Environmental factors associated with a toxic bloom of Microcystis aeruginosa

2000 ◽  
Vol 57 (1) ◽  
pp. 231-240 ◽  
Author(s):  
Jean M Jacoby ◽  
Diane C Collier ◽  
Eugene B Welch ◽  
F Joan Hardy ◽  
Michele Crayton
Keyword(s):  
Environmental Factors ◽  
Microcystis Aeruginosa ◽  
Toxin Production ◽  
Water Transparency ◽  
Cyanobacterial Blooms ◽  
Zooplankton Abundance ◽  
Factors Associated ◽  
Water Column Stability ◽  
Microcystin Concentration ◽  
Toxic Bloom

Environmental factors associated with the occurrence of toxic cyanobacterial blooms and toxin production were investigated during the summers of 1994 and 1995 in Steilacoom Lake, Washington. A pronounced and prolonged toxic bloom of Microcystis aeruginosa occurred during summer 1994 but not during 1995. Lake characteristics that were associated with the toxic bloom in 1994 were higher total phosphorus, decreased water transparency, high water column stability, high surface water temperature and pH, and decreased lake flushing. Decreased water transparency during 1994 may have been due to significantly lower zooplankton abundance. We hypothesize that this decreased transparency was caused by increased planktivory by higher numbers of coho salmon (Oncorhynchus kisutch) fingerlings during 1994 and (or) inhibition of zooplankton grazing by Microcystis. The success of Microcystis over other cyanobacteria was associated with low nitrogen to phosphorus ratios and low nitrate-nitrogen with sufficient ammonium-nitrogen concentrations. Toxin production (i.e., micrograms of microcystin per gram of plankton biomass) was not constant over the duration of detectable toxicity; hence, no relationship was found between Microcystis abundance and microcystin concentration. However, microcystin concentration was positively correlated with increasing soluble reactive phosphorus concentrations between 1 and 10 µg·L-1, indicating that toxin production may have been limited by phosphorus.

Environmental factors associated with toxic cyanobacterial blooms across 20 drinking water reservoirs in a semi-arid region of Brazil

Harmful Algae ◽  
2019 ◽  
Vol 86 ◽  
pp. 128-137 ◽  
Author(s):  
Mário U.G. Barros ◽  
Alan E. Wilson ◽  
João I.R. Leitão ◽  
Silvano P. Pereira ◽  
Riley P. Buley ◽  
...  
Keyword(s):  
Drinking Water ◽  
Environmental Factors ◽  
Arid Region ◽  
Cyanobacterial Blooms ◽  
Water Reservoirs ◽  
Factors Associated ◽  
Semi Arid Region ◽  
Semi Arid

scholarly journals Analysis of Environmental Factors Associated with Cyanobacterial Dominance after River Weir Installation

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1163 ◽  
Author(s):  
Sungjin Kim ◽  
Sewoong Chung ◽  
Hyungseok Park ◽  
Youngcheol Cho ◽  
Heesuk Lee
Keyword(s):  
Environmental Factors ◽  
Field Measurements ◽  
Cyanobacterial Blooms ◽  
Low Flow ◽  
Nakdong River ◽  
Factors Associated ◽  
Parametric Data ◽  
The Nakdong River ◽  
A Minor ◽  
Cyanobacterial Dominance

Following the installation of 16 weirs in South Korea’s major rivers through the Four Rivers Project (2010–2012), the water residence time increased significantly. Accordingly, cyanobacterial blooms have occurred frequently, raising concerns regarding water use and the aquatic ecosystem health. This study analyzed the environmental factors associated with cyanobacterial dominance at four weirs on the Nakdong River through field measurements, and parametric and non-parametric data mining methods. The environmental factors related to cyanobacterial dominance were the seven-day cumulative rainfall (APRCP7), seven-day averaged flow (Q7day), water temperature (Temp), stratification strength (ΔT), electrical conductivity (EC), dissolved oxygen (DO), pH, and NO3–N, NH3–N, total nitrogen (TN), total phosphorous (TP), PO4–P, chlorophyll–a, Fe, total organic carbon (TOC), and SiO2 content, along with biological and chemical oxygen demands. The results indicate that site-specific environmental factors contributed to the cyanobacterial dominance for each weir. In general, the physical characteristics of EC, APRCP7, Q7day, Temp, and ΔT were the most important factors influencing cyanobacterial dominance. The EC was strongly associated with cyanobacterial dominance at the weirs because high EC indicated persistent low flow conditions. A minor correlation was obtained between nutrients and cyanobacterial dominance in all but one of the weirs. The results provide valuable information regarding the effective countermeasures against cyanobacterial overgrowth in rivers.

