Biological Nitrogen Fixation in Sediments of a Cyanobacterial Bloom‐Occurring Bay in One Eutrophic Shallow Lake: Occurrence and Related Environmental Factors

Abstract

The availability of nitrogen affects primary productivity in aquatic environments (McCarthy et al., 2016;Shiozaki et al., 2018). However, excessive nitrogen loading induced by human activities has increased the frequency and duration of harmful cyanobacterial blooms in lake systems (Paerl & Barnard, 2020;Sinha et al., 2017;Wagner et al., 2021). Eutrophication, particularly an increase in the nitrogen load, promotes the proliferation of non-nitrogen-fixing toxic algae (e.g., Microcystis) by replacing the algae in the nitrogen-fixing niche (Deng et al., 2020). Cyanobacterial blooms cause serious water quality problems (Huisman et al., 2018;Paerl & Otten, 2013), such as oxygen depletion and the death of aquatic organisms caused by the degradation of senescent blooms (Rabalais et al., 2010). More importantly, the proliferation of toxic cyanobacteria significantly raises the cyanotoxins exposure risk to humans (Carmichael, 2001;Merel et al., 2013). Improving the water quality of lakes is of great significance to protect water resources.

Nitrogen cycling in aquatic environments of China: Progress and future challenges

“…N fixation has also been attracted attention in freshwater lakes. Yao et al (2018) and Tian et al (2021) reported that N fixation occurred obviously in Taihu Lake, and found that the process rates were comparable to urban rivers as well as estuarine and coastal ecosystems. The concentrations of sulfide, sulfate, and NO 3 − in pore water were critical factors influencing the N fixation in lakes (Tian et al, 2021).…”

“…Yao et al (2018) and Tian et al (2021) reported that N fixation occurred obviously in Taihu Lake, and found that the process rates were comparable to urban rivers as well as estuarine and coastal ecosystems. The concentrations of sulfide, sulfate, and NO 3 − in pore water were critical factors influencing the N fixation in lakes (Tian et al, 2021). Notably, in the most eutrophic aquatic environments of China, the N-fixing cyanobacteria generally break out in summer, which can further increase the more bioavailable N and in return exacerbate eutrophication (Yao et al, 2018).…”

Diazotrophic community in the sediments of Poyang Lake in response to water level fluctuations

“…Biological nitrogen fixation, a microbial process that converts the reduction of dinitrogen gas (N 2 ) to biologically available ammonium, plays a fundamental role in the primary production of aquatic systems (Vitousek and Howarth, 1991;Arp, 2000;Montoya et al, 2004). Diazotrophs in the aquatic environment are widely distributed among Proteobacteria, Euryarchaeota, Cyanobacteria, Bacteroidetes, and Firmicutes based on the diversity of the nifH gene (Kapili et al, 2020;Wang et al, 2020;Tian et al, 2021a). Diazotrophs capable of fixing molecular nitrogen have been found to be present in the water columns and the sediments of lakes (Zhang and Zhang, 2016;Yao et al, 2018;Wang et al, 2020;Tian et al, 2021a).…”

“…Diazotrophs in the aquatic environment are widely distributed among Proteobacteria, Euryarchaeota, Cyanobacteria, Bacteroidetes, and Firmicutes based on the diversity of the nifH gene (Kapili et al, 2020;Wang et al, 2020;Tian et al, 2021a). Diazotrophs capable of fixing molecular nitrogen have been found to be present in the water columns and the sediments of lakes (Zhang and Zhang, 2016;Yao et al, 2018;Wang et al, 2020;Tian et al, 2021a). It is traditionally believed that N 2 -fixing Cyanobacteria are the main diazotrophs in aquatic systems (Yao et al, 2018).…”

“…As mentioned above, WLFs can regulate the release of sediment nutrients in floodplain lakes, and in turn change the nutrient content. Nutrient availability can shape the diazotrophic community in aquatic ecosystems (Weber et al, 2017;Wang et al, 2020;Luo et al, 2021;Tian et al, 2021a;Jabir et al, 2021b). Therefore, elucidating the response of the sediment diazotrophic community to WLFs is of great interest and importance to gain insights into the ecological impacts of WLFs and the nitrogen-cycling processes of the floodplain lake.…”