Institutional Repository of Key Laboratory of Marine Ecology & Environmental Sciences, CAS
|Place of Conferral||中国科学院海洋研究所|
|Keyword||球形棕囊藻赤潮 颗粒附着原核生物 浮游原核生物 原核生群落结构 时空分布|
（1）北部湾北部海域球形棕囊藻囊体时空分布及其影响因素 调查期间囊体丰度介于0–18.98 × 104 col·m-3，囊体丰度峰值出现在冬季月（2017年2月和2019年1月）。随着时间的推移，囊体丰度高值区首先出现在从涠洲岛附近海域（2016年12月和2018年11月），再出现在钦州湾–北海附近海域（2017年2月和2019年1月），最后出现在琼州海峡–涠洲岛海域（2017年3月和2019年2月）。水温和盐度是影响囊体时空分布的主要环境因素，在局部区域丰富的硝酸盐和磷酸盐为囊体的形成奠定了基础。球形棕囊藻囊体丰度与其他浮游植物丰度显著正相关，其他浮游植物群落结构的改变也会影响囊体时空分布。
（2）北部湾北部海域水体异养细菌时空分布特征 2016年9月至2017年8月，该海区异养细菌丰度介于（2.75–56.86）× 105 cell·mL-1，平均值（11.01 ± 6.31）× 105 cell·mL-1，存在明显月际变化，各季节细菌丰度从高至低依次为：夏季（6月、8月和9月）、冬季（12月、1月和2月）、春季（3月和4月）、秋季（11月）。异养细菌丰度由近岸浅水区向远岸深水区逐渐降低；在近岸浅水区异养细菌丰度垂直分布均匀，在水深大于20 m的海区出现季节性分层现象：表层异养细菌丰度高于底层。异养细菌时空分布差异取决于环境条件的变化，尤其是温度、盐度、叶绿素a和溶解氧含量对其有重要影响。除3月、6月和8月外，异养细菌丰度与营养盐呈显著负相关，二者关系受到浮游植物的间接影响。除此之外，在囊体存在时期，异养细菌丰度还与球形棕囊藻囊体丰度密切相关。
Due to the increasingly serious eutrophication in the Beibu Gulf, Phaeocystis globosa blooms occur frequently, and impairs marine ecosystem and social economy in recent years. The spatio-temporal distribution of P. globosa colonies and its relationship with main environmental factors were studied based on the monthly multi-disciplinary investigations from September 2016 to August 2017 and from November 2018 to April 2019. Furthermore, the heterotrophic bacteria dynamics in high-incidence area of P. globosa blooms were analyzed, and the spatio-temporal distribution of particle-attached and free-living prokaryotic communities during P. globosa blooms and the relationship with main environmental factors were discussed as well. The main findings were as follows:
(1) The spatio-temporal distribution of P. globosa colonies and related environmental factors in the northern Beibu Gulf During the survey period P. globosa colony abundance ranged from 0 to 18.98 × 104 col·m-3. The colony abundance peaked in in winter months (February 2017 and January 2019). The high-colony-abundance zone was spatially different with time. It first appeared in the Weizhou Island surrounding waters (December 2016 and November 2018), then appeared in the Qinzhou - Beihai coastal waters (February 2017 and January 2019), and finally appeared in the Qiongzhou Strait - Weizhou Island waters (March 2017 and February 2019). It is indicated that temperature and salinity are main environmental factors affecting the spatio-temporal distribution of P. globosa colonies, and sufficient nitrate and phosphate facilitate the formation of P. globosa colonies in Qiongzhou Strait - Weizhou Island waters. The P. globosa colony abundance was positively correlated with other-phytoplankton abundance, and its spatio-temporal distribution was influenced by the succession of other-phytoplankton community.
(2) The spatio-temporal distribution of heterotrophic bacteria in the northern Beibu Gulf From September 2016 to August 2017, the heterotrophic bacteria abundance ranged in (2.75–56.86) × 105 cell·mL-1, with an average of (11.01 ± 6.31) × 105 cell·mL-1. There were obvious monthly variations, and the heterotrophic bacteria abundance in each season from high to low was: summer (June, August and September), winter (December, January and February), spring (March and April), and autumn (November). Heterotrophic bacteria were densely distributed in the shallow coastal water, and gradually reduced in the deep offshore water. The vertical distribution of heterotrophic bacteria was evenly distributed in the coastal areas, while the seasonal vertical heterogeneity occurred in the areas deeper than 20 m, where the bacteria abundance was higher at surface than at bottom. The spatio-temporal distribution of heterotrophic bacteria was controlled by the environmental conditions, especially the temperature, salinity, chlorophyll a, and dissolved oxygen. Correlations between inorganic nutrients and heterotrophic bacteria abundance were significantly negative in some months, when the phytoplankton indirectly affected them. In addition, the heterotrophic bacteria abundance was also closely related to the P. globosa colony abundance in the period of colony existence.
(3) Particle-attached and free-living prokaryotic community composition and structure during the Phaeocystis globosa bloom in the Beibu Gulf From December 2016 to February 2017, the dominant phyla in the northern Beibu Gulf were Proteobacteria, Cyanobacteria, Thaumarchaeota, Verrucomicrobia, Euryarchaeota, Actinobacteria, and Bacteroidetes. The composition and structure of PA and FL prokaryotic communities were significantly different. The PA fraction was more diverse and unstable temporally compared to the FL fraction. The variations in the composition and structure of the prokaryotic community were closely associated with major environmental variables, particularly DO, NH4+, PO43-, and DOC. The FL fraction was more sensitive to P. globosa than the PA fraction. Rhodobacteraceae, Alteromonadales, Porticoccaceae, Vibrio, Flavobacteriales, and Verrucomicrobiae were the key prokaryotic groups during the outbreak and recession of P. globosa blooms. They could play important roles in degrading the algal-derived organic matter.
(4) Spatial and diel variations of the prokaryotic community in the Phaeocystis globosa blooms area of Beibu Gulf During the outbreak of P. globosa blooms in January 2019, the distributions of prokaryotic communities varied significantly in the horizontal direction, while slightly in the vertical direction. Both spatial distance and environmental variables, particularly P. globosa colony abundance and Chl a, shaped the horizontal distribution of the prokaryotic community structure. The vertical heterogeneity of the prokaryotic community was disrupted by the strong vertical mixing of the water column in winter. PA prokaryotic communities showed significant diel variations, but the diel variations of FL prokaryotic communities were insignificant. Inorganic nitrogen and P. globosa colony abundance were the main environmental variables impacting the diel variations of prokaryotic communities.
In conclusion, this dissertation studied the spatio-temporal distribution of P. globosa colonies and heterotrophic bacteria, and their relationships with main environmental factors were discussed. Furthermore, the differences in the composition and structure of particle-attached and free-living prokaryotic communities during the P. globosa bloom in the Beibu Gulf were studied, and the spatial and diel variations of the prokaryotic community in the P. globosa bloom area of Beibu Gulf were revealed. The results are helpful for better understanding P. globosa blooms in Beibu Gulf, and provide fundamental data and evidence to further elucidate the initiation and termination of P. globosa blooms and to monitor and predict the occurrence of P. globosa blooms in the area, and to further reveal the ecological impact of prokaryotes during P. globosa blooms.
|MOST Discipline Catalogue||理学::海洋科学|
|Table of Contents|
|贺成. 北部湾球形棕囊藻囊体和原核生物群落时空分布特征及其环境响应[D]. 中国科学院海洋研究所. 中国科学院大学,2021.|
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