Palynological record (1483–1994) of Gymnodinium catenatum in Pescadero Basin, southern Gulf of California, Mexico

This paper presents the stratigraphic record of Gymnodinium catenatum during the last ~ 500 years, in Pescadero Basin, southern Gulf of California. Our aim is to help clarify the relation between abundances of cysts of G. catenatum and regional changes in the sea surface temperature and nutrient availability at a decadal scale. The record was obtained from core samples of laminated sediments dated with ¹⁴C, representing conditions in the area from 1483 to 1967 (PCM99-74C-5) and from 1907 to 1994 (PCM00-61C-4). Samples were treated with normal palynological processing, without oxidation, and using Lycopodium spores for quantification. The palynological assemblages observed contain varied and abundant terrestrial and marine components. However, we focus on the abundance of G. catenatum, due to its toxicity and the resulting impact in the area. This species is currently common in the area, and according to our results has been present there since ~ 1483. Cysts of G. catenatum are generally abundant in the 20th century, with maximum concentrations observed from 1888 to 1920, and from 1945 to 1965, but they show a steady decrease in the latter part of the century (1965–1994). Before 1830, abundances of G. catenatum were low because of increased upwelling conditions, probably related to a higher variability of the winter sea surface temperatures in the area. Both our data in the 20th century and the actual reports in the area, indicate a close relation with sea surface temperature. From 1907 to 1994 cyst abundances seem to increase during cool La Niña conditions in the area, and decrease during warmer El Niño events. They also show an evident decrease in cyst abundance from 1970 to 1994, while the sea surface temperature in the area increased during the same period. This inverse relation is also indicated by the low abundances of G. catenatum observed during red tide events, combined with high sea surface temperatures in Mazatlan. Additionally, our results do not show any relation of G. catenatum blooms and anthropogenic activity in the area.     

Development and Evaluation of a PCR Based Assay for Detection of the Toxic Dinoflagellate, <Emphasis Type="Italic">Gymnodinium catenatum</Emphasis>(Graham) in Ballast Water and Environmental Samples

Gymnodinium catenatum is a bloom forming dinoflagellate that has been known to cause paralytic shellfish poisoning (PSP) in humans. It is being reported with increased frequency around the world, with ballast water transport implicated as a primary vector that may have contributed to its global spread. Major limitations to monitoring and management of its spread are the inability for early, rapid, and accurate detection of G. catenatum in plankton samples. This study explored the feasibility of developing a PCR-based method for specific detection of G. catenatumin cultures and heterogeneous ballast water and environmental samples. Sequence comparison of the large sub unit (LSU) ribosomal DNA locus of several strains and species of dinoflagellates allowed the design of G. catenatum specific PCR primers that are flanked by conserved regions. Assay specificity was validated through screening a range of dinoflagellate cultures, including the morphologically similar and taxonomically closely related species G. nolleri. Amplification of the diagnostic PCR product from all the strains of G. catenatum but not from other species of dinoflagellates tested imply the species specificity of the assay. Sensitivity of the assay to detect cysts in ballast water samples was established by simulated spiked experiments. The assay could detect G. catenatum in all ‘blank’ plankton samples that were spiked with five or more cysts. The assay was used to test environmental samples collected from the Derwent river estuary, Tasmania. Based on the results we conclude that the assay may be utilized in large scale screening of environmental and ballast water samples.     

Distribution and selective elimination of paralytic shellfish toxins in different tissues of Octopus vulgaris

