Harmful Algae

Domoic acid (DA) is a neurotoxin produced by the harmful algae Pseudo-nitzschia that has been directly linked to mass stranding events of the California Sea Lion (CSL). The purpose of this paper is to review the anthropogenic influence on the production of this neurotoxin and examine how human activities are impacting this marine mammal species. A comprehensive and interdisciplinary literature review was conducted to evaluate the future sustainability of the CSL population. It was found that while Pseudo-nitzschia bloom developments are vulnerable to anthropogenic influences, the incontestable existence of natural contributing factors adds a certain complexity to the determination of causalities and the development of solutions. Strong evidence exists to show that DA can cause major and irreversible neurological damage in CSLs. Rehabilitation of DA-impacted CSLs is a polarizing issue in the U.S. and presents interesting implications for sustainable development. While the CSL populat...

This thesis is dedicated to my late Uncle Neil, whose relentless zest for life, unstoppable thirst for knowledge, and constant yearning for adventure inspired me to further my education and study in Sweden. "Better to light one small candle than curse the darkness" -Chinese Proverb Lastly, a special thanks goes out to Gai-lan, a wonderful and charming harbour seal who was the very first marine mammal that I was involved in the rescue, rehabilitation, and release of.

We report on a dense bloom (~1.80 × 10 5 cells mL -1 ) of the marine dinoflagellate species Amphidinium carterae (Genotype 2) in a shallow, small intermittently open coastal lagoon in south eastern Australia. This bloom co-occurred with the deaths of >300 individuals of three different species of fish. The opening of the lagoon to the ocean, as well as localized high nutrient levels, preceded the observations of very high cell numbers. A. carterae is usually benthic and sedimentdwelling, but temporarily became abundant throughout the water column in this shallow (<2 m) sandy habitat. Histopathological results showed that the Anguilla reinhardtii individuals examined had damage to epithelial and gill epithelial cells. An analysis of the bloom water indicated the presence of a compound with a retention time and UV spectra similar to Luteophanol A, a compound known from a strain of Amphidinium. Assays with a fish gill cell line were conducted using a purified compound from cells concentrated from the bloom, and was found to cause a loss of 87% in cell viability in 6 h. The fish deaths were likely due to the low dissolved oxygen levels in the water and/or the presence of Luteophanol A-like compounds released during the bloom.

Cyanobacterial harmful algal blooms (CHABs) degrade water quality and may produce toxins. The distribution of CHABs can change rapidly due to variations in population dynamics and environmental conditions. Biological and ecological aspects of CHABs were studied in order to better understand CHABs dynamics. Field experiments were conducted near Hartington, Ontario, Canada in ponds dominated by Microcystis aeruginosa and CHABs floating experiments were conducted at Lake Taihu during the summers of 2015 and 2016. Single colonies composed of hundreds to thousands of cells with an average median of 0.2-0.5 mm in diameter were the basic form assumed by the Microcystis, and this remained the same throughout the growing season. Thorough mixing of the water column followed by calm conditions resulted in over 90% of the cyanobacteria floating after 1 h. Multiple colonies floated on the water surface in four types of assemblages: aggregates, ribbons, patches, and mats. It is the mats that are conventionally considered the blooming stage of cyanobacteria. Presence of CHABs on open water surfaces also depends on environmental influences such as direct and indirect wind effects. For example, field tests revealed that the surface coverage of CHABs can be reduced to half within an hour at wind speeds of 0.5 m/s. Because our findings indicated that blooming involves surface display of cyanobacteria essentially presenting as a two-dimensional plane under defined conditions, the use of surface imagery to quantify CHABs was justified. This is particularly important in light of the fact that traditional detection methods do not provide accurate distribution information. Nor do they portray CHABs events in a real-time manner due to limitations in ondemand surveillance and delays between sample time and analyzed results. Therefore, a new CHAB detection method using small unmanned aerial systems with consumer-grade cameras was developed at a maximum detection altitude of 80 m. When cyanobacteria were floating on the surface, CHABs detection through RGB band cameras and spectral enhancement techniques was efficient and accurate. Small unmanned aerial systems were capable of providing coverage up to 1 km 2 per mission and the short intervals between sampling and results (approx. 2 h) allowed for the rapid analysis of data and for implementing follow-up monitoring or treatments. This method is very cost-effective at an estimate of as low as $100 CAD per mission with an average cyanobacterial detection accuracy of 86%. Thus, it is a good candidate method to fill the urgent need for CHABs detection, providing cost effective, rapid, and accurate information to improve risk management at a local level as well as to help quickly allocate resources for purposes of mitigation.

