以此作为未来监测海洋变化过程的基准。该数据集包含对南极鳞壳翼足类（Limacina helicina antarctica）个体样本通过扫描电子显微镜（SEM）图片进行的外壳溶解评估，还包括SEM分析前用立体显微镜（stereomicroscope）拍摄的翼足类概览图。外壳总溶解严重程度的评估基于原壳（protoconch）和个体外壳前两个螺层（whorls）表面出现的三种溶解类型（I型、II型、III型）。数据集还提供了每个外壳的单独SEM图片，包括概览图以及第二螺层、第一螺层和原壳的特写图。翼足类个体样本通常采集自PS111航次期间威德尔海东部陆架和菲尔希纳-龙尼冰架的500–0米深度。