PDF(Pubmed)
Abstract：
The continental shelf of the Western Antarctic Peninsula (WAP) is a highly variable system characterized by strong cross-shelf gradients, rapid regional change, and large blooms of phytoplankton, notably diatoms. Rapid environmental changes coincide with shifts in plankton community composition and productivity, food web dynamics, and biogeochemistry. Despite the progress in identifying important environmental factors influencing plankton community composition in the WAP, the molecular basis for their survival in this oceanic region, as well as variations in species abundance, metabolism, and distribution, remains largely unresolved. Across a gradient of physicochemical parameters, we analyzed the metabolic profiles of phytoplankton as assessed through metatranscriptomic sequencing. Distinct phytoplankton communities and metabolisms closely mirrored the strong gradients in oceanographic parameters that existed from coastal to offshore regions. Diatoms were abundant in coastal, southern regions, where colder and fresher waters were conducive to a bloom of the centric diatom, Actinocyclus. Members of this genus invested heavily in growth and energy production; carbohydrate, amino acid, and nucleotide biosynthesis pathways; and coping with oxidative stress, resulting in uniquely expressed metabolic profiles compared to other diatoms. We observed strong molecular evidence for iron limitation in shelf and slope regions of the WAP, where diatoms in these regions employed iron-starvation induced proteins, a geranylgeranyl reductase, aquaporins, and urease, among other strategies, while limiting the use of iron-containing proteins. The metatranscriptomic survey performed here reveals functional differences in diatom communities and provides further insight into the environmental factors influencing the growth of diatoms and their predicted response to changes in ocean conditions.
OBJECTIVE: In the Southern Ocean, phytoplankton must cope with harsh environmental conditions such as low light and growth-limiting concentrations of the micronutrient iron. Using metratranscriptomics, we assessed the influence of oceanographic variables on the diversity of the phytoplankton community composition and on the metabolic strategies of diatoms along the Western Antarctic Peninsula, a region undergoing rapid climate change. We found that cross-shelf differences in oceanographic parameters such as temperature and variable nutrient concentrations account for most of the differences in phytoplankton community composition and metabolism. We opportunistically characterized the metabolic underpinnings of a large bloom of the centric diatom Actinocyclus in coastal waters of the WAP. Our results indicate that physicochemical differences from onshore to offshore are stronger than between southern and northern regions of the WAP; however, these trends could change in the future, resulting in poleward shifts in functional differences in diatom communities and phytoplankton blooms.
OBJECTIVE: In the Southern Ocean, phytoplankton must cope with harsh environmental conditions such as low light and growth-limiting concentrations of the micronutrient iron. Using metratranscriptomics, we assessed the influence of oceanographic variables on the diversity of the phytoplankton community composition and on the metabolic strategies of diatoms along the Western Antarctic Peninsula, a region undergoing rapid climate change. We found that cross-shelf differences in oceanographic parameters such as temperature and variable nutrient concentrations account for most of the differences in phytoplankton community composition and metabolism. We opportunistically characterized the metabolic underpinnings of a large bloom of the centric diatom Actinocyclus in coastal waters of the WAP. Our results indicate that physicochemical differences from onshore to offshore are stronger than between southern and northern regions of the WAP; however, these trends could change in the future, resulting in poleward shifts in functional differences in diatom communities and phytoplankton blooms.
摘要：
南极半岛西部大陆架（WAP）是一个高度可变的系统，其特征是强烈的跨架梯度，快速的区域变化，大量的浮游植物，尤其是硅藻。快速的环境变化与浮游生物群落组成和生产力的变化相吻合，食物网动态，和生物地球化学。尽管在WAP中确定影响浮游生物群落组成的重要环境因素方面取得了进展，它们在这个海洋区域生存的分子基础，以及物种丰度的变化，新陈代谢，和分配，基本上没有解决。在物理化学参数的梯度中，我们分析了浮游植物的代谢谱,如通过代谢组学测序所评估的.不同的浮游植物群落和代谢紧密地反映了从沿海到近海地区存在的海洋学参数的强梯度。沿海的硅藻很丰富，南部地区,更冷更新鲜的海水有利于中心硅藻的开花，放线菌。该属的成员在生长和能源生产上投入了大量资金；碳水化合物，氨基酸,和核苷酸生物合成途径；以及应对氧化应激，与其他硅藻相比，产生独特表达的代谢谱。我们在WAP的架子和斜坡区域观察到铁限制的强有力的分子证据，这些地区的硅藻使用铁饥饿诱导的蛋白质，一种香叶基香叶酰还原酶，水通道蛋白,和脲酶，在其他策略中，同时限制含铁蛋白质的使用。此处进行的超转录组学调查揭示了硅藻群落的功能差异，并进一步了解了影响硅藻生长的环境因素及其对海洋条件变化的预测反应。在南大洋的重要性,浮游植物必须应对恶劣的环境条件，例如弱光和微量营养素铁的生长限制浓度。使用metratranscriptomics，我们评估了海洋学变量对浮游植物群落组成的多样性以及对西南极半岛硅藻代谢策略的影响，正在经历快速气候变化的地区。我们发现，海洋学参数的跨架差异，例如温度和可变的养分浓度，是浮游植物群落组成和代谢差异的主要原因。我们机会性地描述了WAP沿海水域中心硅藻放线菌的大量繁殖的代谢基础。我们的结果表明，从陆上到海上的物理化学差异比WAP的南部和北部地区之间的差异更强；但是，这些趋势在未来可能会改变，导致硅藻群落和浮游植物水华的功能差异发生极移。
