Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Blooms

  • Microcysti bloom
  • algal bloom
  • cyanobacterial bloom
  • full bloom
  • harmful algal bloom
  • phytoplankton bloom
  • spring bloom
  • spring phytoplankton bloom
  • water bloom

  • Terms modified by Blooms

  • bloom development
  • bloom dynamics
  • bloom event
  • bloom formation

  • Selected Abstracts


    EVOLUTION, Issue 12 2009
    Joe Felsenstein
    No abstract is available for this article. [source]


    JOURNAL OF PHYCOLOGY, Issue 3 2007
    Delphine Latour
    Analysis of a sediment core taken from the Grangent reservoir in 2004 showed the presence of high concentrations of Microcystis aeruginosa Kütz. colonies at the sediment surface (250 colonies,·,mL sediment,1) and also at depths of 25,35 cm (2300 colonies·mL sediment,1) and 70 cm (600 colonies,·,mL sediment,1). Measurements of radioactive isotopes (7Be, 137Cs, and 241Am) along with photographic analysis of the core were used to date the deep layers: the layer located at ,30 cm dates from summer 2003, and that located at ,70 cm from 1990 to 1991. The physiological and morphological conditions of those benthic colonies were compared with those of planktonic colonies using several techniques (environmental scanning electron microscopy [ESEM], TEM, DNA markers, cellular esterases, and toxins). The ESEM observations showed that, as these colonies age, peripheral cells disappear, with no cells remaining in the mucilage of the deepest colonies (70 cm), an indication of the survival thresholds of these organisms. In the benthic phase, the physiological conditions (enzyme activity, cell division, and intracellular toxins) and ultrastructure (particularly the gas vesicles) of the cells surviving in the heart of the colony are comparable to those of the planktonic form, with all the potential needed for growth. Maintaining cellular integrity requires a process that can provide sufficient energy and is expressed in the reduced, but still existing, enzymatic activity that we measured, which is equivalent to a quiescent state. [source]


    JOURNAL OF PHYCOLOGY, Issue 5 2006
    William G. Sunda
    Harmful algal blooms (HABs) have occurred with increasing frequency in recent years with eutrophication and other anthropogenic alterations of coastal ecosystems. Many of these blooms severely alter or degrade ecosystem function, and are referred to here as ecosystem disruptive algal blooms (EDABs). These blooms are often caused by toxic or unpalatable species that decrease grazing rates by planktonic and benthic herbivores, and thereby disrupt the transfer of nutrients and energy to higher trophic levels, and decrease nutrient recycling. Many factors, such as nutrient availability and herbivore grazing have been proposed to separately influence EDAB dynamics, but interactions among these factors have rarely been considered. Here we discuss positive feedback interactions among nutrient availability, herbivore grazing, and nutrient regeneration, which have the potential to substantially influence the dynamics of EDAB events. The positive feedbacks result from a reduction of grazing rates on EDAB species caused by toxicity or unpalatability of these algae, which promotes the proliferation of the EDAB species. The decreased rates also lower grazer-mediated recycling of nutrients and thereby decrease nutrient availability. Since many EDAB species are well-adapted to nutrient-stressed environments and many exhibit increased toxin production and toxicity under nutrient limitation, positive feedbacks are established which can greatly increase the rate of bloom development and the adverse effects on the ecosystem. An understanding of how these feedbacks interact with other regulating factors, such as benthic/pelagic nutrient coupling, physical forcing, and life cycles of EDAB species provides a substantial future challenge. [source]


    JOURNAL OF PHYCOLOGY, Issue 6 2002
    Karen A. Phillips
    Many shallow lakes in north temperate zones experience reduced dissolved oxygen concentration under ice. However, some shallow lakes display supersaturated dissolved oxygen concentrations (>20 mg·L,1) in late winter under conditions of maximum ice thickness. During the winters of 1996, 1997, and 1999, we collected phytoplankton samples from Arrowwood Lake near Pingree, North Dakota to determine whether a specific alga was involved in dissolved oxygen supersaturation in this lake. Although dissolved oxygen supersaturation was not observed during this period, we did observe an increase in dissolved oxygen concentration that was associated with a phytoplankton bloom during late February and early March in both 1996 and 1997. In 1996, the bloom was composed of the dinoflagellate, Peridinium aciculiferum (Lemm.) Lemm. and several species of cryptomonads. A similar bloom of P. aciculiferum was followed by a bloom of several species of euglenoids in 1997. In contrast, P. aciculiferum was only a minor component of the winter phytoplankton, dissolved oxygen concentrations remained low, and no bloom event was observed in 1999. Statistical analyses indicated a significant relationship (rs = 0.57, P = 0.019) between dissolved oxygen levels and the density of the dinoflagellate, P. aciculiferum, but no significant relationship between dissolved oxygen levels and densities of other phytoplankton. These results suggest that the elevated levels of dissolved oxygen are associated with the dinoflagellate, P. aciculiferum. This bloom was most likely the result of an excystment event rather than a general growth response. [source]


