Prelle Lara R, Graiff Angelika, Gründling-Pfaff Sigrid, Sommer Veronika, Kuriyama Kana, Karsten Ulf
Institute of Biological Sciences, Applied Ecology and Phycology, University of Rostock, Rostock, Germany.
Front Microbiol. 2019 Jul 4;10:1500. doi: 10.3389/fmicb.2019.01500. eCollection 2019.
Eight benthic diatom taxa (, , sp. 1, sp. 2, , , , ) were isolated from sediments sampled in the southern coastal brackish Baltic Sea and established as unialgal cultures. The coastal shallow water sampling area lies close to a fen peat site (Hütelmoor) and both are connected through an underground peat layer, which might facilitate organic matter and nutrient fluxes along the terrestrial-marine gradient. The photosynthetic performance of these diatoms was measured at different photon fluence rates (0-1200 μmol photons m s, always recorded at 20°C) and different temperatures (5-40°C, always measured at saturating ∼270 μmol photons m s), resulting in light saturation points between 32 and 151 μmol photons m s and maximum net primary production rates of 23-144 μmol O mg Chl h. None of the species showed severe photoinhibition, and hence all displayed a high photo-physiological plasticity. Photosynthetic oxygen evolution and respirational oxygen consumption between 5 and 40°C revealed eurythermal traits for half of the studied taxa as photosynthetic efficiency was at least 20% of the maximum values at the extreme temperatures. The remaining taxa also indicated eurythermal characteristics, however, photosynthetic efficiency of at least 20% was at a narrower temperature range [5 (10) °C to 30 (35) °C]. Species-specific optimum temperatures for photosynthesis (15-30°C) were always lower compared to respiration (25-40°C). and were grown in different defined media, some enriched with Hütelmoor water to test for possible effects of organic components. Hütelmoor water media stimulated growth of both diatom species when kept in a light dark cycle. particularly grew in darkness in Hütelmoor water media, pointing to heterotrophic capabilities. The benthic diatoms studied are characterized by high photo-physiological plasticity and a broad temperature tolerance to maintain high primary production rates under wide environmental fluctuations. Organic carbon fluxes from the Hütelmoor into the Baltic Sea may support mixo- and/or heterotrophic growth of microphytobenthic communities. These are essential traits for living in a highly dynamic and variable shallow water environment at the coastal zone of the Baltic Sea.
从波罗的海南部沿海咸淡水区域采集的沉积物中分离出了8种底栖硅藻分类群（、、sp. 1、sp. 2、、、、），并建立了单种培养物。沿海浅水采样区域靠近一个沼泽泥炭地（许特尔 Moor），两者通过地下泥炭层相连，这可能有助于沿着陆地 - 海洋梯度的有机物质和营养物质通量。在不同的光子通量率（0 - 1200 μmol光子 m² s⁻¹，始终在20°C记录）和不同温度（5 - 40°C，始终在约270 μmol光子 m² s⁻¹的饱和光强下测量）下测量了这些硅藻的光合性能，结果光饱和点在32至151 μmol光子 m² s⁻¹之间，最大净初级生产率为23 - 144 μmol O₂ mg Chl⁻¹ h⁻¹。没有一个物种表现出严重的光抑制，因此所有物种都表现出高度的光生理可塑性。在5至40°C之间的光合放氧和呼吸耗氧表明，一半的研究分类群具有广温特性，因为在极端温度下光合效率至少为最大值的20%。其余分类群也显示出广温特征，然而，至少20%的光合效率出现在较窄的温度范围[5（10）°C至30（35）°C]。光合作用的物种特异性最适温度（15 - 30°C）始终低于呼吸作用的最适温度（25 - 40°C）。和在不同的限定培养基中培养，一些培养基添加了许特尔 Moor水以测试有机成分的可能影响。当保持明暗循环时，许特尔 Moor水培养基刺激了两种硅藻的生长。特别是在许特尔 Moor水培养基中在黑暗中生长，表明具有异养能力。所研究的底栖硅藻的特点是具有高光生理可塑性和广泛的温度耐受性，以便在广泛的环境波动下维持高初级生产率。从许特尔 Moor流入波罗的海的有机碳通量可能支持微型底栖植物群落的混合营养和/或异养生长。这些是在波罗的海沿岸高度动态和多变的浅水环境中生存的基本特征。
