Zhao Hui, Zhao Jian, Sun Xingli, Chen Fajin, Han Guoqi
Guangdong Ocean University, Zhanjiang, China.
Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, St. John's, NL, Canada.
PLoS One. 2018 Jan 17;13(1):e0189926. doi: 10.1371/journal.pone.0189926. eCollection 2018.
Summer upwelling occurs frequently off the southeast Vietnam coast in the western South China Sea (SCS), where summer phytoplankton blooms generally appear during June-August. In this study, we investigate inter-annual variation of Ekman pumping and offshore transport, and its modulation on summer blooms southeast of Vietnam. The results indicate that there are low intensities of summer blooms in El Niño years, under higher sea surface temperatures (SST) and weaker winds. However, a different pattern of monthly chlorophyll a (Chl-a) blooms occurred in summer of 2007, a transitional stage from El Niño to La Niña, with weak (strong) wind and high (low) SST before (after) early July. There is a weak phytoplankton bloom before July 2007 and a strong phytoplankton bloom after July 2007. The abrupt change in the wind intensity may enhance the upwelling associated with Ekman pumping and offshore Ekman transport, bringing more high-nutrient water into the upper layer from the subsurface, and thus leading to an evident Chl-a bloom in the region.
夏季上升流频繁出现在南海西部越南东南沿海，这里的夏季浮游植物水华通常在6 - 8月出现。在本研究中，我们调查了埃克曼抽吸和离岸输运的年际变化，及其对越南东南部夏季水华的调节作用。结果表明，在厄尔尼诺年，海面温度较高且风力较弱时，夏季水华强度较低。然而，在2007年夏季，即从厄尔尼诺向拉尼娜的过渡阶段，出现了不同模式的月叶绿素a水华，7月初之前风力较弱（较强）且海面温度较高（较低），7月初之后则相反。2007年7月之前浮游植物水华较弱，7月之后浮游植物水华较强。风强度的突然变化可能会增强与埃克曼抽吸和离岸埃克曼输运相关的上升流，将更多高营养水从次表层带入上层，从而导致该区域出现明显的叶绿素a水华。
