Denitrifier communities differ in mangrove wetlands across China

Denitrifier communities differ in mangrove wetlands across China

Ruili Li*, Sijie Wu, Minwei Chai, Xiaoxue Shen, Lingyun Yu

Key Laboratory for Heavy Metal Pollution Control and Reutilization, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, Guangdong, PR China

*Corresponding author. E-mail address: liruili@pkusz.edu.cn

Abstract:

Denitrification plays an important role in the removal of nitrogen from coastal wetlands. However, knowledge regarding the dynamics of denitrifier communities in mangrove wetlands is limited, and the corresponding influential factors lack quantitative analysis. To explore the geographical variations in the nosZ-denitrifier community and the underlying influential factors, surface sediments in mangrove forest and adjacent mudflat were collected from six mangrove wetlands across China, including high-latitude Yunxiao (YX) and Futian (FT) mangroves, middle-latitude Fangchenggang (FCG), Zhanjiang (ZJ) and Dongzhaigang (DZG) mangroves, and low-latitude Dongfang (DF) mangrove. The nosZ gene abundance in mangrove sediments varied from 1.60×10⁵–1.17×10⁶ copies g^-1 dry sediment, with a higher density in Avicennia marina forest than the mudflat. Denitrifier community richness and diversity increased with decreasing latitude based on the Chao1 richness and Shannon diversity index, with the highest diversity being observed in the DF mangrove. The denitrifier communities could be classified into three groups including low-latitude DF mangrove, middle-latitude FCG, ZJ and DZG mangroves, and high-latitude YX and FT mangroves based on HCA and PCA analysis. The nosZ OTUs could be divided into seven distinct clusters with different proportionality characteristics among mangroves. Environmental factors (TN, TOC, and salinity) could collectively shape denitrifier communities in mangrove sediments.