Effects of simultaneous exposure of Pacific oyster, Crassostrea gigas, to both a harmful dinoflagellate that produces Paralytic Shellfish Toxins (PST), Alexandrium minutum, and cadmium (Cd) and copper (Cu), were assessed. Oysters were exposed to a mix of Cd-Cu with two different diets (i.e. A. minutum or Tisochrysis lutea) and compared to control oysters fed A. minutum or T. lutea, respectively, without metal addition. Metals and PST accumulations, digestive gland lipid composition, and cellular and biochemical hemolymph variables were measured after 4 days of exposure. Oysters exposed to Cd-Cu accumulated about thirty-six times less PSTs than oysters exposed to A. minutum alone. Exposure to Cd-Cu induced significant changes in neutral lipids (increase in diacylglycerol -DAG -and decrease in sterols) and phospholipids (decreases in phosphatidylcholine, phosphatidylethanolamine, cardiolipin and ceramide aminoethylphosphonate) of digestive gland suggesting that lipid metabolism disruptions and/or lipid peroxidation have occurred. Simultaneously, concentrations, percentages of dead cells and phenoloxidase activity of hemocytes increased in oysters exposed to metals while reactive oxygen species production of hemocytes decreased. Feeding on the harmful dinoflagellate A. minutum resulted in significant decreases in monoacylglycerol (MAG) and DAG and ether glycerides (EG), as well as significant increases in hemocyte concentration and phagocytic activity as compared to oysters fed T. lutea. Finally, the present study revealed that short-term, simultaneous exposure to Cd-Cu and A. minutum may induce antagonistic (i.e. hemocyte concentration and phagocytosis) or synergic (i.e. DAG content in digestive gland) effects upon cellular and tissular functions in oysters. ► Oysters, C. gigas, were exposed to both metals and PST-producer A. minutum. ► Oysters exposed to metals accumulated about thirty-six times less PSTs. ► Exposure to both metals and A. minutum induced antagonistic or synergetic effects.

An investigation into the distribution of Dinophysis spp. in coastal waters off the south coast of Ireland was carried out in July 2007. Dinophysis acuta was present as a sub surface layer containing up to 55,000 cells L -1 . The population had a high percentage of viable cells (mean: 89%; median: 94%; n = 24) with a high specific division rate (∼0.55 d -1 ). The layer, of approximately 5 m thickness, did not coincide with the fluorescence maximum and was present as a patch of horizontal dimension less than 10 km × 7 km. Both conventional and towed undulating CTD used in conjunction with high vertical resolution sampling methods showed the patch of Dinophysis to move with a similar speed and direction as the coastal flow, which ran parallel to the coast in the form of a coastal jet with speed of the order of 6.5-7 km day -1 . The implications of the alongshore transport of populations of harmful species in coastal jets for monitoring programmes and predictive models are discussed. ► High density sub-surface thin layer of Dinophysis acuta off south coast of Ireland. ► Transport of small scale patch within a coastal jet. ► Implications for modelling and prediction.

The genus Alexandrium comprises some of the most potentially toxic marine algae. A new toxic species of Alexandrium, A. fragae sp. nov., was found in Guanabara Bay, Rio de Janeiro, southern Brazil. The new species produces GTX2&3 and STX. The cell morphology of A. fragae resembles A. minutum in many characters, including the small size; the rounded-elliptical shape; and the shapes of the apical pore complex (APC), first apical plate (1′), sixth precingular plate (6″), and anterior and posterior sulcal plates (s.a. and s.p.). The main diagnostic characters of A. fragae are the ornamentation pattern, smooth epitheca and reticulated hypotheca, all of which were present in both natural populations and cultures. Phylogenies inferred from the ITS, LSU, and SSU rDNA of A. fragae showed that A. fragae clustered in a well-supported clade, distinct from other Alexandrium species. Morphology and molecular analyses based on ITS and LSU rDNA indicated that A. fragae strains and Alexandrium sp. from Japan (D163C5, D164C6) are a single species. Our findings suggest that the Alexandrium morphotype with a smooth epitheca and reticulated hypotheca, previously identified as A. minutum in different geographic regions, may corresponds to A. fragae.

