43 Testeria gen. nov. (dinophyceae) from manatee cay belize, Central America

Saxitoxin and domoic acid sequestration by bivalve molluscs occurs periodically along the Oregon coast, presumably as a result of harmful algal blooms (HABs). Since 1958 and more continuously since 1979, the Oregon Shellfish Program (OSP) has assayed toxin levels in these molluscs as part of a monitoring program for paralytic (PSP) and amnesic (ASP) shellfish poisoning. We have created a working data base for all PSP sampling by the OSP between 1958 and 2001 and have examined the data for spatial and temporal trends in the appearance of toxin in shellfish, amount of toxin, and apparent duration of toxic events. In this report, we examine the data from the five stations with the longest record of continuous sampling (1979–2000) for evidence of correlation with El Niño events, upwelling, and/or a pattern of increasing frequency or intensity of toxic events. We also compare the pattern of appearance of toxin at open coast stations with the timing of first appearance of toxin in shellfish at adjacent estuarine stations. This is an important analysis because, in Oregon, shellfish closures due to PSP occur frequently in mussel beds on the open coast and the source of toxin-producing organisms is unknown.     

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.     

First report of paralytic shellfish poisoning (PSP) caused by Alexandrium tamiyavanichii in Kuantan Port,Pahang, East Coast of Malaysia

Harmful algal bloom (HAB) is a proliferation of algae, which naturally produce biotoxins and cause harmful effects to humans, the environment and organisms associated with it. Paralytic shellfish poisoning (PSP) was reported for the first time in Kuantan Port, Pahang, Malaysia, in November 2013, followed by a second episode in August 2014. The toxicity level reported during the second event was as high as 3500 μg of STX equiv./100 g shellfish. Ten people were hospitalized with PSP symptoms after consuming contaminated shellfish. This study was conducted at Kuantan Port to identify the organisms responsible for these events. Water samples were collected monthly for a period of 12 months beginning in September 2014. HAB species were identified based on their morphology using light and fluorescence microscopes, and their classification was supported by molecular evidence based on internal transcribed spacer (ITS) sequences. Monthly cell abundance of Alexandrium tamiyavanichii was measured at four sampling stations. Toxin production by three strains isolated from the area was determined using HPLC. Our results revealed the presence of several HAB species, including the PSP‐producing species A . tamiyavanichii . The highest cell density of A . tamiyavanichii was 840 cells L^?1. The presence of GTX components was detected in these strains. However, other toxin components could not be determined. This study reported, for the first time, the presence of PSP‐producing A . tamiyavanichii on the Pahang coast of east Peninsular Malaysia and confirmed that the PSP events in Kuantan Port were attributable to this species. The presence of this species further indicates that several safety measures need to be considered to safeguard public health, particularly in Pahang coastal waters.     

Characterization of nontoxic and toxin-producing strains of Alexandrium minutum (Dinophyceae) in Irish coastal waters

A comparative analysis of the morphology, toxin composition, and ribosomal DNA (rDNA) sequences was performed on a suite of clonal cultures of the potentially toxic dinoflagellate Alexandrium minutum Halim. These were established from resting cysts or vegetative cells isolated from sediment and water samples taken from the south and west coasts of Ireland. Results revealed that strains were indistinguishable, both morphologically and through the sequencing of the D1-D2 domain of the large subunit and the ITS1-5.8S-ITS2 regions of the rDNA. High-performance liquid chromatography fluorescence detection analysis, however, showed that only strains derived from retentive inlets on the southern Irish coast synthesized paralytic shellfish poisoning (PSP) toxins (GTX2 and GTX3), whereas all strains of A. minutum isolated from the west coast were nontoxic. Toxin analysis of net hauls, taken when A. minutum vegetative cells were in the water column, revealed no PSP toxins in samples from Killary Harbor (western coast), whereas GTX2 and GTX3 were detected in samples from Cork Harbor (southern coast). These results confirm the identity of A. minutum as the most probable causative organism for historical occurrences of contamination of shellfish with PSP toxins in Cork Harbor. Finally, random amplification of polymorphic DNA was carried out to determine the degree of polymorphism among strains. The analysis showed that all toxic strains from Cork Harbor clustered together and that a separate cluster grouped all nontoxic strains from the western coast.     

