Manipulating iron availability in nearshore waters
Manipulating iron availability in nearshore waters
复制标题
控制近岸水域的铁供应
DOI：
10.4319/lo.1999.44.4.1002
复制
发表时间：
1999
影响因子：
4.5
通讯作者：
M. Wells
中科院分区：
文献类型：
--
作者：
M. Wells
铁对海洋生态系统影响的考虑主要集中在高硝酸盐低叶绿素区域，但铁在沿海水域可能具有同样重要的调节作用。浅海浮游植物对铁的需求不仅相对较高，而且物种之间差异很大，因此富金属系统内铁的波动应强烈影响浮游植物群落的组成和分布。但与在缺铁水中测试铁效应的简单性不同，由于缺乏能够独立于海水中其他生物活性金属来调节铁可用性的实验工具，因此无法确定铁在明显富集水中的效应。我在此介绍使用真菌铁载体去铁铁肟 B (DFB) 调节沿海上升流水域中铁的可用性的尺寸分级船载培养实验的结果。添加过量的 DFB 在 6 小时内基本上消除了浮游植物和异养细菌对 59Fe 的吸收，并且在培养 5 天内仅允许少量铁吸收。添加 DFB 后，小型（0.2-5.0 µm）浮游植物对碳的吸收立即减少，这表明铁胁迫迅速发生。相比之下，较大（&5.0-μm）浮游植物的短期（0-6小时）碳吸收并未受到影响，这表明较大的细胞含有大量的铁储备。尽管如此，培养 5 天后，DFB 处理的碳同化率明显低于对照组。 54Mn、65Zn 和 57Co 的吸收并未立即受到 DFB 的影响，但在 4 小时后减慢，并在 5 天后显着降低，可能是因为铁的限制降低了细胞对这些生物活性金属的需求。这些发现表明，DFB 可用于操纵生物可利用的铁，以确定铁如何影响铁丰富的水域中的藻类群落结构和碳循环。
The consideration of iron effects on marine ecosystems has focused mainly on high‐nitrate low‐chlorophyll regions, but iron likely has an equally important regulatory role in coastal waters. Iron requirements of neritic phytoplankton not only are comparatively high but also differ substantially among species, so that iron fluctuations within metal‐replete systems should strongly influence the composition and distribution of phytoplankton assemblages. But unlike the simplicity of testing iron effects in iron‐depleted waters, ascertaining iron effects in apparently replete waters has been forestalled by a lack of experimental tools that can regulate iron availability independent of other bioactive metals in seawater. I present here the results of size‐fractionated shipboard culture experiments using the fungal siderophore desferriferrioxime B (DFB) to regulate iron availability in coastal upwelling waters. Addition of excess DFB essentially eliminated 59Fe uptake by both phytoplankton and heterotrophic bacteria over a 6‐h period and allowed only marginal iron uptake over 5 d of incubation. Carbon uptake by small (0.2–5.0‐ µm) phytoplankton was immediately curtailed upon addition of DFB, signifying a rapid onset of iron stress. In contrast, short‐term (0–6 h) carbon uptake by larger (&5.0‐ µm) phytoplankton was not affected, indicating that larger cells contained significant iron reserves. Nonetheless, carbon assimilation was substantially lower in DFB treatments relative to the controls after 5 d of incubation. Uptake of 54Mn, 65Zn, and 57Co was not immediately affected by DFB but then slowed after 4 h and was significantly lower after 5 d, presumably because iron limitation lowered the cellular requirements for these bioactive metals. These findings demonstrate that DFB can be used to manipulate biologically accessible iron to determine how iron affects algal community structure and carbon cycling in iron‐replete waters.