The king scallop, Pecten maximus (L.), fishery is a valuable economic resource in the UK, and is reliant on supplying premium "roe-on" processed scallops to the continental market. A considerable degree of variability is observed in domoic acid (DA) levels among individual P. maximus and their body components, which complicates the management of the fishery during amnesic shellfish poisoning (ASP) events. This study examined the impact of professional processing and three differing laboratory preparation techniques on final gonadal DA levels. DA analysis was conducted using a LC-MS/MS procedure. The results demonstrate that different methods of preparation can significantly alter gonadal toxicities in scallops from the same site, and the extent to which DA within the digestive loop, which passes through the gonad, contributes to total gonadal DA. Mean gonadal toxicity attributed to the digestive loop contents was estimated at 4.7-24.7 g DA g -1 . Despite large individual variations in toxin levels; in scallops with elevated gonadal toxicities resulting from higher digestive loop content toxicity, the effect of flushing out the contents of the digestive loop significantly reduced the DA content of the tissue and lowered the frequency of individuals harbouring levels above the 20 g DA g -1 statutory safety limit. Removal of the digestive loop contents can potentially result in an 87% decrease in gonadal DA burden. Furthermore, the method applied by professional processors effectively removed the contents of the digestive loop and reduced gonadal DA to levels comparable with the laboratory techniques. Deliberate contamination with scallop mucus did not increase gonadal DA levels. The extent of toxin variation resulting from differing gonad preparations demonstrates the need to standardize scallop tissue preparation techniques during ASP events. Consequently, detailed protocols aimed at minimizing the contamination of edible components should be developed and adhered to by both processing facilities and monitoring bodies.

Ciguatera is a human illness caused by ingestion of toxic dinoflagellates. It is endemic to tropical regions, but has expanded globally, facilitated by increased tourism to the tropics and the distribution of frozen fish from the tropics. Fish sourced from the Great Barrier Reef (GBR) and Queensland (Qld) coastal waters are the primary source of ciguatera in Australia, however, environmental drivers of ciguatera remain poorly understood. The main causative dinoflagellate genus, Gambierdiscus, produce ciguatoxins that bioaccumulate through marine food webs. Gambierdiscus species are frequently found on macroalgal substrates and usually co-occur with other benthic dinoflagellates, such as Prorocentrum and Ostreopsis. Gambierdiscus species have been recorded in the GBR (17 °S, 20 – 25 °S, 27°S) and very recently have been recorded as far south as Merimbula (37 °S), New South Wales (NSW). Eco-physiological drivers for population range expansions are unknown, but increasing sea surface t...

Juveniles of the mussel Mytilus chilensis were exposed to a diet containing paralytic shellfish poisoning (PSP) toxins produced by the dinoflagellate Alexandrium catenella (strain ACC02). The feeding behaviour and the dynamics of intoxication and detoxification were evaluated over an intoxication period of nine days, followed by a detoxification period of eight days. A significant reduction in the feeding activity was measured during the first days of exposure to the PSP toxins (days 0 and 2), followed by a period of recovery observed on days 5 and 9, when the clearance rate of the contaminated mussels significantly increased. During the detoxification period, the contaminated bivalves showed a total recovery of clearance rate, and no significant differences were observed between contaminated and control groups. The intoxication dynamic was characterised by a rapid and sustained increase in the amount of PSP toxins accumulated in the tissues of the bivalves. Due to this increase, the level of PSP toxins critical for human consumption was reached on the first day, and at the end of the intoxication period, the mussels had accumulated 1601 μg STX eq. 100 g -1 tissue. During the detoxification period, a decrease of PSP toxins was observed, down to 319 μg STX eq. 100 g -1 tissue. The lower clearance rates observed over the first days of exposure would produce a decrease in the energy intake and could affect the rate of growth of juveniles. Despite this initial effect, the rapid intoxication capacity of M. chilensis corroborates that this species is a good indicator for the early detection of harmful algal blooms.