Octopus (Octopus vulgaris, Cuvier) plays a central role in the marine food web, being an important consumer with high metabolic rates and at the same time an important food item for higher predators. After harmful algal blooms, octopus can accumulate high levels of marine toxins trough trophic interrelationships. The aim of this study is to characterize the distribution of paralytic shellfish toxins (PSTs) in selected tissues of the O. vulgaris, in order to assess the translocation of toxins among organs with different physiological functions. Different retention times and selective elimination of particular toxin analogues were also investigated. Twenty three specimens of O. vulgaris were captured in Peniche (NW coast of Portugal) after PSTs have been detected in molluscan bivalves. Tissue matrices were dissected from organs with digestive function (digestive gland, stomach and salivary glands) and excretory function (kidneys and branchial hearts) and analyzed for toxin determination. Toxin analysis was carried out by high performance liquid chromatography with fluorescence detection (LC-FLD). PSTs were found in all tissues analyzed. The highest toxin concentrations were found in the digestive gland, reaching a maximum of 2980 μg STX equiv. kg⁻¹. The toxin profile was constituted by dcSTX, B1, C1 + 2, dcGTX2 + 3, dcNEO, STX and GTX2 + 3. A lower number of toxins were identified in the remaining organs, with B1 and dcSTX compromising more than 90% in molar fraction. Decarbamoyl saxitoxin was the most abundant toxin detected in digestive gland, stomach and salivary glands, while B1 was dominant in organs with excretory function. A positive correlation of concentrations of B1 and dcSTX were found in the organs analyzed. Results indicate that B1 and dcSTX are assimilated into the digestive gland in a similar proportion. Selective elimination of toxins with higher elimination of B1 and retention of dcSTX is suggested. This study contributes to better understanding of the dynamics of PSTs in O. vulgaris and the fate of PSTs in the food web.     

A fish kill of massive proportion in Kuwait Bay, Arabian Gulf, 2001: the roles of bacterial disease, harmful algae, and eutrophication

In August and September 2001, Kuwait Bay, a semi-enclosed embayment of the Arabian Gulf, experienced a massive fish kill involving over >2500 metric tons of wild mullet (Liza klunzingeri), due to the bacterium Streptococcus agalactiae. In the Bay, this event was preceded by a small fish kill (100–1000 dead fish per day) of gilthead sea bream (Sparus auratus) in aquaculture net pens associated with a bloom of the dinoflagellate Ceratium furca. Sea bream were found to be culture positive for S. agalactiae, but did not show any visible signs of disease. Unusually warm temperatures (up to 35 °C) and calm conditions prevailed during this period. As the wild fish kill progressed, various harmful algae were observed, including Gymnodinium catenatum, Gyrodinium impudicum, and Pyrodinium bahamense var. compressum. Cell numbers of G. catenatum and G. impudicum exceeded 10⁶ l⁻¹ in some locations. All fish tested below the limits of detection for paralytic shellfish poisoning (PSP) and brevetoxins. Clams (Circe callipyga) were positive for PSP but at levels below regulatory limits. Nutrient concentrations, both inorganic and organic, were highly variable with time and from site to site, reflecting inputs from sewage outfalls, the aquaculture operations, a high biomass of decomposing fish, and other sources. It is hypothesized that many factors contributed to the initial outbreak of the bacterial disease, including unusual warm and calm conditions. The same factors, as well as enriched nutrient conditions, also apparently were conducive to the subsequent HAB outbreaks. The detection of PSP, while below regulatory limits, warrants further monitoring to protect human health.     

An unusual Xanthophyllomyces strain from leaves of Eucalyptus globulus in Chile

Xanthophyllomyces sp. was isolated as an epiphytic red yeast from leaves of Eucalyptus glo-bulus in Concepción, Chile. Sexual reproduction was by basidiospores produced from one or rarely two metabasidia arising from a yeast cell without preceding paedogamy. The main carotenoid pigment was astaxanthin. This isolate did not cluster with the X. dendrorhous complex (including Phaffia rhodozyma) in ITS and 26S rDNA-based phylogenetic analyses. The phylloplane may be a further habitat for Xanthophyllomyces, in addition to the well-known spring sap-flows of deciduous trees and the recently-characterised ascostromata of Cyttaria hariotii.     

Does uptake of Alexandrium fundyense cysts contribute to the levels of PSP toxin found in the sea scallop, Placopecten magellanicus?

