Collaborative Research: A Critical Examination of the Relationship Between Marine Phytoplankton Growth Rates and Phosphate Concentrations: Monod or Not

该项目涉及在恒化器实验中使用放射性磷（33 P）作为示踪剂，研究海洋浮游植物单种培养物中磷酸盐浓度与生长率之间的关系。几十年来，这种关系一直被认为是由莫诺方程描述的，但是比色法无法准确测量磷酸盐的生长速率限制浓度，这排除了对这一假设的严格检验。理论分析表明，Monod方程的发散可能与生长速率限制基板通过细胞周围的边界层的扩散。由于限制营养素的细胞定额对于磷比氮更易变，因此可以表明，通过边界层的扩散对生长速率曲线形状的影响对于磷可能比对于氮大得多。所提出的工作的智力价值在于使用示踪量的33 P，以准确地测量磷酸盐的纳摩尔浓度范围内，并使用恒化器，以提供严格的控制增长率。这些方法的结合提供了迄今为止最好的机会来定义磷酸盐浓度和生长速率之间的关系，因此，最终提供了一个严格的测试莫诺生长模型。更广泛的影响，拟议的工作包括，该研究将是一个合作的努力之间的路易斯安那州州立大学（LSU）和夏威夷大学（UH）的事实。并将为每个机构的研究生提供支持。LSU和UH都是EPSCoR机构。Laws博士写了一本名为《海洋学家的数学方法》（John Wiley）的教科书，并在路易斯安那州立大学教授一门利用该教科书的研究生课程。课程和教材包括建模材料。拟议工作的结果将纳入Laws博士的课程和他的书的未来版本，并将提交科学文献出版。然而，拟议的工作的最广泛的影响，将是对我们的理解的关系，控制浮游植物的生长速度在磷限制系统和藻类之间的资源竞争的结果。几十年来，这种关系一直被认为是莫诺方程。这个项目将使用现有的工具来确定它是否是。

This project involves the use radioactive phosphorus (33P) as a tracer in chemostat experiments to study the relationship between phosphate concentrations and growth rate in monospecific cultures of marine phytoplankton. For literally decades that relationship has been assumed to be described by the Monod equation, but the inability of colorimetric methods to accurately measure growth-rate-limiting concentrations of phosphate has precluded a rigorous test of this hypothesis. Theoretical analysis indicates that divergence from the Monod equation may be associated with diffusion of the growth-rate-limiting substrate through the boundary layer around the cell. Because the cell quota of limiting nutrient is more variable for phosphorus than nitrogen, it can be shown that the impact of diffusion through the boundary layer on the shape of the growth rate curve is likely to be much greater for phosphorus than for nitrogen. The intellectual merit of the proposed work lies in the use of tracer amounts of 33P to accurately measure phosphate in the nanomolar concentration range and the use of chemostats to provide rigorous control of growth rates. The combination of these methodologies offers by far the best chance of defining the relationship between phosphate concentration and growth rate and hence at last provide a rigorous test of the Monod growth model.The broader impacts of the proposed work include the fact that the research will be a collaborative effort between Louisiana State University (LSU) and the University of Hawaii (UH) and will provide support for a graduate student at each institution. Both LSU and UH are EPSCoR institutions. Dr. Laws has written a textbook titled Mathematical Methods for Oceanographers (John Wiley) and teaches a graduate course at LSU that makes use of that text. The course and text include material on modeling. The results of the proposed work will be integrated into Dr. Laws' course and into future editions of his book and will be submitted for publication in the scientific literature. The broadest impact of the proposed work, however, will be on our understanding of the relationship that controls phytoplankton growth rates in phosphorus-limited systems and the outcome of resource competition among algae. For literally decades that relationship has been assumed to be the Monod equation. This project will use existing the tools to determine whether it is or is not.