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(a)-(d) Pseudo-nitzschia calliantha, (a) chain of three cells, (b) whole valve, (c) middle part of valve showing central nodule (arrow); (d) – part of valve showing mantle and valve striae structure; (e)-(j) Pseudo-nitzschia fraudulenta, (e) chain of cells showing cell overlap 1/6-1/ 7 of total cell length, (f) whole valve, (g) part of valve showing striae and fibulae, (h) part of valve showing unequal number of striae and fibulae (arrows), (i) middle part of valve showing central nodule (arrow), (j) structure of valve striae. (a, b, e, f) LM, (c, d, g-j) TEM. Scale bar is equal to 10 µm (a, b, e-g) and 1 µm (c, d, i, j, h).
Source publication
Potentially toxic diatomsPseudo- nitzschia calliantha andP. fraudulenta were found in bottle samples of phytoplankton collected in Amurskii Bay (East/Japan Sea) and in the coastal waters of Sakhalin
Island (East/Japan Sea and Sea of Okhotsk) in different seasons during 2002-2006. The mass development of these species occurred
in October and Novembe...
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Citations
... and their maximum concentrations during bloom events are shown in Figure 2 and Table 2. The species that caused bloom events in Peter the Great Bay were identified earlier using the morphological studies and a phylogenetic analysis of ribosomal genes [11,[13][14][15][16]22]. An analysis of long-term data on Pseudo-nitzschia bloom events in Amursky Bay showed that Pseudo-nitzschia multiseries was the dominant species in these areas in the early 1990s. ...
This review aimed to summarize original and published data on the bloom events caused by toxic diatoms of the genus Pseudo-nitzschia and to assess long-term variations in the composition of bloom-forming species in the northwestern Sea of Japan during 1992−2015. This information is crucial to understanding the potential threat of toxic blooms and their effects. A change in species composition was observed within the genus Pseudo-nitzschia: it was dominated by Pseudo-nitzschia multiseries during 1992–1993, 2002, and a shift towards the dominance of Pseudo-nitzschia multistriata and Pseudo-nitzschia calliantha occurred in 2005–2015. We assume that the increased sea surface temperature recorded from Amursky Bay in the period of 1998–2009 compared to the data of 1980–1989 might be one of the causative factors for the shift observed. The absence of highly toxic Pseudo-nitzschia multiseries among the bloom-forming species is considered as one of the possible explanations for the lack of damage from the blooms of Pseudo-nitzschia over the past 15 years in the study area.
... P. fraudulenta (frD2) P. fraudulenta has also been described as a cosmopolitan species, having been identified on all continents except Antarctica, with ongoing expansion of geographic distribution (e.g. Stonik et al., 2008;Moschandreou et al., 2010). The isolates from this study match sequences (taking into consideration the two possible nucleotides for the polymorphic site) available in GenBank from around the globe (North America, Europe and Africa). ...
New sandwich hybridization assay (SHA) probes for detecting Pseudo-nitzschia species (P. arenysensis, P. fraudulenta, P. hasleana, P. pungens) are presented, along with updated cross-reactivity information on historical probes (SHA and FISH; fluorescence in situ hybridization) targeting P. australis and P. multiseries. Pseudo-nitzschia species are a cosmopolitan group of diatoms that produce varying levels of domoic acid (DA), a neurotoxin that can accumulate in finfish and shellfish and transfer throughout the food web. Consumption of infected food sources can lead to illness in humans (amnesic shellfish poisoning; ASP) and marine wildlife (domoic acid poisoning; DAP). The threat of human illness, along with economic loss from fishery closures has resulted in the implementation of monitoring protocols and intensive ecological studies. SHA probes have been instrumental in some of these efforts, as the technique performs well in complex heterogeneous sample matrices and has been adapted to benchtop and deployable (Environmental Sample Processor) platforms. The expanded probe set will enhance future efforts towards understanding spatial, temporal and successional patterns in species during bloom and non-bloom periods.
... Интенсивное развитие водорослей рода Pseudo-nitzschia в дальневосточных морях России наблюдается в начале лета и осенью (Стоник, Орлова, 2007;Stonik et al., 2008). Изучение массовых видов микроводорослей в условиях лабораторной культуры позволяет объяснить механизмы их развития и разработать меры борьбы с этим явлением. ...
Growth of potentially toxic diatom microalga Pseudo-nitzschia calliantha is investigated in laboratory culture under different conditions of cultivation. In the conditions without stirring, the highest abundance of algae was moderate (16131 cells/ml) and observed after 3 days of exposition; many chains of 5-8 cells were formed. Further exposition showed cyclic dynamics of the culture, the chains of 5-12 cells were numerous, chloroplasts looked healthy, their color was olive-green. After stirring, a short lag-phase preceded to the phase of active cells dividing with exponential growth of their number to the peaks of 59828-70566 cells/ml, chains of 2-8 cells were formed but rapidly settled to the vessel bottom, chloroplasts were discrete and bleached that indicated dying of the culture. P. calliantha is potentially toxic species, so the sites with active water circulation or constrained water mixing are recommended for aquaculture farming that protects the environments from its phycotoxins accumulation.
