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A new marine woloszynskioid dinoflagellate Dactylodinium pterobelotum gen. et sp. nov., collected from a southern Vietnamese estuary, was described on the basis of LM, SEM, and TEM, and molecular phylogeny inferred from rDNA sequences. This species had the smallest number of amphiesmal vesicles (5 latitudinal series) in woloszynskioid dinoflagellates assigned to the Suessiaceae and Borghiellaceae. The eyespot was of type B, composed of osmiophilic globules and brick-like material, located in- and outside of the chloroplast respectively. An apical structure comprised a pair of elongate anterior vesicles ( PEV). A large peduncle was conspicuous, located in the sulcal extension in the epicone, and supported by a microtubular strand of ~140 microtubules. Ultrastructural features of trichocysts represent a novel type in the Dinophyceae, bearing lateral hairs besides anterior fibers. The molecular phylogeny based on partial LSU rDNA showed the species in a basal position in the family Suessiaceae; this indicates the eyespot type B and PEV of the Borghiellaceae are ancestral states of the eyespot comprising brick-like material (type E) and an elongate apical vesicle of the Suessiaceae. [ABSTRACT FROM AUTHOR]

We assessed changes in the microbial communities in ballast water during a trans-Pacific voyage from Japan to Australia that included a mid-ocean ballast-water exchange. Uncultured (i.e., total) and culturable bacteria were counted and were characterized by using denaturing gradient gel electrophoresis (DGGE). There was a clear decrease over time in numbers of uncultured microorganisms, except for heterotrophic nanoflagellates, whereas the abundance of culturable bacteria initially decreased after the ballast-water exchange but then increased. The increase, however, was only up to 5.34% of the total number of uncultured bacteria. Cluster analysis showed that the DGGE profiles of uncultured bacteria clearly changed after the exchange. In contrast, there was no clear change in the DGGE profiles of culturable bacteria after the exchange. Multidimensional scaling analysis showed changes in microbial communities over the course of the voyage. Although indicator microbes as defined by the International Convention for the Control and Management of Ships' Ballast Water and Sediments were occasionally detected, no coliform bacteria were detected after the exchange. [ABSTRACT FROM AUTHOR]

Wild and cultured specimens of Prorocentrum lima (Ehrenb.) F. Stein from 26 widely different areas in 13 countries were examined in order to determine consistent characters for delimiting species boundaries in this taxon. The morphological characters valve shape, valve size, valve ornamentation, number and shape of valve pores, number and shape of marginal pores, and periflagellar platelets were observed using LM and SEM, and two molecular genetic regions were sequenced. We identified stable morphological characters that were consistent among wild specimens and all cultures, which were valve shape, valve ornamentation, and number and arrangement of periflagellar platelets. All cultures of P. lima identified by these characters formed a monophyletic group in phylogenetic analyses based on the two genes, which, however, included the species Prorocentrum arenarium. P. arenarium was determined to be within the range of morphological variation of P. lima, and therefore we synonymize the two taxa. Within this monophyletic group, P. lima was divided into several subclades in the all phylogenetic analyses. There were no morphological characters specifically related to any one subclade. The subclades appeared to correlate broadly to sample collection regions, suggesting that geographically separated populations may have become genetically distinct within this epi-benthic species. We have emended species boundaries in P. lima. [ABSTRACT FROM AUTHOR]

Cellular and body scale structure of a new armored dinoflagellate Heterocapsa huensis, collected from Hue, Vietnam were investigated. Morphology of motile cell was observed by light, fluorescent and scanning electron microscopy, and body scale structure was examined by whole mounts of transmission electron microscopy. Cells of H. huensis were ellipsoid with a spherical nucleus located in the posterior and multiple pyrenoids located above the nucleus; this arrangement was similar to that of Heterocapsa pygmaea. Transmission electron microscopy revealed ultrastructure of the body scales consisted of a rounded triangular basal plate and three-dimensional ornaments. Structure of the basal plate resembles that of Heterocapsa illdefina; however, the number of the peripheral spine is different from that of H. illdefina and this structure has never been reported from Heterocapsa species. A new Heterocapsa species, H. huensis Iwataki et Matsuoka sp. nov., is described based on positions of organelles and body scale ultrastructure. [ABSTRACT FROM AUTHOR]

