The filamentous microalga Tribonema sp. (Stramenopiles, Xanthophyceae) plays an important role in shallow water polar (streams and seepages) and seasonally cold habitats in temperate regions (ponds). In these habitats, freezing and desiccation, and thus freeze–thawing and drying–rewetting cycles, are frequent. These regions produce visible biomass and are important components of low temperature-adapted communities. We characterized the annual cycles of a Tribonema cf. minus population in two habitats (seepage and stream) in the High Arctic, Svalbard. Seasonality, locality, and their combination (particularly changing environmental conditions) together with cultivation conditions of strains significantly affected their morphological characteristics. Morphological changes following hardening processes related to preparation for the winter period (transition from vegetative cells to akinete and/or pre-akinete) were recorded. Over the year, positive water temperatures (warmest 13.3°C) occurred for 5 months while negative (lowest temperature was –17.4°C) lasted for 7 months. In winter, there were two melt periods. Vitality staining protocol showed a high number of viable (77.4% and 53.8%) and dormant cells (1.7% and 4.1%; capable of growth and reproduction once suitable conditions return) in the winter seepage and stream, respectively. NPQ and OJIP chlorophyll fluorescence parameters revealed several hours recovery of photosynthesis (both field and control samples). During recovery, only minor or mild stress on photosynthesis was detected. F_V/F_M values (the photosynthetic efficiency of photosystem II in a dark-adapted state) in all field and control samples varied around 0.4. Tribonema cf. minus is capable of surviving winter Arctic conditions (perennial strategy).

中文翻译：

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形成垫的丝状藻 Tribonema 的年度周期 参见。多参数荧光染色揭示了北极高地水生栖息地中的负（原生藻菌、黄藻科）

丝状微藻Tribonema sp。（原生藻纲、黄藻科）在浅水极地（溪流和渗流）和温带地区（池塘）的季节性寒冷栖息地中起着重要作用。在这些栖息地中，经常发生冷冻和干燥，进而冻融和干燥再润湿的循环。这些区域产生可见的生物量，是适应低温群落的重要组成部分。我们描述了Tribonema cf的年度周期。减斯瓦尔巴群岛高北极的两个栖息地（渗流和溪流）中的种群。季节性、地域性和它们的组合（特别是不断变化的环境条件）以及菌株的栽培条件显着影响了它们的形态特征。记录了与冬季准备相关的硬化过程（从营养细胞向 akinete 和/或 pre-akinete 过渡）后的形态变化。全年出现正水温（最高13.3°C）5个月，负水温（最低–17.4°C）持续7个月。在冬季，有两个融化期。活力染色方案显示在冬季渗流和溪流中有大量的活细胞（77.4% 和 53.8%）和休眠细胞（1.7% 和 4.1%；一旦合适的条件恢复，就能够生长和繁殖），分别。NPQ 和 OJIP 叶绿素荧光参数显示光合作用恢复数小时（野外和对照样品）。在恢复期间，仅检测到对光合作用的轻微或轻度胁迫。所有田间和对照样品中的F _V / F _M值（暗适应状态下光系统 II 的光合效率）在 0.4 左右变化。Tribonema参见。减号能够在冬季北极条件下生存（常年策略）。