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

2018 ◽  
Author(s):  
Lei Hou ◽  
Xiabing Xie ◽  
Xianhui Wan ◽  
Shuh-Ji Kao ◽  
Nianzhi Jiao ◽  
...  
Keyword(s):  
Water Mass ◽  
Salinity Gradient ◽  
River Estuary ◽  
Niche Differentiation ◽  
Pearl River Estuary ◽  
Pearl River ◽  
Substrate Availability ◽  
The Pearl River Estuary ◽  
The Pearl River ◽  
Nitrite Oxidizers

Abstract. The niche differentiation between ammonia and nitrite oxidizers are controversial because they display disparate patterns in estuarine, coastal, and oceanic regimes. We analyzed ammonia-oxidizing archaea (AOA) and β-proteobacteria (AOB) amoA genes, nitrite-oxidizing bacteria (NOB) nxrB and 16S rRNA genes, and nitrification rates to identify their niche differentiation along a salinity gradient from the Pearl River estuary to the South China Sea. The archaeal amoA genes were generally more abundant than the β-AOB amoA genes; however, AOB more clearly attached to particles compared with AOA in the upper reaches of the Pearl River estuary. The NOB Nitrospina 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 Nitrospina 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 coupling of ammonia and nitrite oxidizers in the hypoxic waters of the estuary, suggesting 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.

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

2018 ◽  
Vol 15 (16) ◽  
pp. 5169-5187 ◽  
Author(s):  
Lei Hou ◽  
Xiabing Xie ◽  
Xianhui Wan ◽  
Shuh-Ji Kao ◽  
Nianzhi Jiao ◽  
...  
Keyword(s):  
Water Mass ◽  
Salinity Gradient ◽  
River Estuary ◽  
Niche Differentiation ◽  
Pearl River Estuary ◽  
Pearl River ◽  
Substrate Availability ◽  
The Pearl River Estuary ◽  
The Pearl River ◽  
Nitrite Oxidizers

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.

scholarly journals Implications of Nutrient Enrichment and Related Environmental Impacts in the Pearl River Estuary, China: Characterizing the Seasonal Influence of Riverine Input

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3245
Author(s):  
Lixia Niu ◽  
Pieter van Gelder ◽  
Xiangxin Luo ◽  
Huayang Cai ◽  
Tao Zhang ◽  
...  
Keyword(s):  
Nutrient Enrichment ◽  
River Discharge ◽  
Nutrient Dynamics ◽  
Southern China ◽  
Salinity Gradient ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Pearl River ◽  
The Pearl River Estuary ◽  
The Pearl River

The Pearl River estuary is an ecologically dynamic region located in southern China that experiences strong gradients in its biogeochemical properties. This study examined the seasonality of nutrient dynamics, identified related environmental responses, and evaluated how river discharge regulated nutrient sink and source. The field investigation showed significant differences of dissolved nutrients with seasons and three zones of the estuary regarding the estuarine characteristics. Spatially, nutrients exhibited a clear decreasing trend along the salinity gradient; temporally, their levels were obviously higher in summer than other seasons. The aquatic environment was overall eutrophic, as a result of increased fluxes of nitrogen and silicate. This estuary was thus highly sensitive to nutrient enrichment and related pollution of eutrophication. River discharge, oceanic current, and atmospheric deposition distinctly influenced the nutrient status. These factors accordingly may influence phytoplankton that are of importance in coastal ecosystems. Phytoplankton (in terms of chlorophyll) was potentially phosphate limited, which then more frequently resulted in nutrient pollution and blooms. Additionally, the nutrient sources were implied according to the cause–effect chains between nutrients, hydrology, and chlorophyll, identified by the PCA-generated quantification. Nitrogen was constrained by marine-riverine waters and their mutual increase-decline trend, and a new source was supplemented along the transport from river to sea, while a different source of terrestrial emission from coastal cities contributed to phosphate greatly.

scholarly journals Distribution and Activity of Ammonia-Oxidizers on the Size-Fractionated Particles in the Pearl River Estuary

2021 ◽  
Vol 8 ◽  
Author(s):  
Li Ma ◽  
Shangjin Tan ◽  
Hongbin Liu ◽  
Shuh-Ji Kao ◽  
Minhan Dai ◽  
...  
Keyword(s):  
Transcriptional Activity ◽  
Ammonia Oxidation ◽  
Salinity Gradient ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Pearl River ◽  
Ammonia Oxidizing Bacteria ◽  
The Pearl River Estuary ◽  
Large Particles ◽  
The Pearl River

To distinguish between the distribution and activity of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in the Pearl River estuary (PRE), we investigated the DNA- and cDNA-based β-proteobacterial and archaeal amoA genes on three size-fractionated particles of >3.0 μm, 0.45–3.0 μm, and 0.22–0.45 μm. Results showed that AOB were more abundant in the freshwater with high concentrations of ammonium (NH4+) and low dissolved oxygen, whereas AOA were dominant in the NH4+-depleted seawater and sensitive to temperature. Obvious shifts in ammonia-oxidizing communities were found along the salinity gradient in the PRE. AOB clearly presented a particle-associated nature, as evidenced by higher relative abundance of amoA genes attached to the large particles (>3.0 μm) and their transcripts exclusively detected on this fraction. Moreover, higher transcriptional activity (indicated by the cDNA/DNA ratio) of AOB on the large particles, suggesting AOB were actively involved in ammonia oxidation despite their lower abundance in the mid- and lower estuarine regions. In contrast, AOA exhibited higher transcriptional activity on the 0.45–3.0 μm and 0.22–0.45 μm particles, implying the free-living strategy of these microbes. Together, these findings from field observations provide useful information on the ecological strategies of ammonia-oxidizing communities in response to different environmental conditions.

