Subsurface chlorophyll maximum (SCM) layers are prevalent throughout the Arctic Ocean under stratified conditions and are observed both in the wake of retreating sea ice and in thermally stratified waters. The importance of these layers on the overall productivity of Arctic pelagic ecosystems has been a source of debate. In this study, we consider the three principal factors that govern productivity within SCMs: the shape of the chlorophyll profile, the photophysiological characteristics of phytoplankton and the availability of light in the layer. Using the information on the biological and optical parameters describing the vertical structure of chlorophyll, phytoplankton absorption and photosynthesis–irradiance response curves, a spectrally resolved model of primary production is used to identify the set of conditions under which SCMs are important contributors to water-column productivity. Sensitivity analysis revealed systematic errors in the estimation of primary production when the vertical distribution of chlorophyll was not taken into account, with estimates of water-column production using a non-uniform profile being up to 97% higher than those computed using a uniform one. The relative errors were shown to be functions of the parameters describing the shape of the biomass profile and the light available at the SCM to support photosynthesis. Given that SCM productivity is believed to be largely supported by new nutrients, it is likely that the relative contribution of SCMs to new production would be significantly higher than that to gross primary production. We discuss the biogeochemical and ecological implications of these findings and the potential role of new ocean sensors and autonomous underwater vehicles in furthering the study of SCMs in such highly heterogeneous and remote marine ecosystems. This article is part of the theme issue ‘The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.

中文翻译：

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叶绿素剖面的垂直结构：对北冰洋初级生产力的影响

在分层条件下，地下叶绿素最大值 (SCM) 层普遍存在于整个北冰洋，并且在海冰退缩和热分层后均可观察到。这些层对北极远洋生态系统整体生产力的重要性一直是争论的焦点。在这项研究中，我们考虑了控制 SCM 生产力的三个主要因素：叶绿素剖面的形状、浮游植物的光生理特征和层中光的可用性。利用描述叶绿素垂直结构、浮游植物吸收和光合作用-辐照响应曲线的生物和光学参数的信息，初级生产的光谱解析模型用于确定 SCM 对水柱生产力有重要贡献的条件集。敏感性分析显示，在不考虑叶绿素垂直分布的情况下，初级生产力估计存在系统误差，使用非均匀分布的水体产量估计比使用均匀分布计算的高出 97%。相对误差被证明是描述生物量剖面形状的参数和 SCM 可用于支持光合作用的光的函数。鉴于 SCM 生产力被认为主要由新营养素支持，SCM 对新生产的相对贡献可能会显着高于对初级生产总值的贡献。我们讨论了这些发现的生物地球化学和生态影响，以及新型海洋传感器和自主水下航行器在进一步研究这种高度异质和偏远海洋生态系统中的 SCM 方面的潜在作用。本文是主题问题“不断变化的北冰洋：对生物群落、生物地球化学过程和生态系统功能的影响”的一部分。