Characterization of Nontoxic and Toxin-Producing Strains of Alexandrium minutum (Dinophyceae) in Irish Coastal Waters

A comparative analysis of the morphology, toxin composition, and ribosomal DNA (rDNA) sequences was performed on a suite of clonal cultures of the potentially toxic dinoflagellate Alexandrium minutum Halim. These were established from resting cysts or vegetative cells isolated from sediment and water samples taken from the south and west coasts of Ireland. Results revealed that strains were indistinguishable, both morphologically and through the sequencing of the D1-D2 domain of the large subunit and the ITS1-5.8S-ITS2 regions of the rDNA. High-performance liquid chromatography fluorescence detection analysis, however, showed that only strains derived from retentive inlets on the southern Irish coast synthesized paralytic shellfish poisoning (PSP) toxins (GTX2 and GTX3), whereas all strains of A. minutum isolated from the west coast were nontoxic. Toxin analysis of net hauls, taken when A. minutum vegetative cells were in the water column, revealed no PSP toxins in samples from Killary Harbor (western coast), whereas GTX2 and GTX3 were detected in samples from Cork Harbor (southern coast). These results confirm the identity of A. minutum as the most probable causative organism for historical occurrences of contamination of shellfish with PSP toxins in Cork Harbor. Finally, random amplification of polymorphic DNA was carried out to determine the degree of polymorphism among strains. The analysis showed that all toxic strains from Cork Harbor clustered together and that a separate cluster grouped all nontoxic strains from the western coast.     

Tn5 MUTAGENESIS OF PSEUDOMONAS STUTZERI SF/PS, A BACTERIUM ASSOCIATED WITH ALEXANDRIUM LUSITANICUM (DINOPHYCEAE) AND PARALYTIC SHELLFISH POISONING

It is becoming increasingly clear that bacteria can play an important role in the toxin and population dynamics of harmful algal bloom (HAB) events. In this paper, we document protocols and strategies that can be used to identify bacterial genes involved in either the production of toxic compounds and/or the establishment and maintenance of relationships between bacteria and algae. The protocols we tested involved transposon mutagenesis and complementation with broad-host-range plasmids. We tested six bacterial strains thought to be involved, either directly or indirectly, in the production of toxins associated with paralytic shellfish poisoning (PSP). Five strains were resistant to transformation under the growth conditions used. However, a single strain, Pseudomonas stutzeri SF/PS, was readily transformed when grown under appropriate conditions. This bacterium has been shown to accumulate PSP toxins and to increase toxin production when added to axenic cultures of a toxic dinoflagellate, Alexandrium lusitanicum . We conclude that a transposon mutagenesis strategy can be used to identify genes involved in HAB events.     

A fluorimetric method based on changes in membrane potential for screening paralytic shellfish toxins in mussels

To prevent the consumption of bivalves contaminated with paralytic shellfish poisoning (PSP), toxin levels in seafood products are estimated by using the official mouse bioassay. Because of the limitations of this bioassay other methods of monitoring toxins are clearly needed. We have developed a test to screen for PSP toxins based on its functional activity; the toxins bind to the voltage-gated Na+ channels and block their activity. The method is a fluorimetric assay that allows quantitation of the toxins by detecting changes in the membrane potential of human excitable cells. This assay gives an estimate of toxicity, since each toxin present in the sample binds to sodium channels with an affinity which is proportional to its intrinsic toxic potency. The detection limits for paralytic shellfish toxins were found to be 1 ng saxitoxin equivalents/ml compared to the regulatory limit threshold of 400 ng/ml (equivalent to 80 microg/100 g) used in most countries. Our results indicate that this fluorescent assay is a specific, very sensitive, rapid, and reliable method of monitoring PSP toxin levels in samples from seafood products and toxic algae.     

