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T. W. Snell – 1st expert on this subject based on the ideXlab platform
estimating the toxicity of ambient fine aerosols using freshwater rotifer Brachionus calyciflorus rotifera monogonontaEnvironmental Pollution, 2013Co-Authors: Vishal Verma, T. W. Snell, Roberto Ricomartinez, Neel Kotra, Corey Rennolds, Rodney J WeberAbstract:
Abstract The toxicity of atmospheric fine particulate matter (PM 2.5 ) in Atlanta is assessed using freshwater rotifers ( Brachionus calyciflorus ). The PM-laden quartz filters were extracted in both water and methanol. Aerosol extracts were passed through a C-18 column to separate the PM components into hydrophobic and hydrophilic fractions. Toxicity data reported in the units of LC 50 (concentration that kills 50% of the test population in 24 h) shows that ambient particles are toxic to the rotifers with LC 50 values ranging from 5 to 400 μg of PM. The methanol extract of the aerosols was substantially more toxic (8 ± 6 times) to the rotifers compared to the water extracts. A sizeable fraction (>70%) of toxicity was found to be associated with the hydrophobic fraction of PM. However, none of the bulk aerosol species was strongly correlated with the LC 50 values suggesting a complicated mechanism of toxicity probably involving synergistic interactions of various PM components.
effects of atrazine and carbaryl on growth and reproduction of the rotifer Brachionus calyciflorus pallasJournal of Freshwater Ecology, 2012Co-Authors: Zhenghe Lu, Jiaxin Yang, Baokun Zhao, T. W. SnellAbstract:
The functioning of freshwater ecosystems can be altered if rotifers are stressed by atrazine and carbaryl. To detect reproductive responses, rotifer (Brachionus calyciflorus) populations were exposed to atrazine and carbaryl at six concentrations ranging from 0 to 5.12 mg L−1 and the 2-d population growth rate, 3-d mictic rate (MR), 7-d resting egg production (RE), and 3-d resting egg hatching rate (HR) were measured. Data showed that the no effect concentration (NOEC) and lowest effect concentration (LOEC) of atrazine and carbaryl were highest for growth rate. In sexual reproduction, the NOEC and LOEC of atrazine for MR were 0.32 and 1.28 mg L−1. However, carbaryl did not show similar results because 0.06 mg L−1 carbaryl increased the MR compared with the control. The NOEC and LOEC of atrazine for RE and HR were the same (0.08 and 0.32 mg L−1) and the NOEC and LOEC of carbaryl for RE were slightly lower. HR was the most sensitive of all indices with NOEC and LOEC of atrazine ranging from 0.02 to 0.32 mg …
Effects of Fenitrothion on Life History Parameters of the Rotifer Brachionus calyciflorusJournal of Freshwater Ecology, 2010Co-Authors: Linlan Lv, T. W. Snell, Jiaxin Yang, Sungen LiAbstract:
ABSTRACT The effects of fenitrothion on life history parameters, the production of resting eggs and hatching of resting eggs of the rotifer Brachionus calyciflorus were studied on the individual and population level. Neonates (
Yi-long Xi – 2nd expert on this subject based on the ideXlab platform
morphological differentiation of Brachionus calyciflorus caused by predation and coal ash pollutionScientific Reports, 2017Co-Authors: Xiaoxue Yang, Gen Zhang, Yi-long XiAbstract:
Different rotifer stains exhibited remarkably morphological differences which could not be eliminated under laboratory conditions. In the present study, we hypothesized that predation pressure and pollution might be two forces driving morphological differentiation of rotifer. To test this hypothesis, rotifers (Brachionus calyciflorus) belonging to two sibling species were collected from three special lakes (with coal ash pollution, high predation pressure or neither) and cultured for more than three months to investigate their potential differentiation in morphology. Twelve morphological parameters were measured and compared among three lakes at four food density (Scenedesmus obliquus). The results showed that most of the tested morphological parameters changed in response to food level and differed among three habitats. Rotifers from the habitat with high predation pressure evolved stable long posterior lateral spine and relatively small body size. Rotifers collected from the polluted habitat was of smaller body size, compared with those from ordinary habitat. Bigger eggs were laid by rotifers from polluted area or lake with high predation pressure, enabling newborns more resistant to pollution or predation, and thus ensuring the survival rate of newborns. Finally, we concluded that both predation and pollution could affect the morphological differentiation and evolution of rotifers.
Combined Effects of Temperature and the Microcystin MC-LR on the Feeding Behavior of the Rotifer Brachionus calyciflorusBulletin of Environmental Contamination and Toxicology, 2017Co-Authors: Xian-ling Xiang, Ying-ying Chen, Qiu-lei Xu, Yi-long XiAbstract:
The aim of this study was to investigate the responses in filtration and grazing rates of five rotifer strains of the species Brachionus calyciflorus under different temperatures and MC-LR concentrations. The results showed that strain identity, MC-LR concentration, temperature, and the interactions of these factors significantly affected both response variables, with the exception of the interaction of strain and MC-LR on the grazing rates. At low MC-LR concentrations and for the control group, the filtration and grazing rates increased with increasing temperature. The filtering and grazing rates of B. calyciflorus exposed to higher MC-LR concentrations, however, showed no evident enhancement with increasing of temperature. At high temperatures, the filtration and grazing rates of all rotifer strains decreased significantly with increasing concentration of MC-LR, however B. calyciflorus exhibited a refractory stability in the presence of increased MC-LR levels at lower temperatures.
