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This paper examines the character of phytoplankton blooms in a restricted sub-tropical lagoon along the Atlantic coast of central Florida. The results of the 23-year study (1997–2020) provide evidence for multiple types of variability in bloom activity, including cyclical patterns, stochastic events, and most prominently a regime shift in composition and intensity. Cyclical patterns (e.g., El Niño/La Niña periods) and stochastic events (e.g., tropical storms) influenced rainfall levels, which in turn impacted nutrient concentrations in the water column and the timing and intensity of blooms. In 2011, a major change occurred in the character of blooms, with a dramatic increase in peak biomass levels of blooms and the appearance of new dominant taxa, including the brown tide speciesAureoumbra lagunensisand other nanoplanktonic species. Results of quantitative analyses reveal system behavior indicative of a regime shift. The shift coincided with widespread losses of seagrass community and reduced drift algae biomass. A combination of exceptionally low water temperatures in the winters of 2009/2010 and 2010/2011, hypersaline conditions associated with drought conditions, and high light attenuation caused by blooms appear to have contributed to the widespread and protracted decline in seagrass and drift macroalgal communities in the lagoon, leading to shifts in distribution of internal and external nutrient sources toward phytoplankton.

In September and November 2016, eight marine sampling sites along the coast of the southeastern Gulf of Mexico were monitored for the presence of lipophilic and hydrophilic toxins. Water temperature, salinity, hydrogen potential, dissolved oxygen saturation, inorganic nutrients and phytoplankton abundance were also determined. Two samples filtered through glass fiber filters were used for the extraction and analysis of paralytic shellfish toxins (PSTs) by lateral flow immunochromatography (IFL), HPLC with post-column oxidation and fluorescent detection (FLD) and UHPLC coupled to tandem mass spectrometry (UHPLC-MS/MS). Elevated nutrient contents were associated with the sites of rainwater discharge or those near anthropogenic activities. A predominance of the dinoflagellate Pyrodinium bahamense was found with abundances of up to 104 cells L−1. Identification of the dinoflagellate was corroborated by light and scanning electron microscopy. Samples for toxins were positive by IFL, and the analogs NeoSTX and STX were identified and quantified by HPLC-FLD and UHPLC-MS/MS, with a total PST concentration of 6.5 pg cell−1. This study is the first report that confirms the presence of PSTs in P. bahamense in Mexican waters of the Gulf of Mexico.

Pyrodinium bahamense, a harmful alga which causes paralytic shellfish poisoning (PSP), has been found in seawater samples collected along bays in Eastern Visayas in the Philippines. Due to its negative impacts and uncertainty in its occurrence, there is a need to develop a real-time monitoring device of the harmful algal bloom (HAB) occurrence. This study aims to determine whether there is significant relationship between the dependent variable, the P. bahamense cell density, and the independent variables, namely, temperature, rainfall and humidity, bays in Eastern Visayas, and sampling month. This was done through data mining technique of P. bahamense cell density and weather patterns and statistically analyzing the datasets, with P. bahamense cell density as the dependent variable and weather patterns, bays and sampling month as independent variables using M5P regression analysis. Through the regression analysis, the usefulness of the predictive model as an initial development can be assessed. Results of the study showed that the correlation coefficient of P. bahamense with the five independent variables is 0.725 which signified a moderate correlation between P. bahamense cell density and bay, sampling month, temperature, rainfall and humidity. Maximum cell density, which was 20 cells/L occurred during months of wet season in the bays in Eastern Visayas, except in Cancabato bay while the minimum cell density, which was 0 cell/L occurred during months of dry season. It can be concluded from the results that there is enough data to say that there is a significant relationship between P. bahamense occurrence and temperature, rainfall and humidity, so the model is meaningful and useful at alpha = 0.05 or 95% and 0.01 or 99% confidence interval. The data can be used to generate a predictive model for P. bahamense occurrence relative to its cell density.

High-biomass blooms of the toxic dinoflagellate Pyrodinium bahamense occur most summers in Tampa Bay, Florida, USA, posing a recurring threat to ecosystem health. Like many dinoflagellates, P. bahamense forms immobile resting cysts that can be deposited on the seafloor-creating a seed bank that can retain the organism within the ecosystem and initiate future blooms when cysts germinate. In this study, we examined changes in the dormancy status of cysts collected from Tampa Bay and applied lessons from plant ecology to explore dormancy controls. Pyrodinium bahamense cysts incubated immediately after field collection displayed a seasonal pattern in dormancy and germination that matched the pattern of cell abundance in the water column. Newly deposited (surface) cysts and older (buried) cysts exhibited similar germination patterns, suggesting that a common mechanism regulates dormancy expression in new and mature cysts. Extended cool- and warm-temperature conditioning of field-collected cysts altered the cycle of dormancy compared with that of cysts in nature, with the duration of cool temperature exposure being the best predictor of when cysts emerged from dormancy. Extended warm conditioning, on the other hand, elicited a return to dormancy, or secondary dormancy, in nondormant cysts. These results directly demonstrate environmental induction of secondary dormancy in dinoflagellates-a mechanism common and thoroughly documented in higher plants with seasonal growth cycles. Our findings support the hypothesis that a seasonal cycle in cyst germination drives P. bahamense bloom periodicity in Tampa Bay and point to environmentally induced secondary dormancy as an important regulatory factor of that cycle.

In contrast to temperate Harmful Algal Blooms (HABs), knowledge on the mechanisms driving tropical HABs are less well studied. The interaction of a seasonal temperature window, cysts (for certain species) and large-scale transport are some of the key processes in temperate HABs. In the Philippines, HABs occur not along long open coastlines, but in embayments that are highly influenced by run-off and stratification. These embayments are typically also the sites of cultured or wild harvest shellfish and other aquaculture activities. Sorsogon Bay in the northeastern Philippines has experienced prolonged shellfish-harvesting bans due to blooms by Pyrodinium bahamense var. compressum severely affecting the fisheries industry in this area, as well as leading to Paralytic Shellfish Poisoning illnesses and fatalities. A novel integrated model was developed that mechanistically captures the interactions between hydrodynamic conditions, nutrients, the life history (cells and cysts) of Pyrodinium, as well as the cultured shellfish within the bay and their ensuing toxicities due to ingestion of toxic Pyrodinium cells and cysts. This is the second model developed for HABs in the Philippines, and the first to integrate different components of Pyrodinium bloom dynamics. The model is modularly composed of a watershed nutrient and diffusion model, a 3D hydrodynamic model, a Pyrodinium population model and a shellfish toxin model. It was able to capture the observed temporal variations of Pyrodinium and shellfish toxicity. It was also able to represent some aspects of the spatial distribution in Sorsogon Bay though there were discrepancies. To explore the dynamics of blooms, the linkages between the bloom and decline of the Pyrodinium population with shellfish toxicity as affected by temperature, salinity and nutrients were investigated. Comparisons with field results showed the seasonality of blooms in Sorsogon Bay is driven by increased rainfall. The timing of these conditions is important in facilitating Pyrodinium excystment and reproduction. Model results showed as well the potential significance of shellfish grazing and dinoflagellate cell mortality in influencing the decline of the bloom, and toxicity levels. This approach is promising in helping to understand mechanisms for HABs more holistically, and the model can be further improved to provide more precise quantitative information.

Since decades, Indonesia suffers from harmful algal bloom events, resulting in environmental, socio-economic and health problems. The dinoflagellate Pyrodinium bahamense var. compressum is a toxic phytoplankton species that has been found to form blooms and toxic events in Ambon Bay, eastern Indonesia. As a result of monitoring efforts, other potentially toxic phytoplankton species are also frequently detected. However, information regarding toxin composition and dynamics were lacking for Ambon Bay as well as for Indonesia at large. The present study was aimed to investigate dynamics of toxic phytoplankton species and their associated toxins in conjunction with environmental drivers in Ambon Bay. The results revealed several toxic phytoplankton species such as Pseudo-nitzschia spp., Alexandrium spp., Gymnodinium catenatum, and Dinophysis spp. as well as their associated toxins. Further dinocyst analyses revealed high abundances of Polysphaeridium zoharyi (cysts of the toxic Pyrodinium bahamense) in the inner part of Ambon Bay. This region receives massive allochthonous organic matter and major nutrients (N and P) via runoff, which fuel high productivity and promote (toxic) harmful algal blooms. Generally, toxic phytoplankton showed species specific responses to a range of environmental drivers. Yet, factors such as temperature, mixing depth, irradiance attenuation, ammonium and nitrate played major roles in regulating cell abundance and toxin levels. In conclusion, Ambon Bay is a potential seedbank for future harmful algal blooms and toxic outbreaks. Hence, dynamics of potentially toxic species and their toxins should be monitored year round, particularly in the inner bay, to avoid future economic loss and human illness and fatality.