... With the growing consumption of seafood and development of aquaculture in Russia, the problems of microalgal toxicity have become increasingly pressing for this country [3]. Cases of harmful algal blooms (HABs) caused by Pseudo nitzschia species have been regularly registered in the coastal waters of the Sea of Japan and Sakhalin Island, in the areas of aquaculture farms and the coastal tourism infrastructure since 1992 [19,39,41,42]. Previous in vitro tests showed the high toxicity of P. multiseries isolated from water of the Peter the Great Bay (Sea of Japan) [38]. The general taxonomic review of Pseudo nitzschia from the Rus sian waters of the Sea of Japan and Sea of Okhotsk gives detailed information on the species composition and morphology of the members of this genus [42]. ...
... The general taxonomic review of Pseudo nitzschia from the Rus sian waters of the Sea of Japan and Sea of Okhotsk gives detailed information on the species composition and morphology of the members of this genus [42]. However, reliable data (i.e., based on electron micros copy studies, which are necessary for reliable identifica tion of species) on the Pseudo nitzschia population den sity in the Russian Far East seas are scarce [19,39,41]. ...
... Seven Pseudo nitzschia species that were found in the last 10 years in the Peter the Great Bay, Sea of Japan [11,19,41] were recorded here for the first time [4,9] ( Table 2). The increase in the microalgae species list for this region may be explained by the extention of knowledge on the morphology and systematics of this diatom group, as well as by several taxonomic reviews and descriptions of new taxa due to a general increase of interest in this group for the last several decades [26,[34][35][36]. ...
This paper studies the species composition and quantitative distribution of diatoms that belong to the genus Pseudo-nitzschia in the Russian waters of the Sea of Japan and the Sea of Okhotsk. In total, 11 species of this genus were found in the area, including 7 that are known as being potentially toxic. The highest concentrations of Pseudo-nitzschia microalgae (1.4 × 106–2.7 × 106 cells/L) were found in the summer and autumn in the Peter the Great Bay of the Sea of Japan and the lowest concentrations (2.5 × 102–1 × 104 cells/L) were found in the Sakhalinsky and Akademiya bays of the Sea of Okhotsk. The species diversity of potentially toxic diatoms was greatest (seven species) and the cell concentrations highest (over 6 × 105 cells/L) in the Peter the Great Bay, Sea of Japan, and in the Aniva Bay, Sea of Okhotsk. The density of potentially toxic species was highest near the northeastern coast of Sakhalin Island, in the Amur River estuary, and in adjacent waters. This paper also presents geographical distribution maps of Pseudo-nitzschia species and maps of the density distribution of potentially toxic microalgae over the studied area and identifies potential amnesic shellfish poisoning areas.
... Beginning in 1992, the events of blooms of Pseudo-nitzschia species has been observed in the Amursky Bay of the East/Japan Sea: in the vicinity of Vladivostok, in areas of mariculture farms, and in recreational zones (Orlova et al., 1996;Stonik et al., 2001Stonik et al., , 2008. The Vladivostok city region's large human population makes it potentially vulnerable to ASP. ...
... Studies of the natural population dynamics of Pseudo nitzschia are generally focused on elucidating the mechanisms of bloom formation with the aim of predicting bloom events of species of this genus and to prevent toxicity of commercially valuable invertebrates [7][8][9][10]15]. Beginning in 1992, the abundant development of Pseudo nitzschia species has been observed in coastal waters of the Sea of Japan: in the vicinity of Vladivos tok, in areas of mariculture farms, and in recreational zones [4,16,20]. However, either the dynamics of cell densities of species of this genus during the bloom period or their determining factors have not been stud ied in the Far Eastern seas of Russia. ...
A bloom of potentially toxic diatoms of the genus Pseudo-nitzschia was observed in October–November 2005 in the northeastern part of Amursky Bay in the vicinity of Vladivostok (northeastern Sea of Japan) at a salinity of 31–33.5‰ and a water temperature of 6–12°C. The most intense peak of Pseudo-nitzschia spp. cell density (with a mean value of 1428.9 thousand cells/liter), which was recorded in the second half of October after heavy rains, was mainly caused by the massive development of P. multistriata (67% of the total density) and P. calliantha (9%). A negative correlation was found between Pseudo-nitzschia spp. cell density and water salinity and NH4 concentration; a positive correlation was observed between diatom population density and water temperature.
... Samples were taken after intensive stirring at the same time one or two hours after the end of the dark period at day 1, 2, 3, 4, 7, 10, and 14 of the experiment. The collected samples were fixed with Utermohl (Utermohl 1958) solution, and the cells were counted in a Nageotte type chamber in volume 0.044 ml (Stonik et al. 2008). The mean cell size (height and width) of 30 cells from each sample was measured with a calibrated ocular AM-92 micrometer (Russia) under Jenamed 2 microscope. ...