Picophytoplankton abundance and distribution in three contrasting periods in the Pearl River Estuary, South China

2013 ◽  
Vol 64 (8) ◽  
pp. 692 ◽  
Author(s):  
Xia Zhang ◽  
Zhen Shi ◽  
Feng Ye ◽  
Yanyi Zeng ◽  
Xiaoping Huang
Keyword(s):  
South China ◽  
Saline Water ◽  
Salinity Gradient ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Pearl River ◽  
Spatial Gradient ◽  
The Pearl River Estuary ◽  
The Pearl River ◽  
Abundance And Distribution

Abundance and distribution characteristics of three picophytoplankton groups (Synechococcus, Prochlorococcus and picoeukaryotes), identified by flow cytometer, and two types of picocyanobacteria (phycoerythrin and phycocyanin-rich strains), determined by epifluorescence microscope, were assessed in three contrasting periods in the Pearl River Estuary, South China. The average abundance of picophytoplankon and picocyanobacteria was 104 cells mL–1 in the two summer observations and 103 cells mL–1 in winter. Low cell density in the cold season was probably due to high turbidity and low water temperature. Prochlorococcus was detected within the estuarine plume in the summer investigations and was undetectable in the winter. Higher abundance and the further upstream occurrence of Prochlorococcus in the summer of 2011 were mainly associated with extreme low river flows. We presumed that Prochlorococcus abundance and distribution range were balanced by river discharge and saline-water intrusion. Synechococcus was the dominant group in the inner estuary. Similar to Prochlorococcus, Synechococcus distribution was related with freshwater inflow. The river inflow exerted strong limitation on Synechococcus and Prochlorococcus, with this effect weakening along the salinity gradient. Picoeukaryotes were the least abundant category among picophytoplankton and showed a different distribution pattern from that of Synechococcus and Prochlorococcus. For picocyanobacteria, there was a clear spatial gradient with phycocyanin-rich strains dominant in the upper estuary, and phycocyanin-rich and phycoerythrin-rich cells dominant downstream. A significant negative correlation was observed between phycocyanin-rich cells to phycoerythrin-rich cells ratio and salinity.

Effects of climate change and fishing on the Pearl River Estuary ecosystem and fisheries

2019 ◽  
Vol 29 (4) ◽  
pp. 861-875
Author(s):  
Zeyu Zeng ◽  
William W. L. Cheung ◽  
Shiyu Li ◽  
Jiatang Hu ◽  
Ying Wang
Keyword(s):  
Climate Change ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Pearl River ◽  
The Pearl River Estuary ◽  
The Pearl River

scholarly journals The Role of Environmental Factors on the Fishery Catch of the Squid Uroteuthis chinensis in the Pearl River Estuary, China

2021 ◽  
Vol 9 (2) ◽  
pp. 131
Author(s):  
Dongliang Wang ◽  
Lijun Yao ◽  
Jing Yu ◽  
Pimao Chen
Keyword(s):  
River Estuary ◽  
Pearl River Estuary ◽  
Sea Surface ◽  
Spatiotemporal Variability ◽  
Pearl River ◽  
Coastal Current ◽  
Catch Per Unit Effort ◽  
Chl A ◽  
The Pearl River Estuary ◽  
The Pearl River

The Pearl River Estuary (PRE) is one of the major fishing grounds for the squid Uroteuthis chinensis. Taking that into consideration, this study analyzes the environmental effects on the spatiotemporal variability of U. chinensis in the PRE, on the basis of the Generalized Additive Model (GAM) and Clustering Fishing Tactics (CFT), using satellite and in situ observations. Results show that 63.1% of the total variation in U. chinensis Catch Per Unit Effort (CPUE) in the PRE could be explained by looking into outside factors. The most important one was the interaction of sea surface temperature (SST) and month, with a contribution of 26.7%, followed by the interaction effect of depth and month, fishermen’s fishing tactics, sea surface salinity (SSS), chlorophyll a concentration (Chl a), and year, with contributions of 12.8%, 8.5%, 7.7%, 4.0%, and 3.1%, respectively. In summary, U. chinensis in the PRE was mainly distributed over areas with an SST of 22–29 °C, SSS of 32.5–34‰, Chl a of 0–0.3 mg × m−3, and water depth of 40–140 m. The distribution of U. chinensis in the PRE was affected by the western Guangdong coastal current, distribution of marine primary productivity, and variation of habitat conditions. Lower stock of U. chinensis in the PRE was connected with La Niña in 2008.

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