Detection of bacteria originally isolated from Alexandrium spp. in the midgut diverticula of Mytilus edulis after water-borne exposure

Bacteria associated with toxic dinoflagellates have been implicated in the production of paralytic shellfish poisoning (PSP) toxins, but it has not been substantiated that bacteria are truly capable of autonomous PSP toxin synthesis or what role bacteria may play in shellfish toxification. In this study, different putatively PSP toxin producing bacteria originally isolated from toxic Alexandrium spp. were exposed to the blue mussel Mytilus edulis. To document that these bacteria accumulated in the digestive tract of the mussels, hybridization techniques that use rRNA targeted oligonuceotides for in situ identification of these bacteria were applied. The mussel hepatopancreas was dissected and paraffin and frozen sections were made. The dissected glands were hybridized with digoxigenin-labelled 16S rRNA oligonucleotide probes. Results demonstrate that mussels will readily uptake and accumulate these bacteria in the hepatopancreas. However, the mussels were not rendered toxic by the ingestion of the bacteria as determined by HPLC with UV detection for PSP toxins and determination of sodium channel blocking activity using the mouse neuroblastoma assay. Thus, although the role that bacteria play in mussel toxification remains unclear, methods are now available which will aid in further investigation of this relatively unexplored area.     

中国东海和南海有害赤潮高发区麻痹性贝毒素研究

用小白鼠生物检测法和高效液相色谱法对采自浙江舟山和广东深圳海域贝类的麻痹性贝毒素进行了调查和分析,结果表明,舟山海域近岸的贝类毒素检出率为14％,染毒的贝类毒素含量不高,低于小白鼠生物检测法的测定范围;深圳近岸贝类毒素检出率为30％以上,华贵栉孔扇贝是主要的染毒贝类,有1个样品毒素含量达5．1Mu·g-1,超出安全食用标准．从深圳大亚湾华贵栉孔扇贝检测出10种麻痹性贝毒素成分,消化腺的主要毒素成分为GTXl+2和GTX5,Cl+2和GTX2+3,而剔除消化腺后其余贝组织的主要成分为neoSTX和GTX5．贝毒素主要积累在扇贝的消化腺内,消化腺含有的毒素是贝肉组织的8倍．     

Interannual variability of PSP outbreaks on the north east UK coast

Paralytic shellfish poisoning (PSP) occurs sporadically on theNB UK coast. The degree of toxicity shows considerable interannualvariability, but particularly severe events occurred in 1968and 1990. The time sequence of PSP toxin production in 1990is described and compared with 1989 when no significant PSPtoxin occurred. In 1990, PSP toxin was widespread in shellfishsamples taken on 300 km of coastline, from Berwick to Whitby,and toxin was present at high concentrations for >1 month.The distribution of Alerandrium tamarense cysts in the sedimentsis described. High concentrations were found in the Firth ofForth and also in a number of regions offshore of the Scottishand English coasts. A water transport model has been used toestimate back trajectories, with the aim of determining thesource of the A.tamarense bloom. The Firth of Forth has previouslybeen suggested as the seed bed for A.tamarense outbreaks inthe area, but the transport model clearly shows that A.tanwrensemoved inshore over a wide area in 1990; there was no singlesource of the bloom. Sea surface temperatures, estimated fromsatellite imagery, show that water temperatures were much higherat the end of April 1990, when the bloom occurred, than in 1989when PSP toxin incidence was very low. These conditions wouldhave resulted in early seasonal stratification and would havefavoured phytoplankton growth in the water column.     