    JOURNAL OF PHYCOLOGY, Issue 4 2001
    Karen J. McGlathery
    First page of article [source]


    T.A. Nelson
    Blooms of green macroalgae can devastate important finfish and shellfish habitats. Ulvaria obscura, a relatively unstudied green alga, is a major contributor to these blooms in the San Juan Islands, Washington State, USA. The biomass and productivity of this and other ulvoid algae were measured seasonally for two years. Experiments comparing the growth rates, responses to desiccation, photoacclimation, and grazer preference of U. obscura and Ulva fenestrata were conducted. Ulvaria blooms tended to occur in the subtidal while Ulva blooms were often intertidal. Both genera bloomed between late June and September. Despite their superficial similarity, Ulvaria and Ulva display markedly different physiological and ecological responses. Ulva was capable of faster growth, had higher rates of photosynthesis, and was more desiccation tolerant than Ulvaria. Ulvaria, however, appears to be more resistant to grazing than Ulva. [source]

    MRI tumor characterization using Gd-GlyMe-DOTA-perfluorooctyl-mannose-conjugate (Gadofluorine MÔ), a protein-avid contrast agent

    Hans-Jürgen Raatschen
    Abstract The rationale and objectives were to define the MRI tumor-characterizing potential of a new protein-avid contrast agent, Gd-GlyMe-DOTA-perfluorooctyl-mannose-conjugate (Gadofluorine MÔ; Schering AG, Berlin, Germany) in a chemically induced tumor model of varying malignancy. Because of the tendency for this agent to form large micelles in water and to bind strongly to hydrophobic sites on proteins, it was hypothesized that patterns of dynamic tumor enhancement could be used to differentiate benign from malignant lesions, to grade the severity of malignancies and to define areas of tumor necrosis. Gadofluorine M, 0.05,mmol,Gd,kg,1, was administered intravenously to 28 anesthetized rats that had developed over 10 months mammary tumors of varying degrees of malignancy as a consequence of intraperitoneal administration of N -ethyl- N -nitrosourea (ENU), 45,250,mg,kg,1. These tumors ranged histologically from benign fibroadenomas to highly undifferentiated adenocarcinomas. Dynamic enhancement data were analyzed kinetically using a two-compartment tumor model to generate estimates of fractional plasma volume (fPV), apparent fractional extracellular volume (fEV*) and an endothelial transfer coefficient (KPS) for this contrast agent. Tumors were examined microscopically for tumor type, degree of malignancy (Scarff,Bloom,Richardson score) and location of necrosis. Eighteen tumor-bearing rats were successfully imaged. MRI data showed an immediate strong and gradually increasing tumor enhancement. KPS and fEV*, but not fPV obtained from tumors correlated significantly (p,<,0.05) with the SBR tumor grade, r,=,0.65 and 0.56, respectively. Estimates for KPS and fEV* but not fPV were significantly lower in a group consisting of benign and low-grade malignant tumors compared with the group of less-differentiated high-grade tumors (1.61,±,0.64 vs 3.37,±,1.49, p,<,0.01; 0.45,±,0.17 vs 0.78,±,0.24, p,<,0.01; and 0.076,±,0.048 vs 0.121,±,0.088, p,=,0.24, respectively). It is concluded that the protein-avid MRI contrast agent Gadofluorine M enhances tumors of varying malignancy depending on the tumor grade, higher contrast agent accumulation for more malignant lesions. The results show potential utility for differentiating benign and low-grade malignant lesions from high-grade cancers. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Temporal Coherence of Chlorophyll a during a Spring Phytoplankton Bloom in Xiangxi Bay of Three-Gorges Reservoir, China

