scholarly journals Effects of Mixed Allelochemicals on the Growth of Microcystis aeruginosa, Microcystin Production, Extracellular Polymeric Substances, and Water Quality

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1861
Author(s):  
Ping Ouyang ◽  
Chao Wang ◽  
Peifang Wang ◽  
Xiaorong Gan ◽  
Xun Wang ◽  
...  
Keyword(s):  
Ethyl Acetate ◽  
Malonic Acid ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Extracellular Polymeric Substances ◽  
Algal Growth ◽  
Sharp Decrease ◽  
Inorganic Phosphorus ◽  
Nonanoic Acid ◽  
Control Group

The inhibition of cyanobacteria growth by allelochemicals, which controls harmful algal blooms has been examined in many studies. The objective of this work was to compare the efficiencies of different allelochemicals and determine a mixing proportion corresponding to the highest algae inhibiting activity and smallest adverse effect. The obtained results demonstrated that artemisinin, nonanoic acid, malonic acid, and ethyl acetate inhibited algal growth more efficiently than D-menthol and lactic acid. Synergies were observed in five groups of allelochemical combinations with inhibition ratios exceeding 80%, and the concentrations of extracellular microcystin-LR in the groups with high algal inhibition ratios were lower than that in the control group on the 7th day. No changes in extracellular polymeric substances compositions were detected after treatment. The permanganate indices of the treated groups were higher than that of the control group; however, this disparity gradually decreased with time. In addition, a sharp decrease in the concentration of dissolved inorganic phosphorus was observed for all treated groups. From the obtained data, the optimal proportion of mixed allelochemicals corresponding to 3.94 mg L−1 of artemisinin, 6.27 mg L−1 of nonanoic acid, 8.2 mg L−1 of malonic acid, and 6.38 mg L−1 of ethyl acetate was suggested.

scholarly journals Removal effect of algicidal modified clay on Phaeocystis globosa blooms in culturing enclosure experiments: A short communication

2021 ◽  
Vol 869 (1) ◽  
pp. 012068
Author(s):  
X Qin ◽  
X Chen ◽  
F Li ◽  
H Ya ◽  
D Zhu ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Control Group ◽  
Beibu Gulf ◽  
Blank Control Group ◽  
Phaeocystis Globosa ◽  
Marine Aquaculture ◽  
Modified Clay ◽  
The Past ◽  
Field Culture

Abstract With the increased scale of marine aquaculture in the Beibu Gulf, as well as accelerating urbanization and industrialization, frequent harmful algal blooms (HABs) have occurred in this area, especially those formed by Phaeocystis globosa in the past several years. As the P. globosa bloom has been a serious marine ecological disaster in the Beibu Gulf, research on quick and effective methods to eliminate P. globosa blooms is a hot research topic. In this study, the bacteria Streptomyces yatensis B4503 combined with modified diatomite was used to prepare algicidal modified clay, which was then used to study the removal effect on P. globosa blooms in field culture enclosures. The results showed that after 6 h of treatment with algicidal modified clay, compared with the blank control group, the cell density and chlorophyll a content of P. globosa decreased by 26.86% and 64.03%, respectively, and they decreased by 75.23% and 84.81%, respectively, after 24 h. The study indicated that algicidal modified clay can be applied to eliminate HABs caused by P. globosa in coastal water.

scholarly journals Understanding the Differences in the Growth and Toxin Production of Anatoxin-Producing Cuspidothrix issatschenkoi Cultured with Inorganic and Organic N Sources from a New Perspective: Carbon/Nitrogen Metabolic Balance

Toxins ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 724
Author(s):  
Siyi Tao ◽  
Suqin Wang ◽  
Lirong Song ◽  
Nanqin Gan
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Nitrogen Sources ◽  
Dry Weight ◽  
Toxin Production ◽  
Organic N ◽  
Control Group ◽  
Metabolic Balance ◽  
N Sources ◽  
Inorganic And Organic

