Both planktonic and sediment bacterial assemblages are the important components of freshwater lake ecosystems. However, their spatiotemporal shift and the driving forces remain still elusive. Eutrotrophic Dianchi Lake and mesotrophic Erhai Lake are the largest two freshwater lakes on the Yunnan Plateau (southwestern China). The present study investigated the spatiotemporal shift in both planktonic and sediment bacterial populations in these two plateau freshwater lakes at different trophic status. For either lake, both water and sediment samples were collected from six sampling locations in spring and summer. Bacterioplankton community abundance in Dianchi Lake generally far outnumbered that in Erhai Lake. Sediment bacterial communities in Erhai Lake were found to have higher richness and diversity than those in Dianchi Lake. Sediments had higher bacterial community richness and diversity than waters. The change patterns for both planktonic and sediment bacterial communities were lake-specific and season-specific. Either planktonic or sediment bacterial community structure showed a distinct difference between in Dianchi Lake and in Erhai Lake, and an evident structure difference was also found between planktonic and sediment bacterial communities in either of these two lakes. Planktonic bacterial communities in both Dianchi Lake and Erhai Lake mainly included Proteobacteria (mainly Alpha-, Beta-, and Gammaproteobacteria), Bacteroidetes, Actinobacteria, Cyanobacteria, and Firmicutes, while sediment bacterial communities were mainly represented by Proteobacteria (mainly Beta- and Deltaproteobacteria), Bacteroidetes, Chlorobi, Nitrospirae, Acidobacteria, and Chloroflexi. Trophic status could play important roles in shaping both planktonic and sediment bacterial communities in freshwater lakes.
Nutrient
dynamics in lakes are determined by the external anthropogenic
discharges and unobserved internal cycling processes. In this work,
a decadal nutrient data set from the eutrophic Lake Taihu, China,
revealed a strong seasonal pattern of nutrient concentration and limitation.
A nutrient-driven dynamic eutrophication model based on a Bayesian
hierarchical framework was established to quantify the relative contributions
to temporal variations from external discharges and internal processes.
Results showed that after years of efforts on nutrient reduction,
external discharges were relatively small and fluctuated less between
seasons compared to the internal processes. A quantitative relationship
between monthly nutrient concentration and corresponding internal
loading was observed. Lake sediment could transform from a source
of phosphorus in overlying water in summer and autumn to a sink in
winter and spring. Together with temporal variations in nitrification
and denitrification, seasonal transformation from the limitation of
phosphorus induced colimitation of nitrogen and phosphorus. Understanding
the potential impact of internal nutrient cycling on a seasonal pattern
of nutrient concentration and limitation, the growth of phytoplankton,
and, possibly, phytoplankton community composition should be emphasized,
given the change in the relative importance of external discharges
and internal loading in the process of lake restoration.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.