    Yao-Yang Xu
    Abstract Algal bloom phenomenon was defined as "the rapid growth of one or more phytoplankton species which leads to a rapid increase in the biomass of phytoplankton", yet most estimates of temporal coherence are based on yearly or monthly sampling frequencies and little is known of how synchrony varies among phytoplankton or of the causes of temporal coherence during spring algal bloom. In this study, data of chlorophyll a and related environmental parameters were weekly gathered at 15 sampling sites in Xiangxi Bay of Three-Gorges Reservoir (TGR, China) to evaluate patterns of temporal coherence for phytoplankton during spring bloom and test if spatial heterogeneity of nutrient and inorganic suspended particles within a single ecosystem influences synchrony of spring phytoplankton dynamics. There is a clear spatial and temporal variation in chlorophyll a across Xiangxi Bay. The degree of temporal coherence for chlorophyll a between pairs of sites located in Xiangxi Bay ranged from ,0.367 to 0.952 with mean and median values of 0.349 and 0.321, respectively. Low levels of temporal coherence were often detected among the three stretches of the bay (Down reach, middle reach and upper reach), while high levels of temporal coherence were often found within the same reach of the bay. The relative difference of DIN between pair sites was the strong predictor of temporal coherence for chlorophyll a in down and middle reach of the bay, while the relative difference in Anorganic Suspended Solids was the important factor regulating temporal coherence in middle and upper reach. Contrary to many studies, these results illustrate that, in a small geographic area (a single reservoir bay of approximately 25 km), spatial heterogeneity influence synchrony of phytoplankton dynamics during spring bloom and local processes may override the effects of regional processes or dispersal. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Physicochemical and Sensory Characteristics of Fish Gelatin

    S.-S. Choi
    ABSTRACT: The physicochemical differences between pork and fish gelatin and the effect of melting point on the sensory characteristics of a gelatin-water gel were investigated. Gelatin gel strength (measured as Bloom) and melting point of gelatin gels were measured, and quantitative descriptive analysis sensory tests were performed. The dependence of the gelatin gel strength and the melting point of fish gels on gel concentration, maturation time, maturation temperature, pH, and the influence of NaCl and sucrose were similar to those for pork gelatin. The flavored fish gelatin dessert gel product had less undesirable off-flavor and off-odor and a more desirable release of flavor and aroma than the same product made with an equal Bloom, but higher melting point, pork gelatin. [source]

    Bloom Where You Are Planted

    Nancy K. Lowe Editor
    No abstract is available for this article. [source]

    Prognostic value of combined analysis of cyclin D1 and estrogen receptor status in breast cancer patients

    Tae Sook Hwang
    The amplification of cyclin D1, located on chromosome 11q13, in breast cancer patients has been found to be associated with reduced relapse-free and overall survival; however, there still exists strong controversy about these findings. In order to evaluate the prognostic value of cyclin D1 and other prognostic variables in human breast cancers, we have assessed estrogen receptor (ER) status, cyclin D1, c-erbB2 and p53 overexpression in 175 primary breast carcinomas, and investigated the relationships of prognostic variables to the patient clinical outcome and the association between cyclin D1 overexpression and other prognostic variables. There was some degree of variability in staining intensities and proportions within the same tumor. The overexpression of both cyclin D1 and ER revealed a significantly prolonged survival in univariate analysis (P = 0.020). Among the various prognostic variables, distant metastasis showed a statistically significant association with overall survival. A significant correlation was observed between cyclin D1 overexpression and small size of the primary tumor (P = 0.031), low Bloom and Richardson's histological grade (P = 0.001), and positive ER status (P = 0.000). In contrast to what was previously expected, the present study suggests that the overexpression of cyclin D1 has a tendency to have a positive clinical outcome and a potential role in identifying a subset of patients predicting a good prognosis, particularly when ER is coexpressed. [source]

    Jewish mysticism and magic: an anthropological perspective , By Maureen Bloom

    Gideon Bohak

    Mediating Generation: the mother,daughter plot

    ART HISTORY, Issue 1 2002
    Lisa Tickner
    Virginia Woolf famously claimed that: ,We think back through our mothers if we are women, and yet feminine creativity required the murder of the Angel in the House. Woolf and her sister Vanessa Bell could square this circle by drawing on Julia Margaret Cameron's photographs of their mother , her niece and namesake , as a way of memorializing her while staking a claim to a specifically matrilineal artistic heritage. For Harold Bloom, on the other hand, generation is a matter of oedipal rivalry and ,creative misreading,. The ,anxiety of influence,, successfully negotiated, ensures the fertility of a vigorous, patrilineal genealogy. While it is much too tidy to propose a different genealogy for feminine creativity (women mis-read their fathers and struggle with their brothers too), it is important to note that women artists have grown up for the first time in the twentieth century in a landscape of actual as well as elective artist , mothers, and that this is in itself ,generative, and has contributed to their ability to produce new forms of public and monumental art. This paper explores the relevance of Woolf's and Bloom's arguments, among others, to an understanding of the patterns of inheritance and affiliation productive for women artists, with particular reference to the work of Rachel Whiteread. [source]