Blooms of Alexandrium spp. are a well-known phenomenon in Northern European waters. While A. tamarense/ catenella, and A. pseudogonyaulax have been reported from marine waters, high densities of A. ostenfeldii are mainly observed at lower salinities in North Sea estuaries and the Baltic Sea, suggesting salinity as a driver of Alexandrium species composition and toxin distribution. To investigate this relationship, an oceanographic expedition through a natural salinity gradient was conducted in June 2016 along the coasts of Denmark. Besides hydrographic data, phytoplankton and sediment samples were collected for analyses of Alexandrium spp. cell and cyst abundances, for toxin measurement and cell isolation. Plankton data revealed the predominance of A. pseudogonyaulax at all transect stations while A. ostenfeldii and A. catenella generally contributed a minor fraction to the Alexandrium community. High abundances of A. pseudogonyaulax in the shallow enclosed Limfjord were accompanied by high amounts of goniodomin A (GDA). This toxin was also detected at low abundances along with A. pseudogonyaulax in the North Sea and the Kattegat. Genetic and morphological characterization of established strains showed high similarity of the Northern European population to distant geographic populations. Despite low cell abundances of A. ostenfeldii, different profiles of cycloimines were measured in the North Sea and in the Limfjord. This field survey revealed that salinity alone does not determine Alexandrium species and toxin distribution, but emphasizes the importance of habitat conditions such as proximity to seed banks, shelter, and high nutrient concentrations. The results show that A. pseudogonyaulax has become a prominent member of the Alexandrium spp. community over the past decade in the study area. Analyses of long term monitoring data from the Limfjord confirmed a recent shift to A. pseudogonyaulax dominance. Cyst and toxin records of the species in Kiel Bight suggest a spreading potential into the brackish Baltic Sea, which might lead to an expansion of blooms under future climate conditions.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

The freshwater cyanobacterium Microcystis is a nuisance species. It forms large blooms on the water surface and overwhelmingly dominates the ecosystem through the formation of colonies from single cells surrounded by mucilage; however, the mechanism of colony formation is poorly understood. Two mechanisms of Microcystis colony formation have been proposed: cell-division, where cells remain attached after binary fission; and cell-adhesion, where single cells stick together. This paper examined the published literature on Microcystis colony formation to clarify the mechanism of colony formation and its relationship to environmental drivers. This meta-analysis showed that in laboratory experiments, colony formation by celldivision was mainly induced by zooplankton filtrate, high Pb 2+ concentrations, the presence of the cyanobacterium Cylindrospermopsis raciborskii, heterotrophic bacteria, and low temperature and low light intensities. Alternatively, colony formation by cell-adhesion was mainly induced by zooplankton grazing, high Ca 2+ concentrations, and microcystins. Therefore, colony formation by cell-division appears to be a slower process and to occur under an environmental stress factor, while cell-adhesion occurs more quickly to an environmental threat. Applying the criteria to the different morphospecies of Microcystis, found that under natural conditions M. ichthyoblabe colonies formed predominantly through cell-division, whereas M. wesenbergii colonies formed predominantly through cell-adhesion. This 4 study provides new insights into the mechanisms and environmental drivers of colony formation by Microcystis.

In recent years, in-situ fluorometers have been extensively deployed to monitor cyanobacteria in near real-time. Acceptable accuracy can be achieved between measured pigments and cyanobacteria biovolume provided the cyanobacteria species are known. However, cellular photosynthetic pigment content and measurement interferences are site and species specific and can dramatically affect sensor reliability. We quantified the accuracy of an in-situ fluorometer compared with traditional methods using mono-and mixed cultures of four different cyanobacterial species. We found: (1) lower pigment content in cultures in stationary phase, (2) higher precision with the sensor compared to traditional pigment quantification methods of measuring phycocyanin and chlorophyll a, (3) species-specific relationships between sensor readings and measurements related to biovolume, (4) overestimation of pigments in mixed compared with mono cultures, (5) dissolved organic matter causing a loss in signal proportional to its degree of aromaticity, and (6) potential to quantify the degree of cell lysis with a fluorescent dissolved organic matter sensor. This study has provided important new information on the strengths and limitations of fluorescence sensors. The sensor readings can provide accurate biovolume quantification and species determination for a number of bloom-forming species when sensors are properly compensated and calibrated.