Atlantic sea scallops, Placopecten magellanicus, in most areas of the Bay of Fundy, New Brunswick, Canada, have year-round concentrations of paralytic shellfish posioning (PSP) toxins greater than the regulatory concentration of 80 μg STX eq. 100 g⁻¹ wet weight. Scallops (mean shell height of 10.7 cm, age 3–5 years) were collected by SCUBA and individually tagged near Parker Island, Bay of Fundy. Half were hung 2 m below the low tide water level and the remainder were placed on the bottom (11 m depth at low tide) under the scallops held at 2 m. Scallop, water and sediment samples were collected monthly for determination of concentrations of PSP toxins and Alexandrium fundyense.In October, 1993, mean concentrations of PSP toxins in digestive gland, and mantle were 3205 and 1018 μg STX eq. 100 g⁻¹ wet weight, respectively. Eight months later (June 1994), PSP concentrations in digestive glands from the surface and bottom had declined to 504 and 682 μg STX eq. 100 g⁻¹ wet weight, respectively, whereas those in the mantle had declined to 802 and 681 μg STX eq. 100 g⁻¹ wet weight. During July 1994, A. fundyense concentrations observed at Parker Island and offshore were 320 cells l⁻¹ and 14,200 cells l⁻¹, respectively. Subsequently, toxin concentrations in surface and bottom scallop digestive glands increased to 12,720 and 11,408 μg STX eq. 100 g⁻¹ wet weight, whereas concentrations in mantles increased to 2126 and 1748 μg STX eq. 100 g⁻¹ wet weight, respectively. Concentrations of PSP toxins in these tissues in October 1994 were similar to those measured in October 1993. Concentrations of PSP toxin were less than the regulatory concentration in the gonads and non-detectable in adductor muscles of all scallops sampled.There were no statistically significant differences in profiles for uptake and depuration of PSP toxins in scallops held at the surface compared to those from bottom, suggesting that A. fundyense cysts at the concentrations found in the sediment (45 cysts cm⁻³) did not contribute significantly to the year-round presence of PSP toxins within scallop tissues. The year-round occurrence of PSP toxin is probably due to accumulation during summer blooms followed by a very slow rate of depuration.     

The toxigenic marine dinoflagellate Alexandrium tamarense as the probable cause of mortality of caged salmon in Nova Scotia

The toxins associated with paralytic shellfish poisoning (PSP) are potent neurotoxins produced by natural populations of the marine dinoflagellate Alexandrium tamarense. In early June 2000, a massive bloom (>7×10⁵ cells l⁻¹) of this dinoflagellate coincided with an unusually high mortality of farmed salmon in sea cages in southeastern Nova Scotia. Conditions in the water column in the harbour were characterised by the establishment of a sharp pycnocline after salinity stratification due to abundant freshwater runoff. In situ fluorescence revealed a high sub-surface (2–4 m depth) chlorophyll peak related to the plankton bloom. The intense bloom was virtually monospecific and toxicity was clearly related to the concentration of Alexandrium cells in plankton size fractions. Cultured clonal isolates of A. tamarense from the aquaculture sites were very toxic on a per cell basis and yielded a diversity of PSP toxin profiles, some of which were similar to those from plankton concentrates from the natural bloom population. The toxin profile of plankton concentrates from the 21–56 μm size fraction was complex, dominated by the N-sulfocarbamoyl derivative C2, with levels of other PSP toxins GTX4, NEO, GTX5 (=B1), GTX3, GTX1, STX, C1, and GTX2, in decreasing order of relative abundance. Although no PSP toxin was found systemically in the fish tissues (liver, digestive tract) from this salmon kill event, the detection of Alexandrium cells and low levels of PSP toxins in salmon gills provide evidence that the enhanced mortalities were caused by direct exposure to toxic Alexandrium cells and/or to soluble toxins released during the bloom.     

Toxic Alexandrium minutum (Dinophyceae) from Vietnam with new gonyautoxin analogue

Clonal cultures of Alexandrium species collected from a shrimp pond on the northern coast of Vietnam were established and morphologically identified as Alexandrium minutum. Nucleotide sequences of domains 1 and 2 of the large subunit ribosomal (LSU) rRNA gene showed high sequence similarity to A. minutum isolates from Malaysia. Paralytic shellfish toxin profile of the clones was characterized by the dominance of GTX4, GTX1, and NEO. GTX3, GTX2, and dcSTX were also present in trace amount. Toxin content varied among the strains and growth stages, ranged from 3.0 to 12.5 fmol cell⁻¹. In addition to these known toxin components, a new gonyautoxin derivative was detected by HPLC, eluting between GTX4 and GTX1. The peak of this compound disappeared under non-oxidizing HPLC condition but unchanged either after treated with 0.05 M ammonium phosphate/10% mercaptoethanol or 0.1N HCl hydrolysis. LCMS ion scanning showed a parental ion of [M + H]⁺ at m/z 396, [M − SO₃]⁺ at m/z 316, and [M − SO₄]⁺ at m/z 298. Based on these results, the derivative was identified as deoxy-GTX4-12ol, and this represents the first report of this toxin analogue.     