Toxic events in the Northwest Pacific coastline of Mexico during 1992–1995: origin and impact

Previously considered as toxin-free, the Baja California Peninsula has witnessed several toxic algal blooms during the past three years. Apparently these ‘red-tide’ phenomena's outbreaks are not linked to any human related activity. This may just reflect better detection and training. Such events may be periodical and natural rather than induced. The most common types of marine toxins have been detected along the coast of the Peninsula and neighboring waters by mouse bioassay and chromatographic techniques. These are: Tetrodotoxin (TTX), Amnesic Shellfish Poison (ASP), Paralytic Shellfish Poisons (PSP), Diarrhetic Shellfish Poisons (DSP) and even Ciguatera (CFP), which are related to the presence of organisms of Prorocentrum sp. and Alexandrium sp. groups, and the diatom Pseudonitzschia sp. among others. There are also some indications about different kinds of TTX in the puffer fish of the region, and reasons to believe that we are facing a quite different pattern in toxic components, since PSP toxic potency (defined as the number of mouse units per gram(MU/g)of shellfish meat) is very high in spite of low dinoflagellates cell density registered. The ecological and social impact of the above has been considerable, with mass deaths of shellfish, seagulls, dolphins and turtles, and even some human casualties. The locally registered toxicity records: PSP found in one single fanshell reaches to 23 000 MU/100 g of tissue as determined by the mouse bioassay and, on a different event, two persons killed after ingesting puffer fish fillet. The largest reservoir of commercial marine organisms in Mexico is precisely the Northwest coast of the country and important plans for building large harbors and develop aquaculture areas are in progress. Therefore, a monitoring program is essential for an adequate management of such resources. Considering the large extension of the Peninsula (about1600 km)and, at this time, the lack of efficient communication means and scarce population, the implementation of such monitoring programs presents a big challenge. This revised version was published online in August 2006 with corrections to the Cover Date.     

Determination of paralytic shellfish poisoning (PSP) toxins in UK shellfish

A study was conducted to aid the interpretation of data generated by parallel testing of the qualitative Jellett Rapid Test (JRT) and the mouse bioassay (MBA) for detection of paralytic shellfish poisoning (PSP) toxins within the UK statutory shellfish biotoxin monitoring programme. A selection of stored sample extracts subjected to testing by MBA and/or JRT were further analysed by liquid chromatography with fluorescence detection (LC–FLD) to provide additional information on the concentrations of PSP toxins and toxin profiles.Results, from this study, demonstrate the potential of the JRT to effectively screen out PSP toxin negative shellfish samples and samples containing low concentrations of toxins from UK monitoring programmes. Additionally, data generated using LC–FLD highlights the potential of introducing alternative analytical techniques to completely replace the requirement for the MBA.     

A shift in the dominant toxin-producing algal species in central California alters phycotoxins in food webs

In California, the toxic algal species of primary concern are the dinoflagellate Alexandrium catenella and members of the pennate diatom genus Pseudo-nitzschia, both producers of potent neurotoxins that are capable of sickening and killing marine life and humans. During the summer of 2004 in Monterey Bay, we observed a change in the taxonomic structure of the phytoplankton community—the typically diatom-dominated community shifted to a red tide, dinoflagellate-dominated community. Here we use a 6-year time series (2000–2006) to show how the abundance of the dominant harmful algal bloom (HAB) species in the Bay up to that point, Pseudo-nitzschia, significantly declined during the dinoflagellate-dominated interval, while two genera of toxic dinoflagellates, Alexandrium and Dinophysis, became the predominant toxin producers. This change represents a shift from a genus of toxin producers that typically dominates the community during a toxic bloom, to HAB taxa that are generally only minor components of the community in a toxic event. This change in the local HAB species was also reflected in the toxins present in higher trophic levels. Despite the small contribution of A. catenella to the overall phytoplankton community, the increase in the presence of this species in Monterey Bay was associated with an increase in the presence of paralytic shellfish poisoning (PSP) toxins in sentinel shellfish and clupeoid fish. This report provides the first evidence that PSP toxins are present in California's pelagic food web, as PSP toxins were detected in both northern anchovies (Engraulis mordax) and Pacific sardines (Sardinops sagax). Another interesting observation from our data is the co-occurrence of DA and PSP toxins in both planktivorous fish and sentinel shellfish. We also provide evidence, based on the statewide biotoxin monitoring program, that this increase in the frequency and abundance of PSP events related to A. catenella occurred not just in Monterey Bay, but also in other coastal regions of California. Our results demonstrate that changes in the taxonomic structure of the phytoplankton community influences the nature of the algal toxins that move through local food webs and also emphasizes the importance of monitoring for the full suite of toxic algae, rather than just one genus or species.     

