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首页> 外文期刊>Journal of Experimental Marine Biology and Ecology >Effects of salinity changes on coastal Antarctic phytoplankton physiology and assemblage composition
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Effects of salinity changes on coastal Antarctic phytoplankton physiology and assemblage composition

机译：盐度变化对沿海南极浮游植物生理和组合组成的影响

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摘要

A natural marine phytoplankton assemblage from a coastal environment of Antarctica was experimentally exposed to low salinity sea water (30 vs 34 in the control) during 8 days in order to study their physiological and community responses to hypoosmotic stress conditions. Hypoosmotic conditions favour water influx into the cells, which results, in increased turgor pressure and increased oxidative stress. This stress is linked to a number of other cellular toxic processes, including damages to proteins, enzyme inactivation and DNA breakage. Inhibition of the instantaneous growth rate started after 48 h exposure to low salinity, but at the end of experiment, growth was significantly higher in the low than in the normal (control) salinity treatment. Hypoosmotic conditions prevented phytoplankton biomass accumulation, as evidenced by reduced Chlorophyll-a concentrations as compared to the control treatment However, in terms of cell numbers and species composition, we observed a gradual replacement of big centric by small pennate diatoms, which became dominant by the end of the experiment. In addition, the content of reactive oxygen species (ROS) and 2-thiobarbituric acid-reactive substances (TBARS), which are indicative of oxidative stress, were studied. In the low salinity treatments, ROS concentrations were significantly higher than control values on days 4 and 6, decreasing thereafter to nearly initial values. TBARS content increased during the first 48 h and then,decreased until around day 0 values. This coincided with significant increased values of the antioxidants a-tocopherol and beta-carotene in low salinity treatments over the control. These results suggest the existence of protection mechanisms against lipid peroxidation, and lead to the conclusion that the response to stress is species-specific, so that at the community level a change in the relative abundance of phytoplankton taxa appears as a response to hypoosmotic conditions. This could have important consequences for the trophic food web dynamics in areas influenced by high fresh water inputs. (C) 2015 Elsevier B.V. All rights reserved.
机译：为了研究它们对低渗胁迫条件的生理和群落反应，在8天的实验中，将南极沿海环境的天然海洋浮游植物组合暴露于低盐度海水中（对照组为30 vs 34）。低渗条件有利于水流入细胞，这导致膨胀压力增加和氧化应激增加。这种压力与许多其他细胞毒性过程有关，包括蛋白质破坏，酶失活和DNA断裂。暴露于低盐度下48小时后开始抑制瞬时生长速率，但在实验结束时，低盐度下的生长明显高于正常（对照）盐度处理。低渗条件阻止了浮游植物生物量的积累，与对照处理相比，叶绿素a浓度降低证明了这一点。然而，就细胞数量和物种组成而言，我们观察到大中心被小戊二烯硅藻逐渐取代，而小硅藻则成为主要优势。实验结束。此外，还研究了指示氧化应激的活性氧（ROS）和2-硫代巴比妥酸反应性物质（TBARS）的含量。在低盐度处理中，第4天和第6天的ROS浓度显着高于对照值，此后降至接近初始值。 TBARS含量在开始的48小时内增加，然后一直下降，直到第0天左右的值。与低盐度处理相比，抗氧化剂α-生育酚和β-胡萝卜素的值显着增加。这些结果表明存在针对脂质过氧化的保护机制，并得出结论，对压力的反应是物种特异性的，因此在群落一级，浮游植物类群相对丰度的变化表现为对低渗条件的反应。这可能对受高淡水投入影响的地区的营养食物网动态产生重要影响。 （C）2015 Elsevier B.V.保留所有权利。

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    Hernando M.; Schloss I. R.; Malanga G.; Almandoz G. O.; Ferreyra G. A.; Aguiar M. B.; Puntarulo S.;

  • 作者单位

    Comis Nacl Energia Atom, Dept Radiobiol, RA-1429 Buenos Aires, DF, Argentina;

    Inst Antartico Argentino, Buenos Aires, DF, Argentina|Consejo Nacl Invest Cient & Tecn, RA-1033 Buenos Aires, DF, Argentina|Inst Sci Mer Rimouski, Rimouski, PQ, Canada;

    Univ Buenos Aires, CONICET, Inst Biochem & Mol Med IBIMOL, Phys Chem,Sch Pharm & Biochem, RA-1053 Buenos Aires, DF, Argentina;

    Consejo Nacl Invest Cient & Tecn, RA-1033 Buenos Aires, DF, Argentina|Univ Nacl La Plata, Div Ficol, Fac Ciencias Nat & Museo, RA-1900 La Plata, Buenos Aires, Argentina;

    Inst Sci Mer Rimouski, Rimouski, PQ, Canada;

    Comis Nacl Energia Atom, Dept Radiobiol, RA-1429 Buenos Aires, DF, Argentina;

    Univ Buenos Aires, CONICET, Inst Biochem & Mol Med IBIMOL, Phys Chem,Sch Pharm & Biochem, RA-1053 Buenos Aires, DF, Argentina;

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  • 正文语种 eng
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  • 关键词

    Antarctica; DCFH-DA; Diatoms; Meltwater; alpha T; beta C;

    机译：南极洲;DCFH-DA;硅藻;融水;αT;βC;

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