    147 Controlling Harmful Algal Blooms Through Clay Flocculation

    M. R. Sengco
    The potential use of clays to control harmful algal blooms (HABs) has been explored in East Asia, Australia, the United States, and Sweden. In Japan and South Korea, minerals such as montmorillonite, kaolinite, and yellow loess, have already been used in the field effectively, to protect fish mariculture from Cochlodinium spp. and other blooms. Cell removal occurs through the flocculation of algal and mineral particles, leading to the formation of larger aggregates (i.e. marine snow), which rapidly settle and further entrain cells during their descent. In the U.S., several clays and clay-rich sediments have shown high removal abilities (e.g. >80% cell removal efficiency) against Karenia brevis, Heterosigma akashiwo, Pfiesteria piscicida and Aureococcus anophagefferens. In some cases, the removal ability of certain clays was further enhanced with chemical flocculants, such as polyaluminum chloride (PAC), to increase their adhesiveness. However, cell removal was also affected by bloom concentration, salinity, and mixing. Cell mortality was observed after clay addition, and increased with increasing clay concentration, and prolonged exposure to clays in the settled layer. Mesocosm, field enclosure, and flume experiments were also conducted to address cell removal with increasing scale and flow, water-column impacts, and the possible benthic effects from clay addition. Results from these studies will be presented, especially those in regards to water quality, seawater chemistry, bottom erodibility and faunal impacts in the benthos. At this time, clay dispersal continues to be a promising method for controlling HABs and mitigating their impacts based on existing information and experimental data. [source]


    T.A. Nelson
    Blooms of green macroalgae can devastate important finfish and shellfish habitats. Ulvaria obscura, a relatively unstudied green alga, is a major contributor to these blooms in the San Juan Islands, Washington State, USA. The biomass and productivity of this and other ulvoid algae were measured seasonally for two years. Experiments comparing the growth rates, responses to desiccation, photoacclimation, and grazer preference of U. obscura and Ulva fenestrata were conducted. Ulvaria blooms tended to occur in the subtidal while Ulva blooms were often intertidal. Both genera bloomed between late June and September. Despite their superficial similarity, Ulvaria and Ulva display markedly different physiological and ecological responses. Ulva was capable of faster growth, had higher rates of photosynthesis, and was more desiccation tolerant than Ulvaria. Ulvaria, however, appears to be more resistant to grazing than Ulva. [source]

    The recently established diatom Coscinodiscus wailesii (Coscinodiscales, Bacillariophyta) in Brazilian waters.

    I: Remarks on morphology, distribution
    SUMMARY Coscinodiscus wailesii Gran et Angst is a large centric diatom (280,500 ,m diameter) from marine phytoplankton, characterized by a cylindrical frustule with flat valvar surface, two marginal rings of rimoportulae on the mantle, and two macrorimoportulae. Cells from cultured and natural populations collected in Paranaguá Bay, Paraná, southern Brazil were observed under light and scanning electron microscopes to verify the populations' correct identity and morphology. In both populations, a typical central rosette or a hyaline area was found in the valvar center. The species' distribution in Brazilian waters was revised, and a discussion on possible vectors of transport was made. Blooms of the species occur sporadically in the coast of Paraná, seeming to affect the local trophic chain. [source]

    Strategic Plots and Spatial Blooms

    Neil Spiller
    Abstract Stifled by ,architect's block'? Reached an insurmountable creative impasse? Neil Spiller directs us back to that old stalwart the drawing; and in so doing introduces the inspiring output of Perry Kulper, ,the Michigan Magus', which ,provokes the mind into tangents, to ambitions and delightful juxtapositions not only of forms but also of ideas'. Copyright © 2010 John Wiley & Sons, Ltd. [source]

    Contrasting microcystin production and cyanobacterial population dynamics in two Planktothrix -dominated freshwater lakes

