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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 156
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Book Description
Toxic cyanobacterial blooms threaten freshwaters worldwide. We have learned much about the environmental factors promoting cyanobacterial success: high growth rates in increased water temperatures, predator avoidance, an ability to store nitrogen (N) and phosphorus (P), positive buoyancy, high affinity for inorganic carbon (C) and efficiency for converting bicarbonate to carbon dioxide (CO2), and the ability of some to fix dinitrogen (N2). However, the physiological and ecological role of cyanotoxins eludes us. Furthermore, complex population dynamics of toxic and non-toxic cyanobacterial strains confounds many ecosystem-based studies. Thus, our research has focused on describing spatial and temporal cyanobacterial population dynamics and cyanotoxin production in eutrophic lakes. Our results indicate that vertical heterogeneity in lakes is important for partitioning individual cyanobacterial taxa within the photic zone on short time scales (hourly-daily). However, on the time-scales that toxic blooms occur (days-weeks), physics likely plays a larger role in distributing cyanobacterial biomass and toxins throughout the epilimnion. Similarly, horizontal heterogeneity in lakes can be extremely patchy. We observed on daily time-scales, cyanotoxins could vary by orders of magnitude in different parts of the lake. Thus, toxic blooms are not evenly distributed horizontally or vertically in lakes on short time scales, but were also not significantly different beyond several days. Conversely, cyanobacterial communities and toxin concentrations changed significantly over the course of the open water season. Intra-annual changes in temperature, lake stratification, and nutrient concentrations had a profound impact on cyanobacterial community composition and measured toxin concentrations. In particular, inorganic nitrogen drawdown during stratification resulted in large N2 fixing Aphanizomenon blooms. Shortly thereafter, Microcystis abundance and microcystin concentrations increased significantly. Aphanizomenon and Microcystis were both abundant in the fall, but toxin concentrations decreased. Three Microcystis genotypes were abundant at different times of the year, suggesting they occupy different niches. We proposed that microcystin production was caused by N stress, particularly the rapid drawdown of ammonium, and present a metabolic model for regulation of microcystin synthesis in Microcystis. Together, these results have implications for lake management, public health, and modeling toxin production in eutrophic lakes.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 156
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Book Description
Toxic cyanobacterial blooms threaten freshwaters worldwide. We have learned much about the environmental factors promoting cyanobacterial success: high growth rates in increased water temperatures, predator avoidance, an ability to store nitrogen (N) and phosphorus (P), positive buoyancy, high affinity for inorganic carbon (C) and efficiency for converting bicarbonate to carbon dioxide (CO2), and the ability of some to fix dinitrogen (N2). However, the physiological and ecological role of cyanotoxins eludes us. Furthermore, complex population dynamics of toxic and non-toxic cyanobacterial strains confounds many ecosystem-based studies. Thus, our research has focused on describing spatial and temporal cyanobacterial population dynamics and cyanotoxin production in eutrophic lakes. Our results indicate that vertical heterogeneity in lakes is important for partitioning individual cyanobacterial taxa within the photic zone on short time scales (hourly-daily). However, on the time-scales that toxic blooms occur (days-weeks), physics likely plays a larger role in distributing cyanobacterial biomass and toxins throughout the epilimnion. Similarly, horizontal heterogeneity in lakes can be extremely patchy. We observed on daily time-scales, cyanotoxins could vary by orders of magnitude in different parts of the lake. Thus, toxic blooms are not evenly distributed horizontally or vertically in lakes on short time scales, but were also not significantly different beyond several days. Conversely, cyanobacterial communities and toxin concentrations changed significantly over the course of the open water season. Intra-annual changes in temperature, lake stratification, and nutrient concentrations had a profound impact on cyanobacterial community composition and measured toxin concentrations. In particular, inorganic nitrogen drawdown during stratification resulted in large N2 fixing Aphanizomenon blooms. Shortly thereafter, Microcystis abundance and microcystin concentrations increased significantly. Aphanizomenon and Microcystis were both abundant in the fall, but toxin concentrations decreased. Three Microcystis genotypes were abundant at different times of the year, suggesting they occupy different niches. We proposed that microcystin production was caused by N stress, particularly the rapid drawdown of ammonium, and present a metabolic model for regulation of microcystin synthesis in Microcystis. Together, these results have implications for lake management, public health, and modeling toxin production in eutrophic lakes.
Author: Sara L. Caldwell Eldridge
Publisher: CreateSpace
ISBN: 9781500491277
Category : Technology & Engineering
Languages : en
Pages : 40
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Book Description
Phytoplankton blooms dominated by cyanobacteria that occur annually in hypereutrophic Upper Klamath Lake, Oregon, produce microcystins at concentrations that may contribute to the decline in populations of endangered Lost River (Deltistes luxatus) and shortnose (Chasmistes brevirostris) suckers. During 2007–09, water samples were collected from Upper Klamath Lake to determine the presence and concentrations of microcystins and cylindrospermopsins and to relate the spatial and temporal occurrences of microcystins to water quality and other environmental variables.
