Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543;
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543.
Proc Natl Acad Sci U S A. 2020 Jun 2;117(22):12215-12221. doi: 10.1073/pnas.1918439117. Epub 2020 May 15.
Picophytoplankton are the most abundant primary producers in the ocean. Knowledge of their community dynamics is key to understanding their role in marine food webs and global biogeochemical cycles. To this end, we analyzed a 16-y time series of observations of a phytoplankton community at a nearshore site on the Northeast US Shelf. We used a size-structured population model to estimate in situ division rates for the picoeukaryote assemblage and compared the dynamics with those of the picocyanobacteria at the same location. We found that the picoeukaryotes divide at roughly twice the rate of the more abundant and are subject to greater loss rates (likely from viral lysis and zooplankton grazing). We describe the dynamics of these groups across short and long timescales and conclude that, despite their taxonomic differences, their populations respond similarly to changes in the biotic and abiotic environment. Both groups appear to be temperature limited in the spring and light limited in the fall and to experience greater mortality during the day than at night. Compared with , the picoeukaryotes are subject to greater top-down control and contribute more to the region's primary productivity than their standing stocks suggest.
微微型浮游植物是海洋中最丰富的初级生产者。了解它们的群落动态是理解它们在海洋食物网和全球生物地球化学循环中作用的关键。为此，我们分析了美国东北部近海地区一个浮游植物群落 16 年的时间序列观测数据。我们使用了一个基于大小结构的种群模型来估计微微型真核生物组合的现场分裂率，并将其与同一地点的微微型蓝藻的动态进行了比较。我们发现，微微型真核生物的分裂速度大约是更丰富的微微型蓝藻的两倍，并且它们的损失率更高（可能来自病毒裂解和浮游动物摄食）。我们描述了这些群体在短时间和长时间尺度上的动态，并得出结论，尽管它们在分类上存在差异，但它们的种群对生物和非生物环境的变化反应相似。这两个群体在春季似乎受到温度限制，在秋季受到光照限制，白天的死亡率比夜间高。与微微型蓝藻相比，微微型真核生物受到更大的自上而下的控制，对该地区的初级生产力的贡献比它们的现存量所表明的要大。