Effects of Multi-metal (Cu, Zn, Cd, Cr, and Mn) Mixtures on the Reproduction of Freshwater Rotifer Brachionus calyciflorus.Bulletin of Environmental Contamination and Toxicology, 2015Co-Authors: Xiaoping Xu, Yi-long Xi, Lin Huang, Xian-ling XiangAbstract:
In the field, organisms are usually exposed to mixtures of various metals. However, the effects of multi-metal mixtures on growth and reproduction of rotifers remain unknown. In the present study, effects of multi-metal mixtures (Cu, Zn, Cd, Cr, and Mn) on reproduction of the freshwater rotifer Brachionus calyciflorus were assessed by determining various endpoints, including the ratio of ovigerous females to nonovigerous females, the ratio of mictic to amictic females, the mictic rate, the fertilization rate, the population growth rate, and the resting eggs production. The results demonstrated that reproduction of rotifers was significantly affected by all multi-metal mixtures assessed. Moreover, the ratio of mictic to amictic females was the most sensitive endpoint and might be suitable to evaluate effects of multi-metal mixtures to rotifers.
Lilan Zhang – 3rd expert on this subject based on the ideXlab platform
full life cycle toxicity assessment on triclosan using rotifer Brachionus calyciflorusEcotoxicology and Environmental Safety, 2016Co-Authors: Lilan Zhang, Yujuan WangAbstract:
Abstract Triclosan (TCS) is an antimicrobial and is an aquatic contaminant. Little is known on aquatic toxicity of TCS. Rotifers are common members of freshwater zooplankton. In this study, Brachionus calyciflorus was chosen as a test organism to assess the acute and complete life cycle toxicity of TCS in this study. The acute toxicity results showed that the 24-h median lethal concentration (LC50) of TCS was 345±0.11 μg/L (95% confidence limits of 212–564 µg/L). Reproductive bioassays demonstrated that TCS could inhibit the population growth rate at the concentration higher than 1.0 μg/L. Resting egg production encompasses the full life-cycle of rotifer, and thus its hatching rate were explored to assess the toxicity of TCS towards rotifer population at TCS concentrations ranging from 0.1 to 200 µg/L at two different growth periods. When resting eggs were exposed to TCS during the formation period, 0.1 and 1.0 µg/L of TCS increased the hatching rate from 0.402 to 0.502, and 0.475, respectively. Exposure to 100 and 200 µg/L of TCS reduced the hatching rate to 0.309 and 0.275, respectively. When the resting eggs were formed in the control medium and hatched in medium with TCS, their hatching rates were not significantly influenced by TCS, except that 200 µg/L of TCS decreased the hatching rate from 0.402 to 0.34 significantly. The effects of TCS exposure on the hatching rate during the formation period were greater than those during the resting egg hatching period.
toxicity assessment of perfluorinated carboxylic acids pfcas towards the rotifer Brachionus calyciflorusScience of The Total Environment, 2014Co-Authors: Yujuan Wang, Lilan ZhangAbstract:
Abstract The effects of acute toxicity, 3-day population growth and morphological effects of perfluorinated carboxylic acids (PFCAs) with carbon chain lengths of 2–6 on the freshwater rotifer Brachionus calyciflorus were investigated. The results indicated that the 24-h median lethal concentration (LC50) values of trifluoroacetic acid (TFA), perfluoropropionic acid (PFPrA), perfluorobutanoic acid (PFBA), perfluopentanoic acid (PFPeA), and perfluorohexanoic acid (PFHxA) towards B. calyciflorus were 70, 80, 110, 130 and 140 mg L− 1, respectively. The acute effects of PFCAs decreased with the increase of carbon chain length. The parameters used to determine 3-day population growth on these compounds were the rate of population increase (r) and mictic ratio. With the increase of fluorinated carbon-chain length, the r values of TFA, PFPrA, PFBA, PFPeA and PFHxA decreased by 0.99%, 16.8%, 16.5%, 22.4% and 32.0%, respectively. Mictic ratios ranged from 0.707 to 0.953 for PFCAs with carbon chain lengths of 2–6. In addition, the mictic ratio, body size and egg size exposed to some PFCAs were higher than those of the controls. These results offer a useful method for the ecological risk assessment of these short chain PFCAs.
evaluating the sub lethal toxicity of pfos and pfoa using rotifer Brachionus calyciflorusEnvironmental Pollution, 2013Co-Authors: Lilan Zhang, Yang Li, Yujuan WangAbstract:
Abstract The acute and chronic effects of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) on the rotifer Brachionus calyciflorus (B. calyciflorus) were investigated at the organismal and the population level. The acute toxicity of PFOS to rotifers was approximately 2.5-fold greater than that of PFOA. From 0.25 to 2.0 mg L−1, PFOS exhibited higher toxicity than PFOA on the F0-generation of B. calyciflorus, including effects on body size, juvenile periods, net reproductive rate, and generation time. Both PFOS and PFOA exposure induced a smaller egg size in B. calyciflorus, suggesting that these risks can be transferred from mother to offspring. The 28-day population growth studies showed that PFOS and PFOA reduced the population density and increased the mictic ratio. Our results demonstrated that both PFOS and PFOA had adverse effects on B. calyciflorus, not only at the individual level but also at the population level.