Phytoplankton blooms during austral summer in the Ross Sea, Antarctica: Driving factors and trophic implications
Phytoplankton blooms during austral summer in the Ross Sea, Antarctica: Driving factors and trophic implications
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DOI：
10.1371/journal.pone.0176033
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发表时间：
2017-04-21
期刊：
影响因子：
3.7
通讯作者：
Saggiomo, Maria
中科院分区：
文献类型：
--
作者：
Mangoni, Olga;Saggiomo, Vincenzo;Saggiomo, Maria
2014年夏季，在罗斯海中尺度实验项目框架内，在罗斯海进行了一次海洋学巡航。在三个不同的区域内对43个水文站进行了采样：北方罗斯海（罗马1）、特拉诺瓦湾（罗马2）和罗斯海南部（罗马3）。调查了浮游植物的生态和生理特征（即，尺寸结构、官能团、PSII最大量子效率、光保护颜料），与水文和化学特征有关。目的是确定调节浮游植物水华的机制，从而确定水华产生的有机物质的命运。观察到的生物量现存量非常高（例如，在顶部100 m处，叶绿素a的累积量高达371 mg m（-2）。浮游植物群落组成、功能群的相对贡献和光合参数在3个亚系统中存在较大差异。硅藻（在不同的生理状态）的优势类群，在罗马1和罗马3;罗马1，一个后开花阶段被确定，而罗马3，活跃的浮游植物水华发生。在罗马2中，硅藻与南极棕囊藻共存，但被上层混合层垂直分隔，上层以衰老硅藻为主，南极棕囊藻在深层开花。浮游植物微组分在整个区域和高叶绿素a的优势表明非放牧大细胞的流行，独立的两个功能组的分布。这些数据强调发生显着的时间变化，在罗斯海的浮游植物生物量在南方夏季。驱动这种变化的机制和碳生产的命运可能与罗斯海的水文变化引起的限制因素的变化有关，它们仍有待充分澄清。将2014年夏季观测到的情况与前几年报告的情况进行比较，发现生态资产可能存在很大差异，这可能是当前气候变化的结果。这表明未来可能会发生进一步的变化，即使是在更大的海洋规模上。
During the austral summer of 2014, an oceanographic cruise was conducted in the Ross Sea in the framework of the RoME (Ross Sea Mesoscale Experiment) Project. Forty-three hydrological stations were sampled within three different areas: the northern Ross Sea (RoME 1), Terra Nova Bay (RoME 2), and the southern Ross Sea (RoME 3). The ecological and photophysiological characteristics of the phytoplankton were investigated (i.e., size structure, functional groups, PSII maximum quantum efficiency, photoprotective pigments), as related to hydrographic and chemical features. The aim was to identify the mechanisms that modulate phytoplankton blooms, and consequently, the fate of organic materials produced by the blooms. The observed biomass standing stocks were very high (e.g., integrated chlorophyll-a up to 371 mg m(-2) in the top 100 m). Large differences in phytoplankton community composition, relative contribution of functional groups and photosynthetic parameters were observed among the three subsystems. The diatoms (in different physiological status) were the dominant taxa in RoME 1 and RoME 3; in RoME 1, a post-bloom phase was identified, whereas in RoME 3, an active phytoplankton bloom occurred. In RoME 2, diatoms co-occurred with Phaeocystis antarctica, but were vertically segregated by the upper mixed layer, with senescent diatoms dominating in the upper layer, and P. antarctica blooming in the deeper layer. The dominance of the phytoplankton micro-fraction over the whole area and the high Chl-a suggested the prevalence of non-grazed large cells, independent of the distribution of the two functional groups. These data emphasise the occurrence of significant temporal changes in the phytoplankton biomass in the Ross Sea during austral summer. The mechanisms that drive such changes and the fate of the carbon production are probably related to the variations in the limiting factors induced by the concurrent hydrological modifications to the Ross Sea, and they remain to be fully clarified. The comparison of conditions observed during summer 2014 and those reported for previous years reveal considerably different ecological assets that might be the result of current climate change. This suggests that further changes can be expected in the future, even at larger oceanic scales.