The recently described red alga Tsunamia transpacifica (Stylonematophyceae) was previously isolated from plastic drift found at the pacific coast, but the natural habitat remains unknown. Here, we investigate ultrastructural details and the low molecular weight soluble carbohydrate composition to get further insight into the adaptation to this uncommon habitat. By means of high pressure freeze fixation, followed by freeze substitution, we could detect an up to 2-µm-thick cell wall surrounded by a distinct layer of extracellular polymeric substances (EPS), likely responsible for the adhering capacities of Tsunamia. The central position of the nucleus and multilobed parietal chloroplast, already observed by light microscopy, could be confirmed. The ultrastructure revealed large electron-dense bodies (EB) in the central cytoplasm, likely resembling degradation products of the chloroplast. Interestingly, these structures contained phosphorous and cobalt, and iron was found in smaller rounded electron-dense bodies by electron energy loss spectroscopy (EELS). Accumulation of these elements suggests a high biosorption activity of Tsunamia. Liquid chromatography-mass spectrometry (LC–MS) data showed the presence of two heterosides (floridoside and digeneaside) together with the polyol sorbitol, which are known as organic osmolytes and compatible solutes. Taken together, these are the first observations on ultrastructural details, element storage and accumulation of protective compounds are contributing to our understanding of the ultrastructural and osmotic solute basis for the ability of Tsunamia to thrive on plastic surfaces.

最近描述的红藻跨太平洋海啸（Stylonematophyceae）以前是从太平洋沿岸发现的塑料漂流中分离出来的，但自然栖息地仍然未知。在这里，我们研究了超微结构细节和低分子量可溶性碳水化合物成分，以进一步了解对这种不常见栖息地的适应情况。通过高压冷冻固定，然后进行冷冻替代，我们可以检测到由一层不同的细胞外聚合物 (EPS) 包围的高达 2 µm 厚的细胞壁，这可能是造成海啸粘附能力的原因. 可以确认已通过光学显微镜观察到的细胞核和多叶壁叶绿体的中心位置。超微结构揭示了中央细胞质中的大电子致密体（EB），可能类似于叶绿体的降解产物。有趣的是，这些结构含有磷和钴，通过电子能量损失光谱 (EELS) 在较小的圆形电子致密体中发现了铁。这些元素的积累表明海啸的高生物吸附活性. 液相色谱-质谱 (LC-MS) 数据显示存在两种杂苷（floridoside 和 digeneaside）以及多元醇山梨糖醇，它们被称为有机渗透物和相容溶质。总之，这些是对超微结构细节、元素储存和保护性化合物积累的首次观察，有助于我们了解海啸在塑料表面上茁壮成长的能力的超微结构和渗透溶质基础。