Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 15, issue 16
Biogeosciences, 15, 5169–5187, 2018
https://doi.org/10.5194/bg-15-5169-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Biogeosciences, 15, 5169–5187, 2018
https://doi.org/10.5194/bg-15-5169-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 29 Aug 2018

Research article | 29 Aug 2018

Niche differentiation of ammonia and nitrite oxidizers along a salinity gradient from the Pearl River estuary to the South China Sea

Lei Hou1,2,*, Xiabing Xie1,*, Xianhui Wan1, Shuh-Ji Kao1,2, Nianzhi Jiao1,2, and Yao Zhang1,2 Lei Hou et al.
  • 1State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361101, China
  • 2College of Ocean and Earth Sciences, Xiamen University, Xiamen 361101, China
  • *These authors contributed equally to this work.

Abstract. The niche differentiation of ammonia and nitrite oxidizers is controversial because they display disparate patterns in estuarine, coastal, and oceanic regimes. We analyzed diversity and abundance of ammonia-oxidizing archaea (AOA) and β-proteobacteria (AOB), nitrite-oxidizing bacteria (NOB), and nitrification rates to identify their niche differentiation along a salinity gradient from the Pearl River estuary to the South China Sea. AOA were generally more abundant than β-AOB; however, AOB more clearly attached to particles compared with AOA in the upper reaches of the Pearl River estuary. The NOB Nitrospira had higher abundances in the upper and middle reaches of the Pearl River estuary, while Nitrospina was dominant in the lower estuary. In addition, AOB and Nitrospira could be more active than AOA and Nitrospina since significantly positive correlations were observed between their gene abundance and the nitrification rate in the Pearl River estuary. There is a significant positive correlation between ammonia and nitrite oxidizer abundances in the hypoxic waters of the estuary, suggesting a possible coupling through metabolic interactions between them. Phylogenetic analysis further revealed that the AOA and NOB Nitrospina subgroups can be separated into different niches based on their adaptations to substrate levels. Water mass mixing is apparently crucial in regulating the distribution of nitrifiers from the estuary to open ocean. However, when eliminating water mass effect, the substrate availability and the nitrifiers' adaptations to substrate availability via their ecological strategies essentially determine their niche differentiation.

Publications Copernicus
Download
Short summary
The niche differentiation of ammonia and nitrite oxidizers is controversial because they display disparate patterns in different environments. Combining molecular and nitrification rate analyses, our study clarified that water mass mixing and the substrate availability primarily regulated the niche differentiation of nitrifier populations along a salinity gradient. The nitrifier populations may have specific adaptations to different substrate conditions through their ecological strategies.
The niche differentiation of ammonia and nitrite oxidizers is controversial because they display...
Citation