Effect of the endoparasite Amoebophrya sp. on toxin content and composition in the paralytic shellfish poisoning dinoflagellate Alexandrium fundyense (Dinophyceae)

Members of the Amoebophrya ceratii complex are endoparasitic dinoflagellates that parasitize a number of their dinoflagellate relatives, including toxic and/or harmful algal bloom-forming species. Despite many studies on the occurrence, prevalence, biology and molecular phylogeny of Amoebophrya spp., little attention has been given to toxin dynamics of host population following parasitism. Using Amoebophrya sp. infecting the paralytic shellfish toxin (PSP)-producing dinoflagellate Alexandrium fundyense, we addressed the following questions: (1) does parasitism by Amoebophrya sp. alter toxin content and toxin profiles of the dinoflagellate A. fundyense over the infection cycle? and (2) do parasite dinospores produced at the end of the infection cycle retain host toxins and thus potentially act as a vector to convey PSP toxin through the marine microbial food-web? Toxin time-course experiments showed that the PSP toxin contents did not vary significantly over the infection cycle, but mean toxin content for infected cultures was significantly higher than that for uninfected cultures. Host toxins were not detected in the free-living, dinospore stage of the parasite. Therefore, our results indicate that Amoebophrya sp. does not function as a vector for transferring PSP toxins to higher trophic levels. Rather, Amoebophrya infections appear to play an important role in maintaining healthy ecosystems by transforming potent toxins-producing dinoflagellates into non-toxic dinospores, representing “edible food” for consumers of the marine microbial food-web during toxic algal bloom event.     

A receptor binding assay for paralytic shellfish poisoning toxins: recent advances and applications

We recently described a high throughput receptor binding assay for paralytic shellfish poisoning (PSP) toxins, the use of the assay for detecting toxic activity in shellfish and algal extracts, and the validation of 11-[3H]-tetrodotoxin as an alternative radioligand to the [3H]-saxitoxin conventionally employed in the assay. Here, we report a dramatic increase in assay efficiency through application of microplate scintillation technology, resulting in an assay turn around time of 4 h. Efforts are now focused on demonstrating the range of applications for which this receptor assay can provide data comparable to the more time consuming, technically demanding HPLC analysis of PSP toxins, currently the method of choice for researchers. To date, we have compared the results of both methods for a variety of sample types, including different genera of PSP toxin producing dinoflagellates (e.g. Alexandrium lusitanicum, r2 = 0.9834, n = 12), size-fractioned field samples of Alexandrium spp. (20-64 microm; r2 = 0.9997, n = 10) as well as its associated zooplankton grazer community (200-500 microm: r2 = 0.6169, n = 10; >500 microm: r2 = 0.5063, n = 10), and contaminated human fluids (r2 = 0.9661, n = 7) from a PSP outbreak. Receptor-based STX equivalent values for all but the zooplankton samples were highly correlated and exhibited close quantitative agreement with those produced by HPLC. While the PSP receptor binding assay does not provide information on toxin composition obtainable by HPLC, it does represent a robust and reliable means of rapidly assessing PSP-like toxicity in laboratory and field samples. Moreover, this assay should be effective as a screening tool for use by public health officials in responding to suspected cases of PSP intoxication.     