Effects of growth medium, temperature, salinity and seawater source on the growth of Gymnodinium catenatum (Dinophyceae) from Bahia Concepcion, Gulf of California, Mexico

Laboratory studies were performed to determine the effect oftemperature, salinity, seawater sources and culture media onthe vegetative growth of clonal cultures of Gymnodinium catenatumisolated from Bahía Concepción, Mexico. Theseisolates were heterothallic and isogamous. Exponential growthrates of G. catenatum in f/2 with different selenium concentrationsand soil extract and GSe media were moderate. Maximum cell yieldswere obtained in GSe and f/2 media with selenium (10^–8and 10^–7 M), while in f/2 medium with soil extract cellyields were considerably lower. The highest percentage of longchains was found in f/2 media supplied with selenium (10^–8M). The optimal temperature range for growth was 11.5–30°C,with the highest growth rates between 21 and 29°C. The rangeof salinity tolerated by G. catenatum changed with seawatersource. With seawater from Vineyard Sound (Massachusetts, USA),G. catenatum grew at salinities from 15 to 36, with an optimalgrowth rate obtained at salinities between 26 and 30. With seawaterfrom Bahía Concepción, this species toleratedsalinities from 25 to 40, with optimal growth at salinitiesbetween 28 and 38. Ecophysiological measurements reported hereare consistent with the environment of the bay, which has limitedinput of humic materials from runoff and high salinity and temperature.These data, when viewed with data from studies of globally distributedG. catenatum, demonstrate the ability of this species to livein a broad array of habitats.     

Diet, habitat use, and relative abundance of pampas fox (Pseudalopex gymnocercus) in northern Patagonia, Argentina

Diet, habitat use and relative abundance of pampas fox Pseudalopex gymnocercus were studied in grassland, sand dune, and scrubland habitats, on the Bahía San Blas and Isla Gama Reserve, Argentina. Scat contents showed a generalist diet, where mammals, insects, and fruits were the main food items. Dietary composition differed among habitats; fruits were mainly consumed in sand dunes; insects, mammals, and fruits predominated in grassland; while insects and mammals were frequent in scrubland habitat. The European hare was the most common vertebrate prey and had the major contribution to the biomass of consumed prey. Pampas fox was the most common carnivore of the reserve and used all available habitats, frequenting more regularly scrubland and sand dune than grassland habitat.

Zusammenfassung

Nahrung, Habitatnutzung und relative Abundanz von Pampasfüchsen (Pseudalopex gymnocercus) im nördlichen Patagonien, Argentinien Die Nahrung, Habitatnutzung und relative Abundanz von Pampasfüchsen Pseudalopex gymnocercus wurde auf Grasflächen, Sanddünen und in Strauchhabitaten des Bahía San Blas and Isla Gama Reserve, Argentinien untersucht. Die Analyse von Kotproben ergab eine typische Diät für Generalisten, wobei Säugetiere, Insekten und Früchte die wichtigsten Nahrungsbestandteile waren. Die Nahrungszusammensetzung unterschied sich zwischen verschiedenen Lebensräumen. Früchte wurden hauptsächlich in Sanddünen konsumiert, Insekten, Säugetiere und Früchte auf Grasflächen; und Insekten und Säugetiere in Strauchhabitaten. Der europäische Hase war die häufigste Beuteart unter den Wirbeltieren und stellte den Hauptanteil an der Biomasse genutzter Beute. Der Pampasfuchs ist das häufigste Raubtier im Reservat und nutzt alle vorhandenen Habitate, jedoch kommt er etwas häufiger in Strauchhabitaten und Sanddünen vor als auf Grasflächen.     