Harmful Algae Blooms (HAB) have been documented for at least fifty years in Latin America and the Caribbean (LAC), however, their impacts at social, ecological and economic levels are still little known. To contribute to the impact assessment of HABs in LAC region, the available information in HAEDAT, OBIS, CAREC, and CARPHA databases, and scientific literature was analyzed. This historical analysis allows identification of the main syndromes and causal organisms. Considering the existence of two regional working groups of the Intergovernmental Oceanographic Commission (IOC): Algas Nocivas del Caribe (ANCA) and Floraciones Algales Nocivas en Sudamerica (FANSA), representing Central American/Caribbean and South American countries, respectively, the analysis is presented both globally and subregional. For the FANSA region, the HAEDAT data base listed 249 records from 1970 to 2019, with a total of 1432 human intoxications, including 37 fatalities. The majority of these events comprised Paralytic Shellfish Toxins (49%), Diarrhetic Shellfish Toxins (34%), Cyanotoxins (12%) and 6 % other toxins. The total number of harmful taxa in the OBIS database includes 79 species distributed over 25 genera. The most commonly reported species are Alexandrium catenella/tamarense, Gymnodinium catenatum and the Dinophysis acuminata complex. Two new species Prorocentrum caipirignum Fraga, Menezes and Nascimento and Alexandrium fragae Branco and Menezes were newly described from Brazilian waters. In the ANCA region, HAEDAT listed 131 records from 1956 to 2018. The main problems are PSP and Ciguatera and common HAB taxa are Gambierdiscus, Gymnodinium, Pyrodinium, Alexandrium and Dinophysis. The most reported HAB forming species are Gymnodinium catenatum, Pyrodinium bahamense and Gambierdiscus spp. In recent years Margalefidinium polykrikoides blooms have become frequent, causing fish and invertebrates massive mortalities and impacts on touristic activities. In the LAC region, the greatest economic losses were produced by ichthyotoxic massive events causing salmon deaths associated to Pseudochattonella verruculosa and Alexandrium catenella in Chile and tuna deaths related to Tripos furca and Chattonella spp. in the Mexican Pacific. In the last decade, several studies in LAC have linked HAB events with local mesoscale oceanographic and atmospheric phenomena. Trends analyzed up to 2019 are related to the increasing awareness about presence of toxic species, the geographical expansion of already known species, the detection of new toxins for the region, and HAB events duration and/or impacts.

Pyrodinium bahamense is a dinoflagellate of concern in subtropical and tropical coastal environments. To date, there is only a single published study on its fatty acids, but no published data on its sterol composition. Sterols, which are membrane-reinforcing lipids in eukaryotes, display a great diversity of structures in dinoflagellates, with some serving as chemotaxonomic markers. We have examined the sterol compositions of two isolates of P. bahamense from Indian River Lagoon and Tampa Bay, Florida, and have found both to produce three sterols: cholesterol, dinosterol, and 4α-methylgorgostanol. All three sterols are found in closely related, armored taxa.

Proteins, lipids, and carbohydrates from the harmful algal bloom (HAB)-causing organism Pyrodinium bahamense were characterized to obtain insights into the biochemical processes in this environmentally relevant dinoflagellate. Shotgun proteomics using label-free quantitation followed by proteome mapping using the P. bahamense transcriptome and translated protein databases of Marinovum algicola, Alexandrium sp., Cylindrospermopsis raciborskii, and Symbiodinium kawagutii for annotation enabled the characterization of the proteins in P. bahamense. The highest number of annotated hits were obtained from M. algicola and highlighted the contribution of microorganisms associated with P. bahamense. Proteins involved in dimethylsulfoniopropionate (DMSP) degradation such as propionyl CoA synthethase and acryloyl-CoA reductase were identified, suggesting the DMSP cleavage pathway as the preferred route in this dinoflagellate. Most of the annotated proteins were involved in amino acid biosynthesis and carbohydrate degradation and metabolism, indicating the active roles of these molecules in the vegetative stage of P. bahamense. This characterization provides baseline information on the cellular machinery and the molecular basis of the ecophysiology of P. bahamense.

During the months of January–February and May–June 2013 coinciding with the red tide occurrence in Kota Kinabalu, Sabah, Malaysia, six episodes involving 58 cases of paralytic shellfish poisoning (PSP) or saxitoxin (STX) poisoning and resulting in four deaths were reported. Many of them were intoxicated from consuming shellfish purchased from the markets, whereas others were intoxicated from eating shellfish collected from the beach. Levels of STX in shellfish collected from the affected areas were high (mean 2,920 ± 780 and 360 ± 140 µg STX equivalents/100 g shellfish meat respectively for the two periods). The count of toxic dinoflagellates (Pyrodinium bahamense var compressum) of the sea water sampled around the coast was also high (mean 34,200 ± 10,300 cells/L). Species of shellfish containing high levels of STX were Atrina fragilis, Perna viridis, and Crassostrea belcheri. The age of victims varied from 9 to 67 years. Symptoms presented were typical of PSP, such as dizziness, numbness, vomiting, and difficulty in breathing. Recommended steps to prevent or reduce PSP in future red tide season include better monitoring of red tide occurrence, regular sampling of shellfish for determination of STX level, wider dissemination of information on the danger of eating contaminated shellfish among the communities, fishermen, and fishmongers.

We examined organic-walled dinoflagellate cysts from one 210Pb-dated sediment core and 39 surface sediment samples from the northern Gulf of Mexico to determine the relationship between nutrient enrichment and cyst assemblages in this region characterized by oxygen deficiency. The core spans from 1962 to 1997 and its sampling location is directly influenced by the Mississippi River plume. Surface sediments were collected in 2006, 2007, 2008, and 2014 and represent approximately 1 to 4 years of accumulation. A total of 57 cyst taxa were recorded, and four heterotrophic taxa in particular were found to increase in the top section (1986–1997) of the core—Brigantedinium spp., cysts of Archaeperidinium minutum, cysts of Polykrikos kofoidii, and Quinquecuspis concreta. These taxa show a similar increasing trend with variations in US fertilizer consumption and Mississippi River nitrate concentrations, both of which increased substantially in the 1970s and 1980s. The same four heterotrophic taxa dominated dinoflagellate cyst assemblages collected near the Mississippi River Bird’s Foot Delta where nutrient concentrations were higher, especially in 2014. We propose that these cyst taxa can be used as indicators of eutrophication in the Gulf of Mexico. A canonical correspondence analysis (CCA) supports this proposition. The CCA identified sea-surface nutrient concentrations, sea-surface temperature, and sea-surface salinity as the most important factors influencing the cyst assemblages. In addition, cysts produced by the potentially toxic dinoflagellates Pyrodinium bahamense and Lingulodinium polyedrum were documented, but did not appear to have increased over the past 50 years.

Three major hypotheses have been proposed to explain why dinoflagellate bioluminescence deters copepod grazing: startle response, aposematic warning, and burglar alarm. These hypotheses propose dinoflagellate bioluminescence (A) startles predatory copepods, (B) warns potential predators of toxicity, and (C) draws the attention of higher order visual predators to the copepod's location. While the burglar alarm is the most commonly accepted hypothesis, it requires a high concentration of bioluminescent dinoflagellates to be effective, meaning the bioluminescence selective advantage at lower, more commonly observed, dinoflagellate concentrations may result from another function (e.g. startle response or aposematic warning). Therefore, a series of experiments was conducted to evaluate copepod grazing (Acartia tonsa) on bioluminescent dinoflagellates (during bioluminescent and nonbioluminescent phases, corresponding to night and day, respectively) at different concentrations (10, 1000, and 3000 cells mL-1 ), on toxic (Pyrodinium bahamense var. bahamense) and nontoxic (Lingulodinium polyedrum) bioluminescent dinoflagellates, and in the presence of nonluminescent diatoms (Thalassiosira eccentrica). Changes in copepod ingestion rates, clearance rates, and feeding preferences as a result of these experimental factors, particularly during the mixed trails with nonluminescent diatoms, indicate there is a concentration threshold at which the burglar alarm becomes effective and below which dinoflagellate bioluminescence functions as an aposematic warning.

