Mechanism study on the frequent variations of cell-bound microcystins in cyanobacterial blooms in Lake Taihu: Implications for water quality monitoring and assessments (original) (raw)
Related papers
—At present, the occurrence of harmful algal bloom has become a serious environmental problem in China. A survey of the seasonal variations of algal bloom characteristics has been investigated in a shallow hypertrophic urban lake from June to October 2013 in this study. LC-MS results indicated that there are two main cyanobacteria toxins variants (MC-LR and MC-RR) during harmful algal blooms. The community structure of cyanobacteria showed that 81.04 % of total cyanobacteria biomass belongs to Microcystis spp. and the average biomass of Microcystis spp. was 2.335 mg·L-1. In addition, multivariate analyses by principal component and classifying analysis (PCCA) suggest that microcystins were mainly produced by Microcystis spp. and TP could promote MC production.
Oceanological and Hydrobiological Studies, 2010
The present study describes for the first time the toxin production by Microcystis aeruginosa blooms in three rainwater ponds in Saudi Arabia. The cell density of M. aeruginosa correlated with chlorophyll-a, temperature and nutrient concentrations. Microcystis blooms produced the hepatotoxin microcystin (MCYST) with concentrations of 0.988-3.04 mg g-1 dry weight, and a toxin profile consisting mainly of MCYST-RR, -YR and -LR. MCYSTs were also detected in pond waters at levels exceeding the WHO guideline value (11.2-34.6 μg l-1). The study suggests the monitoring of toxic cyanobacteria in such potable water sources to protect the public from potent toxins.
Sedimentation Patterns of Toxin-Producing Microcystis Morphospecies in Freshwater Reservoirs
2013
Understanding the annual cycle of Microcystis is essential for managing the blooms of this toxic cyanobacterium. The current work investigated the sedimentation of microcystin-producing Microcystis spp. in three reservoirs from Central Spain during the summer and autumn of 2006 and 2007. We confirmed remarkable settling fluxes during and after blooms ranging 10 6 -10 9 cells m −2 d −1 , which might represent 0.1%-7.6% of the organic matter settled. A comprehensive analysis of the Valmayor reservoir showed average Microcystis settling rates (0.04 d −1 ) and velocities (0.7 m d −1 ) that resembled toxin settling in the same reservoir and were above most reported elsewhere. M. aeruginosa settling rate was significantly higher than that of M. novacekii and M. flos-aquae. Despite the fact that colony sizes did not differ significantly in their average settling rates, we observed extremely high and low rates in large colonies (>5000 cells) and a greater influence of a drop in temperature on small colonies (<1000 cells). We found a 4-14 fold decrease in microcystin cell quota in settling Microcystis of the Cogotas and Valmayor reservoirs compared with pelagic populations, and the hypothetical causes of this are discussed. Our study provides novel data on Microcystis settling patterns in Mediterranean Europe and highlights the need for including morphological, chemotypical and physiological criteria to address the sedimentation of complex Microcystis populations.
Journal of the Serbian Chemical Society, 2010
ABSTRACT In spite of substantial research on health and ecological risks associated with cyanobacterial toxins in past decades, our understanding to natural dynamics and variability of toxic cyanobacterial blooms is still limited. Here we report results of the long term monitoring 1998-1999 / 2001-2008 of three reservoirs (Vír, Brno, Nové Mlýny) where toxic blooms develop annually. These three reservoirs provide a unique model, because they are interconnected by a river Svratka, which allows possible transfer of phytoplankton as well as toxins from one reservoir to another. Frequency of occurrence and dominance of the major cyanobacterial taxa Microcystis aeruginosa did not change during the investigated period but substantial variability was observed in the composition of other phytoplankton. Although absolute concentrations of studied toxins (microcystins) differed among reservoirs, there were apparent parallel trends. For example, during certain years, microcystin concentrations were systematically elevated in all three studied reservoirs. Further, concentration profiles in three sites were also correlated (parallel trends) within individual seasons based on monthly samplings. Microcystin-LR, a variant for which World Health Organization recommended a guideline value, formed only about 30-50% of total microcystins. This is of importance especially in the Vír reservoir, which serves as a drinking water supply. Maxima in the cell-bound microcystins (intracellular; expressed per dry weight biomass) generally preceded the maxima of total microcystins (expressed per volume of water sample). Overall maximum concentration in biomass (all three reservoirs, period 1993-2005) was 6.1 mg/g dry weight; median values ranged 0.065 - 2.3 mg/g dry weight. These are generally high concentrations in comparison with both Czech Republic and worldwide reported data. Our data reveal substantial variability of both toxic cyanobacteria and their peptide toxins that should be reflected by detailed monitoring programs.