Cyst and radionuclide evidence demonstrate historic Gymnodinium catenatum dinoflagellate populations in Manukau and Hokianga Harbours, New Zealand

Between May 2000 and February 2001, a major bloom of the toxic dinoflagellate Gymnodinium catenatum (a causative organism of Paralytic Shellfish Poisoning, PSP) affected over 1500 km of coastline of New Zealand’s North Island. As this was the first record of this species in New Zealand, we aimed to resolve whether this represented a recent introduction/spreading event or perhaps an indigenous cryptic species stimulated by environmental/climatic change. To answer this question, we analysed for G. catenatum resting cysts in ²¹⁰Pb dated sediment cores (18–34 cm long; sedimentation rates 0.34–0.69 cm per year) collected by SCUBA divers from Manukau Harbour, where the species was first detected, and from Hokianga Harbour, where the highest shellfish toxicity was recorded, while using Wellington Harbour as a well-monitored control site. The results of this study conclusively demonstrate that abundant G. catenatum has been in northern New Zealand at least since the early 1980s, increasing up to 1200 cysts/g around the year 2000, but with low cyst concentrations possibly present since at least 1937. In contrast, Wellington Harbour cores contained only very sparse G. catenatum cysts (8 cysts/g), present only to a depth of 7 cm (surface mixed layer depth), reflecting an apparent recent range expansion of this dinoflagellate in New Zealand, possibly stimulated by unusual climatic conditions associated with the 2000 La Nina event. The significant increases since the early 1980s also of Protoperidinium cysts at Hokianga Harbour and of Gonyaulax, Protoperidinium and Protoceratium cysts at Manukau Harbour suggest a broad scale environmental change has occurred in Northland, New Zealand.     

Morphology and taxonomy of chain-forming species of the genus Cochlodinium (Dinophyceae)

The morphology of an unarmored chain-forming harmful dinoflagellate Cochlodinium polykrikoides and its similar species such as Cochlodinium catenatum, Cochlodinium fulvescens, and Cochlodinium convolutum was carefully observed, emphasizing the single cell stage for clarifying taxonomically important morphological features. To differentiate C. polykrikoides from C. convolutum, the shape and the position of the nucleus are useful characters. C. polykrikoides also differs from C. fulvescens in being smaller in size, possessing many rod-shaped chloroplasts and having the sulcus running just below the cingulum on the dorsal surface. Careful observation of the ichnotype of C. catenatum suggests that C. catenatum sensu Kofoid and Swezy collected from off La Jolla, CA, USA, is not identical to C. catenatum sensu Okamura and is probably a different species, in having no chloroplasts and a nucleus positioned at the center of the cell. In addition, C. polykrikoides has many morphological features in common with C. catenatum sensu Okamura except for slightly elongate cells and is probably a junior synonym of this species.     

Estimating the contribution of N-sulfocarbamoyl paralytic shellfish toxin analogs GTX6 and C3 + 4 to the toxicity of mussels (Mytilus galloprovincialis) over a bloom of Gymnodinium catenatum

Gymnodinium catenatum, a dinoflagellate species with a global distribution, is known to produce paralytic shellfish poisoning (PSP) toxins. The profile of toxins of G. catenatum is commonly dominated by sulfocarbamoyl analogs including the C3 + 4 and GTX6, which to date has no commercial certified reference materials necessary for their quantification via chemical methods, such as liquid chromatography. The aim of this study was to assess the presence of C3 + 4 and GTX6 and their contribution to shellfish toxicity. C3 + 4 and GTX6 were indirectly quantified via pre-column oxidation liquid chromatography with fluorescence detection after hydrolysis conversion into their carbamate analogs. Analyses were carried out in mussel samples collected over a bloom of G. catenatum (>63 × 10³ cells l⁻¹) in Aveiro lagoon, NW Portuguese coast. Concentration levels of sulfocarbamoyl toxin analogs were two orders of magnitude higher than decarbamoyl toxins, which were in turn one order of magnitude higher than carbamoyl toxins. Among the sulfocarbamoyl toxins, C1 + 2 were clearly the dominant compounds, followed by C3 + 4 and GTX6. The least abundant sulfocarbamoyl toxin was GTX5. The most important compounds in terms of contribution for sample toxicity were C1 + 2, which justified 26% of the PSP toxicity. The lesser abundant dcSTX constitutes the second most important compound with similar % of toxicity to C1 + 2, C3 + 4 and GTX6 were responsible for approximately 11% and 13%, respectively. The median of the sum of C3 + 4 and GTX6 was 27%. These levels reached a maximum of 60% as was determined for the sample collected closest to the G. catenatum bloom. This study highlights the importance of these low potency PSP toxin analogs to shellfish toxicity. Hydrolysis conversion of C3 + 4 and GTX6 is recommended for determination of PSP toxicity when LC detection methods are used for PSP testing in samples exposed to G. catenatum.     

