Effects of iron on the elemental stoichiometry during EIFEX and in the diatoms Fragilariopsis kerguelensis and Chaetoceros dichaeta
Effects of iron on the elemental stoichiometry during EIFEX and in the diatoms Fragilariopsis kerguelensis and Chaetoceros dichaeta
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DOI：
10.5194/bg-4-569-2007
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发表时间：
2007-01-01
期刊：
影响因子：
4.9
通讯作者：
Lochte, K.
中科院分区：
文献类型：
--
作者：
Hoffmann, L. J.;Peeken, I.;Lochte, K.
铁的可用性和浮游植物元素组成之间的相互作用进行了研究，在原位铁施肥实验EIFEX和南大洋硅藻物种Fragilariopsis kerguelensis和Chaetoceros dichaeta的实验室实验。相反，其他原位铁施肥实验中，我们观察到增加BSi：POC，BSi：PON，和BSi：POP比例内的铁施肥补丁在EIFEX。这可能是由于硅藻丰度相对于其他浮游植物群体的相对较强的增加造成的，并不一定代表单个硅藻细胞的硅化量。在实验室实验中，F. kerguelensis和C. dichaeta的POC：PON，PON：POP和POC：POP的比例没有变化，发现在两个物种的铁供应量的变化。与对照相比，高铁处理的BSi：POC、BSi：PON和BSi：POP比率显著降低。in F. kerguelensis这是由细胞BSi浓度的降低引起的，因此可能较少的硅化。in C.在高铁条件下，BSi：POC、BSi：PON和BSi：POP比值的降低是由于细胞内C、N和P的增加所致。这些结果表明，铁限制并不总是增加硅化硅藻和BSi：POC，BSi：PON，和BSi：POP比铁施肥在该领域的变化是由各种不同的机制。因此，我们的研究结果意味着，简单的因果关系并不总是适用于建模的元素比。
The interaction between iron availability and the phytoplankton elemental composition was investigated during the in situ iron fertilization experiment EIFEX and in laboratory experiments with the Southern Ocean diatom species Fragilariopsis kerguelensis and Chaetoceros dichaeta. Contrary to other in situ iron fertilization experiments we observed an increase in the BSi:POC, BSi:PON, and BSi:POP ratios within the iron fertilized patch during EIFEX. This is possibly caused by a relatively stronger increase in diatom abundance compared to other phytoplankton groups and does not necessarily represent the amount of silicification of single diatom cells. In laboratory experiments with F. kerguelensis and C. dichaeta no changes in the POC:PON, PON:POP, and POC:POP ratios were found with changing iron availability in both species. BSi:POC, BSi:PON, and BSi:POP ratios were significantly lower in the high iron treatments compared to the controls. In F. kerguelensis this was caused by a decrease in cellular BSi concentrations and therefore possibly less silicification. In C. dichaeta no change in cellular BSi concentration was found. Here lower BSi:POC, BSi:PON, and BSi:POP ratios were caused by an increase in cellular C, N, and P under high iron conditions. These results indicate that iron limitation does not always increase silicification in diatoms and that changes in the BSi:POC, BSi:PON, and BSi:POP ratios under iron fertilization in the field are caused by a variety of different mechanisms. Our results therefore imply that simple cause-and-effect relationships are not always applicable for modeling of elemental ratios.