Harmful algal bloom (HAB) toxins have severe negative impacts on marine mammals, particularly for Florida bottlenose dolphins (Tursiops truncatus) which frequently experience mass mortality events. Dolphins on the Florida Atlantic coast inhabit a region endemic to two HAB species, Karenia brevis and Pyrodinium bahamense, which produce the neurotoxins brevetoxin (PbTx) and saxitoxin (STX), respectively. Although toxic HABs and associated dolphin mortality events have been reported from this region, there is a lack of available data necessary for comparing toxin exposure levels between bloom (‘exposed’) conditions and non-bloom (‘baseline’) conditions. Here we present a 10-year dataset of PbTx and STX concentrations detected in dolphins stranding in this region, and compare the toxin loads from HAB-exposed dolphins to those detected in dolphins recovered in the absence of a HAB. We analyzed liver tissue samples from dead-stranded dolphins (n = 119) recovered and necropsied between 2002–2011, using an enzyme-linked immunosorbent assay (ELISA) modified for use with mammalian tissues. For dolphins recovered during baseline conditions, toxin-positive samples ranged in concentration from 0.27 to 1.2 ng/g for PbTx and from 0.41 to 1.9 ng/g for STX. For K. brevis-exposed dolphins, concentrations of up to 12.1 ng PbTx/g were detected, and for P. bahamense-exposed dolphins, concentrations of up to 9.9 ng STX/g were detected. Baseline PbTx values were similar to those reported in other regions where K. brevis blooms are more frequent and severe, but HAB-exposed PbTx values were considerably lower relative to these other regions. Since no baseline STX dolphin data exist for any region, our data serve as a first step towards establishing reference STX values for potential dolphin mortality events associated with STX-producing blooms in the future. This study demonstrates that although HABs in eastern Florida are only infrequently associated with dolphin mortalities, the presence of toxins in these animals may pose significant health risks in this region.

Pyrodinium bahamense produces saxitoxins and can cause paralytic shellfish poisoning (PSP). This species has caused more human illnesses and fatalities than any other toxic dinoflagellate in Mexico. The distribution of dinoflagellate cysts with their vegetative stage is broad, mainly along Mexican Pacific coasts from the central Gulf of California to Chiapas, as well as in the southern Gulf of Mexico and the Mexican Caribbean Sea on the Atlantic coast. In vitro germination of living cysts from the southern Gulf of California occurs under thermophilic (20–35°C) and euryhaline (20–35 ups) conditions. Blooms occurred typically during summer rainy season (June through September), inside of restricted shallow lagoons surrounded by mangrove forests. The data obtained so far on P. bahamense spatial and population variability in Mexican Pacific and the Gulf of Mexico, suggest a seasonal and latitudinal pattern. Also, in these regions, the abundance, seasonality, and species distribution tend to decrease from tropical to subtropical areas. The local strain toxicity has only been corroborated in one isolate from the southern Gulf of California, which exhibited a high saxitoxin concentration of 95 pg STX eq cell-1. PSP outbreaks linked with P. bahamense in the Gulf of Tehuantepec from 1989 to 2007, caused at least ∼200 human cases, with 15 fatalities. This mini-review ends with a viewpoint of management and research strategies to better understand the factors that play essential roles in the bloom dynamics and toxicity of this species.

Distribution and abundance of Pyrodinium bahamense cyst in the harmful algal blooms risk waters in Indonesia. Pyrodinium bahamenseas Harmful Algal Blooms (HABs) is one of the rising environmental problems in the coastal areas of Southeast Asia, particularly in Indonesia. Cyst bank formed after the blooms of P. bahamense is a potential source for the future blooming events. Therefore, an effort to describe the distribution and abundance of P. bahamense cyst banks in Indonesian coastal waters is necessary as a part of the mitigation strategy against the negative impacts of those toxic dinoflagellate blooms. This study was done as a desk study, which included a literature study, reanalysed of previous research data, and reanalysed of preserved samples or stored raw samples. Data and samples used in this study were collected and analysed from part of past researches in Lampung Bay, Jakarta Bay, Cirebon coastal waters, and Ambon Bay. This study also included an analysis to determine the P. Bahamense HABs risk level in the studied areas based on the cyst density and distribution data. Results showed a low density of P. bahamense cyst in Lampung Bay and Jakarta Bay, with cyst density -1 wet sediment. In contrast, the bottom sediments of Ambon Bay and Cirebon coastal waters contained high cyst density, which reached >1,000 cysts.g-1 wet sediment. Based on those data, the P. Bahamense HABs risk in Jakarta Bay and Lampung Bay would be generally much lower compared to Ambon Bay and Cirebon waters. The existence of cyst banks in those coastal waters may indicate a possibility of future blooms of P. bahamense.

In the Southeast Asian region, the Philippines and Malaysia are two of the most affected by Harmful Algal Blooms (HABs). Using long-term observations of HAB events, we determined if these are increasing in frequency and duration, and expanding across space in each country. Blooms of Paralytic Shellfish Toxin (PST)-producing species in the Philippines did increase in frequency and duration during the early to mid-1990s, but have stabilized since then. However, the number of sites affected by these blooms continue to expand though at a slower rate than in the 1990s. Furthermore, the type of HABs and causative species have diversified for both toxic blooms and fish kill events. In contrast, Malaysia showed no increasing trend in the frequency of toxic blooms over the past three decades since Pyrodinium bahamense was reported in 1976. However, similar to the Philippines, other PST producers such as Alexandrium minutum and Alexandrium tamiyavanichii have become a concern. No amnesic shellfish poisoning (ASP) has been confirmed in either Philippines or Malaysia thus far, while ciguatera fish poisoning cases are known from the Philippines and Malaysia but the causative organisms remain poorly studied. Since the 1990s and early 2000s, recognition of the distribution of other PST-producing species such as species of Alexandrium and Gymnodinium catenatum in Southeast Asia has grown, though there has been no significant expansion in the known distributions within the last decade. A major more recent problem in the two countries and for Southeast Asia in general are the frequent fish-killing algal blooms of various species such as Prorocentrum cordatum, Margalefidinium polykrikoides, Chattonella spp., and unarmored dinoflagellates (e.g., Karlodinium australe and Takayama sp.). These new sites affected and the increase in types of HABs and causative species could be attributed to various factors such as introduction through mariculture and eutrophication, and partly because of increased scientific awareness. These connections still need to be more concretely investigated. The link to the El Niño Southern Oscillation (ENSO) should also be better understood if we want to discern how climate change plays a role in these patterns of HAB occurrences.

Decreases in bioluminescence in Bahia Fosforescente have been associated with alternations between bioluminescent (Pyrodinium bahamense) and non-bioluminescent (Ceratium furca) dinoflagellates, two potentially harmful algal bloom species (HABs). Until now, these changes in bioluminescence have never been quantified, and their relationship with seasonality remains unclear. This study quantified the bioluminescence potential (BP) in the bay with a high spatiotemporal resolution to evaluate the status of this phenomenon and to determine the link between seasonality on the BP and dinoflagellate composition. Biweekly measurements, from August 2012 to July 2013, were conducted at six stations with an Underwater Bioluminescent Assessment Tool. The highest BP were observed during the wet season and were correlated (Spearman rank correlation: r = 0.89, n = 64, p

Objective: To determine the presence of consistent spatial or temporal patterns to the abundance of Pyrodinium bahamense (P. bahamense) in Mosquito Bay, Vieques, Puerto Rico. Methods: Measurements of dissolved oxygen, pH, salinity, water temperature, tide level, wind speed, and density counts of P. bahamense were taken at six sites in the bay over approximately one year. The data were analyzed statistically to determine if spatial or temporal patterns were present. Results: There were statistically significant patterns of P. bahamense seasonally, which was similar to other studies done in other subtropical locations with phytoplankton. Also, trends were seen that rain events caused short-term increases in abundance and shallow areas of the bay had lower abundance than that of deeper areas. The average number of organisms from 736 samples was 26.8 per mL. The average water temperature was 29.0 °C, the average salinity was 36.8 ppt, the average pH was 8.11, and the average dissolved oxygen level was 4.27 mg/L. Conclusions: The abundance of P. bahamense varies seasonally over shorter time periods. The abundance also varies over a few meters in small coastal bays. This information indicates that economically important bioluminescent bays are vulnerable to changes in freshwater input, water temperature, water circulation patterns and possibly the nutrient inputs from the land surrounding such bays.

