Microscale patchiness leads to large and important intraspecific internal nutrient heterogeneity in phytoplankton
Microscale patchiness leads to large and important intraspecific internal nutrient heterogeneity in phytoplankton
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DOI：
10.1007/s10452-011-9384-6
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发表时间：
2012-03-01
期刊：
影响因子：
1.8
通讯作者：
Hellweger, Ferdi L.
中科院分区：
文献类型：
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作者：
Bucci, Vanni;Nunez-Milland, Daliangelis;Hellweger, Ferdi L.
浮游植物的化学计量或营养成分在许多维度（物种、条件、时间、空间）上都有变化，但在特定时间和地点，一个物种内部的异质性及其潜在的机制和重要性尚未得到探讨。有许多机制可以产生种内异质性，理论表明它可以影响种群增长率。研究了波士顿查尔斯河淡水硅藻meneghiniana环藻P含量的异质性。利用基于同步加速器的x射线荧光单细胞观察显示，营养状态从缺磷到补磷变化。我们使用基于agent的模型来模拟单个细胞，该模型解释了一些可以产生异质性的机制，包括基于表面积的摄取、死亡率分化、状态和行为的随机生物变异、宏观尺度的混合和微观尺度的营养斑块相遇。通过对各种机制进行多次模拟，并与数据进行比较，我们得出结论，这种异质性主要是由于微尺度的斑块（85%）。我们通过模拟基于人口平均内部营养的增长率来探讨模型中考虑异质性的重要性，正如在传统的人口水平模型中所做的那样。这表明忽略异质性会使人口增长率增加1.47倍。为了考虑实验室和野外的不同异质性，种群水平的生态系统模型应该降低最大增长率。这种修正的幅度取决于当地的情况，在我们的例子中，它是0.72的因数。
Phytoplankton stoichiometry or nutrient content has been shown to vary in a number of dimensions (species, condition, time, space), but the heterogeneity within a species at a given time and location, and the underlying mechanisms and importance have not been explored. There are a number of mechanisms that can create intraspecific heterogeneity, and theory suggests it can affect the population growth rate. We studied heterogeneity in P content of the freshwater diatom Cyclotella meneghiniana in the Charles River in Boston. Single-cell observations using synchrotron-based X-ray fluorescence show that the nutrient status varies from P-starved to P-replete. We simulate individual cells using an agent-based model that accounts for a number of mechanisms that can create heterogeneity, including surface area-based uptake, mortality differentiation, stochastic biological variability in states and behavior, macroscale mixing, and microscale nutrient patch encounter. By performing a number of simulations with various mechanisms turned on/off and comparing to data, we conclude that the heterogeneity is mostly due to microscale patchiness (85%). We explore the importance of accounting for heterogeneity in models by performing a simulation with the growth rate based on the population-average internal nutrient, as is done in conventional population-level models. This shows that ignoring heterogeneity increases the population growth rate by a factor of 1.47. To account for different heterogeneity in the laboratory and field, population-level ecosystem models should reduce maximum growth rates. The magnitude of this correction depends on local conditions, and in our case, it is a factor of 0.72.