MARBEC (Marine Biodiversity, Exploitation and Conservation), Centre National de la Recherche Scientifique, Université de Montpellier, Institut Français de Recherche pour l'Exploitation de la Mer, Institut de Recherche pour le Développement, Montpellier, France.
MEDIMEER (Mediterranean Platform for Marine Ecosystems Experimental Research), Observatoire de Recherche Méditerranéen de l'Environnement, Centre National de la Recherche Scientifique, Université de Montpellier, Institut de Recherche pour le Développement, Institut National de Recherche en Sciences et Technologies pour l'Environnement et l'Agriculture, Sète, France.
PLoS One. 2019 Apr 5;14(4):e0214933. doi: 10.1371/journal.pone.0214933. eCollection 2019.
Phytoplankton blooms are an important, widespread phenomenon in open oceans, coastal waters and freshwaters, supporting food webs and essential ecosystem services. Blooms are even more important in exploited coastal waters for maintaining high resource production. However, the environmental factors driving blooms in shallow productive coastal waters are still unclear, making it difficult to assess how environmental fluctuations influence bloom phenology and productivity. To gain insights into bloom phenology, Chl a fluorescence and meteorological and hydrological parameters were monitored at high-frequency (15 min) and nutrient concentrations and phytoplankton abundance and diversity, were monitored weekly in a typical Mediterranean shallow coastal system (Thau Lagoon). This study was carried out from winter to late spring in two successive years with different climatic conditions: 2014/2015 was typical, but the winter of 2015/2016 was the warmest on record. Rising water temperature was the main driver of phytoplankton blooms. However, blooms were sometimes correlated with winds and sometimes correlated with salinity, suggesting nutrients were supplied by water transport via winds, saltier seawater intake, rain and water flow events. This finding indicates the joint role of these factors in determining the success of phytoplankton blooms. Furthermore, interannual variability showed that winter water temperature was higher in 2016 than in 2015, resulting in lower phytoplankton biomass accumulation in the following spring. Moreover, the phytoplankton abundances and diversity also changed: cyanobacteria (< 1 μm), picoeukaryotes (< 1 μm) and nanoeukaryotes (3-6 μm) increased to the detriment of larger phytoplankton such as diatoms. Water temperature is a key factor affecting phytoplankton bloom dynamics in shallow productive coastal waters and could become crucial with future global warming by modifying bloom phenology and changing phytoplankton community structure, in turn affecting the entire food web and ecosystem services.
浮游植物水华是开阔海域、沿海和淡水的一种重要且广泛的现象，它支撑着食物网和基本的生态系统服务。在受开发影响的沿海地区，水华对于维持高资源生产力更为重要。然而，驱动浅海富营养化沿海地区水华的环境因素仍不清楚，这使得难以评估环境波动如何影响水华物候和生产力。为了深入了解水华物候，我们在一个典型的地中海浅海沿海系统（塞文泻湖）中以高频（15 分钟）监测叶绿素 a 荧光和气象及水文参数，并每周监测营养盐浓度以及浮游植物丰度和多样性。这项研究在两年的连续时间里，于冬季到晚春进行，期间气候条件不同：2014/2015 年是典型的，但 2015/2016 年的冬季是有记录以来最温暖的。水温升高是浮游植物水华的主要驱动因素。然而，水华有时与风和有时与盐度相关，这表明营养物质是通过风和更咸的海水摄入、雨水和水流事件来输送的。这一发现表明这些因素在确定浮游植物水华的成功方面具有共同作用。此外，年际变化表明，2016 年冬季水温高于 2015 年，导致次年春季浮游植物生物量积累减少。此外，浮游植物丰度和多样性也发生了变化：蓝藻（<1μm）、微微型真核生物（<1μm）和纳米真核生物（3-6μm）增加，而大型浮游植物如硅藻则减少。水温是影响浅海富营养化沿海地区浮游植物水华动态的关键因素，随着未来全球变暖，它可能变得至关重要，因为它会改变水华物候并改变浮游植物群落结构，进而影响整个食物网和生态系统服务。