The mussel Perna viridis is used in the Philippine saxitoxin monitoring program as an indicator organism for the presence of saxitoxin in shellfish in an effort to assess concentration beyond a level considered safe for public consumption. Saxitoxin bioaccumulates in mussels through ingestion of saxitoxin-producing algae Pyrodinium bahamense var. compressum (Pbc). This study focuses on the relationship between mussel length and mussel toxicity in mussels exposed to a natural bloom of Pbc. Mussel toxicity was assessed weekly in a 134-day sampling period using Receptor Binding Assay (RBA). Smaller mussels are more toxic than larger mussels at low Pbc cell density ( ≈ 10 2 cells/L) and the reverse is true at higher Pbc cell density ( ≈ 5 × 10 3 cells/L). These results can be useful in developing strategies for the collection of mussel samples in a toxic algal bloom monitoring program.

espanolPara definir la composicion de la comunidad fitoplanctonica con enfasis en las especies nocivas en los bancos ostricolas de la laguna de Terminos, SE del Golfo de Mexico, 6 sitios de muestreo fueron monitoreados mensualmente desde agosto 2012 a septiembre 2013. Se midio la temperatura del agua, salinidad, potencial de hidrogeno, saturacion de oxigeno, nutrientes inorganicos y la abundancia de fitoplancton. La temperatura y la salinidad se caracterizaron por diferencias estacionales marcadas. Los valores de pH y saturacion de oxigeno sugirieron un predominio de la actividad fotosintetica. La comunidad fitoplanctonica se caracterizo por el predominio de nanoflagelados y diatomeas. La abundancia de fitoplancton y su variacion estacional presentaron los valores minimos (10³ celulas L-1) durante la epoca de secas (febrero-mayo) y valores altos (10(6) celulas L-1) durante la temporada de lluvias (junio-septiembre). Otra caracteristica importante de la comunidad fitoplanctonica fue la presencia de especies de dinoflagelados nocivos: Akashiwo sanguinea, Karenia cf. mikimotoi, Pyrodinium bahamense var. bahamense, Prorocentrum mexicanum y P. minimum. Las cianobacterias Anabaena y Cylindrospermopsis cuspis alcanzaron abundancias de 1.9x10(6) y 1.3x10(6) celulas L-1, respectivamente. Los generos Alexandrium y Pseudo-nitzschia estuvieron presentes, pero los taxones no fueron identificados a nivel de especie. En conclusion, la comunidad fitoplanctonica se somete a cambios en la composicion de especies y en la estructura de la comunidad durante cada temporada climatica, en respuesta a la variacion ambiental, que permite el desarrollo de la comunidad fitoplanctonica de acuerdo a las condiciones imperantes. EnglishTo define the composition of the phytoplankton community, with an emphasis on harmful species, 6 stations were monitored monthly in the oyster beds of Terminos Lagoon, SE Gulf of Mexico, from August 2012 to September 2013. Water temperature, salinity, hydrogen potential, oxygen saturation, inorganic nutrients and abundance of phytoplankton were determined. Temperature and salinity were characterized by marked seasonal differences. The pH values and the oxygen saturation suggest a predominance of photosynthetic activity. The phytoplankton community was characterized by the dominance of nanoflagellates and diatoms. The abundance and seasonal variation of phytoplankton showed minimum values (10³ cells L-1) during the dry season (February-May) and high values (10(6) cells L-1) during the rainy season (June-September). Another significant feature of the phytoplankton community was the presence of the harmful dinoflagellate species Akashiwo sanguinea, Karenia cf. mikimotoi, Pyrodinium bahamense var. bahamense, Prorocentrum mexicanum and P. minimum. The cyanobacteria Anabaena and Cylindrospermopsis cuspis reached abundance of 1.9x10(6) and 1.3x10(6) cells L-1, respectively. The genera Alexandrium and Pseudo-nitzschia were present, but the taxa were not identified to the species level. In conclusion, the phytoplankton community undergoes changes in both species composition and structure of the community during each climatic season, in response to environmental variation, which allows the development of the phytoplankton community according to the conditions.

Palynological and geochemical analyses were carried out on a sediment core collected in the shallow Alvarado lagoon (Veracruz, Southwestern Gulf of Mexico) in order to evaluate the impact of the significant decline in the surrounding native coastal vegetation on phytoplankton assemblages. The sedimentary sequence encompasses the last millennium and provides information on pre-industrial phytoplankton assemblages. Results highlight a recent increase of freshwater-sourced organic matter relative to marine organic matter in line with reduced total concentrations of cyst-producing dinoflagellates. These changes appear to be synchronous to the extensive conversion of wetlands into agricultural areas, with consequences on the stability and water retention capacity of the soils bordering the lagoon system. The data also show that Polysphaeridium zoharyi, a cyst produced by the potentially toxic dinoflagellate Pyrodinium bahamense, is present in high abundance in the dinoflagellate population of the lagoon. Consequently, the modern cyst bank of P. bahamense in sediment has the potential to initiate harmful blooms since surface sediments are prone to resuspension events related to strong seasonal winds and human activities.

Monsoon-driven changes of environmental factors have been reported to be significantly variable and affects the phytoplankton community in tropical waters. This study examined the monsoonal changes of environmental parameters and the coastal phytoplankton community, including potential harmful algal bloom species, in the waters of Kota Kinabalu, Sabah, Malaysia. Bi-weekly observations were conducted from August 2017 to January 2019, covering the Southwest Monsoon (SWM), Northeast Monsoon (NEM), and inter-monsoon periods (IMPs). Sea surface temperature, salinity, and daily average photosynthetic active radiation (PAR) were significantly different between the SWM and the NEM. Total phytoplankton densities were significantly higher in the SWM with median cell densities of 1.12 × 104 cells L−1 compared to the NEM with 3.98 × 103 cells L−1. Nutrient measurements indicated that the waters were mesotrophic, with low phosphate (P) levels ( μ M-P on average). N:P ratios were often above the Redfield ratio (16N:1P), while high Si:N (>1) and Si:P ratios (>16Si:1P) indicated that silicate was not limiting, a condition favourable for diatom growth. Phytoplankton dynamics shifted from a dinoflagellate-dominant community (Protoperidinium spp. and Prorocentrum spp.) to a diatom-dominant community (Leptocylindrus spp. and Dactyliosolen spp.) during the NEM, which was preceded by a peak in silicate and nitrate. Later, Chaetoceros spp. became dominant during the second SWM. The presence of intermittent increases in Margalefidinium polykrikoides and Pyrodinium bahamense var. compressum cell densities may trigger future blooms in these waters. Canonical Correspondence Analysis suggests that the dinoflagellate-dominant community was driven by changes in PAR and Si:N while changes in N:P and salinity shaped the diatom-dominant community. The shifts of the phytoplankton community composition in relation to the different monsoonal periods suggests that the monsoons function as environmental drivers which structure the phytoplankton community of this coastal ecosystem.

Saxitoxin (STX) and its analogs are a broad group of natural neurotoxic alkaloids, commonly known as paralytic shellfish toxins. SxtA is the initial gene in the biosynthesis of saxitoxin. It has been proposed that the genes for STX biosynthesis had a bacterial origin and were acquired in the dinoflagellates by a horizontal gene transfer (HGT). In Gymnodinium catenatum, the origin of the STX genes is not well established. In this paper, we sequenced sxtA gene (domains sxtA1 and sxtA4) and determined the gene copy number in the genome in four Mexican strains of G. catenatum. We compare them with sequences of G. catenatum, Pyrodinium bahamense, and Alexandrium spp. from other geographic regions, and non-toxic producing dinoflagellates. Amplifications were performed for domains sxtA1 and sxtA4 from strains of G. catenatum and the phylogenetic analyses was done by maximum likelihood and Bayesian inference. The copy number determination was carried out using qPCR. The phylogenetic tree of domain sxtA4 showed the formation of two clades where G. catenatum sequences separated from the Alexandrium/Pyrodinium clade. The domain sxtA1 formed a higher number of clades than sxtA4. Sequences of G. catenatum were grouped together with sequences of Alexandrium. Dinoflagellates sequences that do not produce saxitoxin formed a separate clade. The gene copy number was 64 ± 30 and 110 ± 50 copies of sxtA1 and sxtA4 respectively. The identification of the gene sxtA of G. catenatum shows that the sequences are similar to those of Alexandrium species with low variations between species. These results may indicate that the acquisition of the gene sxtA was an early HGT event in the evolution of dinoflagellates. The possible loss of the ability to produce STX in some species suggests that the HGT from Alexandrium species towards G. catenatum is not possible.

Life cycle-based adaptations are integral to the ecology of most organisms. For the toxic microalgal species Pyrodinium bahamense, Alexandrium fundyense, Pseudo-nitzschia spp., and Nodularia spumigena, the properties and behaviours of their life cycle stages enable them to thrive in diverse marine environments. Planktonic blooms of these species are associated with a range of negative impacts including fisheries closures and animal die-offs. As a result, their bloom dynamics have been studied extensively, illustrating the ways that each organism’s life cycle is adaptive to recurring biotic and abiotic stressors. Both P. bahamense and A. fundyense form thick-walled resting cysts that play a major role in the dynamics of episodic blooms and can lie dormant for extended intervals in bottom sediments. These cysts function effectively in both tropical and temperate habitats. Nodularia spumigena uses a related but different strategy by producing akinetes that help in its recurrence. Pseudo-nitzschia species do not form resting or benthic stages, but undergo sexuality to counteract the progressive decrease in cell size due to cell division with a rigid siliceous frustule. These life cycles are clearly adaptable to a broad range of environments as shown by their widespread distribution and abundance. Continued investigation of these life cycles, especially stage-specific interactions with biotic and abiotic conditions, is likely to provide further insights into algal species ecology broadly, including responses to global climate change, ocean acidification, and coastal nutrient enrichment.