Cyanotoxins are the underlying cause of the threat that globally pervasive Cyanobacteria Harmful algal blooms (CyanoHABs) pose to humans. Major attention has been focused on the cyanobacterial hepatotoxin microcystins (MCs); however, there is a dearth of studies on cyanobacterial neurotoxin anatoxins. In this study, we explored how an anatoxin-producing Cuspidothrix issatschenkoi strain responded to culture with inorganic and organic nitrogen sources in terms of growth and anatoxins production. The results of our study revealed that ʟ- alanine could greatly boost cell growth, and was associated with the highest cell productivity, while urea significantly stimulated anatoxin production with the maximum anatoxin yield reaching 25.86 μg/mg dry weight, which was 1.56-fold higher than that in the control group (BG11). To further understand whether the carbon/nitrogen balance in C. issatschenkoi would affect anatoxin production, we explored growth and toxin production in response to different carbon/nitrogen ratios (C/N). Anatoxin production was mildly promoted when the C/N ratio was within low range, and significantly inhibited when the C/N ratio was within high range, showing approximately a three-fold difference. Furthermore, the transcriptional profile revealed that anaC gene expression was significantly up-regulated over 2–24 h when the C/N ratio was increased, and was significantly down-regulated after 96 h. Overall, our results further enriched the evidence that urea can stimulate cyanotoxin production, and ʟ-alanine could boost C. issatschenkoi proliferation, thus providing information for better management of aquatic systems. Moreover, by focusing on the intracellular C/N metabolic balance, this study explained the anatoxin production dynamics in C. issatschenkoi in response to different N sources.

What Happened in 1950?

Dead Zones ◽  
2021 ◽  
pp. 52-71
Author(s):  
David L. Kirchman
Keyword(s):  
Gulf Of Mexico ◽  
Mississippi River ◽  
Organic Material ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Mark Twain ◽  
Dead Zone ◽  
Algal Growth ◽  
Fish Kills ◽  
Dead Zones

This chapter discusses what happened around 1950 that led to the expansion of dead zones. For the Gulf of Mexico, there are many reasons to think the flow of the Mississippi River has changed since the days of Mark Twain, considering the construction of so many levees, dikes, floodways, spillways, weirs, and revetments. Rain-absorbing grasslands and forests have been replaced by asphalt, roof shingles, and other hydrophobic material that hasten rainwater to the Gulf. But the flow of the Mississippi has not changed enough to explain why the Gulf dead zone grew around 1950. As the chapter discusses, what did change was nutrients. It shows that concentrations doubled in the Mississippi River from the 1930s to the 1990s, which stimulated algal growth and production of organic material that eventually led to depletion of dissolved oxygen. In addition to creating dead zones, the increase in nutrients has stimulated harmful algal blooms, leading to fish kills and beach closings.

scholarly journals Zooming in on dynamics of marine microbial communities in the phycosphere of Akashiwo sanguinea (Dinophyta) blooms

2020 ◽  
Author(s):  
Seung Won Jung ◽  
Joonsang Park ◽  
Junsoo Kang ◽  
Hyun-Jung Kim ◽  
Hyung Min Joo ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Microbial Communities ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Close Association ◽  
Time Lag ◽  
Inorganic Phosphorus ◽  
Dna Viruses ◽  
Akashiwo Sanguinea ◽  
Nucleocytoplasmic Large Dna Viruses