Effect of salinity on abundance dynamics and cell size of microalga Corethron hystrix Hensen (Bacillariophyta) were studied. C. hystrix can normally grow within a rather narrow salinity range between 32 and 280/00. The viable cells of this microalga change their morphological characters at a salinity of 240/00. This salinity level probably marks the beginning of cell division restriction, because the general number of cells by the end of the experiment was lower than in the control. The decrease of salinity to 160/00 caused pronounced irreversible morphological changes: cell height increased, chloroplasts compressed, protoplasm became granular, cytoplasm retracted, and spines shortened.
Forty-eight isolates of Pseudo-nitzschia species were established from the Miri coast of Sarawak (Malaysian Borneo) and underwent TEM observation and molecular characterization. Ten species were found: P. abrensis, P. batesiana, P. fukuyoi, P. kodamae, P. lundholmiae, P. multistriata, P. pungens, P. subfraudulenta, as well as two additional new morphotypes, herein designated as P. bipertita sp. nov. and P. limii sp. nov. This is the first report of P. abrensis, P. batesiana, P. kodamae, P. fukuyoi and P. lundholmiae in coastal waters of Malaysian Borneo. Pseudo-nitzschia bipertita differs from its congeners by the number of sectors that divide the poroids, densities of band striae and its cingular band structure. Pseudo-nitzschia limii, a pseudo-cryptic species in the P. pseudodelicatissima complex sensu lato, is distinct by having wider proximal and distal mantles, a higher number of striae and greater poroid height in the striae of the valvocopula. The species were further supported by the phylogenetic reconstructions of the nuclear-encoded large subunit ribosomal gene and the second internal transcribed spacer. Phylogenetically, P. bipertita clustered with its sister taxa (P. subpacifica+P. heimii); P. limii appears as a sister taxon to P. kodamae and P. hasleana in the ITS2 tree. Pairwise comparison of ITS2 transcripts with its closest relatives revealed the presence of both hemi- and compensatory base changes. Toxicity analysis showed detectable levels of domoic acid in P. abrensis, P. batesiana, P. lundholmiae and P. subfraudulenta, but both new species tested below the detection limit.
A survey focusing on species belonging to the diatom genus Pseudo-nitzschia was conducted in the western North Pacific (the northwestern Sea of Japan and the Sea of Okhotsk). Light and electron microscopic examination of 314 phytoplankton field samples collected from 1995 to 2006 revealed the presence of 11 Pseudo-nitzschia species: P. americana, P. cf. caciantha, P. calliantha, P. delicatissima/arenysensis, P. fraudulenta, P. cf. heimii, P. multiseries, P. multistriata, P. obtusa, P. pungens and P. seriata. Detailed morphological descriptions and illustrations as well as distributional data are provided for all 11 Pseudo-nitzschia taxa. The study presents a taxonomical baseline investigation of Pseudo-nitzschia from the western North Pacific and provides distributional data from an area otherwise not thoroughly examined earlier. Morphological deviation from the current description of P. cf. heimii, P. obtusa and P. caciantha is presented. It is established that P. calliantha, P. multistriata, P. multiseries and P. pungens occur in bloom proportions and are widely distributed in the Sea of Japan and the Sea of Okhotsk. In the literature, P. seriata is characterized as being restricted to the northern hemisphere where it occurs in the North Atlantic Ocean exclusively. The current study, however, documents that P. seriata is found in the North Pacific and hence is widespread in the northern hemisphere. One species, P. cf. caciantha, is a new record for the western North Pacific, whereas two others, P. cf. heimii and P. multistriata, are new records for the Sea of Okhotsk. The geographical distribution of P. cf. caciantha, P. multistriata and P. obtusa in the North Pacific is expanded by the current study.
Pseudo-nitzschia is a globally distributed diatom genus, some species of which produce domoic acid (DA), the neurotoxin that causes amnesic shellfish poisoning. This toxin killed at least three humans in 1987, launching numerous studies concerning the identification, distribution, ecology and physiology of Pseudo-nitzschia spp. Since previous reviews in 1998, knowledge has been gained about the fate of DA, including its accumulation by marine animals and its degradation by light and bacteria. Molecular techniques and more precise microscopy have enabled the description of new Pseudo-nitzschia species, 15 since 2002, including ones that are cryptic and pseudo-cryptic. An increasing number of the 37 identified species, including oceanic and coastal species, have been studied in laboratory culture. The sexual reproduction of 14 species has been documented. Fourteen species have now been shown to be toxigenic, although some strains are not always toxic under the testing conditions. The biotic and abiotic factors that modify DA production are reviewed, with a focus on how new discoveries have changed our original hypotheses about control mechanisms. Recent studies confirm that silicate and phosphate limitation trigger DA production. However, stress by low concentrations of iron or high concentrations of copper are newly discovered triggers, suggesting a trace-metal chelation role for DA. Organic sources of nitrogen (urea and glutamine), as well as changes in pH, CO2, salinity and bacterial concentration, also enhance DA production. Laboratory and field studies sometimes give divergent results for conditions that are conducive to toxin production. Gaps in knowledge include further information about the whole genome of Pseudo-nitzschia (including sexual stages), mechanisms of DA production and decline, presence or absence of a resting stage, heterotrophic ability, impact of viruses and fungi, and a more complete description of the ecological and physiological roles of DA.