The dinoflagellate sub-class Prorocentrophycidae has a distinct morphology, lacking the typical dinoflagellate cell structure of a clear cingulum and sulcus. It includes species that produce the toxin okadaic acid. Despite its uniqueness, the group has been found polyphyletic in some previous molecular phylogenetic studies. We have re-investigated the phylogeny of this sub-class by culturing and sequencing new strains, comparing sequences from three genes, the mitochondrial cytochrome c oxidase subunit 1 (cox 1) and the nuclear large and small subunit rRNA (LSU and SSU) encoding genes. We analyzed sequences from twenty-five named and two still undescribed species of Prorocentrophycidae. We used newly recognized features of the secondary structure to align regions of the LSU rRNA. The phylogeny based on cox 1 provided the most well-supported tree and showed strong support for the monophyly of prorocentroid dinoflagellates, while the LSU phylogeny was inconclusive. As in previous studies, phylogeny based on SSU shows the group to appear paraphyletic, however, support values were low. Two strongly supported sub-clades were consistently identified. Benthic and planktonic modes appear to have evolved on multiple occasions within both clades of Prorocentriphycidae. The capability to synthesize toxins appears to have arisen early in prorocentroid evolution and, in particular, okadaic acid synthesis is present in some, but not all, members of Clade 2. The D2a region of the LSU rRNA appears to have developed a deletion in three definable steps during prorocentroid evolution. While the phylogenies inferred from the three genes were not congruent, our results give reserved support to the monophyly of the group. [Copyright &y& Elsevier]

Previously we reported that a significant level of domoic acid, a causative toxin for amnesic shellfish poisoning, was detected in bivalves belonging to a genus Spondylus from various tropical Asian countries. These findings indicate that causative plankton species for domoic acid widely distribute in these areas. In the present study, we monitored seasonal change of domoic acid level of Spondylus versicolor in association with that of plankton samples in Nha Phu Bay, Khanh Hoa, Vietnam from December 2004 to October 2005. The toxicity of S. versicolor showed distinct seasonal variation. During the period when domoic acid level of S. versicolor was increasing, a significant level of domoic acid was detected in the plankton samples, showing the correlation between these two parameters. These findings show that plankton causative for domoic acid occurred in the bay, and S. versicolor accumulate domoic acid during a bloom of the toxic plankton by food web transfer. [ABSTRACT FROM AUTHOR]

Tetrodotoxin (TTX) was detected by HPLC and LC-MS/MS in specimens of the horseshoe crab Carcinoscorpius rotundicauda collected from Tan Hai village, Vung Tau province, Vietnam, where cases of poisoning due to the consumption of horseshoe crab have frequently been reported. The soft tissue from 10 out of the 12 specimens analyzed showed considerable levels of TTX, making them unsafe for human consumption (81.2 ± 50.3 MU/g). Paralytic shellfish poisoning (PSP) toxins were also detected in all of the specimens, but the levels were low. These findings show that the frequency of occurrence of C. rotundicauda specimens with a high level of TTX is significantly high, and that the TTX is responsible for the food poisonings caused by the consumption of C. rotundicauda in this area. [ABSTRACT FROM AUTHOR]

Harmful algal blooms (HABs) occur frequently in the South China Sea (SCS), causing enormous economic losses in aquaculture. We analyzed historical HAB records during the period from 1980 to 2003 in SCS. We found that HABs-affected areas have expanded and the frequency of HABs varied during this period. The seasonal and annual variations, as well as causative algal species of HABs are different among the four regions. Areas with frequent HABs include the Pearl River Estuary (China), the Manila Bay (the Philippines), the Masinloc Bay (the Philippines), and the western coast of Sabah (Malaysia). HABs occurred frequently during March–May in the northern region of SCS, May–July in the eastern region, July in the western region, and year-round in the southern region. Among the species that cause HABs, Noctiluca scintillans dominated in the northern region, and Pyrodinium bahamense in the southern and eastern regions. Causative species also varied in different years for the entire SCS. Both P. bahamense and N. scintillans were the dominant species during 1980–2003. Some species not previously recorded formed blooms during 1991–2003, including Phaeocystis globosa, Scrippsiella trochoidea, Heterosigma akashiwo, and Mesodinium rubrum. Variations in HABs are related to various regional conditions, such as a reversed monsoon wind in the entire SCS, river discharges in the northern area, upwelling in Vietnam coastal waters during southwest winds and near Malaysia coastal waters during northeast winds, and eutrophication from coastal aquaculture in the Pearl River estuary, Manila Bay, and Masinloc Bay. [ABSTRACT FROM AUTHOR]