A group of marine dinoflagellates (Alveolata, Eukaryota), consisting of similar to 10 species of the genus Alexandrium, Gymnodinium catenatum and Pyrodinium bahamense, produce the toxin saxitoxin and its analogues (STX), which can accumulate in shellfish, leading to ecosystem and human health impacts. The genes, sxt, putatively involved in STX biosynthesis, have recently been identified, however, the evolution of these genes within dinoflagellates is not clear. There are two reasons for this: uncertainty over the phylogeny of dinoflagellates; and that the sxt genes of many species of Alexandrium and other dinoflagellate genera are not known. Here, we determined the phylogeny of STX-producing and other dinoflagellates based on a concatenated eight-gene alignment. We determined the presence, diversity and phylogeny of sxtA, domains A1 and A4 and sxtG in 52 strains of Alexandrium, and a further 43 species of dinoflagellates and thirteen other alveolates. We confirmed the presence and high sequence conservation of sxtA, domain A4, in 40 strains (35 Alexandrium, 1 Pyrodinium, 4 Gymnodinium) of 8 species of STX-producing dinoflagellates, and absence from non-producing species. We found three paralogs of sxtA, domain A1, and a widespread distribution of sxtA1 in non-STX producing dinoflagellates, indicating duplication events in the evolution of this gene. One paralog, clade 2, of sxtA1 may be particularly related to STX biosynthesis. Similarly, sxtG appears to be generally restricted to STX-producing species, while three amidinotransferase gene paralogs were found in dinoflagellates. We investigated the role of positive (diversifying) selection following duplication in sxtA1 and sxtG, and found negative selection in clades of sxtG and sxtA1, clade 2, suggesting they were functionally constrained. Significant episodic diversifying selection was found in some strains in clade 3 of sxtA1, a clade that may not be involved in STX biosynthesis, indicating pressure for diversification of function. (C) 2015 Elsevier Inc. All rights reserved.

Mangrove Lagoon, located on the island of St. Croix, US Virgin Islands (USVI), is one of few actively bioluminescent lagoons in a location experiencing significant anthropogenic impacts. The bioluminescence is due to an abundance of the dinoflagellate Pyrodinium bahamense in the water column. We recovered surface sediments and sediment cores from Mangrove Lagoon to analyze the spatial distribution and temporal variability of P. bahamense cysts in this system. Surface sediment P. bahamense cyst concentrations ranged from 0 to 466 cysts g−1 dry sediment, with higher abundances associated with elevated surface water nutrient concentrations and a mixed terrestrial–marine organic matter source regime. In combination with available bioassay data, we hypothesize that phytoplankton utilize nutrients rapidly and subsequent decay of organic matter makes nutrients available for dinoflagellates at the sediment–water interface in the eastern and northern quadrants of the lagoon. However, the nutrients are rapidly exhausted during counterclockwise lagoon circulation resulting in the decline of primary productivity and dinoflagellate abundance in the western quadrants. Downcore profiles suggest that P. bahamense blooms have been occurring for decades, declining in recent years. No cysts were present in sediments predating dredging activities of the 1960s that created Mangrove Lagoon. Recent reductions in cyst abundance may be the result of limited primary productivity caused by restricted water exchange with Salt River Bay due to shallowing of a sill at the mouth of the lagoon. This research highlights the need for more comprehensive geochemical and fossil analyses to better understand long-term ecological variability and inform conservation efforts of these unique habitats.

BACKGROUND: In July 2013, the Philippines' Event-Based Surveillance & Response Unit received a paralytic shellfish poisoning (PSP) report from Tarangnan, Western Samar. A team from the Department of Health conducted an outbreak investigation to identify the implicated source and risk factors in coastal villages known for green mussel production and exportation. METHODS: A case was defined as a previously well individual from Tarangan, Western Samar who developed gastrointestinal symptoms and any motor and/or sensory symptoms after consumption of shellfish from 29 June to 4 July 2013 in the absence of any known cause. The team reviewed medical records, conducted active case finding and a case-control study. Relatives of cases who died were interviewed. Sera and urine specimens, green mussel and seawater samples were tested for saxitoxin levels using high performance liquid chromatography. RESULTS: Thirty-one cases and two deaths were identified. Consumption of > 1 cup of green mussel broth was associated with being a case. Seawater sample was positive for Pyrodinium bahamense var. compressum and green mussel samples were positive for saxitoxin. Inspection revealed villagers practice open defecation and improper garbage disposal. CONCLUSION: This PSP outbreak was caused by the consumption of the green mussel broth contaminated by saxitoxin. As a result of this outbreak, dinoflagellate and saxitoxin surveillance was established, and since the outbreak, there have been no harmful algal blooms event or PSP case reported since. A "Save Cambatutay Bay" movement, focusing on proper waste disposal practice and clean-up drives has been mobilized. Language: en

In Indonesia, Pyrodinium bahamense var. compressum was first recorded in Kao Bay in 1994. In 1996 the illness of more than 30 people and the death of 3 children after consuming shellfish from Ambon Bay was reported. Until the shellfish poisoning cases was reported, occurrences and blooms of P. bahamense, neither its toxic events had never been known in Ambon Bay. It has generated monitoring on the species occurrence which has been carried out since 2008. The bloom of P. bahamense was detected in July 2012. During the bloom event, concentrationsof phosphate, nitrate and dissolved oxygen were measured. Vertical profiles of temperature, salinity, turbidity and chlorophyll a were also measured during the red tide. Cells of P. bahamense, the PSP responsible species, were recorded abundant up to 2,496 cells/ml when red-brown water discoloration was observed in Ambon Bay. After the toxic red tide, human illness of 7 people due to shellfish consumption was also reported. In addition, the bloom event has damaged aquaculture products, due to mass mortality of cultured fish in inner Ambon Bay.

Harmful algal blooms (HABs) cause various problems, such as water quality degradation, fauna mass mortality and impairment of human health. Water quality monitoring in Lampung Bay has been conducted by Lampung Marine Aquaculture Office (BBL) of the Ministry of Marine Affairs and Fisheries since 1994. Occurrence of Pyrodinium bahamense var. compressum (Pbc), a causative organism of paralytic shellfish poisoning (PSP), has been recorded but threats caused by HABs have never been reported. A study aimed to know the level of public knowledge and awareness about HABs in Lampung Bay has been conducted. The components of group respondents consisted oflocal governments, academics and coastal communities. Awareness from each component was examined includinggeneral HAB knowledge, HAB impact to the community, HAB occurence and local knowledge of HAB. Data of HAB knowledge were collected through questionnaire and focus group discussion. The result showed that 40.5% of respondents had knowledge of HABs phenomena and 51.3% respondents only know signs or indicators of HAB occurrence, while only 1.4% respondents had knowledge of local HAB occurences. The direct impact of HABs to the community was not commonly known by the respondents. Only a few cases of poisoning after eating seafood were reported. It can be concluded that there was lack of public knowledge and awareness on HABs in LampungBay. Intensive public awareness programs about HABs should be conducted in order to reduce risk towards HABs in Lampung Bay.

Pyrodinium bahamense Plate 1906 is a tropical to subtropical dinoflagellate that can cause paralytic shellfish poisoning (PSP). Based on differences in the morphology of the motile stage, as well as geographic distribution, this species was separated into two varieties, the toxic var. compressum and the non-toxic var. bahamense by Steidinger et al. (1980). Thereafter, Balech (1985) carefully reinvestigated the two varieties and concluded there were no significant morphological differences between them. We re-examined the motile cell and cyst morphology of these two varieties, concurring with the arrangement of the sulcal plates, but demonstrating the plate overlap for the first time. The observed size-frequency spectra of cell body diameter, cyst body diameter and cyst process length were unimodal. Overall, we agree with Balech (1985) that there is no consistent criterion to unequivocally separate both varieties based on morphology. We therefore recommend ceasing the use of these varieties (and forma). In addition, we suggest that observations of both varieties in a single plankton sample should be interpreted as the occurrence of different life stages at the sampling time. However, the phylogenetic analysis using partial LSU rDNA sequence data revealed two clearly separated ribotypes within the Pyrodinium clade, an Indo-Pacific and Atlantic-Caribbean ribotype, suggesting that Pyrodinium bahamense is a species complex. The genetic distance between these ribotypes is short, which suggests a late Quaternary separation. Geochemical analyses of the cyst walls also show differences between specimens from both geographical regions.