scholarly journals Importance of strain type to predict the toxicological risk associated with Microcystis aeruginosa blooms: comparison of Microtox® analysis and immunoassay

2012 ◽  
Vol 10 (2) ◽  
pp. 256-261 ◽  
Author(s):  
A. D'ors ◽  
M. C. Bartolomé ◽  
S. Sánchez-Fortún
Keyword(s):  
Microcystis Aeruginosa ◽  
Potential Risk ◽  
Cyanobacterial Blooms ◽  
Aquatic Environments ◽  
Preliminary Screening ◽  
Microcystin Concentration ◽  
Bioluminescence Assay ◽  
Strain Type ◽  
Toxicological Risk

The occurrence of toxic cyanobacterial blooms in aquatic environments, associated with human health problems and animal deaths, has increased the need for rapid, reliable and sensitive methods to determine the toxicity of microcystin produced by cyanobacteria. An in vitro Microtox® system and a commercially available microcystin ELISA were used to screen out the potential risk associated with selected Microcystis aeruginosa strains (Ma1D–Ma8D). Results showed the existence of three differentiated groups in the selected M. aeruginosa strains. Strains Ma7D and Ma6D were determined to be very toxic, strains Ma2D, Ma1D and Ma5D as moderately toxic and strains Ma8D, Ma4D and MA3D as non-toxic. These results agreed with the microcystin concentration values obtained by immunoassay. Although the data obtained by other authors clearly show that Microtox® is not sensitive to microcystins, our results suggested that this bioluminescence assay may prove useful in the preliminary screening of cyanobacterial blooms for microcystin-based toxicity. Additionally, the combination of immunodetection and toxicity-based Microtox® provides a useful addition to the methods already available for detection of cyanobacterial toxins.

scholarly journals Seasonal Occurrence of Cyanobacteria and First Detection of Microcystin-LR in Water Column of Foum-Gleita Reservoir, Mauritania

2021 ◽  
Author(s):  
Ahmed Sidi Sadegh ◽  
Zeinebou Sidoumou ◽  
Mamadou Dia ◽  
Juan Luis Gómez Pinchetti ◽  
Noureddine Bouaïcha
Keyword(s):  
Surface Water ◽  
Environmental Factors ◽  
Water Column ◽  
Microcystis Aeruginosa ◽  
Total Phosphorus ◽  
Inorganic Nitrogen ◽  
Cyanobacterial Blooms ◽  
World Health ◽  
Seasonal Occurrence ◽  
Dissolved Inorganic Nitrogen

Abstract This work was carried out to study the seasonal occurrence of cyanobacteria and their microcystin-LR in water column of Foum-Gleita reservoir (Mauritania). Limnological and biological factors were investigated at three depths (surface, -3, and -6 m) in this reservoir during a full year. Nutrients were analyzed by Spectrophotometry, phytoplankton was analyzed by Inverted Microscopy, microsystins were analyzed by High Performance Liquid Chromatography-tandem Mass Spectrometry and environmental factors relationships were analyzed by Pearson's correlation and Multiple Linear Regression. Physicochemical analyzes have shown that this reservoir is hypereutrophic with dissolved inorganic nitrogen and total phosphorus concentrations relatively high, varying from 1.39 to 6.53 and 0.21 to 0.57 mg/L, respectively. Annual surface water temperature was exceptionally high (27.8 ± 3.6°C), characterizing of a Sahelian climatic conditions. Phytoplankton analyzes have shown dominance of two toxic cyanobacteria species Microcystis aeruginosa and Dolichospermum flos-aquae during warm season (May-September). Microcystins analysis revealed presence of only most toxic variant, microcystin-LR. Microcystin-LR concentration in the surface water samples, during cyanobacterial blooms, was consistently high (5.638 µg/L), exceeding 5-times the World Health Organization drinking water limit (1 µg/L), however, it was much lower (0.83 µg / L) at depth (-6 m). Analysis of environmental factors relationships showed that the most influential factors on abundance of Microcystis aeruginosa and Dolichospermum flos-aquae and variability of microcystin-LR concentrations were total phosphorus, dissolved inorganic nitrogen, iron, temperature and pH. Finally, the study clearly demonstrated need for regular monitoring of cyanobacteria and cyanotoxins in the waters of studied reservoir.

