VARIABILITY IN CELL SIZE, NUTRIENT DEPLETION, AND GROWTH RATES OF THE SOUTHERN OCEAN DIATOM FRAGILARIOPSIS KERGUELENSIS (BACILLARIOPHYCEAE) AFTER PROLONGED IRON LIMITATION 1
VARIABILITY IN CELL SIZE, NUTRIENT DEPLETION, AND GROWTH RATES OF THE SOUTHERN OCEAN DIATOM FRAGILARIOPSIS KERGUELENSIS (BACILLARIOPHYCEAE) AFTER PROLONGED IRON LIMITATION 1
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DOI：
10.1111/j.1529-8817.2010.00827.x
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发表时间：
2010-06
影响因子：
2.9
通讯作者：
K. Timmermans;B. van der Wagt
中科院分区：
文献类型：
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作者：
K. Timmermans;B. van der Wagt
硅藻是南大洋的主要初级生产者，控制着主要的营养循环。拟脆杆藻是南大洋最丰富的硅藻物种，其古海洋学记录经常被用来重建南极极锋过去的位置和营养特征。在这里，我们报告的响应F。kerguelensis长时间暴露于一系列铁浓度，允许表征与铁状态相关的形态学和营养素耗竭变化。在铁限制条件下，F. kerguelensis生长缓慢，细胞变小，链变短，营养消耗率发生变化。长期暴露于铁限制导致F。使其表面积和体积减少2倍，并使其表面积与体积比增加25%。随着生长速率的降低，每个电池的硅（Si）和磷（P）消耗保持相当恒定，但当归一化每个表面积（Si）或每个电池体积（P）时，消耗增加。相反，每个细胞的氮（N）消耗显著降低，同时生长速率下降，但当归一化每个细胞体积时是恒定的。Si、P和N消耗的不同反应导致营养物消耗比率的变化，最显著的是Si：N比率，其显著增加，以及N：P比率，其随着生长速率的降低而显著降低。因此，在铁限制下，细胞大小的变化和/或营养盐耗竭最终会导致海洋生态地球化学营养循环的变化。它使得能够使用F的单元大小。kerguelensis作为古海洋学的代表。
Diatoms are the main primary producers in the Southern Ocean, governing the major nutrient cycles. Fragilariopsis kerguelensis (O’Meara) Hust. is the most abundant diatom species in the Southern Ocean and its paleo‐oceanographic record is frequently used to reconstruct the past position and nutrient characteristics of the Antarctic polar front. Here we report on the responses of F. kerguelensis on prolonged exposure to a range of iron concentrations, allowing a characterization of morphological and nutrient‐depletion changes in relation to iron status. Under iron limitation, F. kerguelensis grew slower, cells became smaller, chains became shorter, and the nutrient‐depletion ratios changed. Prolonged exposure to iron limitation caused F. kerguelensis to decrease its surface area and volume 2‐fold, and to increase its surface‐to‐volume ratio by 25%. With the decrease in growth rates, silicon (Si) and phosphorus (P) depletion per cell remained fairly constant, but when normalized per surface area (Si) or per cell volume (P), depletion increased. In contrast, nitrogen (N) depletion per cell decreased significantly together with the decrease in growth rates but was constant when normalized per cell volume. The different response in Si, P, and N depletion resulted in changes in the nutrient‐depletion ratios, most notably in the Si:N ratio, which significantly increased, and in the N:P ratio, which significantly decreased with decreasing growth rates. It is concluded that under iron limitation, variation in cell size and/or nutrient depletion ultimately can cause changes in oceanic biogeochemical nutrient cycles. It enables the use of cell size of F. kerguelensis as a paleo‐oceanographic proxy.