Heterotrophic dinoflagellates are ubiquitous protists in marine environments and play diverse roles in marine food webs . They are known to feed on bacteria, microalgae, heterotrophic protists, eggs and larvae of larger plankton, early nauplius stages, and adults of metazoo-

Monitoring of cyanobacterial bloom biomass in large lakes at high resolution is made possible by remote sensing. However, monitoring cyanobacterial toxins is only feasible with grab samples, which, with only sporadic sampling, results in uncertainties in the spatial distribution of toxins. To address this issue, we conducted two intensive "HABs Grabs" of microcystin (MC)-producing Microcystis blooms in the western basin of Lake Erie. These were one-day sampling events during August of 2018 and 2019 in which 100 and 172 grab samples were collected, respectively, within a six-hour window covering up to 2,270 km 2 and analyzed using consistent methods to estimate the total mass of MC. The samples were analyzed for 57 parameters, including toxins, nutrients, chlorophyll, and genomics. There were an estimated 11,513 kg and 30,691 kg of MCs in the western basin during the 2018 and 2019 HABs Grabs, respectively. The bloom boundary poses substantial issues for * Corresponding author.

Massive developments of potentially toxic cyanobacteria in Lake Stechlin, an oligo-mesotrophic lake in the Baltic Lake District of Germany raised concerns about toxic contamination of these important ecosystems. Field samples in the phase of mass developments of cyanobacteria were used for genetic and toxicological analyses. Microcystins and microcystin genes were detected in field samples of the lake for the first time. However, the toxins were not produced by the dominant taxa (Dolichospermum circinale and Aphanizomenon flos-aquae) but by taxa, which were present only in low biomass in the samples (Microcystis cf. aeruginosa and Planktothrix rubescens). The phytoplankton

To investigate the distribution of Heterocapsa including a harmful species H. circularisquama, cells were surveyed in three Vietnamese coasts, Ha Long Bay, Hue and Phu Quoc Island in 2006. Cells of Heterocapsa were detected from Lang Co Lagoon and adjacent coast in Hue. Cell of the species possesses thecal plates corresponding to the typical of Heterocapsa. Under TEM, body scales approximately 500 nm in diameter are observed. The scale structure is similar to that of H. illdefina, however, number of the marginal spine is different. We concluded it is an undescribed Heterocapsa species possessing a new body scale ultrastructure.

Diatoms are often the dominating group of benthic microalgae living on different types of bottom substrates. Their effects on invertebrate consumers is not well-documented. We here investigate the effects of feeding on another two benthic diatoms, Cocconeis scutellum and Diploneis sp., isolated from leaves of the seagrass Posidonia oceanica, on the sea urchin Paracentrotus lividus. Our results indicate a noxious effect on sea urchin embryos spawned from adults fed on Diploneis sp., with an increasing number of malformed embryos with respect to those spawned from adults fed on Ulva rigida (used as a feeding control). In contrast C. scutellum did not induce any morphological effect on embryos, similar to control non-diatom diets. Moreover, de novo obtained transcriptome indicated that oxidation-reduction process, translation, proton and electron transmembrane transport, ATP/ RNA/GTP/heme/calcium and metal ion binding, NADH dehydrogenase activity, cytochrome c oxidase were affected by feeding of sea urchins on Diploneis sp. Our findings have considerable ecological significance considering that diatom biomass ingested by the sea urchin in these experiments is within the range of cell densities characterizing P. oceanica leaves where sea urchins live and spawn.

Many marine dinoflagellates, including several species of the genus Alexandrium, Gymnodinium catenatum, and Pyrodinium bahamense are known for their capability to produce paralytic shellfish toxins (PST), which can cause severe, most often food-related poisoning. The recent discovery of the first PST biosynthesis genes has laid the foundation for the development of molecular detection methods for monitoring and study of PST-producing dinoflagellates. In this study, a probe-based qPCR method for the detection and quantification of the sxtA4 gene present in Alexandrium spp. and Gymnodinium catenatum was designed. The focus was on Alexandrium ostenfeldii, a species which recurrently forms dense toxic blooms in areas within the Baltic Sea. A consistent, positive correlation between the presence of sxtA4 and PST biosynthesis was observed, and the species was found to maintain PST production with an average of 6 genomic copies of sxtA4. In August 2014, A. ostenfeldii populations were studied for cell densities, PST production, as well as sxtA4 and species-specific LSU copy numbers in Fo ¨glo ¨, A ˚land, Finland, where an exceptionally dense bloom, consisting of 6.3 Â 10 6 cells L À1 , was observed. Cell concentrations, and copy numbers of both of the target genes were positively correlated with total STX, GTX2, and GTX3 concentrations in the environment, the cell density predicting toxin concentrations with the best accuracy (Spearman's r = 0.93, p < 0.01). The results indicated that all A. ostenfeldii cells in the blooms harbored the genetic capability of PST production, making the detection of sxtA4 a good indicator of toxicity.