The influence of size on domoic acid concentration in king scallop, Pecten maximus (L.)

Concentrations of domoic acid (DA), the biotoxin responsible for amnesic shellfish poisoning (ASP), exceeding the regulatory limit of 20 μg g⁻¹ have caused restricted harvesting and closures of wild king scallop fisheries. Toxin monitoring programmes have reported significant inter-animal variation in DA concentration between scallops from the same area. For the development of reliable sampling and management protocols an understanding of the magnitude and causes of inter-animal variation in toxin concentration are important. Ten samples were collected from an aquaculture site in Clew Bay, Co. Mayo off the west coast of Ireland between February 2003 and February 2004, each sample comprising 12 scallops of each of the following size groups: small (70–85 mm), medium (85–100 mm), large (100–115 mm) and very large (>115 mm). DA concentration in each hepatopancreas and in composite samples of both gonad and adductor muscle from each size group on each sampling occasion were measured. High inter-animal variability in DA concentration in hepatopancreas was recorded; CVs ranging from 12.5% to 82.5%. One negative correlation (R² = 0.7079) between DA concentration in hepatopancreas and scallop shell length, three positive but weak correlations (R² = 0.4536, 0.3459 and 0.4665) and six no correlations were exhibited. Negative correlations were attributed to faster DA uptake by smaller scallops, positive correlations to faster DA depuration by smaller scallops. If only scallops greater than or equal to 100 mm shell length, the minimum commercial size of this species were considered, no correlation occurred on any of the 10 sampling occasions.     

Toxin profile of Alexandrium catenella from the Chilean coast as determined by liquid chromatography with fluorescence detection and liquid chromatography coupled with tandem mass spectrometry

The profile of tetrahydropurine neurotoxins associated with paralytic shellfish poisoning (PSP) was determined from a Chilean strain of the marine dinoflagellate Alexandrium catenella. The toxin composition was compared with that of toxic shellfish, presumably contaminated by natural blooms of A. catenella from the same region in southern Chile. Ion pair-liquid chromatography with post-column derivatization and fluorescence detection (LC-FD) was employed for relative quantitative analysis of the toxin components, whereas unambiguous identification of the toxins was confirmed by tandem mass spectrometry (LC–MS/MS). In the dinoflagellate strain from Chile, the N-sulfocarbamoyl derivatives (C1/C2, B1) and the carbamoyl gonyautoxins GTX1/GTX4 comprise >90% of the total PSP toxin content on a molar basis. This toxin composition is consistent with that determined for A. catenella populations from the Pacific coast in the northern hemisphere. The characteristic toxin profile is also reflected in the shellfish, but with evidence of epimerization and metabolic transformations of C1 and C2 to GTX2 and GTX3, respectively. This work represents the first unequivocal identification and confirmation of such PSP toxin components from the Chilean coast.     

Phylogeny, biogeography, and species boundaries within the Alexandrium minutum group

The geographic range and bloom frequency of the toxic dinoflagellate Alexandrium minutum and other members of the A. minutum group have been increasing over the past few decades. Some of these species are responsible for paralytic shellfish poisoning (PSP) outbreaks throughout the world. The origins of new toxic populations found in previously unaffected areas are typically not known due to a lack of reliable plankton records with sound species identifications and to the lack of a global genetic database. This paper provides the first comprehensive study of minutum-group morphology and phylogeny on a global scale, including 45 isolates from northern Europe, the Mediterranean, Asia, Australia and New Zealand.Neither the morphospecies Alexandrium lusitanicum nor A. angustitabulatum was recoverable morphologically, due to large variation within and among all minutum-group clonal strains in characters previously used to distinguish these species: the length:width of the anterior sulcal plate, shape of the 1′ plate, connection between the 1′ plate and the apical pore complex, and the presence of a ventral pore. DNA sequence data from the D1 to D2 region of the LSU rDNA also fail to recognize these species. Therefore, we recommend that all isolates previously designated as A. lusitanicum or A. angustitabulatum be redesignated as A. minutum. A. tamutum, A. insuetum, and A. andersonii are clearly different from A. minutum on the basis of both genetic and morphological data.A. minutum strains from Europe and Australia are closely related to one another, which may indicate an introduction from Europe to Australia given the long history of PSP in Europe and its recent occurrence in Australia. A minutum from New Zealand and Taiwan form a separate phylogenetic group. Most strains of A. minutum fit into one of these two groups, although there are a few outlying strains that merit further study and may represent new species. The results of this paper have greatly improved our ability to track the spread of A. minutum species and to understand the evolutionary relationships within the A. minutum group by correcting inaccurate taxonomy and providing a global genetic database.     

