In-Situ Determination of Iron Limitation in the Peruvian Upwelling System

中尺度铁施肥实验有些争议，过于昂贵，后勤困难，在许多开放的海洋环境中进行，不适合精细尺度的生态海洋研究。 铁限制的原位诊断指标可以避免上述问题。 研究人员将与痕量金属化学家和生物学家合作，探索利用原位生物化学和生物物理指标评估其有用性和有效性的适用性。 在这样做时，科学家们还将参与调查秘鲁沿海涌升系统是铁有限的假设。 将研究的两个原位指标包括（1）使用快速重复频率荧光计的光化学效率测量和（2）作为铁营养状况指标的藻类中铁氧还蛋白和黄素还蛋白浓度的定量测量（使用组合高效液相色谱和毛细管电泳方法）。 这两种方法将提供有关藻类铁限制在宏营养丰富的秘鲁上升流区的补充证据。 此外，藻类的特定类群的生长速率将使用14 C色素标记，以帮助解释和支持测量环境铁浓度的其他调查人员，以及从铁添加实验，将同时运行在一个横断面上的整个秘鲁上升流区域的结果。

Mesoscale iron fertilization experiments are somewhat controversial, prohibitively expensive, logistically difficult to perform in many open ocean environments and not suitable for fine scale ecological ocean studies. In situ diagnostic indicators of iron limitation can circumvent the above stated problems. The investigators will collaborate with trace metal chemists and biologists to explore the applicability of utilizing in situ biochemical and biophysical indicators to assess their usefulness and validity. In so doing, the scientists will also participate in investigating the hypothesis that the Peru coastal upwelling system is iron-limited. The two in situ indicators that will be investigated include (1) photochemical efficiency measurements using a fast repetition rate fluorometer and (2) quantitative measurements (using a combined high performance liquid chromatography and capillary electrophoresis method) of ferredoxin and flavodoxin concentrations in algae as an indicator of iron-nutritional status. These two methods will provide complimentary evidence regarding algal iron-limitation in the macro-nutrient replete Peru upwelling region. In addition, taxon-specific growth rates of algae will be measured using 14C pigment labeling to help interpret and support measurements by other investigators of the ambient iron concentration as well as the results from iron-addition experiments that will be run concomitantly on a transect across the Peru upwelling region.