environment, such as MC-LR (50 mg kg À1 , Krishnamurthy et al., 1986) and MC-RR (600 mg kg À1 , . Microcystins are produced by strains of several bloom-forming cyanobacterial genera, globally most common of which are Microcystis, Anabaena and Planktothrix (Sivonen and Jones, 1999). With the growing awareness of the toxins and their producers, the demand for risk assessment and monitoring methods is increasing. Since the discovery of the genetic background of microcystin biosynthesis (

Cyanobacterial harmful algal blooms (CHABs) degrade water quality and may produce toxins. The distribution of CHABs can change rapidly due to variations in population dynamics and environmental conditions. Biological and ecological aspects of CHABs were studied in order to better understand CHABs dynamics. Field experiments were conducted near Hartington, Ontario, Canada in ponds dominated by Microcystis aeruginosa and CHABs floating experiments were conducted at Lake Taihu during the summers of 2015 and 2016. Single colonies composed of hundreds to thousands of cells with an average median of 0.2-0.5 mm in diameter were the basic form assumed by the Microcystis, and this remained the same throughout the growing season. Thorough mixing of the water column followed by calm conditions resulted in over 90% of the cyanobacteria floating after 1 h. Multiple colonies floated on the water surface in four types of assemblages: aggregates, ribbons, patches, and mats. It is the mats that are conventionally considered the blooming stage of cyanobacteria. Presence of CHABs on open water surfaces also depends on environmental influences such as direct and indirect wind effects. For example, field tests revealed that the surface coverage of CHABs can be reduced to half within an hour at wind speeds of 0.5 m/s. Because our findings indicated that blooming involves surface display of cyanobacteria essentially presenting as a two-dimensional plane under defined conditions, the use of surface imagery to quantify CHABs was justified. This is particularly important in light of the fact that traditional detection methods do not provide accurate distribution information. Nor do they portray CHABs events in a real-time manner due to limitations in ondemand surveillance and delays between sample time and analyzed results. Therefore, a new CHAB detection method using small unmanned aerial systems with consumer-grade cameras was developed at a maximum detection altitude of 80 m. When cyanobacteria were floating on the surface, CHABs detection through RGB band cameras and spectral enhancement techniques was efficient and accurate. Small unmanned aerial systems were capable of providing coverage up to 1 km 2 per mission and the short intervals between sampling and results (approx. 2 h) allowed for the rapid analysis of data and for implementing follow-up monitoring or treatments. This method is very cost-effective at an estimate of as low as $100 CAD per mission with an average cyanobacterial detection accuracy of 86%. Thus, it is a good candidate method to fill the urgent need for CHABs detection, providing cost effective, rapid, and accurate information to improve risk management at a local level as well as to help quickly allocate resources for purposes of mitigation.

Lots of research has demonstrated that macroalgae can strongly inhibit the growth of harmful algal bloom (HAB) species in general. However, the effects of HABs or HAB-forming species on macrophytes are still largely uncharacterized until now. In the present study, the effects of the dinoflagellate Karenia mikimotoi cell density gradient, live cell suspension (LC), ruptured cell suspension (RC) as well as the cell-free supernatant (FC) of K. mikimotoi at 1000 μg Chla l -1 (~1.0 × 10 5 cells ml -1 ) on the development and photosynthesis of Sargassum fusiforme embryos were investigated in a series of laboratory experiments. The results showed that co-cultivation with K. mikimotoi at 500 μg Chla l -1 (~5.0 × 10 4 cells ml -1 ) and higher cell densities significantly (P<0.05) inhibited the development, pigment content and photosynthetic activities of the embryos. In addition, the inhibitory effects increased with increased cell densities and prolonged exposure time. Compared to the embryos cultured with the F/2 medium (Control), exposure to LC, RC and FC of K. mikimotoi at 1000 μg Chla l -1 for 2 weeks all led to decreased relative growth rate (RGR), chlorophyll (Chl) a content, carotenoids (Car) content and photosynthetic activities of the embryos, with LC and RC exhibiting the maximal and the minimal suppression. The dominant inhibitory effects of FC on the embryos indicated that the suppression was mainly caused by the allelochemicals, while the slightest inhibitory effects of RC on the embryos suggested that some intracellular growth-promoting substances were synchronously released when K. mikimotoi cells lyzed. In addition, the most severe growth suppression of embryos by LC indicated that intact cell contact by K. mikimotoi probably also contributed to the inhibitory effects. These results indicated that a dense HAB formed by K. mikimotoi could seriously suppress the development and photosynthesis of S. fusiforme embryos and eventually reduce the seedlings stock.

