Divergent Patterns of Bacterial Community Structure and Function in Response to Estuarine Output in the Middle of the Bohai Sea

Abstract

Understanding environment-community relationships under shifting environmental conditions helps uncover mechanisms by which environmental microbial communities manage to improve ecosystem functioning. This study investigated the microbial community and structure near the Yellow Sea River estuary in 12 stations across the middle of the Bohai Sea for over two seasons to elucidate the influence of estuarine output on them. We found that the dominant phyla in all stations were Proteobacteria, Cyanobacteria, Bacteroidetes, Actinobacteria, and Planctomycetes. Alpha-diversity increased near the estuary and bacterial community structure differed with variation of spatiotemporal gradients. Among all the environmental factors surveyed, temperature, salinity, phosphate, silicon, nitrate, and total virioplankton abundance played crucial roles in controlling the bacterial community composition. Some inferred that community functions such as carbohydrate, lipid, amino acid metabolism, xenobiotics biodegradation, membrane transport, and environmental adaptation were much higher in winter; energy and nucleotide metabolism were lower in winter. Our results suggested that estuarine output had a great influence on the Bohai Sea environment and changes in the water environmental conditions caused by estuarine output developed distinctive microbial communities in the middle of the Bohai Sea. The distinctive microbial communities in winter demonstrated that the shifting water environment may stimulate changes in the diversity and then strengthen the predicted functions.

Bacterial and Protistan Community Variation across the Changjiang Estuary to the Ocean with Multiple Environmental Gradients

“…Moreover, Gammaproteobacteria was not the major class in this survey area, which was inconsistent with many previous studies [ 19 , 32 , 77 ]. The seasonal pattern of Gammaproteobacteria in the Bohai Sea, reported by Wang et al [ 78 ], which was consistent with our winter data (data not shown), might be the reason. Lack of Chloroflexi in high-salinity waters in our study was in accordance with the hypothesis that origins of pelagic Chloroflexi are likely from soil and sediment habitats, and freshwater habitats harbor the most diverse phylogenetic assemblages in comparison to brackish and marine habitats [ 79 ].…”

Spatiotemporal Shift of T4-Like Phage Community Structure in the Three Largest Estuaries of China

“…High salinity seemed to have a strong inhibitory effect on riverine bacteria ( 49 – 51 ), which may inhibit viral production in cells that are derived from upstream estuarine regions. Significant changes in the microbial community structure along environmental gradients were reported for these three estuaries ( 52 – 54 ). The close nature of the virus-microbe relationship makes it reasonable that shifts in the microbial community composition could lead to corresponding changes in the coexisting viral communities.…”

“…Owing to the host-specific natures of viruses, the higher diversity of bacterial communities in winter may be the main reason for the higher α-diversities of the T4-like phages that were observed in winter in the three estuaries. Indeed, the α-diversities of the bacterial communities from YZRE, YRE, and PRE were also significantly higher in winter than in summer, despite the lower bacterial abundances in winter ( 52 – 54 ). Enhanced vertical mixing and a higher level of nutrients in winter, especially phosphorus, can trigger the activation of some dormant bacterial taxa ( 69 , 70 ), which makes the bacterial community more complex and further promotes the proliferation of their corresponding phages ( 70 , 71 ).…”

“…The covariation of the abundance and the genetic diversity of different host-virus pairs (e.g., Synechococcus and cyanophages as well as Roseobacteria and roseophages) in seasonal transitions have been previously observed in different environments (e.g., the Chesapeake Estuary) ( 66 – 68 ). Distinct seasonal patterns of bacterial abundance and community structure were reported in the three largest estuaries of China ( 45 , 52 – 54 ). The shift in the bacterial communities and different prokaryotic activities between winter and summer may be the driving force of the seasonal transition of the T4-like viral communities in the three estuaries.…”

Comparison of assembly process and co-occurrence pattern between planktonic and benthic microbial communities in the Bohai Sea

“…The increasing anthropogenic activities have caused serious ecological problems to the BS, such as eutrophication, algal blooms, and hypoxia in the bottom water (Song et al, 2016;Zhai et al, 2019;Zheng et al, 2020). Consistently, microbial communities in the BS have been influenced by hypoxia (Wu et al, 2022), river input (Wang et al, 2021), and heavy metals (Ming et al, 2021). However, the microbial assembly pattern in this highly disturbed ecosystem is largely unknown.…”