Species of prorocentroid dinoflagellates are common in marine benthic sediment and epibenthic habitats, as well as in planktonic habitats. Marine planktonic prorocentroids typically possess a small spine in the apical region. In this study, we describe a new, potentially widely distributed benthic species of Prorocentrum, P. fukuyoi sp. nov. , from tidal sand habitats in several sites in Australia and from central Japan. This species was found to possess an apical spine or flange and was sister species to P. emarginatum. We analyzed the phylogeny of the group including this new species, based on large subunit (LSU) rDNA sequences. The genus contained a high level of divergence in LSU rDNA, in some cases among sister taxa. P. fukuyoi and P. emarginatum were found to be most closely related to a clade of generally planktonic taxa. Several morphological features may constitute more informative synapomorphies than habitat in distinguishing clades of prorocentroid species. [ABSTRACT FROM AUTHOR]

Abstract: For the first time, a Prorocentrum minimum bloom at a maximum cell density of 4.7×105cells/L was recorded on January 31 to February 4, 2002 at Bolinao, Pangasinan, Northern Philippines where intensive and extensive aquaculture of Chanos chanos (milkfish) in fish pens and cages has been practiced for years now. The fish kill, which lasted almost simultaneously with the bloom of the organism had its peak when the organisms bloom was declining. Lack of oxygen in the cages and pens was the fundamental cause of the fish kill. Losses due to the fish kill were estimated at six million pesos (equivalent to US$ 120,000), which includes only the worth of dead cultivated fish. Lack of oxygen in the cages and pens was the fundamental cause of the fish kill, and toxicity of the Prorocentrum could not be confirmed. The cells had minute spinules equally all over the surface of valves. Intercalary striae were wide with many ridges perpendicular to valve margin. Outline of cells was rounder than typical P. minimum cells and similar to P. balticum. Recommendations for future research on the organism are incorporated together with monitoring and management interventions in order to mitigate or possibly prevent damages in similar future events. [Copyright &y& Elsevier]

Domoic acid production was screened in the Nitzschia-like strains of benthic diatom collected from Ishigaki Island (subtropical area), Tohoku District of Japan (temperate area) and Manila Bay, the Philippines (tropical area). Domoic acid was detected in 88 out of 183 strains collected from these areas. The cellular domoic acid content of these strains ranged from 0.1 to 15.3 pg/cell. All the strains positive for domoic acid production were identified as Nitzschia navis-varingica, a new domoic acid-producing benthic diatom species that was recently found in Vietnam. This species was collected only from brackish water. These results indicate that domoic acid-producing N. navis-varingica is distributed widely in brackish water from tropical to temperate areas. [ABSTRACT FROM AUTHOR]

The seasonal bloom of the toxic dinoflagellate Alexandrium tamarense , with reference to the ambient oceanographic conditions in Hiroshima Bay, Seto Inland Sea, Japan is described. Long-term observations on the vegetative cells of A. tamarense were conducted biweekly to monthly at one fixed station in northern Hiroshima Bay, where recurrent paralytic shellfish poisoning (PSP) incidents have been occurring since 1992. Over the 5-year study period, from April 1994 to December 1998, vegetative cells of A. tamarense were detected each year within the period from January to June. Observed annual maximum cell densities of A. tamarense reached 103 –104 cells/L, and mostly peaked at a depth layer of 5 m at the sampling station in April or May. Oceanographic conditions during the bloom period were as follows: water temperatures ranged from 10.2°C to 20.2°C, and thermal stratification gradually developed around April. Inorganic nutrient concentrations were markedly low throughout the bloom period. Particularly, the annual lowermost concentration of SiO2 -Si was observed each year during this period. These environmental features indicate that the occurrence of vegetative cells of A. tamarense seems to be explained by temperature and nutrient conditions and that the A. tamarense bloom developed subsequently to or concomitantly with the diatom spring bloom. [ABSTRACT FROM AUTHOR]

