Modeled inherent scattering properties of small light-limited phytoplankton: implications for deep phytoplankton size class distributions

摘要

Small phytoplankton, ubiquitous throughout the world's oceans, numerically dominate many open ocean ecosystems with increasing importance towards the base of the euphotic zone. As an example, light-limited deep secondary chlorophyll maxima are usually dominated by small phytoplankton species. Theoretical models describing light-particle interactions predict that small particles scatter light less efficiently than their larger counterparts. To investigate a possible relationship between the dominance of small phytoplankton in light-limited situations and efficiency predictions, a light scattering efficiency model based on Mie theory as approximated by Van de Hulst is used to determine scattering efficiency as a function of size. This scattering efficiency model, which approximates light-phytoplankton interactions by considering phytoplankton as homogeneous spheres, is driven by the spectral light field from an observed deep phytoplankton population dominated by small phytoplankton. This deep secondary chlorophyll maximum is discussed as an example of a highly efficient small phytoplankton population at the threshold of the euphotic zone which could benefit as a result of its size distribution.