Abstract Background: Characterising ecological relationships between viruses, bacteria, and phytoplankton in the ocean are critical to understanding the ecosystem, yet these relationships are infrequently investigated together. To understand the dynamics of microbial communities and environmental factors in harmful algal blooms (HABs), we examined the environmental factors and microbial communities during Akashiwo sanguinea HABs in the Jangmok coastal waters of South Korea by metagenomics. Results: Specific bacterial communities showed synergistic and antagonistic relationships with A. sanguinea bloom. Endoparasitic dinoflagellate Amoebophrya sp. 1 controlled the bloom dynamics, as an increase in their abundance was correlated with HAB decline. In the nucleocytoplasmic large DNA viruses, abundance of Pandoraviridae increased following an increase in HAB. Operational taxonomic units and environmental factors associated with A. sanguinea were also visualized by network analysis: A. sanguinea-Amoebophrya sp. 1 (r=0.81, Time-lag: 2 day) and A. sanguinea-Pandoravirus dulcis (0.64, 0 day) relationships showed close association. A. sanguinea-dissolved organic carbon and -dissolved inorganic phosphorus relationships were also very closely correlated (each 0 day time-lag, respectively). Conclusions: Microbial communities and the environment dynamically and complexly changed in A. sanguinea bloom, and a rapid turnover of microorganisms could respond to ecological interactions. A. sanguinea bloom dramatically changes the environments through their exudation of dissolved carbohydrates by autotrophic processes, followed by changes in microbial communities involving host-specific viruses, bacteria, and parasitoids. Thus, microbial communities in HAB ecology are composed of various organisms and they interact in a complex way. Therefore, to interpret their ecosystem, the complex reactions among various microorganisms should be studied rather than studying a simple 1:1 reaction, such as a prey-predator interaction.

scholarly journals Adsorption Strategy for Removal of Harmful Cyanobacterial Species Microcystis aeruginosa Using Chitosan Fiber

2020 ◽  
Vol 12 (11) ◽  
pp. 4587 ◽  
Author(s):  
Yun Hwan Park ◽  
Sok Kim ◽  
Ho Seon Kim ◽  
Chulhwan Park ◽  
Yoon-E Choi
Keyword(s):  
Microcystis Aeruginosa ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Control Group ◽  
Environmental Damage ◽  
Environment And Public Health ◽  
Predominant Species ◽  
Cyanobacterial Species ◽  
Cyanobacterial Harmful Algal Blooms ◽  
Chitosan Fiber

Microcystis aeruginosa is one of the predominant species responsible for cyanobacterial-harmful algal blooms (Cyano-HABs) in water bodies. Cyano-HABs pose a growing number of serious threats to the environment and public health. Therefore, the demand for developing safe and eco-friendly solutions to control Cyano-HABs is increasing. In the present study, the adsorptive strategy using chitosan was applied to remove M. aeruginosa cells from aqueous phases. Using a simple immobilization process, chitosan could be fabricated as a fiber sorbent (chitosan fiber, CF). By application of CF, almost 89% of cyanobacterial cells were eliminated, as compared to those in the control group. Field emission scanning electron microscopy proved that the M. aeruginosa cells were mainly attached to the surface of the sorbent, which was correlated well with the measurement of the surface area of the fiber. We tested the hypothesis that massive applications of the fabricated CF to control Cyano-HABs might cause environmental damage. However, the manufactured CF displayed negligible toxicity. Moreover, we observed that the release of cyanotoxins and microcystins (MCs), during the removal process using CF, could be efficiently prevented by a firm attachment of the M. aeruginosa cells without cell lysis. Our results suggest the possibility of controlling Cyano-HABs using a fabricated CF as a non-toxic and eco-friendly agent for scaled-up applications.

scholarly journals Promotion of harmful algal blooms by zooplankton predatory activity

2006 ◽  
Vol 2 (2) ◽  
pp. 194-197 ◽  
Author(s):  
Aditee Mitra ◽  
Kevin J Flynn
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Harmful Algal Bloom ◽  
Algal Species ◽  
Algal Growth ◽  
Nutrient Stress ◽  
Nutrient Ratios ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Hab Species

The relationship between algae and their zooplanktonic predators typically involves consumption of nutrients by algae, grazing of the algae by zooplankton which in turn enhances predator biomass, controls algal growth and regenerates nutrients. Eutrophication raises nutrient levels, but does not simply increase normal predator–prey activity; rather, harmful algal bloom (HAB) events develop often with serious ecological and aesthetic implications. Generally, HAB species are outwardly poor competitors for nutrients, while their development of grazing deterrents during nutrient stress ostensibly occurs too late, after the nutrients have largely been consumed already by fast-growing non-HAB species. A new mechanism is presented to explain HAB dynamics under these circumstances. Using a multi-nutrient predator–prey model, it is demonstrated that these blooms can develop through the self-propagating failure of normal predator–prey activity, resulting in the transfer of nutrients into HAB growth at the expense of competing algal species. Rate limitation of this transfer provides a continual level of nutrient stress that results in HAB species exhibiting grazing deterrents protecting them from top-down control. This process is self-stabilizing as long as nutrient demand exceeds supply, maintaining the unpalatable status of HABs; such events are most likely under eutrophic conditions with skewed nutrient ratios.