ABSTRACT: The survey on scallop toxicity in association with causative dinoflagellates was conducted when the cultured scallops Patinopecten yessoensis were found to accumulate paralytic shellfish toxins in late November of 1997 at Otsuchi Bay, Iwate Prefecture, Japan. Alexandrium catenella was observed in high density at the beginning of the survey. The cell density of A. catenella decreased and completely disappeared in early December. The scallop toxicity also decreased with decrease of the cell density of A. catenella. The toxin profile of the scallop was similar to that of natural and cultured cells of A. catenella isolated from the Bay, showing that scallop toxicity is due to A. catenella. This is the first case in which paralytic shellfish toxins were confirmed in scallops during a bloom of A. catenella in Sanriku coast of Iwate Prefecture. [ABSTRACT FROM AUTHOR]

Domoic acid (DA), a neuroexcitatory amino acid, was detected in batch culture of the newly recognized species Nitzschia navis-varingica Lundholm et Moestrup. The production of DA by this diatom was confirmed by electrospray ionization mass spectrometry. The diatom was collected from a shrimp-culture pond in Do Son, Vietnam. The production of DA (1.7 pg·cell-1) is within the levels reported for Pseudo-nitzschia multiseries (Hasle) Hasle. The DA production started during the late exponential growth phase and reached a maximum during the early stationary growth phase. Maximum DA levels in the axenic culture decreased to about half that of the nonaxenic culture (0.9 pg·cell-1 vs. 1.7 pg·cell-1), suggesting that DA production by the new species is influenced by bacteria. [ABSTRACT FROM AUTHOR]

The gonyaulacoid dinogflagellate, Alexandrium satoanum Yuki et Fukuyo sp. Nov. is described from Matoya Bay, Pacific coast of Central Japan. The species is distinctive in its conical epitheca with almost straight sides and dorsal concavity of the hypotheca. The plate formula is P0,Pcm 4', 6", 6c, 10s, 5'", and 2"", including two accessory plates inside the sulcus. The apical pore plate is triangular and possesses an anterior attachment pore at the right margin. The first apical plate does not make contact with the apical pore place and lacks a ventral pore. A posterior attachment pore lies at the center of the posterior sulcat plate. In Matoya Bay, vegetative cells occur as solitary cells or sometimes in pairs during late spring and early summer in low concentrations. In connection with this study, the following new combination is proposed: Alexandrium, pseudogonyaulax (Biecheler) Horigushi ex Yuki et Fukuyo comb. Nov. [ABSTRACT FROM AUTHOR]

The article focuses on the cyst and theca of gonyaulax verior sournia and their implication for the systematics of the genus gonyaulax. Some species of the dinofiagellate genus gonyaulax are known to produce fossilizable resting cysts during their life cycle. The purpose of this report is to document the ptaxonomyreviously undescribed cyst-theca relationship of gonyaulax verior sournia and to discuss the taxonomic significance of the cyst with respect to the systematics of the genus gonyaulax. Germination was monitored for individual cysts in tissue culture wells, viewed from below with an inverted microscope.

Reports the occurrence of Heterocapsa circularisquama (Dinophyceae) in a coastal area of Hong Kong, South China Sea. Observation of red samples collected in Hong Kong waters; Cell density; Findings of preliminary bioassay; Observation of thecal plate arrangement and fine structure of bioassay using mice and juvenile fishes; Technique used to identify the dinoflagellates; Importance of body scale presentation in the identification of the Heterocapsa species..

