Department of Oceanography, Dalhousie University, Halifax B3H 4R2, Canada; email:
Ann Rev Mar Sci. 2015;7:207-39. doi: 10.1146/annurev-marine-010213-135111. Epub 2014 Sep 17.
The phenomenon of subsurface chlorophyll maximum layers (SCMLs) is not a unique ecological response to environmental conditions; rather, a broad range of interacting processes can contribute to the formation of persistent layers of elevated chlorophyll a concentration (Chl) that are nearly ubiquitous in stratified surface waters. Mechanisms that contribute to the formation and maintenance of the SCMLs include a local maximum in phytoplankton growth rate near the nutricline, photoacclimation of pigment content that leads to elevated Chl relative to phytoplankton biomass at depth, and a range of physiologically influenced swimming behaviors in motile phytoplankton and buoyancy control in diatoms and cyanobacteria that can lead to aggregations of phytoplankton in layers, subject to grazing and physical control. A postulated typical stable water structure characterizes consistent patterns in vertical profiles of Chl, phytoplankton biomass, nutrients, and light across a trophic gradient structured by the vertical flux of nutrients and characterized by the average daily irradiance at the nutricline. Hypothetical predictions can be tested using a nascent biogeochemical global ocean observing system. Partial results to date are generally consistent with predictions based on current knowledge, which has strong roots in research from the twentieth century.
次表层叶绿素最大值层（SCMLs）现象并不是对环境条件的独特生态响应；而是一系列相互作用的过程可以促成持久性的高叶绿素浓度（Chl）层的形成，这种现象在分层地表水层中几乎无处不在。促成 SCML 形成和维持的机制包括营养层附近浮游植物生长率的局部最大值、色素含量的光驯化，这导致 Chl 相对于深层浮游植物生物量的升高，以及在运动性浮游植物中受生理影响的游动行为和在硅藻和蓝藻中的浮力控制的范围，这可能导致浮游植物在层中聚集，受到摄食和物理控制。假定的典型稳定水结构特征是在营养层的垂直剖面中 Chl、浮游植物生物量、营养物质和光的一致模式，这是由营养物质的垂直通量构成的营养梯度，并以营养层的平均日辐照度为特征。可以使用新兴的生物地球化学全球海洋观测系统来测试假设性预测。迄今为止的部分结果与基于当前知识的预测大致一致，这些预测具有 20 世纪研究的坚实基础。