First report of Alexandrium taylori and Alexandrium peruvianum (Dinophyceae) in Malaysia waters

The occurrence of Alexandrium taylori and Alexandrium peruvianum is reported for the first time in Malaysia waters. The Malaysian A. taylori isolates were pyriform in shape with a transdiameter range of 36–40 μm and a cell length range of 33–37 μm. The first apical plate (1′) was pentagonal with two distinctive anterior margins. No direct connection between 1′ and the apical pore complex was observed. The posterior sulcal plate (S.p.) was large, elongated and oblique to the right with anterior projections. The ventral pore (vp) was relatively large and situated at a confluence point of 1′, the second apical (2′) and the fourth apical (4′) plates. Cells of A. peruvianum were slightly anteriorly and posteriorly compressed. S.p. had an irregular pentagonal shape, with the anterior margin divided into 2 portions. 1′ was boomerang-shaped with a large and truncated ventral pore in the middle right margin. The anterior right margin of 1′ was straight. The sixth precingular plate (6″) was wider than long. The anterior sulcal plate (S.a.) was triangular and lacked a left portion extension. In laboratory cultures, both A. taylori and A. peruvianum produced paralytic shellfish toxins, with GTX4 and GTX6 as the predominant toxin, respectively. This is the first report of PSP toxins production for both species as well as the occurrences in Malaysia waters.     

Paralytic shellfish toxin profiles of different geographic populations of Gymnodinium catenatum (Dinophyceae) in Korean coastal waters

Paralytic shellfish poisoning toxin profiles of dinoflagellate cultures of Gymnodinium catenatum Graham from the Yellow and South Seas in Korea were investigated by high performance liquid chromatography fluorometric detection. Strains from the Yellow Sea had predominantly carbamate toxins, while strains from Sujeongri and Chindong in the South Sea contained the N‐sulfocarbamoyl toxins, Cl,2, as major components including the presence of GTX5 and dcSTX in some strains. Toxin profiles from St. Deukryang Bay strains (South Sea) showed both characteristics of those in the South Sea and those in the Yellow Sea. Thirty strains could be divided into three groups based on cluster analysis of toxin compositions. Group I (Yellow Sea strains) was distinguished from Group II (Sujeongri and Chindong strains) by the absence of GTX5 and dcSTX. Group III comprised Deukryang Bay strains. In conclusion, the Yellow Sea and the South Sea were found to have different dinoflagellate populations with different toxin compositions.     

Molecular quantification of toxic Alexandrium fundyense in the Gulf of Maine using real-time PCR

The toxic dinoflagellate Alexandrium fundyense is widespread in the northeastern part of North America, including the Gulf of Maine, and is responsible for seasonal harmful algal blooms in these regions. Even at low cell densities, A. fundyense toxins can accumulate in shellfish and result in paralytic shellfish poisoning (PSP). PSP can be debilitating or lethal to humans and other shellfish consumers and is a public health concern. As a result, accurate measurements of A. fundyense distributions, particularly at low cell density, are critical to continued PSP monitoring and mitigation efforts. Towards this end we have developed a real-time quantitative PCR (qPCR) method to monitor A. fundyense. Laboratory validation indicates that the qPCR assay is sensitive enough to detect 10 cells per sample, and that it does not detect co-occurring dinoflagellates such as Alexandrium ostenfeldii. The qPCR methodology was used to quantify A. fundyense cell densities in samples collected during a spring 2003 transect in the Gulf of Maine, and the data were compared to those obtained in parallel from light microscope and DNA hybridization-based methods. Results show that A. fundyense cell density was low during this period relative to typical cell densities required for PSP contamination of local shellfish, and that qPCR values were comparable to numbers determined by independent methods.