Response to Sea Ice Melt Indicates High Seeding Potential of the Ice Diatom Thalassiosira to Spring Phytoplankton Blooms: A Laboratory Study on an Ice Algal Community From the Sea of Okhotsk
Response to Sea Ice Melt Indicates High Seeding Potential of the Ice Diatom Thalassiosira to Spring Phytoplankton Blooms: A Laboratory Study on an Ice Algal Community From the Sea of Okhotsk
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DOI：
10.3389/fmars.2020.00613
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发表时间：
2020-07
期刊：
影响因子：
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通讯作者：
Dong Yan;Kazuhiro Yoshida;J. Nishioka;Masato Ito;T. Toyota;Koji Suzuki
中科院分区：
文献类型：
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作者：
Dong Yan;Kazuhiro Yoshida;J. Nishioka;Masato Ito;T. Toyota;Koji Suzuki
季节性冰覆盖区的浮游植物群落在很大程度上受到冰藻的影响。鄂霍次克海是北方最南端的海冰区，有相当大的季节性冰盖，因此鄂霍次克海冰的冰藻有很大的潜力在早春开花。对鄂霍次克冰藻群落及其播种效应知之甚少。我们研究了在为期6天的实验室培养实验，模拟自然融冰条件下的鄂霍次克冰藻群落的组成和生物生理学性能的动态。中心硅藻，特别是海链藻属，绝大多数占主导地位的冰藻群落在整个孵化，而羽状硅藻，主要是舟形藻和菱形藻，表现出很高的死亡率几乎没有增长。光系统II的最大光化学效率（Fv/Fm）是最低的开始时的冰融化，这表明抑制光合功能的变化，盐度。细胞色素含量下降了30%，由于渗透胁迫，证明了在显微镜下的质体变形。rbcL基因编码的大亚基RubisCO的转录水平显着较高，在冰融化和非冰期间下降，这表明迫切需要在融化条件下的碳固定。冰完全融化后，光合作用和生长也完全恢复。我们的研究结果表明，海链藻的高播种潜力，春季开花，由于其生理可塑性的动态盐度变化。
Phytoplankton communities in seasonally ice-covered areas are largely affected by ice algae. The Okhotsk Sea is the southernmost sea ice zone in the northern hemisphere with a sizeable seasonal ice cover, thus ice algae of the Okhotsk sea ice have a large potential to seed the early spring bloom. Little is known about the Okhotsk ice algal communities and their seeding effects. We investigated the dynamics of the composition and the photophysiological performances of an Okhotsk ice algal community in a 6-day laboratory incubation experiment that simulated the natural ice melt conditions. Centric diatoms, especially Thalassiosira spp., overwhelmingly dominated the ice algal community throughout incubation, whereas pennate diatoms, mostly Navicula and Nitzschia, showed little growth with much higher mortality. The maximum photochemical efficiency of Photosystem II (Fv/Fm) was the lowest at the beginning of the ice melt, suggesting a suppressed photosynthetic functioning by changes in salinity. The cellular pigment contents decreased by 30% due to osmotic stress, evidenced by deformed plastids under a microscope. The transcript level of the rbcL gene that encodes the large subunit of RubisCO was significantly higher during ice melt and decreased in the no-ice period, suggesting an urgent need for carbon fixation under the melt condition. Full recovery of photosynthesis and growth was also made after complete ice melt. Our results indicated high seeding potential of Thalassiosira to spring blooms owing to their photophysiological plasticity to dynamic salinity changes.