Relationships between shifts in climatic and other environmental conditions and changes in the character and dynamics of phytoplankton blooms were examined in three interconnected subtropical lagoons on the east coast of Florida, i.e., Mosquito Lagoon, Indian River Lagoon, and Banana River Lagoon, from 1997 to 2013. Phytoplankton blooms were a common feature through most of the study period in two of the lagoons. From 1997 to 2009, blooms in the latter two lagoons were typically dominated by dinoflagellates in the warm wet season and diatoms in the cool dry season. Blooms of the dominant bloom-forming dinoflagellate species Pyrodinium bahamense were positively correlated to rainfall levels, indicating a link to enhanced external nutrient loads. In 2011–2013, major blooms were observed in all three lagoons, but unlike the previous 14 years, they were dominated by picoplanktonic eukaryotes, including a chlorophyte, Pedinophyceae sp., and the brown tide species Aureoumbra lagunensis. The results suggest that extreme climatic conditions, including record cold winter water temperatures and low rainfall levels, were major driving factors in this state shift in the character of blooms, through a wide range of effects including die-offs of benthic flora and fauna, suppression of grazer populations, alteration of nutrient regimes, and uncharacteristic water column conditions, such as elevated salinities and light attenuation.

Pellicle or temporary cysts of Pyrodinium bahamense var. compressum (Bohm) Steidinger, Tester & F.J.R. Taylor and their role in bloom dynamics have not yet been adequately characterized and understood. We investigated the role of temperature- and nutrient-mediated stress as factors that could induce pellicle formation in batch cultures. Cellular features and their implications for temporary cyst viability were examined using confocal laser scanning microscopy (CLSM). Our data suggest that temperature change is one of the key factors influencing pellicle formation, preserving viability at low temperature (i.e. 13°C). Hypnocysts (resting cysts) were not observed. During pellicle formation, motile cells generally undergo ecdysis, extrusion of cytoplasmic materials and bacteria, compaction of the nucleus and non-motility. The outermost covering of the temporary cysts shows red autofluorescence and it contains lower concentrations of chlorophyll (chl) a and no detectable chl c. The nuclear region is surrounded...

Pyrodinium bahamense (bioluminescent) and Ceratium furca (non-bioluminescent), two potentially harmful algal bloom species (HABs), are the most abundant dinoflagellates in the tropical bioluminescent bay Bahia Fosforescente. Reductions in bioluminescence have been attributed to fluctuations in their abundances. It is unclear how short-term changes in the environment influence these fluctuations and how seasonality regulates their presence and abundance. Thus, temperature, salinity, nutrient concentrations, rainfall, wind velocity and direction, and counts of both dinoflagellates were examined at six stations, during five consecutive days, and during two climate extremes (i.e., the wet and dry seasons). During the wet season, P. bahamense abundances surpassed those of C. furca, reaching bloom conditions. Positive correlations were found between P. bahamense abundance, temperature, and salinity. The higher phosphates and nitrites + nitrates concentrations (PO4 −, 0.09–1.92 μmol L−1; N + N, 0.34–7.67 μmol L−1) recorded during this season and their negative correlations with P. bahamense cell densities suggest efficient nutrient uptake and indicate that watershed-derived nutrients were important for the formation of blooms. C. furca cell densities were higher during the dry season, when nutrient concentrations were low (PO4 −, 0.17–0.5 μmol L−1; N + N, 0.2–1.23 μmol L−1). Physiological characteristics and adaptive strategies of C. furca, such as mixotrophy, osmotrophy, and luxury consumption, may explain the higher abundances of this species under low-nutrient conditions. The spatial distribution of both organisms was similar during both seasons with higher cell densities in the east/southeast regions of the bay. This study provides new insights on the ecology of Bahia Fosforescente that are important for its management and broadens the knowledge on the factors that regulate the presence and abundance of two potentially HABs species.

The first record of harmful algae bloom (HAB) in Sabah was in 1976 where 202 victims were reported to be suffering from Paralytic Shellfish Poisoning (PSP) and 7 deaths. The causative organism was Pyrodinium bahamense, a dinoflagellate which produces saxitoxin. Since then, Department of Fisheries Sabah has been doing monitoring to safeguard seafood safety, especially shellfish harvested for food consumption. Cochlodinium polykrikoides bloom for the first time in Sabah in year 2005 where Kota Kinabalu and Tuaran experienced fish kill. Since then, other HAB species such as Gymnodinium catenatum, Gonyaulax polygramma and Noctiluca scintillans were identified in waters of Sabah. Sabah is the only state in Malaysia in which the monitoring program is done consistently throughout the year since 1976. Samples were collected once or twice a month, according to high and low risks areas which have been identified, most of which are in the west coast. The collection frequency may be increased depending on the situation such as whether there is an outbreak of red tide or PSP in the area. Due to this effort, PSP cases involving the public have declined during the last 40 years without duly affecting the income of fishermen and the fisheries industry. After successfully implementing toxin monitoring between 1984 to 2013, it recurred back in 2013 when 3 deaths were reported. The purpose of this paper is to review all HABs incidences that occured in Sabah over the last few years from January 2000 – December 2017.

Paralytic Shellfish Poisoning (PSP) is a serious human illness caused by ingestion of seafood enriched with paralytic shellfish toxins (PSTs). PSTs are neurotoxic compounds produced by marine dinoflagellates, specifically by Alexandrium spp., Gymnodinium catenatum and Pyrodinium bahamense . Every year, massive monitoring of PSTs and their producers is undertaken worldwide to avoid PSP incidences. Here we developed a sensitive, hydrolysis probe-based quantitative PCR (qPCR) assay to detect a gene essential for PST synthesis across different dinoflagellate species and genera and tested it on cDNA generated from environmental samples spiked with Alexandrium minutum or Alexandrium fundyense cells. The assay was then applied to two environmental sample series from Norway and Spain and the results were complemented with cell counts, LSU-based microarray data and toxin measurements (enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR) biosensor method). The overall agreement between the results of the qPCR assay and the complementary data was good. The assay reliably detected sxtA transcripts from Alexandrium spp. and G. catenatum , even though Alexandrium spp. cell concentrations were mostly so low that they could not be quantified microscopically. Agreement between the novel assay and toxin measurements or cell counts was generally good; the few inconsistencies observed were most likely due to disparate residence times of sxtA transcripts and PSTs in seawater, or, in the case of cell counts, to dissimilar sxtA4 transcript numbers per cell in different dinoflagellate strains or species.

Blooms of Pyrodinium bahamense var. compressum were detected from July to December 2010 in Costa Chica, Guerrero. To estimate the cell abundance of this dinoflagellate, phytoplankton samples were collected from 7 July to 9 December 2010 at five sampling sites. Wild rock oysters and specimens from fishing cooperatives were only collected during November-December 2010. Abundance of P. bahamense var. compressum ranged from –1 in the first three samplings performed in July. Low densities ( –1 ) were observed at the end of November and December. Rock oyster toxicity from the fishing areas ranged from 46.24 to 788.85 μg STXeq 100 g –1 . Rock oyster samples collected in the fishing cooperatives had toxicity from 52.2 to 440.88 μg STXeq 100 g –1 . Although rock oysters were collected at the end of the blooms, their toxicity could be associated to this dinoflagellate both during this period and during previous blooms that occurred from on July-August in the study area. Florecimientos de Pyrodinium bahamense var. compressum y toxicidad en ostion de roca en Costa Chica, Guerrero, Mexico Se detectaron florecimientos de Pyrodinium bahamense var. compressum de julio a diciembre de 2010 en Costa Chica, Guerrero. Con el fin de calcular la abundancia de este dinoflagelado se recolectaron muestras de fitoplancton desde el 7 de Julio hasta el 9 de diciembre en cinco estaciones de muestreo. Asimismo, se recolecto ostion de roca en los sitios naturales de captura y en cooperativas pesqueras de la region de noviembre a diciembre. La abundancia de P. bahamense var. compressum alcanzo valores –1 en los tres primeros muestreos realizados en julio; se observaron bajas densidades ( –1 ) a finales de noviembre y diciembre. La toxicidad del ostion de roca recolectado en los sitios de captura comercial vario entre 46.24 y 788.85 μg STXeq 100 g –1 . La toxicidad en las muestras de ostion recolectado en las cooperativas pesqueras vario entre 52.2 y 440.88 μg STXeq 100 g –1 . Aunque el ostion de roca fue recolectado al final de los florecimientos, su toxicidad puede asociarse a la presencia del dinoflagelado, tanto en estas fechas como por los florecimientos previos ocurridos entre julio-agosto en el area de estudio.

