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首页> 外文期刊>Journal of Experimental Marine Biology and Ecology >Photophysiological effects of Fe concentration gradients on diatom-dominated phytoplankton assemblages in the Antarctic Peninsula region
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Photophysiological effects of Fe concentration gradients on diatom-dominated phytoplankton assemblages in the Antarctic Peninsula region

机译：Fe浓度梯度对南极半岛地区以硅藻为主的浮游植物组合的光生理效应

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The Southern Ocean is generally a high-nutrient and low-chlorophyll (HNLC) area, primarily due to the limitation of micronutrients, such as iron (Fe). Nevertheless, microphytoplankton may bloom if Fe is available and if light and mixing conditions are suitable. This study aimed to investigate the ecological and photophysiological responses of the phytoplankton, such as size, community composition, nutrient usage and photosynthetic potential, under high irradiance levels and over an iron concentration gradient. A 6-day deck incubation experiment was conducted during the austral summer of 2013, using phytoplankton populations from the upper mixed layer in the Bransfield Strait waters. After sampling the water (Fe clean protocol), experimental units were maintained in on-deck incubation in triplicate for 6 days with 3 treatments (Control: natural sea water; + Fe: Fe addition; + DFA: Fe less available). + Fe treatment samples were inoculated with FeCl2 (1 nM), while in the + DFA treatment, a Fe-binding agent (desferrioxamine) was added which reduces Fe availability tenfold. Values of chlorophyll a, phytoplankton biovolume, PSII maximum quantum efficiency (F-v/F-m) and the relative electron transport rate (rETR) were measured in all treatments. After six days of experimentation, chlorophyll a in the + DFA treatment increased by a lower proportion (6A mg m(-3), compared with the + Fe treatment, which increased to 10.2 mg m(-3)) and presented F-v/F-m values of 0.55 +/- 0.02 (compared with the + Fe treatment, with a value of 0.62 +/- 0.02). Microscopic analysis showed the preponderance of larger diatoms in the + Fe treatment, while smaller diatoms dominated in the + DFA, in particular the Pseudo-nitzschia species. Although desferrioxamine might have inhibited biogenic Fe uptake in the + DFA treatment, phytoplankton continued to grow, however with lower responses within the measured physiological parameters, indicating the first signs of Fe limitation. Considerable phytoplankton growth, represented by a doubling of chlorophyll a concentration and a massive biovolume increase after 6 days in all three treatments, indicates that the waters of the study region in the Bransfield Strait were not limited by the microelement Fe. (C) 2015 Elsevier B.V. All rights reserved.
机译：南部海洋通常是高营养低叶绿素（HNLC）区域，这主要是由于微量营养素（例如铁（Fe））的限制。但是，如果有铁，并且在合适的光照和混合条件下，浮游植物可能会开花。这项研究旨在调查在高辐照度和铁浓度梯度下浮游植物的生态和光生理响应，例如大小，群落组成，养分利用和光合潜力。在2013年的南方夏季，进行了为期6天的甲板孵化实验，使用了布兰斯菲尔德海峡水域上层混合层中的浮游植物种群。在对水进行采样（Fe清洁方案）后，将实验单元在甲板上进行3次处理，一式三份，共孵育6天（对照：天然海水； + Fe：Fe； + DFA：Fe较少）。用FeCl2（1 nM）接种+ Fe处理样品，而在+ DFA处理中，添加了Fe结合剂（去铁胺），使Fe的利用率降低了十倍。在所有处理中均测量了叶绿素a，浮游植物的生物量，PSII最大量子效率（F-v / F-m）和相对电子传输速率（rETR）的值。经过6天的实验，+ DFA处理中的叶绿素a的增加比例较低（6A mg m（-3），而+ Fe处理中的叶绿素a增加至10.2 mg m（-3）），并呈现Fv / Fm值为0.55 +/- 0.02（与+ Fe处理相比，值为0.62 +/- 0.02）。显微分析显示，在+ Fe处理中，较大的硅藻占优势，而在+ DFA中，较小的硅藻占优势，尤其是假尼茨菌属。尽管去铁胺可能在+ DFA处理中抑制了生物中的铁吸收，但浮游植物继续生长，但是在测得的生理参数范围内响应较低，表明铁限制的最初迹象。在所有三种处理中，浮游植物的显着浮游植物生长均表现为叶绿素a浓度加倍，并且在6天后生物量大量增加，这表明布朗斯菲尔德海峡研究区的水不受微量元素铁的限制。 （C）2015 Elsevier B.V.保留所有权利。

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