Profiles of Alexandrium catenella cysts in Puget Sound sediments and the relationship to paralytic shellfish poisoning events

The magnitude of paralytic shellfish poisoning (PSP) toxins in shellfish and the geographical scope of shellfish closures in Puget Sound have increased in recent decades. PSP, monitored by the Washington Department of Health, has spread from Sequim Bay in the 1950s into central Puget Sound in the 1970s and throughout Puget Sound by the 1990s. Alexandrium catenella, the species responsible for PSP toxins, produces a benthic resting cyst that, upon germinating, can seed blooms. This study examined whether there is a relationship between profiles of cysts in the sediment and temporal variation in PSP in shellfish and if the history of the toxin's southward expansion through Puget Sound can be seen in the cyst record. To address this question, sediment cores were collected from three Puget Sound basins, Sequim Bay, Penn Cove, and Carr Inlet, and cyst profiles were determined. Activities of ²¹⁰Pb were fitted to a depth-dependent diagenetic model to date the sediment cores and determine mixing and sediment-accumulation rates. In order to compare historical variation in PSP with cyst profiles that have been altered by bioturbation, a depth and time-dependent diagenetic model was then used to predict vertical profiles of cysts that would occur under the assumption that cyst deposition rates are proportional to PSP concentration in shellfish measured over several decades at each site. The cyst profiles predicted by the model were compared to measured cyst profiles. These comparisons suggested that Alexandrium blooms and resulting PSP concentration in shellfish are more closely linked to cyst germination and deposition at some stations than at others. Sequim Bay had relatively large numbers of cysts and it is likely that the persistent toxicity here is the result of recurrent seeding from the cyst bed. Penn Cove and Carr Inlet had few cysts despite occasional blooms, suggesting that blooms are transported into those areas, perhaps from other sites of cyst germination. Sequim Bay and Penn Cove had cysts from top to bottom of the cores so it was not possible to determine the date when cysts were first introduced into these bays, but it is likely that A. catenella has been in Penn Cove since at least 1955 or for about two decades before the WDOH PSP toxicity data would indicate. The cyst profile in Carr Inlet suggested a first appearance date of 1985 that is consistent with the first appearance of PSP in shellfish in 1988.     

Prorocentrum lima (Dinophyceae) in northeastern USA coastal waters: II: Toxin load in the epibiota and in shellfish

The seasonal variation in diarrhetic shellfish poisoning (DSP)-type toxins was followed in the epibiotic community and in shellfish between 41° and 44°N in coastal waters of the northwest Atlantic during a 2-year period. Low levels of okadaic-acid equivalents were detected at all stations in the <90 μm fraction of the collected epibiota as measured by the protein phosphatase inhibition assay, but only 3.5% of the samples had values greater than 100 ng (g dry weight of epibiota)⁻¹. No seasonal pattern could be detected due to differences in intensity, duration and timing of toxin content in the epibiota between the 2 years and between stations. Nevertheless, the concentration of DSP-type toxins in the epibiota correlated weakly but significantly with the abundance of Prorocentrum lima, when data from all stations were considered. A very limited toxin uptake by shellfish was measured at only one station in October and November 2001 and in June and July 2002 at times of maximum cell concentration of P. lima in the epibiota. Toxin levels in shellfish remained well below regulatory limits that would have required quarantine or bans on harvesting. Results from our 2-year survey suggest that, at this time, the threat of DSP events appears minimal. However, the presence of a known toxin producer and its demonstrated ingestion by shellfish would argue for further studies to better understand conditions leading to DSP outbreaks generated by an epiphytic dinoflagellate.     

