Effects of chronic, low levels of UV radiation on carbon allocation in Cryptomonas erosa and competition between C.erosa and bacteria in continuous cultures
Effects of chronic, low levels of UV radiation on carbon allocation in Cryptomonas erosa and competition between C.erosa and bacteria in continuous cultures
复制标题
DOI：
10.1093/plankt/22.7.1277
复制
发表时间：
2000-07
影响因子：
2.1
通讯作者：
A. Plante;M. T. Arts
中科院分区：
文献类型：
--
作者：
A. Plante;M. T. Arts
我们进行了长期（4周）的连续培养研究，以测量紫外线辐射的慢性影响的隐单胞菌erosa，使用三种不同的能量密度率的紫外线辐射。我们测量了碳分配到碳水化合物，蛋白质和脂质池，以及叶绿素a浓度和藻类和细菌密度。21天后，藻类密度在控制和最低的UV处理（处理1 = 3.4 W m-2 UVR未加权）显着低于两个最高的UV处理（处理2 = 14.9 W m-2和处理3 = 16.2 W m-2 UVR未加权），并没有恢复在接下来的一周没有UV暴露。对照和处理1的叶绿素a和碳水化合物含量（ng藻细胞-1）在第15天明显低于处理2和3，并且在第28天没有恢复。与处理2和3相比，在暴露期结束时，对照组和处理1的总脂质百分比也降低。然而，到第21天，对照和处理1的蛋白质含量显著高于处理2和3，并且到第28天进一步增加。结果在很大程度上归因于在这些非纯培养物中糜烂假丝酵母和细菌之间的竞争效应。与两个最高UV处理相比，对照和最低UV处理的细菌密度显著（-4）高。我们的研究结果表明，在这些条件下，浮游植物比细菌具有竞争优势。如果紫外线辐射一般对细菌的影响大于对藻类的影响，则（i）细菌对浮游植物产生的溶解有机物的利用，（ii）浮游植物和细菌之间对营养矿物质的竞争，以及（iii）微鞭毛虫对细菌的捕食率可能会发生变化。
We conducted a long term (4 week) continuous culture study to measure the chronic effects of UV radiation on the alga, Cryptomonas erosa, using three different fluence rates of UV radiation. We measured carbon allocation into carbohydrate, protein and lipid pools, as well as chlorophyll a concentrations and algal and bacterial density. After 21 days, algal density in the control and lowest UV treatment (treatment 1 = 3.4 W m-2 UVR unweighted) was significantly lower than in the two highest UV treatments (treatment 2 = 14.9 W m-2 and treatment 3 = 16.2 W m-2 UVR unweighted), and did not recover in the following week of no UV exposure. Chlorophyll a and carbohydrate content (ng algal cell-1) for the control and treatment 1 were clearly lower than treatments 2 and 3 by day 15, and did not recover by day 28. Percentage total lipid for the control and treatment 1 also decreased compared with treatments 2 and 3 by the end of the exposure period. However, by day 21, protein content for the control and treatment 1 was significantly higher than treatments 2 and 3, and demon- strated a further increase by day 28. The results were largely attributed to competition effects between C.erosa and bacteria in these non-axenic cultures. Bacterial density was significantly (� 4) higher in the control and lowest UV treatment compared with the two highest UV treatments. Our findings suggest a competitive advantage of phytoplankton over bacteria under these conditions. If UV radiation, in general, affects bacteria to a greater extent than algae, there are likely to be changes in (i) bacterial utilization of dissolved organic matter produced by phytoplankton, (ii) competition between phytoplankton and bacteria for nutrient minerals and (iii) predation rates on bacteria by micro-flagellates.