## 3 Results
### Bacterial Abundance and Composition  
The bacterial abundance within the BMs rapidly increased from day 0 (\(2.24\times 10^{6}\) cells-mL\({}^{-1}\)) to day 2 (\(1.04\times 10^{7}\) cells-mL\({}^{-1}\)) after the bioreactor installation. It then decreased until the end of the mesocosm experiment and finished on day 15 at \(2.97\times 10^{6}\) cells-mL\({}^{-1}\) (Figure 8A). The bacterial abundance within the CMs increased from day 1 to day 4 reaching \(9.58\times 10^{6}\) cells-mL\({}^{-1}\) (Figure 8A). At the end of the mesocosm experiment, the CMs contained a similar bacterial abundance (\(1.09\times 10^{7}\) cells-mL\({}^{-1}\)) compared to the BMs, but the highest abundance (\(1.09\times 10^{7}\) cells-mL\({}^{-1}\)) was reached on day 13. Cluster  
Figure 6: Dynamics of abundance of _Tetraselmis striata_ cells cultured in bioreactors, and concentrations of dissolved organic carbon in bioreactor installed mesoccosms and control mesoccosms during mesoccosm experiment period (15 days).  
Figure 7: Total concentrations of dissolved organic carbon (DOC) and relative ratios of four fractions of DOC (PLF, FLF, HLF and THLF), and its changes of each day in bio-reactor installed mesoccosm and control mesoccosm. Grey bars indicate the relative DOC concentrations, each ratio of orange, green, violet and yellow bar indicates the ratios of four fractions, respectively, and changed amounts of ratio of each four DOC fractions are indicated as blue (plus) and red (minus) bars, respectively.  
analysis revealed five clades (A-E) of bacteria across all sampling days and both mesocosms (Figure 9). The bacteria grouped in the same clade (B) until day 0, separated into two clades (D and E) on day 4, and separated into another two clades (C and E) on day 9. By day 15, the bacterial communities of BMs were separated into clade A alone.  
In BMs, an Alteromonadaceae group dominated on day 1, but its proportion gradually decreased throughout the experiment. Alternatively, the Flavobacteriaceae and Oceanospirillaceae groups increased from day 4 to 9, a Cellvibrionaceae group increased from day 9, and a Rhodobacteraceae group gradually increased throughout the experiment. In the CMs, Alteromonadaceae and Oceanospirillaceae groups dominated at day 1. The proportion of the Alteromonadaceae group decreased, but that of the Flavobacteriaceae group noticeably increased from days 4 to 6 (Figure 9). The proportions of ect. bacterial groups (\(<\)2%), which dominated two days prior to the beginning of the experiment and rapidly decreased in both mesocosms, but increased again in the CMs from days 9 to 15. At the end of mesocosm experiment, the Shannon diversity index decreased to 4.8 and 4.1 in each BM, but relatively higher diversities (6.0) were observed in the CMs compared to the BMs. ANOVA analysis revealed that the bacterial diversity of clade A (day 15 of BMs) was significantly (\(p<0.05\)) lower than that of clades B and C.  
Figure 8: Dynamics of abundance of biotic factors: bacteria (**A**), heterotrophic nano-flagellates (**B**), phytoplankton (**C**), ciliate (**D**), and zooplankton (**E**) during mesocosm experiment period (15 days). Each value of white and dark circles was averaged using two measured values of bioreactor installed mesocosms or control mesocosms, respectively.