Abstract
Bacterial communities are an important part of biological diversity and biogeochemical cycling in aquatic ecosystems. In this study, the relationship amongst the phytoplankton species composition and abiotic environmental factors on seasonal changes in the community composition of free-living and attached bacteria in Lake Erhai were studied. Using Illumina high-throughput sequencing, we found that the impact of environmental factors on both the free-living and attached bacterial community composition was greater than that of the phytoplankton community, amongst which total phosphorus, Secchi disk, water temperature, dissolved oxygen and conductivity strongly influenced bacterial community composition. Microcystis blooms associated with subdominant Psephonema occurred during the summer and autumn, and Fragilaria, Melosira and Mougeotia were found at high densities in the other seasons. Only small numbers of algal species-specific bacteria, including Xanthomonadaceae (Proteobacteria) and Alcaligenaceae (Betaproteobacteria), were tightly coupled to Microcystis and Psephonema during Microcystis blooms. Redundancy analysis showed that although the composition of the bacterial communities was controlled by species composition mediated by changes in phytoplankton communities and abiotic environmental factors, the impact of the abiotic environment on both free-living and attached bacterial community compositions were greater than the impact of the phytoplankton community. These results suggest that the species composition of both free-living and attached bacterial communities are affected by abiotic environmental factors, even when under strong control by biotic factors, particularly dominant genera of Microcystis and Psephonema during algal blooms.
Highlights
Bacterial communities adapt to environmental changes due to their small size, short biological life cycles and genetic variability (Lenski 2017; McAdams et al 2004)
We investigated the seasonal variation in the species composition of free-living and attached bacteria over an 18-month period, and analyzed the response of the community composition of free-living and attached bacteria to changes in both phytoplankton composition and abiotic environmental factors in Lake Erhai
The variation partitioning analysis showed that the attached bacteria accounted for 16% of the variation in the free-living bacterial community, environmental factors accounted for 9% of the variation, and phytoplankton accounted for 2% of the variation (Fig. 5e)
Summary
Bacterial communities adapt to environmental changes due to their small size, short biological life cycles and genetic variability (Lenski 2017; McAdams et al 2004). Similar bacterial species are often attached to similar algal taxa or groups (Rooney-Varga et al 2005; Sapp et al 2007) It remains to be elucidated how abiotic environmental factors and phytoplankton species composition interactively influence attached and free-living bacterial communities. To address this issue, we investigated the seasonal variation in the species composition of free-living and attached bacteria over an 18-month period, and analyzed the response of the community composition of free-living and attached bacteria to changes in both phytoplankton composition and abiotic environmental factors in Lake Erhai. Understanding the effects of changes in phytoplankton species composition and abiotic factors on the seasonal patterns of bacterial species composition will provide important insight into the factors controlling species composition of the bacterial communities in lakes, and will improve our ability to predict the bacterial response to both abiotic and biotic environmental changes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