scholarly journals Remediation Strategies to Control Toxic Cyanobacterial Blooms: Effects of Macrophyte Aqueous Extracts on Microcystis aeruginosa (Growth, Toxin Production and Oxidative Stress Response) and on Bacterial Ectoenzymatic Activities

2021 ◽  
Vol 9 (8) ◽  
pp. 1782
Author(s):  
Zakaria Tazart ◽  
Maura Manganelli ◽  
Simona Scardala ◽  
Franca Maria Buratti ◽  
Federica Nigro Di Gregorio ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stress Response ◽  
Microcystis Aeruginosa ◽  
Nutrient Recycling ◽  
Toxin Production ◽  
Oxidative Stress Response ◽  
Cyanobacterial Blooms ◽  
Negative Effects ◽  
Species Specific ◽  
And Oxidative Stress

Increasing toxic cyanobacterial blooms in freshwater demand environmentally friendly solutions to control their growth and toxicity, especially in arid countries, where most drinking water is produced from surface reservoirs. We tested the effects of macrophyte allelochemicals on Microcystis aeruginosa and on the fundamental role of bacteria in nutrient recycling. The effects of Ranunculus aquatilis aqueous extract, the most bioactive of four Moroccan macrophyte extracts, were tested in batch systems on M. aeruginosa growth, toxin production and oxidative stress response and on the ectoenzymatic activity associated with the bacterial community. M. aeruginosa density was reduced by 82.18%, and a significant increase in oxidative stress markers was evidenced in cyanobacterial cells. Microcystin concentration significantly decreased, and they were detected only intracellularly, an important aspect in managing toxic blooms. R. aquatilis extract had no negative effects on associated bacteria. These results confirm a promising use of macrophyte extracts, but they cannot be generalized. The use of the extract on other toxic strains, such as Planktothrix rubescens, Raphidiopsis raciborskii and Chrysosporum ovalisporum, caused a reduction in growth rate but not in cyanotoxin content, increasing toxicity. The need to assess species-specific cyanobacteria responses to verify the efficacy and safety of the extracts for human health and the environment is highlighted.

Mass School Shootings in the United States: A Novel Root Cause Analysis Using Lay Press Reports

2019 ◽  
Vol 58 (13) ◽  
pp. 1423-1428 ◽  
Author(s):  
Chris A. Rees ◽  
Lois K. Lee ◽  
Eric W. Fleegler ◽  
Rebekah Mannix
Keyword(s):  
United States ◽  
Environmental Factors ◽  
Root Cause Analysis ◽  
The United States ◽  
School Shootings ◽  
Contributing Factors ◽  
Mass Shootings ◽  
Cause Analysis ◽  
Factors Associated ◽  
Root Cause

School shootings comprise a small proportion of childhood deaths from firearms; however, these shootings receive a disproportionately large share of media attention. We conducted a root cause analysis of 2 recent school shootings in the United States using lay press reports. We reviewed 1760 and analyzed 282 articles from the 10 most trusted news sources. We identified 356 factors associated with the school shootings. Policy-level factors, including a paucity of adequate legislation controlling firearm purchase and ownership, were the most common contributing factors to school shootings. Mental illness was a commonly cited person-level factor, and access to firearms in the home and availability of large-capacity firearms were commonly cited environmental factors. Novel approaches, including root cause analyses using lay media, can identify factors contributing to mass shootings. The policy, person, and environmental factors associated with these school shootings should be addressed as part of a multipronged effort to prevent future mass shootings.

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