    Ingmar Janse
    Summary Microcystin concentrations in two Dutch lakes with an important Planktothrix component were related to the dynamics of cyanobacterial genotypes and biovolumes. Genotype composition was analysed by using denaturing gradient gel electrophoresis (DGGE) profiling of the intergenic transcribed spacer region of the rrn operon (rRNA-ITS), and biovolumes were measured by using microscopy. In Lake Tjeukemeer, microcystins were present throughout summer (maximum concentration 30 µg l,1) while cyanobacterial diversity was low and very constant. The dominant phototroph was Planktothrix agardhii. In contrast, Lake Klinckenberg showed a high microcystin peak (up to 140 µg l,1) of short duration. In this lake, cyanobacterial diversity was higher and very dynamic with apparent genotype successions. Several genotypes derived from DGGE field profiles matched with genotypes from cultures isolated from field samples. The microcystin peak measured in Lake Klinckenberg could be confidently linked to a bloom of Planktothrix rubescens, as microscopic and genotypic analysis showed identity of bloom samples and a toxin-producing P. rubescens culture. Toxin-producing genotypes were detected in the microbial community before they reached densities at which they were detected by using microscopy. Cyanobacterial biovolumes provided additional insights in bloom dynamics. In both lakes, the microcystin content per cell was highest at the onset of the blooms. Our results suggest that while genotypic characterization of a lake can be valuable for detection of toxic organisms, for some lakes a monitoring of algal biomass has sufficient predictive value for an assessment of toxin production. [source]

    Phenotypic and genotypic characterization of encapsulated Escherichia coli isolated from blooms in two Australian lakes

    Michelle L. Power
    Summary Escherichia coli has long been used as an indicator organism for water quality assessment. Recently there has been an accumulation of evidence that suggests some strains of this organism are able to proliferate in the environment, a characteristic that would detract from its utility as an indicator of faecal pollution. Phenotypic and genotypic characterization of E. coli isolated from blooms in two Australian lakes, separated by a distance of approximately 200 km, identified that the blooms were dominated by three E. coli strains. A major phenotypic similarity among the three bloom strains was the presence of a group 1 capsule. Genetic characterization of a conserved region of the cps gene cluster, which encodes group 1 capsules, identified a high degree of genetic variation within the bloom isolates. This differs from previously described encapsulated E. coli strains which are highly conserved at the cps locus. The phenotypic or genotypic profiles of the bloom strains were not identified in 435 E. coli strains isolated from vertebrates. The occurrence of these encapsulated strains suggests that some E. coli have evolved a free-living lifestyle and do not require a host in order to proliferate. The presence of the same three strains in bloom events in different geographical regions of a temperate climate, and at different times, indicates that free-living E. coli strains are able to persist in these water reservoirs. This study provides further evidence of circumstances where caution is required in using E. coli as an indicator organism for water quality. [source]

    Linking the composition of bacterioplankton to rapid turnover of dissolved dimethylsulphoniopropionate in an algal bloom in the North Sea

    Mikhail V. Zubkov
    The algal osmolyte, dimethylsulphoniopropionate (DMSP), is abundant in the surface oceans and is the major precursor of dimethyl sulphide (DMS), a gas involved in global climate regulation. Here, we report results from an in situ Lagrangian study that suggests a link between the microbially driven fluxes of dissolved DMSP (DMSPd) and specific members of the bacterioplankton community in a North Sea coccolithophore bloom. The bacterial population in the bloom was dominated by a single species related to the genus Roseobacter, which accounted for 24% of the bacterioplankton numbers and up to 50% of the biomass. The abundance of the Roseobacter cells showed significant paired correlation with DMSPd consumption and bacterioplankton production, whereas abundances of other bacteria did not. Consumed DMSPd (28 nM day,1) contributed 95% of the sulphur and up to 15% of the carbon demand of the total bacterial populations, suggesting the importance of DMSP as a substrate for the Roseobacter -dominated bacterioplankton. In dominating DMSPd flux, the Roseobacter species may exert a major control on DMS production. DMSPd turnover rate was 10 times that of DMS (2.7 nM day,1), indicating that DMSPd was probably the major source of DMS, but that most of the DMSPd was metabolized without DMS production. Our study suggests that single species of bacterioplankton may at times be important in metabolizing DMSP and regulating the generation of DMS in the sea. [source]

