To investigate the responses of a natural microbial plankton community of coastal Mediterranean waters to warming, which are still poorly known, an in situ mesocosm experiment was carried out in Thau Lagoon during autumn 2018. Several microorganisms, including virio-, bacterio-, and phytoplankton < 10 µm in size, were monitored daily and analysed using flow cytometry for 19 consecutive days in six mesocosms. Three mesocosms (control) had the same natural water temperature as the lagoon, and the other three were warmed by + 3 °C in relation to the control temperature. The cytometric analyses revealed an unexpected community dominated by picophytoplanktonic cells, including Prochlorococcus-like and Picochlorum-like cells, which had not previously been found in Thau Lagoon. The experimental warming treatment increased the abundances of nanophytoplankton, cyanobacteria, bacteria and viruses during the experiment and triggered earlier blooms of cyanobacteria and picoeukaryotes. Only the abundance of Picochlorum-like cells was significantly reduced under warmer conditions. The growth and grazing rates of phytoplankton and bacterioplankton estimated on days 2 and 8 showed that warming enhanced the growth rates of most phytoplankton groups, while it reduced those of bacteria. Surprisingly, warming decreased grazing on phytoplankton and bacteria at the beginning of the experiment, while during the middle of the experiment it decreased the grazing on prokaryote only but increased it for eukaryotes. These results reveal that warming affected the Thau Lagoon plankton community from viruses to nanophytoplankton in fall, inducing changes in both dynamics and metabolic rates.

为了研究仍然鲜为人知的地中海沿海水域天然微生物浮游生物群落对变暖的响应，2018年秋天在Thau Lagoon进行了原位介观试验。几种微生物，包括玻璃体，细菌和浮游植物小于10 µm的大小，每天进行监测，并使用流式细胞仪在六个中型视野中连续19天进行分析。三个中观世界（对照组）的自然水温与泻湖相同，其他三个中温相对于对照组温度升高了+ 3°C。在流式细胞分析揭示picophytoplanktonic细胞，包括主导的意外社区绿球藻样和Picochlorum类细胞，以前在Thau泻湖中未发现。实验性增温处理在实验过程中增加了纳米浮游植物，蓝藻细菌，细菌和病毒的含量，并引发了蓝藻细菌和微核生物的更早开花。只有大量的四氯化磷类细胞在温暖的条件下显着减少。在第2天和第8天估算的浮游植物和浮游植物的生长和放牧速度表明，变暖提高了大多数浮游植物群体的生长速度，而减少了细菌的生长速度。出乎意料的是，在实验开始时变暖减少了浮游植物和细菌的放牧，而在实验中间，变暖仅减少了对原核生物的放牧，而对真核生物则增加了。这些结果表明，变暖在秋季影响了Thau Lagoon浮游生物群落，从病毒到纳米浮游植物，导致动力学和代谢率发生变化。