SYMBIOTIC PHOTOSYNTHESIS IN A PLANKTONIC FORAMINIFERAN, GLOBIGERINOIDES-SACCULIFER (BRADY), STUDIED WITH MICROELECTRODES
SYMBIOTIC PHOTOSYNTHESIS IN A PLANKTONIC FORAMINIFERAN, GLOBIGERINOIDES-SACCULIFER (BRADY), STUDIED WITH MICROELECTRODES
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DOI：
10.4319/lo.1985.30.6.1253
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发表时间：
1985-01-01
影响因子：
4.5
通讯作者：
COHEN, Y
中科院分区：
文献类型：
--
作者：
JORGENSEN, BB;EREZ, J;COHEN, Y
使用分辨率为 50-100 μm 的 O2 和 pH 微电极研究了来自红海北部亚喀巴湾的刺有孔虫 Globigerinoides Sacculifer 的化学环境和共生光合作用。在黑暗中，有孔虫呼吸将壳表面的 O2 浓度降低至空气饱和度的 50%，同时 pH 值从环境值 8.23 降低至 8.15。在光照下，O2增加至空气饱和度的2.5倍，pH值达到8.62。 这些陡峭的化学梯度是在刺之间的扩散边界层上建立的，该边界层将动物与大量海水部分分开。外壳周围的氧气池非常动态，在光照下的停留时间可缩短至 5 秒。绘制了动物周围和体内的光合速率。共生体-宿主系统的补偿光强度为26-30μEinst m-2 s-1，而光饱和强度Ik为160-170μEinst m-2 s-1。共生体光合作用的作用光谱显示由于叶绿素 a 而在 450 和 670 nm 处出现峰值，以及在 500-550 nm 处出现宽的多甲素峰值。一种共生体-宿主系统的总呼吸量为3.0 nmol O2 h-1，并且在黑暗和光照下没有显着差异。每个有孔虫在光饱和度下的总光合作用为 18.1 nmol O2 h-1。高净光合作用表明虫黄藻理论上可以提供宿主生长和呼吸所需的全部有机碳。然而，模型计算表明，有孔虫在吸收溶解的氮和磷方面受到扩散限制。因此，捕获猎物是这些营养物质的必要来源，而共生光合作用可以满足能量需求并实现营养物质的有效内部循环。
The chemical environment and the symbiotic photosynthesis of the spinose foraminiferan Globigerinoides Sacculifer, from the Gulf of Aqaba, northern Red Sea, were studied with O2 and pH microelectrodes at a resolution of 50-100 .mu.m. In the dark, the foraminiferan respiraton lowered the O2 concentration at the shell surface to 50% of air saturation, while pH was lowered from the ambient value of 8.23 to 8.15. In the light, the O2 increased to 2.5 times air saturation while pH reached 8.62. These steep chemical gradients were established over a diffusive boundary layer between the spines, which partly separated the animal from the bulk seawater. The O2 pool around the shell was very dynamic, with residence times down to 5 s in the light. Photosynthetic rates were mapped around and within the animal. The compensation light intensity of the symbiont-host system was 26-30 .mu.Einst m-2 s-1, while the light saturation intensity, Ik, was 160-170 .mu.Einst m-2 s-1. The action spectrum of symbiont photosynthesis showed peaks at 450 and 670 nm due to chlorophyll a as well as broad peridinin peak at 500-550 nm. total respiration of one symbiont-host system was 3.0 nmol O2 h-1 and was not significantly different between dark and light. Gross photosynthesis at light saturation was 18.1 nmol O2 h-1 per foraminiferan. The high net photosynthesis showed that the zooxanthellae could theoretically provide all organic carbon required for growth and respiration of the host. Model calculations indicated, however, that the foraminifera were diffusion-limited in the uptake of dissolved nitrogen and phosphorous. The capture of prey was therefore a necessary source of these nutrients, while symbiotic photosynthesis could cover the energy requirements and allow efficient internal recycling of nutrients.