    A new morphospecies of Microcystis sp. forming bloom in the Cheffia dam (Algeria): Seasonal variation of microcystin concentrations in raw water and their removal in a full-scale treatment plant

    Hichčm Nasri
    Abstract Toxic cyanobacterial blooms are an increasing problem in Algeria. The production of cyanotoxins (microcystins) and their presence in drinking water represent growing hazards to human health. In this study, seasonal variations in the concentrations of total microcystins and physicochemical parameters (pH, temperature, dissolved oxygen, nitrate, orthophosphate, and chlorophyll- a) were analyzed in the Cheffia dam (Algeria), mainly used to supply drinking water. The removal of cyanobacterial cells and microcystins was also evaluated in full-scale plant associated with the Cheffia reservoir. The levels of microcystins (MCYSTs) in both raw and drinking water were evaluated using the protein phosphatase type 2A (PP2A) inhibition test as MCYST-LR equivalents. Identification of microcystin variants was achieved by LC/MS/MS. During the period of study (March,December 2004), microscopic observation showed the dominance in the autumn months (September,November) of a new morphospecies of Microcystis sp. The MCYST-LR equivalent concentrations in raw water varied between 50.8 and 28,886 ng L,1. The highest level of toxins was observed in October 2004 and was significantly correlated with the chlorophyll- a. Three variants of microcystins assigned as microcystin-YR (MCYST-YR), microcystin-LR (MCYST-LR), and 6Z -Adda stereoisomer of MCYST-LR were observed in the crude extract of the Microcystis sp. bloom sample. During the bloom period, total elimination of Microcystis sp. and toxins were achieved through a classical treatment plant comprised of coagulation and flocculation, powdered activated carbon at 15 mg L,1, slow sand filtration and chlorination before storage. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 347,356, 2007. [source]

    Genetic diversity of the toxic cyanobacterium Microcystis in Lake Mikata

    Mitsuhiro Yoshida
    Abstract The aim of the present study was to clarify the bloom dynamics and community composition of hepatotoxin microcystin-producing and non-microcystin-producing Microcystis genotypes in the environment. In Lake Mikata (Fukui, Japan) from April 2003 to January 2004, seasonal variation in the number of cells with microcystin (mcy) genotypes and the genetic diversity of the total population were investigated using quantitative competitive PCR and a 16S rDNA clone library, respectively. Using competitive PCR, cells with mcyA genotypes were quantified in August and October, and the ratio of the number of these mcyA genotypes to colony-forming Microcystis cells was 0.37 and 2.37, respectively. The 16S rDNA clones obtained could be divided into 12 ribotypes: a,l. Sixty-one Microcystis strains isolated from Lake Mikata during the sampling period were subjected to toxicity tests using HPLC and ELISA, PCR-based detection of the mcyA gene, and sequence analysis of the 16S rDNA. All isolates could be differentiated into 11 ribotypes (a, b, d, f, h, i, and m,q). Ribotypes b, f, i, m, n, and p had at least one strain that was a microcystin producer. In natural communities ribotypes b and f accounted for 85% of the 16S rDNA clones in August, and ribotypes b and i accounted for 24% of the clones in October. Thus, in some bloom stages the presence of microcystin genotypes identified using the 16S rDNA clone library correlated with that of mcy genotypes determined using competitive PCR. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 229,234, 2005. [source]

    Anatoxin-a toxin in the cyanobacterium Planktothrix rubescens from a fishing pond in northern Italy

    Emanuela Viaggiu
    Abstract A heavy algal bloom occurring in a fishing pond in northern Italy full of Salmo trutta was examined for algae taxonomy and toxic production. The dominant algal species (98%) was identified as the cyanobacterium Planktothrix rubescens (D.C. ex GOMONT) Komarek Anagnostidis, based on morphological examination, and it was revealed to be toxic in mouse and Vibrio fischeri bioassays. The toxin was identified as anatoxin-a using high-performance liquid chromatography and confirmed using liquid chromatography,mass spectrometry (LC-MS). The mouse bioassay gave signs of poisoning, as previously reported for anatoxin-a. The LC-MS confirmed the presence of an anatoxin-a peak at m/z 166 (M+H+). The content of toxin in the field population was estimated at 12.13 ,g/g of fresh cells. The bloom was sustained by the very high N/P ratio in the water. This is the first report in Italy of an anatoxin-a-producing Planktothrix rubescens population. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 191,197, 2004. [source]

