Coastal zones of Antarctica harbor rich but highly variable phytoplankton communities. The mechanisms that control the dynamics of these communities are not well defined. Here we elucidate the mechanisms that drive seasonal species succession, based on algal photophysiological characteristics and environmental factors. For this, phytoplankton community structure together with oceanographic parameters was studied over a 5-year period (2012-2017) at Rothera Station at Ryder Bay (Western Antarctic Peninsula). Algal pigment patterns and photophysiological studies based on fluorescence analyses were combined with data from the Rothera Time-Series program. Considerable interannual variation was observed, related to variations in wind-mixing, ice cover and an El Nino event. Clear patterns in the succession of algal classes became manifest when combining the data collected over the five successive years. In spring, autotrophic flagellates with a high light affinity were the first to profit from increasing light and sea ice melt. These algae most likely originated from sea-ice communities, stressing the role of sea ice as a seeding vector for the spring bloom. Diatoms became dominant towards summer in more stratified and warmer surface waters. These communities displayed significantly lower photoflexibility than spring communities. There are strong indications for mixotrophy in cryptophytes, which would explain much of their apparently random occurrence. Climate models predict continuing retreat of Antarctic sea-ice during the course of this century. For the near-future we predict that the marginal sea-ice zone will still harbor significant communities of haptophytes and chlorophytes, whereas increasing temperatures will mainly be beneficial for diatoms.

中文翻译：

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由环境驱动因素解释的南极沿海水域浮游植物物候的年度模式

南极洲沿海地区拥有丰富但高度可变的浮游植物群落。控制这些社区动态的机制没有明确定义。在这里，我们基于藻类光生理特征和环境因素阐明了驱动季节性物种演替的机制。为此，在莱德湾（南极半岛西部）的 Rothera 站对浮游植物群落结构和海洋参数进行了为期 5 年（2012-2017 年）的研究。基于荧光分析的藻类色素模式和光生理学研究与来自 Rothera 时间序列程序的数据相结合。观察到相当大的年际变化，与风混合、冰盖和厄尔尼诺事件的变化有关。将连续五年收集的数据结合起来，藻类类别的继承模式变得明显。在春天，具有高光亲和力的自养鞭毛虫首先受益于增加光和海冰融化。这些藻类很可能起源于海冰群落，强调了海冰作为春季开花的种子载体的作用。在更分层和更温暖的地表水中，硅藻在夏季占主导地位。这些群落的光灵活性明显低于春季群落。隐生植物中存在混合营养的强烈迹象，这可以解释它们明显随机发生的大部分原因。气候模型预测在本世纪期间南极海冰将继续消退。