Deals with a study which describes the morphology and toxicity of Alexandrium minutum Halim found in northern Vietnam. Prevalence of paralytic shellfish poisoning (PSP) in Southeast Asia; Information on the plankton samples used in the study; Overview of the high-performance liquid chromatography analysis for PSP.

Ciguatera fish poisoning (CFP) is a type of food poisoning caused by the consumption of a variety of toxic ciguatera fish species in the tropical and subtropical waters. Although there have been a large number of suspected CFP cases in the Southeast Asian countries, few were confirmed with causative ciguatoxins (CTXs), and reliable information on the symptoms still remains rather limited. In the present study, CTXs in red snapper Lutjanus bohar, implicated in two suspected CFP cases in Vietnam in 2014 and 2016, were determined by use of the single-quadrupole selected ion monitoring (SIM) liquid chromatography/mass spectrometry (LC/MS). Ciguatoxin-1B (CTX-1B), 54-deoxyCTX-1B, and 52-epi-54-deoxyCTX-1B were detected in the red snapper by our LC/MS method. Moreover, CTX-1B, 54-deoxyCTX-1B, and 52-epi-54-deoxyCTX-1B were further identified by the time of flight (TOF) LC/MS with the exact mass spectrum. The CTX profile of the red snapper in Vietnam is similar to those of ciguatera fish from Australia, Okinawa Islands in Japan, Kiribati, and Hong Kong. This is the first comprehensive report unambiguously identifying the causative toxins in fish implicated with reliable information on the poisoning symptoms in CFP in Vietnam and/or Southeast Asian countries. [ABSTRACT FROM AUTHOR]

Abstract: This paper constitutes the first cyst record of a eutrophic tropical mariculture area with harmful algal blooms since 2002 and provides contribution to the global record on dinoflagellate cysts, specifically from Northern part of Southeast Asia. Surface sediment samples from 54 stations in October 2006 and 5 stations from 2004 to 2006 Bolinao, Pangasinan were processed palynologically and by fluorescent techniques. Exploratory data analysis using Two-Way Indicator Species Analysis (TWINSPAN) to identify major patterns of distribution and Canonical Correspondence Analysis (CCA) ordinated stations and species along sediment and environmental variables have been done to determine spatial variations in community structure. Thirty-six cyst types have been identified which include the toxic species, Alexandrium minutum. Species richness and diversity correlated with silt, mud, carbonates and depth but have been observed to be generally low in the area (p <0.05). Multivariate analysis shows that sediment grain size, nutrients and water depth are important variables related to cyst distribution. Two accumulation points that can be source and sinks of blooms have been identified. The decrease in species richness and diversity of dinoflagellate cysts from 2005 to 2006 has been attributed to intensive mussel farming. Heterotrophs have dominated during the northeast and southwest monsoon seasons while autotrophs which included A. minutum, have dominated during tradewinds. Results indicate that the cysts accumulation points could possibly seed blooms particularly during the tradewinds season and thus should be monitored effectively to prevent negative public health impacts. [Copyright &y& Elsevier]

Abstract: Nitzschia navis-varingica is a diatom that is known to produce significant levels of amnesic shellfish poisoning (ASP) toxins. A total of 33 N. navis-varingica strains were isolated from four brackish water localities in the Philippines and Indonesia, and cultured to characterize the toxins produced. The isolates were analyzed for domoic acid (DA) and isodomoic acids A (IA) and B (IB) by HPLC with fluorescence detection. Two toxin composition types were detected that have not been previously described: strains producing only IB and strains producing DA–IA–IB. These two types were isolated from two different localities. Eighteen strains were isolated from the Philippines (northern Luzon Island). Among them, 10 isolates from Alaminos produced only IB with an average toxin content of 3.05pgcell−1, seven isolates from Bulacan produced DA and IB with average toxin contents of 0.68pgcell−1 and 1.18pgcell−1, respectively. One isolate from Cavite produced DA, IA, and IB with a toxin content of 0.58, 0.20, and 0.92pgcell−1, respectively. Fifteen isolates from Indonesia (Bone, South Sulawesi) produced only DA (four isolates) or DA with trace amounts of IB (eleven isolates), with an average toxin content of 2.38pgcell−1 and 0.06pgcell−1, respectively. Sub-strains were established from strains producing either of the three toxin types: IB, DA–IA–IB, and DA-trace IB. Results showed that the toxin composition type was the same for parent and sub-strains, indicating that the toxin composition is a stable character for a strain. [Copyright &y& Elsevier]