In order to document the distribution of organic-walled dinoflagellate cysts (dinocysts) and their relationship with sea-surface parameters (temperature, salinity, primary productivity), palynological analyses were performed on 44 surface sediment samples from the Gulf of Mexico (17°N to 29°N). Samples display low to moderate concentrations with values ranging from 78 to 3576 dinocysts·g − 1 dry weight sediment. Assemblages are dominated by either Brigantedinium spp. or Polysphaeridium zoharyi along with the phototrophic taxa Spiniferites spp. and Operculodinium spp. Redundancy analyses (RDA) identified the distance to the coast and/or water depth and annual temperature as being the most important factors that control cyst distribution in the Gulf of Mexico. The first two axes explain respectively 44.7% and 20% of the total variance. The inshore to offshore trend in cyst distribution emphasized by the RDA involves changes in associations of species with the presence of Impagidinium spp. in more oceanic assemblages and higher representation of P. zoharyi nearshore. This latter species, produced by the potentially toxic dinoflagellate Pyrodinium bahamense , reaches very high abundances notably on the west Florida shelf and in the Mexican lagoons. Additionally, Melitasphaeridium choanophorum , which was considered to have gone extinct by the end of the Pleistocene, appears as a modern component of marine sediment from the north and southwestern Gulf. Our results thus demonstrate a biostratigraphical range extending to the present, at least in the study area. This palynological investigation highlights the importance of the Gulf of Mexico as potential refuge for late Cenozoic species thought to be extinct.

Coastal lagoons are valuable natural resources and ecotourism hotspots that are at great risk due to human development and global climate change. In order to protect these resources it is important that we fully understand the paleoenvironmental history of these unique ecosystems and their sensitivity to environmental change. Here we present a multi-proxy (pollen, charcoal, grain-size, dinoflagellate cyst, stable isotope geochemistry, and foraminifera) 3600 cal yr B.P. record of paleoenvironmental change for Laguna Grande, Puerto Rico, which is a particularly unique coastal lagoon as it contains high abundances of the bioluminescent dinoflagellate Pyrodinium bahamense . Sedimentary evidence indicates that the Laguna Grande basin began accumulating sediment ~ 3600 cal yr B.P. coincident with regional sea level rise, but the modern lagoon itself is geologically quite young and did not become fully enclosed until ~ 575 cal yr B.P. due to longshore depositional processes and mangrove swamp development. Foraminifera assemblages suggest a potential breach of a protective barrier ~ 1550 cal yr B.P. perhaps as a result of a tropical storm or tsunami and is coincident with an increase in fire activity. Only two high-energy depositional units (tempestites) could be identified in the lagoon sediments over the last 575 cal yr B.P. indicating minimal impact by tropical storms or tsunamis on the lagoon since isolation from the open ocean. Fossil dinoflagellate cyst concentrations and influxes do not approach modern levels until ~ 200 cal yr B.P. and are currently at the highest levels in the history of the lagoon, indicating the lagoon may have become bioluminescent only recently, perhaps as a result of anthropogenic nutrient additions. Sedimentation rates support this hypothesis indicating a recent tripling of sedimentation rates when compared to millennial-scale sedimentation rates. This study highlights the utility of paleolimnological data in the management and preservation of at-risk coastal lagoon ecosystems.

We examined the environmental and biological factors related to blooms of the toxic dinoflagellate Pyrodinium bahamense in three shallow, restricted subtropical lagoons in the Gulf of California during the rainy summer. In the San José, Yavaros, and El Colorado lagoons, the vegetative stage peaked at 63, 108, and 151 (×103 cells l-1), respectively. At San José, production of cysts peaked at 9.7×103 g-1 of dry sediment mass as the bloom declined. Large diatoms predominated, with P. bahamense the most common dinoflagellate during the blooms. Abundance of P. bahamense at San José was positively correlated with salinity (r=0.50, p=0.0003), seawater temperature (r=0.44, p=0.005), silicates (r=0.45, p=0.003), and ammonium (r=0.32, p=0.005), and negatively correlated with dissolved oxygen (r=-0.34, p

In the east coast of Sabah, no Harmful Algal Bloom (HAB) case has been reported although Pyrodinium bahamense var. compressum had been reported a decade ago. Therefore, this study was performed to evaluate the current situation of HAB in the east coast of Sabah. Samples were collected during northeast monsoon and southwest monsoon at 3 sites (St. 1, St. 2 and St. 3). Physical and chemical parameters such as nutrients (phosphate and nitrate), salinity, pH, temperature and dissolved oxygen were measured. Rainfall data were obtained from Meteorological Department, Sabah. Eight potential HAB species were identified. Ceratium furca dominated the area during both monsoons. Monsoons did not significantly affect the occurrence of HAB species. Based on location, St. 3 has high cell density of HAB and high nutrient concentration. Aquaculture activity and river effluents near St. 3 were believed to contribute to this high nutrient concentration. The presence of potential HAB species indicates that the east coast of Sabah may experience HAB problem in the future if factors triggering the bloom are not managed well.

It has been 40 years since the first recorded toxic bloom of Pyrodinium bahamense occurred in Papua New Guinea in 1972. Subsequently this species has increased in importance as a paralytic shellfish poisoning toxin (PSTs) producer in several regions of the world, especially in the Indo-west Pacific. P. bahamense is a thecate tropical/subtropical euryhaline dinoflagellate. Available data indicate that it forms blooms only in waters of 20 psu or higher salinity and at temperatures above 20 °C. It is monospecies with two varieties, namely var. compressum and var. bahamense. For many years it was widely accepted that only var. compressum is toxic and is limited to the tropical Pacific while var. bahamense is nontoxic and is limited to the tropical Atlantic. It is now known, however, that there are at least two locations where the varieties co-occur and it has also been proven that var. bahamense in Florida waters also produce PST. P. bahamense has a life cycle typical of many dinoflagellates. It has a heterothallic sexual cycle that produces a large spiny spherical resting cyst. The toxicity profile of P. bahamense is also very simple with most isolates producing only dc-STX, STX, neoSTX, B1 and B2 toxins. Further studies are needed in order to resolve the varietal status of the species and also to understand the environmental factors that determine its toxicity and bloom dynamics.

Harmful algal blooms are a recurrent, expensive and at times fatal problem plaguing the Philippines. In particular, Sorsogon Bay in the Bicol region has experienced prolonged shellfish bans due to blooms by the Paralytic Shellfish Poisoning causative species Pyrodinium bahamense var. compressum (Pbc). In order to help explore and understand the population dynamics of Pbc in Sorsogon Bay in relation to environmental factors, an individual-based model has been developed. This model accounts for key life history processes (reproduction, mortality, encystment, excystment) in a spatially-explicit setting. Vegetative cells and resting cysts are separately represented. Movement is due to advection rates from a 3D hydrodynamic model, as well as sinking rates. Asexual reproduction (population growth) occurs in response to light, temperature, salinity and nutrient conditions where the cells are spatially situated. Encystment and excystment processes are also spatially-explicit based on intrinsic factors, and environmental factors. Grazing effects on blooms are also being explored in the model. Results from field studies in the past years indicate that Pbc blooms develop a few months after the onset of rains, relatively lower temperature, and stratification of the water column. Pronounced blooms are observed at a particular time of the year and in certain areas of the Bay. Bloom formation patterns in the model are compared with these field results. This model will be used to further investigate the conditions leading to blooms and their decline, specifically the roles of transport, stratification, nutrients, cyst dynamics, and grazing on Pbc blooms in Sorsogon Bay.

Pyrodinium bahamense var. compressum is a toxic dinoflagellate that produces paralytic shellfish poisoning toxins. It is responsible for the chronic toxicity of shellfish in many coastal areas of the Philippines and other South East Asian countries. For the purpose of using antibiotic treatment to possibly generate axenic cultures and understand their growth requirements, the antibiotic tolerances of two local P. bahamense var. compressum isolates and their associated bacteria were determined. The antibacterial compounds ampicillin, chloramphenicol, ciprofloxacin, kanamycin, neomycin, penicillin G, and streptomycin were tested, as well as two antifungals, amphotericin B, and nystatin. All except chloramphenicol, amphotericin B, and nystatin were generally well-tolerated. An antibiotic mixture composed of ciprofloxacin, kanamycin, neomycin, and streptomycin completely inhibited the cultivable bacteria associated with P. bahamense var. compressum MZRVA, although epifluorescence microscopy revealed that residual bacteria were still present. From long-term tests with this antibiotic mix, it was observed that survival of isolate MZRVA post-antibiotic treatment appeared to be associated with re-growth of heterotrophic bacteria and that excess vitamins could potentially enhance dinoflagellate survival. These results suggest that the associated heterotrophic bacterial populations help support the growth of P. bahamense var. compressum MZRVA in culture and possibly in nature. This is the first report on the growth responses of P. bahamense var. compressum and associated cultivable bacteria to a variety of single and combinations of antibiotics.

