Racault M-F, Sathyendranath S, Menon N, Platt T
1Plymouth Marine Laboratory (PML), Prospect Place, The Hoe, Plymouth, UK.
2National Centre for Earth Observation (NCEO), PML, Plymouth, PL1 3DH UK.
Surv Geophys. 2017;38(1):277-293. doi: 10.1007/s10712-016-9391-1. Epub 2016 Nov 9.
Phenology relates to the study of timing of periodic events in the life cycle of plants or animals as influenced by environmental conditions and climatic forcing. Phenological metrics provide information essential to quantify variations in the life cycle of these organisms. The metrics also allow us to estimate the speed at which living organisms respond to environmental changes. At the surface of the oceans, microscopic plant cells, so-called phytoplankton, grow and sometimes form blooms, with concentrations reaching up to 100 million cells per litre and extending over many square kilometres. These blooms can have a huge collective impact on ocean colour, because they contain chlorophyll and other auxiliary pigments, making them visible from space. Phytoplankton populations have a high turnover rate and can respond within hours to days to environmental perturbations. This makes them ideal indicators to study the first-level biological response to environmental changes. In the Earth's climate system, the El Niño-Southern Oscillation (ENSO) dominates large-scale inter-annual variations in environmental conditions. It serves as a natural experiment to study and understand how phytoplankton in the ocean (and hence the organisms at higher trophic levels) respond to climate variability. Here, the ENSO influence on phytoplankton is estimated through variations in chlorophyll concentration, primary production and timings of initiation, peak, termination and duration of the growing period. The phenological variabilities are used to characterise phytoplankton responses to changes in some physical variables: sea surface temperature, sea surface height and wind. It is reported that in oceanic regions experiencing high annual variations in the solar cycle, such as in high latitudes, the influence of ENSO may be readily measured using annual mean anomalies of physical variables. In contrast, in oceanic regions where ENSO modulates a climate system characterised by a seasonal reversal of the wind forcing, such as the monsoon system in the Indian Ocean, phenology-based mean anomalies of physical variables help refine evaluation of the mechanisms driving the biological responses and provide a more comprehensive understanding of the integrated processes.
物候学涉及对植物或动物生命周期中周期性事件发生时间的研究，这些事件受环境条件和气候强迫的影响。物候指标提供了量化这些生物生命周期变化所必需的信息。这些指标还使我们能够估计生物体对环境变化的响应速度。在海洋表面，微小的植物细胞，即所谓的浮游植物，生长并有时形成水华，其浓度可达每升1亿个细胞，并延伸至许多平方公里。这些水华会对海洋颜色产生巨大的总体影响，因为它们含有叶绿素和其他辅助色素，使其在太空中可见。浮游植物种群的周转率很高，能够在数小时到数天内对环境扰动做出反应。这使它们成为研究对环境变化的一级生物响应的理想指标。在地球气候系统中，厄尔尼诺-南方涛动（ENSO）主导着环境条件的大规模年际变化。它是一个自然实验，用于研究和理解海洋中的浮游植物（以及因此处于较高营养级的生物）如何对气候变化做出反应。在这里，通过叶绿素浓度、初级生产力以及生长期开始、峰值、结束和持续时间的变化来估计ENSO对浮游植物的影响。物候变异性用于表征浮游植物对一些物理变量变化的响应：海面温度、海面高度和风。据报道，在太阳周期年变化较大的海洋区域，如高纬度地区，可以使用物理变量的年平均异常值轻松测量ENSO的影响。相比之下，在ENSO调节以风强迫季节性逆转特征的气候系统的海洋区域，如印度洋的季风系统，基于物候的物理变量平均异常值有助于完善对驱动生物响应机制的评估，并提供对综合过程更全面的理解。