    Nodularin uptake by seafood during a cyanobacterial bloom

    P. G. Van Buynder
    Abstract The problem of blue-green algal toxin contamination of recreational waters and drinking water catchments is well described, as is the potential contamination of associated seafood. Algal contamination of Victorian waterways is now a widespread annual occurrence and, in some regions, the intersection of blooms and commercial fishing threatens the food safety of large numbers of people. Toxin levels which produce no observed adverse effect in animal studies were used to derive safe tolerable daily intake levels. These ,acceptable levels' were then modified to protect against potential acute health risks associated with short-term exposures. National food surveys were used to derive likely seafood intakes and thus, in combination with ,safe toxin levels', health alert levels for seafood were formulated. During the summer of 2001 a bloom of Nodularia spumigena occurred in the Gippsland Lakes area of Southern Victoria. During the bloom, seafood samples were collected and nodularin concentrations were estimated. Nodularin concentrations reached levels of concern in mussels and in prawn viscera at cell counts as low as 30,000 cells/ml. Nodularin concentrations in the flesh of finfish remained low. Boiling the seafood redistributed toxin between viscera and flesh. The results were used to restrict some seafood harvesting. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 468,471, 2001 [source]

    Effects of dietary N -acetylcysteine on the oxidative stress induced in tilapia (Oreochromis Niloticus) exposed to a microcystin-producing cyanobacterial water bloom,

    María Puerto
    Abstract Fish can be exposed to toxic cyanobacterial cells in natural waters and fish farms and suffer from oxidative damage. The present study investigates the effects of N-acetylcysteine (NAC), a glutathione (GSH) precursor, on the oxidative stress induced by Microcystis cyanobacterial cells containing microcystins (MCs) in tilapia fish (Oreochromis niloticus). Variation in lipid peroxidation (LPO) levels, carbonyl group content, reduced glutathione to oxidized glutathione ratio (GSH: GSSG), and catalase (Enzyme Commission [EC], superoxide dismutase (SOD; EC, glutathione reductase (GR; EC, glutathione peroxidase (GPx; EC, and glutathione S-transferase (EC activities in liver and kidney of tilapia exposed to a single oral dose of 120 ,g MC-LR (with leucine [L] and arginine [R])/fish and killed in 24 h were investigated in the absence and presence of 20.0, 44.0, and 96.8 mg NAC/fish/d. Results showed a protective role of NAC, depending on the dose and the biomarker considered. The increase in LPO (1.9-and 1.4-fold in liver and kidney, respectively) and the decreased protein content and GSH:GSSG in the liver induced by MCs were recovered mainly by the lower doses of NAC employed. Antioxidant enzyme activities increased (range, 1.4-to 1.7-fold) by MCs also were ameliorated by NAC, although the highest level used induced significant alteration of some enzymatic activities, such as SOD, GPx, and GR. Thus, NAC can be considered to be a useful chemoprotectant that reduces hepatic and renal oxidative stress in the prophylaxis and treatment of MC-related intoxications in fish when careful attention is given to its application dose because of its own pro-oxidant activity, as shown in the present study at 96.8 mg NAC/ fish/d. [source]

    Triacylglycerol migration and bloom in filled chocolates: Effects of low-temperature storage

    Frédéric Depypere
    Abstract This study investigated the effect of storage temperature on triacylglycerol (TAG) migration, visual fat bloom and taste of industrially produced milk chocolates with a hazelnut-based filling. The chocolates were stored for up to 10,months at 18,°C, either directly after production or with the inclusion of a variable time at ,20 or 4,°C immediately after production and prior to further storage at 18,°C. TAG migration from the filling through the chocolate shell was quantified by HPLC analysis of chocolate sampled from the chocolates' surface. Both [OOO/SOS] and [LOO/SOS] were used as markers for oil migration. Compared to storage at 18,°C only, chilling or freezing of the chocolates for part of the storage time was found to reduce the amount of TAG migration. Effects on diffusion, capillary transport and TAG immobilization during the thermal treatment can be raised as possible reasons for this decrease. Furthermore, storage at ,20,°C decreased oil migration during subsequent storage at 18,°C. This suggests a crystallization effect during the storage at ,20,°C, leading to permanent (micro)structural changes. Although a thermal treatment at 4,°C compared to ,20,°C was less effective in retarding TAG migration, storage at low positive temperatures immediately after production appears already beneficial in the prevention of visual fat bloom. Adverse effects of the thermal treatments on the chocolates' taste were not observed. [source]

