On May 30th, the latest research article, “Succession of marine bacteria in response to Ulva prolifera-derived dissolved organic matter”, was published online by the internationally renowned Environment International. This achievement was completed in collaboration with Jinchang Liang, Associate Professor Jiwen Liu, and Professor Xiaohua Zhang  from the Frontiers Science Center for Deep Ocean Multispheres and Earth System (DOMES) at Ocean University of China, among others.

         Increasing macroalgal blooms as a consequence of climate warming and coastal eutrophication have profound effects on the marine environment. The outbreaks of Ulva prolifera in the Yellow Sea of China occurring every summer since 2007 to present have formed the world’s largest green tide. The green tide releases huge amounts of dissolved organic matter (DOM) to the seawater, causing an organic overload. However, how marine bacteria respond to this issue and the potential impact on the marine environment are still unclear. Here, a 168-h microcosm incubation experiment was performed to monitor the highly temporally resolved dynamics of marine bacterial community that occur in response to Ulva prolifera-derived DOM. DOM inputs significantly increased bacterial abundances within 6 h, decreased bacterial diversity and triggered clear community successions during the whole period of incubation. Vibrio of Gammaproteobacteria robustly and rapidly grew over short timescales (6–24 h), with its relative abundance accounting for up to 52.5% of active bacteria. From 24 to 48 h, some genera of Flavobacteriia grew rapidly, which was more conspicuous at a higher DOM concentration than at a lower concentration. The genus Donghicola of Alphaproteobacteria was predominant at later time points (>48 h). This bacterial community succession was accompanied by significant variations in the activity of 12 different extracellular enzymes, resulting in a rapid reduction of dissolved organic carbon by 74.5% within the first 36 h. In summary, this study demonstrates rapid successions of bacterial community and extracellular enzyme activity after DOM inputs, suggesting that the bacterial response to Ulva prolifera-derived organic matter may contribute to environmental restoration and may pose a health threat due to the bloom of potential pathogenic Vibrio.

Fig. A schematic diagram of different phases in the degradation of U. prolifera-derived DOM. The line chart showing the succession of dominant bacterial group across the incubation in T2.