Ecosystem dynamics in monomictic lakes are characterized by seasonal thermal mixing and stratification. These physical processes bring about seasonal variations in nutrients and organic matter fluxes, affecting the biogeochemical processes that occur in the water column. Physical and chemical dynamics are generally reflected in seasonal structural changes in the phytoplankton and bacterio-plankton community. In this study, we analyzed, using 16S rRNA amplicon sequencing, the structure of the bacterial community associated with large particles (>20 μm) in Lake Kinneret (Sea of Galilee, Israel), and its associations to phytoplankton populations. The study was carried out during late winter and early spring, a highly dynamic period in terms of thermal mixing, nutrient availability, and shifts in phytoplankton composition. Structural changes in the bacterioplankton population corresponded with limnological variations in the lake. In terms of the entire heterotrophic community, the structural patterns of particle-associated bacteria were mainly correlated with abiotic factors such as pH, ammonia, water temperature and nitrate. However, analysis of microbial taxon-specific correlations with phytoplankton species revealed a strong potential link between specific bacterial populations and the presence of different phytoplankton species, such as the cyanobacterium Microcystis, as well as the dinoflagellates Peridinium and Peridiniopsis. We found that Brevundimonas, a common freshwater genus, and Bdellovibrio, a well-known Gram-negative bacteria predator, were positively associated to Microcystis, suggesting a potentially important role of these three taxa in the microbial ecology of the lake. Our results show that the dynamics of environmental abiotic conditions, rather than specific phytoplankton assemblages, are the main factors positively correlated with changes in the community structure as a whole. Nevertheless, some specific bacteria may interact and be linked with specific phytoplankton, which may potentially control the dynamic patterns of the microbial community.
Bibliographical noteFunding Information:
We thank Captains Oz Tzabari-Dar and Moti Diamant for their skillful assistance with sample collection. We would like to acknowledge the assistance of Mr. Mati Michael in editing the final version of this manuscript. Funding. This study was financially supported by the Israeli Ministry of Science and Technology (MOST) infrastructure project, grant no. 3-10342 (to DS and AS) and by a joint Israel Science Foundation (ISF) and National Natural Science Foundation of China (NSFC) research grant no. 2033/15 (to AS). OS-N was partially supported by an Israel Water Authority fellowship. Computations presented in this work were performed on the Hive computer cluster at the University of Haifa, which is partly funded by ISF grant no. 2155/15. The continued support of Israel Water Authority to the Kinneret Limnological Laboratory (IOLR) is acknowledged.
© Copyright © 2019 Schweitzer-Natan, Ofek-Lalzar, Sher and Sukenik.
- heterotrophic bacteria
- lake microbiome
- microbial community
ASJC Scopus subject areas
- Microbiology (medical)