scholarly journals Distribution of Harmful Algal Growth-Limiting Bacteria on Artificially Introduced Ulva and Natural Macroalgal Beds

2020 ◽  
Vol 10 (16) ◽  
pp. 5658
Author(s):  
Nobuharu Inaba ◽  
Isamu Kodama ◽  
Satoshi Nagai ◽  
Tomotaka Shiraishi ◽  
Kohei Matsuno ◽  
...  
Keyword(s):  
Biological Control ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Algal Growth ◽  
Macroalgal Species ◽  
Chattonella Antiqua ◽  
Cultured Fish ◽  
Wet Weight ◽  
Artificial Introduction ◽  
Hab Species

The intensity and frequency of harmful algal blooms (HABs) have increased, posing a threat to human seafood resources due to massive kills of cultured fish and toxin contamination of bivalves. In recent years, bacteria that inhibit the growth of HAB species were found to be densely populated on the biofilms of some macroalgal species, indicating the possible biological control of HABs by the artificial introduction of macroalgal beds. In this study, an artificially created Ulva pertusa bed using mobile floating cages and a natural macroalgal bed were studied to elucidate the distribution of algal growth-limiting bacteria (GLB). The density of GLB affecting fish-killing raphidophyte Chattonella antiqua, and two harmful dinoflagellates, were detected between 106 and 107 CFU g−1 wet weight on the biofilm of artificially introduced U. pertusa and 10 to 102 CFU mL−1 from adjacent seawater; however, GLB found from natural macroalgal species targeted all tested HAB species (five species), ranging between 105 and 106 CFU g−1 wet weight in density. These findings provide new ecological insights of GLB at macroalgal beds, and concurrently demonstrate the possible biological control of HABs by artificially introduced Ulva beds.

scholarly journals Effects of Modified Clay on Phaeocystis globosa Growth and Colony Formation

2021 ◽  
Vol 18 (19) ◽  
pp. 10163
Author(s):  
Xiangzheng Ren ◽  
Zhiming Yu ◽  
Lixia Qiu ◽  
Xihua Cao ◽  
Xiuxian Song
Keyword(s):  
Colony Formation ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Cell Damage ◽  
Extracellular Polysaccharide ◽  
Inorganic Phosphorus ◽  
Colony Development ◽  
Stress Concentrations ◽  
Phaeocystis Globosa ◽  
Modified Clay

Phaeocystis globosa is a globally distributed harmful algal blooms (HABs) species dominated by the colonial morphotype, which presents dramatic environmental hazards and poses a threat to human health. Modified clay (MC) can effectively flocculate HAB organisms and prevent their subsequent growth, but the effects of MC on colony-dominated P. globosa blooms remain uncertain. In this paper, a series of removal and incubation experiments were conducted to investigate the growth, colony formation and colony development of P. globosa cells after treatment with MC. The results show that the density of colonies was higher at MC concentrations below 0.2 g/L compared to those in the control, indicating the role of P. globosa colonies in resistance to environmental stress. Concentrations of MC greater than 0.2 g/L could reduce the density of solitary cells and colonies, and the colony diameter and extracellular polysaccharide (EPS) content were also decreased. The adsorption of MC to dissolved inorganic phosphorus (DIP) and the cell damage caused by collision may be the main mechanisms underlying this phenomenon. These results elucidate that the treatment with an appropriate concentration of MC may provide an effective mitigation strategy for P. globosa blooms by preventing their growth and colony formation.

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