Toxic dinoflagellates in the Mediterranean sea

Abstract

A review of the distribution of toxic dinoflagellates and related toxic events in the Mediterranean Sea is provided. Diarrhetic shellfish poisoning (DSP) and paralytic shellfish poisoning (PSP) are the main seafood contaminations, that have been reported since 1987. In 1994 four lethal cases for PSP were reported in Morocco. DSP seems to be restricted in the Northern part of the basin, while PSP contamination presents a wider distribution. Potentially DSP species, belonging to the genus Dinophysis, are widely distributed in the Mediterranean Sea, suggesting a wider extension of this contamination. The lack of monitoring programs in the Southern Mediterranean could be responsible of DSP overlooking. The species responsible for PSP are Gymnodinium catenatum in the Alboran Sea and Alexandrium minutum in various parts of the basin. Ichtyotoxic effects, due to Gymnodinium and Gyrodinium species, have been sporadically reported in some Mediterranean areas.     

Comparative accumulation and composition of lipophilic marine biotoxins in passive samplers and in mussels (M. edulis) on the West Coast of Ireland

Monitoring of lipophilic marine toxins was carried out in three shellfish production sites on the West Coast of Ireland. The toxins were monitored using passive samplers (solid phase adsorption toxin tracking; SPATT) and toxin-free mussels that were replaced weekly in the selected sampling stations. The toxin profiles and concentrations obtained in the SPATT and in the transplanted mussels were compared with those observed in indigenous (native) mussels from each production site as well as with the phytoplankton that was detected in the water. Numerous lipophilic toxins were detected in the SPATT discs by ultra-performance liquid-chromatography–mass spectrometry/mass spectrometry (UPLC–MS/MS) and included okadaic acid (OA), dinophysistoxin-2 (DTX2), pectenotoxin-2 (PTX2), AZA1, AZA2, yessotoxin (YTX) and SPX-13-DesMe-C. The accumulation rate of toxins in the indigenous mussels and in the SPATT discs correlated well. Toxins were detected in all SPATT discs from all locations, even in the absence of toxin-producing phytoplankton, as observed previously by other research groups. It is quite clear from our data that the presence of okadaic acid in the water (even at high concentrations) did not induce toxicity in the transplanted mussels in the absence of phytoplankton. A severe toxic event of azaspiracids (AZAs) occurred in one of the sampling stations. The SPATT discs accumulated predominantly AZA1 and -2 suggesting that both toxins are biosynthesized by the AZA-producing organism. As opposed to the DSP event, the AZA event resulted in the contamination of the transplanted mussels for several consecutive weeks. This is the first study that reports the presence of YTX and SPX-13-DesMe-C in Irish waters. In our study conditions, the SPATT did not enable the forecasting of shellfish contamination as the increase in toxin concentration occurred at the same time in the shellfish and in the SPATT.     

Alexandrium (Dinophyceae) species in Malaysian waters

A study was carried out to determine the presence of paralytic shellfish poisoning (PSP) toxin-producing dinoflagellates in the coastal waters of Peninsula Malaysia. This followed first ever occurrences of PSP in the Straits of Malacca and the northeast coast of the peninsula. The toxic tropical dinoflagellate Pyrodinium bahamense var. compressum was never encountered in any of the plankton samples. On the other hand, five species of Alexandrium were found. They were Alexandrium affine, Alexandrium leei, Alexandrium minutum, Alexandrium tamarense and Alexandrium tamiyavanichii. Not all species were present at all sites. A. tamiyavanichii was present only in the central to southern parts of the Straits of Malacca. A. tamarense was found in the northern part of the straits, while A. minutum was only found in samples from the northeast coast of the peninsula. A. leei and A. affine were found in both the north and south of the straits. Cultured isolates of A. minutum and A. tamiyavanichii were proven toxic by the receptor binding assay for PSP toxins but A. tamarense clones were not toxic. Mean toxin content for the A. tamiyavanichii and A. minutum clones were 26 and 15 fmol per cell STX equivalent, respectively. This study has provided evidence on the presence of PSP toxin-producing Alexandrium species in Malaysian waters which suggests that PSP could increase in importance in the future.