Nitrogen uptake dynamics of a persistent cyanobacterium <i>Cyanothece</i> sp. bloom in Lake St Lucia, South Africa

Plooy, Schalk J. du; Smit, A. J.; Perissinotto, Renzo; Muir, D. A.

doi:10.2989/1814232x.2014.922124

Cited by 8 publications

(2 citation statements)

References 39 publications

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“…More specifically, some taxa were more abundant in DC than in HXH at different taxonomical level. Firstly, as algal blooms related to eutrophication world-wide 14 , Cyanobacteria was characterized as the main causative organism 15 (D-C, 0.65–2.33%, D-W, 5.31–15.83%). Secondly, in our study, Synechococcaceae (D-C, 0.12–1.52%, D-W, 4.38–15.67%) appeared as the main clade of Cyanobacteria ( Fig.…”

Section: Resultsmentioning

confidence: 99%

Comparison and Interpretation of Taxonomical Structure of Bacterial Communities in Two Types of Lakes on Yun-Gui plateau of China

Han

Gong

Zhou

et al. 2016

Sci Rep

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Bacterial communities from freshwater lakes are shaped by various factors such as nutrients, pH value, temperature, etc. Their compositions and relative abundances would undergo changes to adapt the changing environments, and in turn could affect the environments of freshwater lakes. Analyses of the freshwater lake’s bacterial communities under different environments would be of pivotal importance to monitor the condition of waterbody. In this study, we have collected freshwater samples from two lakes on Yun-Gui plateau of China, Lake Dianchi and Lake Haixihai, and analyzed the bacterial community structures from these samples based on 16S rRNA sequencing. Results have shown that: Firstly, the bacterial community of these samples have very different taxonomical structures, not only between two lakes but also among the intra-groups for samples collected from Dianchi. Secondly, the differences between samples from two lakes are highly associated with the chemical-geographical properties of the two lakes. Thirdly, for samples of Dianchi and Haixihai, analytical results of physicochemical, taxonomical structure and relative abundance of community revealed that extreme physicochemical factors caused by human activities have strongly affected the bacterial ecosystem in Dianchi. These results have clearly indicated the importance of combining biological profiling and chemical-geographical properties for monitoring Chinese plateau freshwater bacterial ecosystem, which could provide clues for Chinese freshwater ecosystem remediation on plateau.

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Section: Resultsmentioning

confidence: 99%

Comparison and Interpretation of Taxonomical Structure of Bacterial Communities in Two Types of Lakes on Yun-Gui plateau of China

Han

Gong

Zhou

et al. 2016

Sci Rep

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“…Previous work by Muir & Perissinotto (2011) identified the bloom organism and provided preliminary information on the ecological drivers of the bloom. Further, du Plooy et al (2014) showed that there were no interactive effects of environmental variables on the nitrogen uptake dynamics of this Cyanothece sp. Thus, the focus of the present study is on nutrient dynamics (uptake of N and P, and N 2 fixation) over a full salinity range, with the aim of expanding on the initial research to understand better the physiological aspects of Cyanothece sp.…”

Section: Introductionmentioning

confidence: 93%

Role of salinity, nitrogen fixation and nutrient assimilation in prolonged bloom persistence of Cyanothece sp. in Lake St Lucia, South Africa

Plooy¹,

Perissinotto²,

Smit³

et al. 2015

Aquat. Microb. Ecol.

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Worldwide, cyanobacterial blooms are becoming more frequent, exacerbated by eutrophication and other anthropogenic actions and also associated with global climate change. In June 2009, a widespread bloom of the unicellular cyanobacterium Cyanothece sp. appeared in North Lake and False Bay of Lake St Lucia, a large (360 km 2 ) estuarine lake system in KwaZulu-Natal, South Africa, and persisted for 18 mo. It remains unclear how the bloom status was maintained for so long. This study investigated aspects of the nutrient (N and P) assimilation of Cyanothece sp. and how these may relate to maintaining a persistent bloom state during hypersaline conditions. The effects of salinity and nutrient limitation on the nutrient uptake dynamics of Cyanothece sp. were evaluated with 15 NO 3 − uptake, PO 4 3− uptake and 15 N 2 fixation experiments. Nitrogen fixation was observed in this Cyanothece sp. isolate from St Lucia. Highest nutrient assimilation rates in all experiments were recorded at the lowest salinities, decreasing progressively up to a salinity of 120, with very little activity observed above this level. No 15 N 2 fixation was measured above this salinity. Results indicate that Cyanothece sp. was well suited to take advantage of the conditions present during the onset of the bloom at salinities <100. However, once salinity increased above 120, nutrient uptake abilities would have been drastically reduced. Regardless, cells still survived under these extreme saline conditions, as most of their potential grazers and autotrophic competitors disappeared from the St Lucia Estuary.

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Robust photosystem I activity by Cyanothece sp. (Cyanobacteria) and its role in prolonged bloom persistence in lake St Lucia, South Africa

et al. 2018

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Worldwide, cyanobacterial blooms are becoming more frequent, exacerbated by eutrophication, anthropogenic effects, and global climate change. Environmental factors play a direct role in photosynthesis of cyanobacteria and subsequent cellular changes, growth, and bloom dynamics. This study investigated the photosynthetic functioning of a persistent bloom-forming (18 months) cyanobacterium, Cyanothece sp., isolated from Lake St Lucia, South Africa. DUAL-PAM fluorometric methods were used to observe physiological responses in Cyanothece sp. photosystems I and II. Results show that photosystem I activity was maintained under all environmental conditions tested, while photosystem II activity was not observed at all. Out of the environmental factors tested (temperature, salinity, and nitrogen presence), only temperature significantly influenced photosystem I activity. In particular, high temperature (40 °C) facilitated faster electron transport rates, while effects of salinity and nitrogen were variable. Cyanothece sp. has shown to sustain bloom status for long periods largely because of the essential role of photosystem I activity during highly dynamic and even extreme (e.g., salinities higher than 200) environmental conditions. This ensures the continual supply of cellular energy (e.g. ATP) to important processes such as nitrogen assimilation, which is essential for protein synthesis, cell growth and, therefore, bloom maintenance.

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Nitrogen uptake dynamics of a persistent cyanobacterium Cyanothece sp. bloom in Lake St Lucia, South Africa

Cited by 8 publications

References 39 publications

Comparison and Interpretation of Taxonomical Structure of Bacterial Communities in Two Types of Lakes on Yun-Gui plateau of China

Comparison and Interpretation of Taxonomical Structure of Bacterial Communities in Two Types of Lakes on Yun-Gui plateau of China

Role of salinity, nitrogen fixation and nutrient assimilation in prolonged bloom persistence of Cyanothece sp. in Lake St Lucia, South Africa

Robust photosystem I activity by Cyanothece sp. (Cyanobacteria) and its role in prolonged bloom persistence in lake St Lucia, South Africa

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