Author: Som Cit Si Nang
Publisher:
ISBN:
Category : Cyanobacteria
Languages : en
Pages : 216
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Book Description
[Truncated abstract] Excessive growth of cyanobacteria, commonly known as cyanobacterial blooms, appear to be increasing in magnitude and frequency worldwide, thus posing a serious threat to the safety and security of water resources. With the increasing global water stress, there is a need for effective management of cyanobacterial blooms in water bodies. So far, it has been a great challenge to mitigate and assess public health risks associated with cyanobacterial blooms due to difficulty in predicting the level of cyanobacterial biomass and microcystin concentrations in water bodies. Moreover, the effectiveness of the current bloom prevention and risk assessment strategies depend upon the understanding of the dynamics of cyanobacteria and microcystin under natural conditions. Thus, this research aims to: i) assess the variability of the relationship between cyanobacterial biomass and microcystin concentration, which is currently used to assess the risk to human and ecosystems health; ii) determine the environmental drivers of the dynamics of cyanobacterial dominance and microcystin concentration and assess site specificity of the environmental drivers; and iii) investigate how changes in the structure of phytoplankton community and cyanobacterial composition in response to nutrient concentration affect the dynamics of microcystin concentration. The results contained in this thesis revealed that the biomass-toxin relationship is a function of spatiotemporal patterns that affect cyanobacterial and microcystin dynamics. The correlation between the biomass and toxin is weak and site-specific, and large changes in total microcystin concentrations occur even at stable cyanobacterial biomass concentrations. This could pose a significant threat to the risk assessment associated with microcystin contamination in water bodies...
Author: Sharon E. Kroening
Publisher:
ISBN:
Category : Earth sciences
Languages : en
Pages : 122
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Author: Angeline R. Tillmanns
Publisher:
ISBN:
Category : University of Ottawa theses
Languages : en
Pages : 316
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Author: Anton F Post
Publisher: Frontiers Media SA
ISBN: 2889193187
Category : Microbiology
Languages : en
Pages : 128
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Book Description
The cyanobacteria inhabit every illuminated environment on Earth, from polar lakes to desert crusts and through their phototrophic metabolism play essential roles in global geochemical cycles. With the discovery of marine Synechococcus and Prochlorococcus almost 30 years ago, cyanobacteria have now earned their place as dominant primary producers contributing over 25 percent of global photosynthesis. Their global abundance is now explained from the coexistence of ecotypes that occupy different niches along spatial and temporal gradients. New ecotypes of Synechococcus have been identified as abundant components of microbial communities in freshwater environments and marginal seas. Extensive comparative genomics of marine and freshwater picocyanobacteria have begun to unmask adaptations to light and nutrient (N, P, Fe) limitation that these diverse environments present. Novel types of cyanobacterial diazotrophy input new N and structure microbial communities in the open sea. Current challenges include the understanding of the interactions between marine cyanobacteria and other microbes in their immediate community. In contrast, mesotrophic and eutrophic environments such as the Laurentian Great Lakes have been increasingly affected by nuisance and toxic cyanobacterial blooms that have yielded severe declines in water quality. Factors promoting bloom formation and the functional roles of toxins are important issues being addressed today.
Author: Sara L. Caldwell Eldridge
Publisher:
ISBN:
Category : Aphanizomenon
Languages : en
Pages : 34
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Book Description
Phytoplankton blooms dominated by cyanobacteria that occur annually in hypereutrophic Upper Klamath Lake, Oregon, produce microcystins at concentrations that may contribute to the decline in populations of endangered Lost River (Deltistes luxatus) and shortnose (Chasmistes brevirostris) suckers. During 2007-09, water samples were collected from Upper Klamath Lake to determine the presence and concentrations of microcystins and cylindrospermopsins and to relate the spatial and temporal occurrences of microcystins to water quality and other environmental variables. Samples were analyzed for intracellular (particulate) and extracellular (dissolved) microcystins and cylindrospermopsins using enzyme-linked immunosorbent assays (ELISA). Samples contained the highest and most variable concentrations of microcystins in 2009, the year in which an earlier and heavier Aphanizomenon flos-aquae-dominated phytoplankton bloom occurred. Concentrations were lowest in 2008 when the bloom was lighter, overall, and delayed by nearly 1 month. Microcystins occurred primarily in dissolved and large (> 63 [micro]m) particulate forms in all years of the study, and overall, concentrations were highest at MDT (the deepest site in the study) and HDB, although HDB was sampled only in 2007 and MDT was not sampled in 2008. Comparisons among daily median total microcystin concentrations; chlorophyll a concentrations; total, dissolved, and particulate nutrient concentrations; and nutrient ratios measured in 2009 and between 2007 and 2009 indicate that microcystin concentrations generally increase following the decline of the first A. flos-aquae-dominated bloom of each season in response to an increase in bioavailable nitrogen and phosphorus. Nitrogen fixation by A. flos-aquae early in the sample season appears to provide new nitrogen for growth of toxigenic Microcystis aeruginosa, whereas, later in the season, these species appear to co-exist. Understanding the ecological interactions between these species may be important for predicting periods of elevated cyanotoxin concentrations and has important implications for management of this lake.
Author: Luis M. Botana
Publisher: Walter de Gruyter GmbH & Co KG
ISBN: 3110625733
Category : Science
Languages : en
Pages : 669
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Book Description
The increasingly widespread production of toxins by marine and freshwater microalgae raises serious concerns regarding seafood and drinking water safety. This book compiles studies on the influence of climate change on the spreading of toxin-producing species in aquatic systems. The chemistry and biology of toxin production is revised and an outlook on control and prevention of the toxins' impact on human and animal health is given.
Author: Shinjini Pal
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Jussi Meriluoto
Publisher: John Wiley & Sons
ISBN: 1119068681
Category : Science
Languages : en
Pages : 576
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Book Description
A valuable handbook containing reviews, practical methods and standard operating procedures. A valuable and practical working handbook containing introductory and specialist content that tackles a major and growing field of environmental, microbiological and ecotoxicological monitoring and analysis Includes introductory reviews, practical analytical chapters and a comprehensive listing of almost thirty Standard Operating Procedures (SOPs) For use in the laboratory, in academic and government institutions and industrial settings Those readers will appreciate the research that validates and updates cyanotoxin monitoring and analysis plus adding to approaches for setting standard methods that can be applied worldwide. Wayne Carmichael, Analytical and Bioanalytical Chemistry (2018).