Abstract: A massive fish kill and water discoloration were reported off the western coast of Puerto Princesa, Palawan, Philippines in March 2005. Phytoplankton analysis revealed a near monospecific bloom of the dinoflagellate, Cochlodinium polykrikoides, with cell concentrations ranging from 2.5×105 to 3.2×106 cells per liter. Ground truth data were supplemented by processed satellite images from MODIS Aqua Level 2 data (1km resolution) from January to April 2005, which revealed high surface chlorophyll-a levels (up to 50mg/m3) offshore of west and southwest Palawan as early as February 2005. The bloom extended 310km in length and 80km in width at its peak in March off the central coast (Puerto Princesa). By April, the bloom declined in intensity, but was still apparent along the northern coast (El Nido). Fluctuations in chlorophyll levels off the western coast of Sabah, Malaysia and Brunei during this time period suggested that the bloom was not limited to the coast of Palawan. Satellite imagery from Sabah in late January revealed a plume of chl-a that is believed to be the source of the C. polykrikoides bloom in Palawan. This plume drifted offshore, advected northward via the basin-wide counterclockwise gyre, and reached nutrient-rich, upwelled waters near Palawan (due to a positive wind stress curl) where the dinoflagellate bloomed and persisted for 2 months from March to April 2005. [Copyright &y& Elsevier]

Abstract: Phylogenetic relationships among chain-forming Cochlodinium species, including the harmful red tide forming dinoflagellate Cochlodinium polykrikoides, were investigated using specimens collected from coastal waters of Canada, Hong Kong, Japan, Korea, Malaysia, México, Philippines, Puerto Rico, and USA. The phylogenetic tree inferred from partial (D1–D6 regions) large subunit ribosomal RNA gene (LSU rDNA) sequences clearly differentiated between C. polykrikoides and a recently described species, Cochlodinium fulvescens. Two samples collected from the Pacific coasts of North America (British Columbia, Canada and California, USA) having typical morphological characters of C. fulvescens such as the sulcus located in the intermediate region of the cingulum, were closely related to C. fulvescens from western Japan in the phylogenetic tree. Cochlodinium polykrikoides formed a monophyletic group positioned as a sister group of the C. fulvescens clade with three well-supported sub-clades. These three clades were composed of (1) East Asian, including specimens collected from Hong Kong, western Japan, and southern Korea, (2) Philippines, from Manila Bay, Philippines and Omura Bay, Japan, and (3) American/Malaysian, from the Atlantic coasts of USA, the Pacific coast of México, Puerto Rico, and Borneo Island, Malaysia. Each of these clades is considered to be a so-called “ribotype” representing the population inhabiting each region, which is distinguished based on ribosomal RNA gene sequences in the species despite similarities in their morphological characters. [Copyright &y& Elsevier]

Abstract: The International Maritime Organization (IMO), the United Nations body which administers the international regulatory regime for shipping, noted the negative impact of non-indigenous organisms transported in the ballast water of ships already in the early 1970s. Consequently, measures were taken with the aim to minimize ballast water mediated species invasions through IMO Marine Environmental Protection Committee (MEPC) Resolutions. As a result of long-term IMO efforts, it was determined that an international convention would best meet the needs of the global community, hence the International Convention for the Control and Management of Ships’ Ballast Water and Sediments was adopted in a Diplomatic Conference in 2004 and is now open for signature by IMO Member States. This very complex (and by no means “simple”) Convention aims to reduce the transfer and subsequent impact of aquatic organisms in the ballast water and sediment of ships by acting to reduce the load of these organisms in discharged ballast water. A set of 15 guidelines provides technical guidance for the implementation of the Convention principles. This review considers critical aspects of this Convention and selected guidelines seen from perspectives of biological, shipping and regulatory concerns. [Copyright &y& Elsevier]