Analysis of Microcystins in Cyanobacterial Blooms from Freshwater Bodies in England
Toxins, 2018
Cyanobacterial blooms in freshwater bodies in England are currently monitored reactively, with samples containing more than 20,000 cells/mL of potentially toxin-producing species by light microscopy resulting in action by the water body owner. Whilst significantly reducing the risk of microcystin exposure, there is little data describing the levels of these toxins present in cyanobacterial blooms. This study focused on the quantitative LC-MS/MS analysis of microcystins in freshwater samples, collected across England during 2016 and found to contain potentially toxin-producing cyanobacteria. More than 50% of samples contained quantifiable concentrations of microcystins, with approximately 13% exceeding the WHO medium health threshold of 20 μg/L. Toxic samples were confirmed over a nine-month period, with a clear increase in toxins during late summer, but with no apparent geographical patterns. No statistical relationships were found between total toxin concentrations and environmenta...
Microbial Ecology, 2014
The aim of this study was to understand: (1) how environmental conditions can contribute to formation of Microcystis-dominated blooms in lowland, dam reservoirs in temperate climate-with the use of quantitative molecular monitoring, and what is the role of toxic Microcystis genotypes in the bloom functioning. Monitoring of the Sulejow Reservoir in 2009 and 2010 in two sites Tresta (TR) and Bronislawow BR), which have different morphometry, showed that physicochemical conditions were always favorable for cyanobacterial bloom formation. In 2009, the average biomass of cyanobacteria reached 13 mg L −1 (TR) and 8 mg L −1 (BR), and in the second year, it decreased to approximately 1 mg L −1
Environmental Monitoring and Assessment, 2010
Mansour Eddahbi (MED) (30°55′N, 6°53′W) and Almassira (ALM) (31°95′N, 6°72′W) are two Moroccan lake reservoirs located at an arid and semi-arid hydrographic basin, respectively. Both are used for irrigation, recreational activities and drinking-water production. This paper deals with the characterization and quantification of microcystins (MC) from two Microcystis aeruginosa blooms occurring in those reservoirs. The toxicity of the blooms was confirmed and evaluated by both mouse and Artemia bioassays. The calculated LD50 values revealed that the MED bloom had a medium toxicity (LD50 = 358 mg kg − 1 body weight), whereas the ALM bloom had low toxicity (LD50 = 829 mg kg − 1 body weight). The 24-h LC50 values were 1.88 and 4.15 mg ml − 1 for the MED and ALM blooms, respectively, using Artemia assay. The identification and quantification of MC variants were carried out by high performance liquid chromatography (HPLC) equipped with a photodiode array detector, and HPLC coupled to mass spectrometry. The MC content, as Microcystin-LR (MC-LR) equivalents, was higher in the MED bloom (64.4 μg g − 1 dry weight) than in the ALM bloom (9.9 μg g − 1 dry weight). Five MC variants were identified in the MED cyanobacteria bloom (MC-RR, MC-YR, MC-LR, MC-FR, and MC-WR) and only one (MC-LR) in the ALM bloom. The results show that the occurrence of toxic cyanobacteria blooms in the studied reservoirs may be regarded as a health hazard; therefore, cyanotoxin monitoring in them is highly recommended.
2017
Dayet-Aaoua lake (DA) is a freshwater aquatic ecosystem of ecological interest, located at a middle Atlas mountains under humid hydrographic basin (Ifran, Morocco) (33° 39′ 10′′ N, 5° 02′ 30′′ W). This work deals on the toxicity assessment of Microcystis aeruginosa strain isolated from DA lake, using both Artemia bioassay and the highperformance liquid chromatography (HPLC) equipment provided with a photodiode array detector (PDA. HPLC-PDA identification and quantification of hepatotoxins cyanotoxins (Microcystins). The toxicity of the cultural Microcystis biomass evaluated by Artemia bioassay revealed a positive letal concentions (LC) (24-h LC50 = 9.01 mg mL -1 and 40-h LC50 = 6.87 mg mL -1 ). Microcystins (MC) variants selected by HPLC-PDA showed a high MC content concentration (185.56 μg g -1 Dry weight) which confirmed the toxicity assessed. Four MC variants were clearly identified in the DA biomass (MC-WR, MCRR, DM-WR, MCYR). For the first time in this natural lake, the obtaine...