PHOTOADAPTATION OF HIGH ARCTIC ICE ALGAE
PHOTOADAPTATION OF HIGH ARCTIC ICE ALGAE
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DOI：
10.1038/315219a0
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发表时间：
1985-01-01
期刊：
影响因子：
64.8
通讯作者：
COTA, GF
中科院分区：
文献类型：
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作者：
COTA, GF
在水生系统中，适合正净光合作用的层（真光层）通常被认为是从表面向下延伸到表面辐照度1%的穿透深度，这相当于北极高纬度沃茨夏末太阳正午时的15 µE m−2s− 1。在极地地区，春季浮游藻类（与海冰下界面相关的单细胞藻类，其光合特性尚不清楚2 -4）在很少或短暂暴露于超过表面入射光1-2%的光照水平的条件下发展。我在这里报告说，epontic藻类从加拿大北极地区显示出异常高的光合效率归一化的色素含量，这增加了减少在人口增长的光照水平。光合作用是可测量的光强度远低于环境（0.01%的表面辐照度）。在最阴适应的populations 5下较深的积雪，光合作用是最佳的光强度接近最大的环境水平，并在较高的强度抑制。此外，即使在暴露于升高的光照水平（表面辐照度的1.3 -4%）近2个月后，生物量和生物量标准化的生产力在几乎没有积雪的地区的藻类中仍然最低。两者合计，这些结果表明，epontic藻类从高北极可以被认为是一个专性的阴影植物群遗传限制非常低的光子通量。
In aquatic systems, the layer that is suitable for positive net photosynthesis (the euphotic zone) is usually considered to extend from the surface down to the depth of penetration of 1% of the surface irradiance, which corresponds to ∼15 µE m−2s−1at solar noon during late summer in open waters in the high Arctic1. In polar regions, vernal blooms of epontic algae (unicellular algae associated with the lower interface of sea ice whose photosynthetic characteristics are not well known2–4) develop under conditions where they are only rarely or briefly exposed to light levels exceeding 1–2% of that incident at the surface. I report here that epontic algae from the Canadian Arctic show unusually high photosynthetic efficiencies normalized to pigment content, which increase with a decrease in the light levels at which the populations are growing. Photosynthesis was measurable at light intensities well below ambient (0.01% of surface irradiance). In the most shade-adapted populations5under deeper snow cover, photosynthesis was optimal at light intensities close to the maximum ambient level, and inhibited at higher intensities. Furthermore, even after almost 2 months of exposure to elevated light levels (≈3–4% of surface irradiance), biomass and productivity normalized to biomass were still lowest in algae from an area almost free of snow cover. Taken together, these results indicate that epontic algae from the high Arctic can be considered as an obligate shade flora genetically constrained to very low photon fluxes.