    Dominance of a clonal green sulfur bacterial population in a stratified lake

    Lea H. Gregersen
    Abstract For many years, the chemocline of the meromictic Lake Cadagno, Switzerland, was dominated by purple sulfur bacteria. However, following a major community shift in recent years, green sulfur bacteria (GSB) have come to dominate. We investigated this community by performing microbial diversity surveys using FISH cell counting and population multilocus sequence typing [clone library sequence analysis of the small subunit (SSU) rRNA locus and two loci involved in photosynthesis in GSB: fmoA and csmCA]. All bacterial populations clearly stratified according to water column chemistry. The GSB population peaked in the chemocline (c. 8 × 106 GSB cells mL,1) and constituted about 50% of all cells in the anoxic zones of the water column. At least 99.5% of these GSB cells had SSU rRNA, fmoA, and csmCA sequences essentially identical to that of the previously isolated and genome-sequenced GSB Chlorobium clathratiforme strain BU-1 (DSM 5477). This ribotype was not detected in Lake Cadagno before the bloom of GSB. These observations suggest that the C. clathratiforme population that has stabilized in Lake Cadagno is clonal. We speculate that such a clonal bloom could be caused by environmental disturbance, mutational adaptation, or invasion. [source]

    Seasonal dynamics and toxicity of Cylindrospermopsis raciborskii in Lake Guiers (Senegal, West Africa)

    Céline Berger
    Abstract Cylindrospermopsis raciborskii is a toxic bloom-forming cyanobacterium that occurs at tropical and temperate latitudes. Despite several reports from Africa, no data were previously available about its dynamics or toxic potential there. We therefore carried out a 1-year survey of the dynamics of C. raciborskii in the main water reservoir in Senegal, Lake Guiers. Cylindrospermopsis raciborskii never formed a bloom in this lake during the period studied, but was dominant during the dry season. The only observed bloom-forming species was a diatom, Fragilaria sp., which displayed a seasonal pattern contrary to that exhibited by C. raciborskii. Principal component analysis applied to environmental and phytoplankton data showed that high C. raciborskii biomasses were mainly related to high temperature and water column stability. Tests for C. raciborskii species-related toxicity and/or toxin synthesis were performed on 21 isolated clones. All the strains isolated tested negative in mouse toxicity bioassays, toxin analysis (MS/MS) and tests for known cylindrospermopsin genes (ps, pks). The limited number of isolates studied, and the occurrence of toxic and nontoxic clones in natural cyanobacterial populations, mean that we cannot conclude that there is no C. raciborskii- associated health risk in this drinking water reservoir. [source]

    Baltic Sea cyanobacterial bloom contains denitrification and nitrification genes, but has negligible denitrification activity

    Jaana M Tuomainen
    Abstract A cyanobacterial bloom in the Gulf of Finland, Baltic Sea, was sampled throughout the development and senescence of aggregates in August 1999. While conditions inside the aggregates were favourable for denitrification (rich in nitrogen and carbon, with anoxic microzones), essentially none was detected by a sensitive isotope pairing method. Polymerase chain reaction-based methods, targeting functional genes encoding the key enzymes of denitrification and nitrification processes (nirS, nirK, amoA), revealed that the non-aggregated filaments harboured amoA gene fragments with high similarity to Nitrosospira amoA sequences, as well as both types of nitrite reductase genes, nirS and nirK. Only the nirS -type nitrite reductase gene and no amoA was detected in aggregated filaments. Thus, despite optimal environmental conditions and genetic potential for denitrification, the blooms of filamentous nitrogen-fixing cyanobacteria must be seen solely as a source, and not as a sink of nitrogen in the Baltic Sea. [source]

    Shrimp (Pandalus borealis) growth and timing of the spring phytoplankton bloom on the Newfoundland,Labrador Shelf

    Abstract We examined latitudinal and temporal changes in the availability of food for young shrimp (Pandalus borealis) on the Newfoundland,Labrador Shelf, using a suite of quantitative characteristics of the spring phytoplankton bloom determined from satellite ocean colour data, including bloom initiation time, maximum chlorophyll concentration, timing of the maximum, and bloom duration. We found significant correlations between bloom intensity, timing, and the size of young shrimp. The results are discussed in relation to the observation that, since the early 1990s, carapace lengths of shrimp have been decreasing in many Northwest Atlantic stocks. [source]