Over the seasons, Arctic diatom species occupy shifting habitats defined by contrasting light climates, constrained by snow and ice cover dynamics interacting with extreme photoperiod and solar angle variations. How Arctic diatom photoadaptation strategies differ across their heterogeneous light niches remains a poorly documented but crucial missing link to anticipate Arctic Ocean responses to shrinking sea-ice and increasing light. To address this question, we selected five Arctic diatom species with diverse life traits, representative of distinct light niches across the seasonal light environment continuum: from snow-covered dimly lit bottom ice to summer stratified waters. We studied their photoacclimation plasticity to two growth light levels and the subsequent responses of their nonphotochemical quenching (NPQ) and xanthophyll cycle to both dark incubations and light shifts. We deciphered NPQ and xanthophyll cycle tuning in darkness and their light-dependent induction kinet-ics, which aligned with species' light niche occupancy. In ice-related species, NPQ was sustained in darkness and its induction was more reactive to moderate light shifts. Open-water species triggered strong NPQ induction in darkness and reached higher maximal NPQ under high light. Marginal ice zone species showed strong adaptation to light fluctuations with a dark response fine-tuned depending upon light history. We argue these traits are anchored in diverging photoadaption strategies fostering Arctic diatom success in their respective light niches.

中文翻译：

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对比高光和黑暗下的非光化学淬灭模式与北极硅藻中的光生态位占有率一致

在整个季节中，北极硅藻物种占据由对比鲜明的气候定义的不断变化的栖息地，受到雪和冰盖动态与极端光周期和太阳角度变化相互作用的限制。北极硅藻的光适应策略在其异质光生态位之间有何不同，仍然是一个记录不足但至关重要的缺失环节，以预测北冰洋对缩小的海冰和增加的光的反应。为了解决这个问题，我们选择了五种具有不同生命特征的北极硅藻物种，它们代表了整个季节性光环境连续体中不同的光生态位：从白雪覆盖的昏暗底冰到夏季分层水域。我们研究了它们对两种生长光水平的光驯化可塑性以及它们的非光化学淬灭 (NPQ) 和叶黄素循环对黑暗孵化和光移的后续反应。我们破译了黑暗中的 NPQ 和叶黄素循环调节及其依赖于光的诱导动力学，这与物种的光生态位占有率一致。在与冰有关的物种中，NPQ 在黑暗中持续存在，其诱导对适度的光偏移更具反应性。开放水域物种在黑暗中触发强烈的 NPQ 诱导，并在高光下达到更高的最大 NPQ。边缘冰区物种表现出对光波动的强烈适应，并根据光历史对暗响应进行微调。