Development of harmful algal blooms (HABs) in coastal waters of Kota Kinabalu, Malaysia, is a recurring problem. The blooms are caused by Pyrodinium bahamense var. compressum and Cochlodinium polykrikoides . Recently, another potential HAB species, Gymnodinium catenatum , was identified. The occurrence of these species is known to be related to a range of factors, including seasonal monsoons, nutrients, physical parameters and geomorphology. To understand the occurrence and distribution of the three species, extensive samplings were carried out over a period of one year, including the South West Monsoon (SWM), North East Monsoon (NEM) and Inter-Monsoon (IM) periods, at 5 stations located in 3 different bays off Kota Kinabalu. Cell density of the three HAB species and in situ physical parameters (salinity, pH and temperature) were recorded. Secondary data such as rain fall and wind speed were obtained from the Meteorology Department, Kota Kinabalu. C. polykrikoides and G . catenatum occurred year-round with the highest cell densities of 1.54 × 10 7 cells L −1 and 1.24 × 10 6 cells L −1 in December (NEM). P. bahamense var. compressum was found in low numbers with maximum cell density of 2 × 10 4 cells L −1 in August (SWM). The absence of P. bahamense var. compressum during the highest peak of C. polykrikoides and G . catenatum was related to nutrient concentrations and composition. The three species tended to occur at stations near the river and in a sheltered area. The results of the study indicate that the coastal area of Kota Kinabalu may continue to experience HAB problems, unless environmental conditions change significantly.

For the first time the potential of Noctiluca scintillans, a non-toxic mixotrophic dinoflagellate, in bioconverting and/or excreting saxitoxin has been illustrated, thus contributing to the limited knowledge on the aspects of toxin pathways in the food chain/web and predator-prey preferences. Noctiluca growth rate increased with higher Pyrodinium concentration but the ratio of Noctiluca to Pyrodinium should at least be 1:250 cells per mL. Noctiluca fed with Pyrodinium alone was found to decrease in number suggesting that the nutrients from this prey were insufficient. This was confirmed by the improved cell density of Noctiluca upon addition of 0.01% casitone to the Pyrodinium-fed Noctiluca. The alternative prey (Gymnodinium sanguineum) slowed down the grazing impact of Noctiluca on Pyrodinium. Noctiluca depleted Gymnodinium earlier than Pyrodinium showing preference over a prey with less saxitoxin. After the feeding experiments, total saxitoxin levels decreased to 72% in the Noctiluca-Pyrodinium setup whereas no saxitoxin was detected in the Noctiluca culture fed with Pyrodinium and G. sanguineum. It is possible that Gymnodinium can provide some nutrients needed to make Noctiluca more efficient in bioconverting saxitoxin.

Plankton feeders such as bivalves often become toxic. Human consumption of the toxic bivalve causes severe food poisoning, including paralytic shellfish poisoning (PSP) which is the most dangerous because of the acuteness of the symptoms, high fatality and wide distribution throughout the world. Accumulation of PSP toxins in shellfish has posed serious problems to public health and fisheries industry. The causative organisms of PSP toxins are known to be species of dinoflagellates including those belonging to the genus Alexandrium, Gymnodinium catenatum and Pyrodinium bahamense var. compressum. Bivalves accumulate PSP toxins during a bloom of these dinoflagellates. Thus, the dinoflagellate toxins have been considered as being concentrated in bivalves through food web transfer. However, field studies on the toxin level of bivalves in association with the abundance of toxic dinoflagellates could not support the idea. A kinetics study on toxins by feeding experiments of cultured dinoflagellate cells to bivalves also showed similar results, indicating that toxin accumulation of bivalves is not caused by simple accumulation of toxins due to food-web transfer. Based on the discovery of toxin-producing bacterium in the cells of toxic dinoflagellates, this study suggests that PSP toxins in toxic dinoflagellates are catabolites of bacterial substance in dinoflagellate cells. On the other hand, tetrodotoxin (TTX), a puffer toxin, is reported to be produced by some species of bacteria. Thus, the origin of TTX of puffer is considered to be bacteria. However, the mechanism for puffer to possess TTX through bacteria is unknown. The present study revealed that organisms bearing either TTX or PSP toxins possess both toxins, although the proportion of both is different among the specimens. In fact, a significant level of TTX is detected in A. tamarense. In addition, TTX-like toxin-producing bacteria are found to be infected in the liver of toxic specimens of puffer. These findings strongly suggest that a similar mechanism between bacteria and toxic organisms is involved in the production of TTX and/or PSP toxins in toxic organisms. Aqua-BioScience Monographs Vol. 3, No. 1, pp. 1–38 (2010) www.terrapub.co.jp/onlinemonographs/absm/ © 2010 TERRAPUB, Tokyo. All rights reserved. doi:10.5047/absm.2010.00301.0001 Received on September 8, 2009 Accepted on October 13, 2009 Published online on April 9, 2010

Harmful algal bloom occurrences worldwide have prompted the testing and use of methods to control and mitigate their detrimental effects. This study investigates the potential of Philippine clay minerals to physically remove phytoplankton cells under laboratory conditions. Ball clay had the highest removal efficiency (∼95%) for Pyrodinium bahamense (paralytic shellfish poisoning causative organism) cells. A slight decrease in the efficiency by 10–20% was seen when culture volume was increased from 50 mL to 1 L. Removal efficiency was reduced to ∼95% when water motion was introduced. Removal of other phytoplankton species (Gymnodinium sanguineum, Amphidinium carterae, Pyrophacus horologium, Chatonella marina, and Alexandrium sp.) using ball clay was less efficient (

This paper describes the results of 10 years of water quality monitoring in the Indian River Lagoon Florida, with special emphasis on the relationships between trends in climatic conditions and the distribution, composition, and abundance of the phytoplankton community. The Indian River Lagoon, which spans 220 km of Florida’s east coast, is a region of particular concern because of the rapid rate of human development throughout the region and the hydrologically restricted character of the lagoon, which heightens the potential for algal bloom. Water sampling was carried out on a monthly to twice-monthly basis at six sites located in the northern and central lagoon. The 10-year study included both extended periods of below and above average rainfall. A number of ecologically distinct regions exist within the lagoon, which differ considerably in water exchange properties and watershed inputs. The northern lagoon is characterized by longer water residence times, lower phosphorus concentrations, higher nitrogen concentrations, and more stable salinity conditions than the central lagoon. Mean phytoplankton biovolumes were substantially higher at the sites in the northern lagoon than at the sites in the central lagoon, and algal blooms were more common and intense in the former region. Inter-annual patterns of phytoplankton biovolume were also different in the northern and central lagoon. In the northern lagoon, phytoplankton biovolumes were lowest during the drought period, from the autumn of 1998 to the spring of 2001. By contrast, algal bloom events in the central lagoon were not only less frequent but were not tied to periods of high rainfall. The most widespread and common bloom formers were the potentially toxic dinoflagellate Pyrodinium bahamense var. bahamense and two centric diatoms, Dactyliosolen fragilissimus and Cerataulina pelagica. Many of the biovolume peaks observed over the study period were attributable to these three species. The results of time series modeling of phytoplankton dynamics further highlighted the disparities between the two regions of the lagoon in terms of the suite of parameters that best predict the observed trends in the biomass of phytoplankton. Overall, the outcome of this initial modeling effort in the Indian River Lagoon suggests that time series approaches can help define the factors that influence phytoplankton dynamics.

Currently Angola does not possess a monitoring programme for shellfish contamination with marine biotoxins. Among other potentially toxic microalgae, the presence of Gymnodinium catenatum and Pyrodinium bahamense has been reported at the Angola coast, two species associated worldwide with production of paralytic shellfish poisoning toxins (PSTs). A preliminary assessment of contamination with PSTs was carried out by HPLC with pre-column derivatization in samples of Semele proficua from Luanda Bay and samples of Senilia senilis from Mussulo Bay, collected between June 2007 and February 2008. An unusual profile was found, not matching any of the 10 oxidation products expected from the known hydrophilic PSTs normally reported in marine dinoflagellates: the N-sulfocarbamoyl, the decarbamoyl or the carbamoyl analogues of saxitoxin (STX). Four major compounds were noted, and designated A through D. These were not autofluorescent, additionally A and D presented much stronger response after peroxide oxidation than after periodate oxidation. Fluorescence emission and ultraviolet absorption maxima were similar to oxidation products of STX analogues. Separation carried out in two different C18 columns clearly showed the retention times did not match the oxidation products of standards. In the period of August through October 2007, samples of S. proficua from Luanda Bay presented a strong cross-reaction with a commercial antibody towards STX, in the range of 2600-5800STXequiv./kg, while for the same period levels in the samples of S. senilis from Mussulo Bay ranged between30 and 340STXequiv./kg. This reaction was directly proportional to the presence of the four unknown fluorescent peaks. The presence of these compounds was very persistent throughout the studied period, in particular in Luanda Bay. This contamination might not be characteristic of a dinoflagellate blooming, but could be related to a persistent cyanobacterial contamination, due to the strong sewage pollution of the area.