Toxic strains of Pfiesteria spp. produce toxin(s) that can cause finfish death, but much less is known about impacts of Pfiesteria on shellfish. Here we conducted 4 experiments to examine interactions between shellfish and toxic (actively toxic or TOX-A from finfish-killing cultures and potentially toxic or TOX-B from cultures without finfish) and non-inducible (NON-IND, apparently incapable of killing fish via a toxic effect) strains of P. piscicida. First (Expt 1), we documented direct physical attack by P. piscicida TOX-A, TOX-B, and NON-IND zoospores on larvae of the bay scallop Argopecten irradians (Lamarck, 1819) and the eastern oyster Crassostrea virginica (Gmelin, 1791). Within 5 min zoospores swarmed around larvae that had discarded their vela, and attached with their peduncles. Within 15 min they had penetrated into the shellfish visceral cavity and had begun to feed aggressively; after 30 min all shellfish tissues except the adductor muscle had been consumed. Second, we tested the response of scallop larvae to P. piscicida (TOX-A or TOX-B) or cryptomonads (as controls) that were held in dialysis tubing (0.22 µm porosity) to prevent direct contact. After 60 min larval survival was 0% in the TOX-A treatment, 100% in the cryptomonad control, and intermediate in TOX-B and TOX-B + cryptomonad treatments. The data indicate a toxic effect of P. piscicida zoospores on the larvae, separate from the physical effect shown in Expt 1. Third, we compared grazing by juvenile and adult oysters on TOX-A, TOX-B, and NON-IND P. piscicida zoospores from the medium. After 60 min, grazing by juvenile oysters significantly differed as NON-IND >> TOX-B >> TOX-A. In contrast, adult oysters grazed significantly fewer TOX-A zoospores and maintained comparable grazing on TOX-B and NON-IND zoospores. Thus juvenile oysters, but not adults, were sensitive to residual toxicity of TOX-B zoospores, and both life-history stages were sensitive to TOX-A zoospores. The adverse effects of toxic strains on larval survival and juvenile grazing indicate that P. piscicida could potentially affect shellfish recruitment. Fourth, we assessed zoospore survival after passage through the digestive tract of adult oysters. The feces contained many temporary cysts from zoospores, and within 24 h > 75% of the cysts produced motile cells. The data indicate that adult oysters would be poor biocontrol agents of P. piscicida, given the high survival of ingested zoospores following gut passage and fecal elimination; and that oysters could act as vectors of toxic P. piscicida strains if transported from affected estuaries to other waters.

Over the last three years, several blooms of Heterosigma akashiwo (Raphidophyceae) were documented in South Carolina (SC) brackish waters, including areas containing extensive oyster (Crassostrea virginica) beds. This study examined the sublethal effects of H. akashiwo on C. virginica, based on cellular biomarker responses after exposure to laboratory cultures of H. akashiwo isolated from SC waters, and to water collected from two SC H. akashiwo blooms. Exposure to laboratory cultures or blooms of H. akashiwo significantly increased oyster hepatopancreas lysosomal destabilization rates, but had little effect on gill p-glycoprotein (p-gp) expression. Lysosomal destabilization in oysters continued to increase even after a 7-day recovery period in clean seawater, suggesting that H. akashiwo toxin or other cellular byproducts continued to damage the hepatopancreas. These results suggest that even short-term exposures of oysters to high cell densities of H. akashiwo could have long-term adverse physiological effects, and imply that oyster health may be compromised in areas where repetitive H. akashiwo blooms occur.

Species of the genus Gambierdiscus are epiphytic dinoflagellates well known from tropical coral reef areas at water temperatures from 24 to 29 8C. Gambierdiscus spp. are able to produce ciguatoxins (CTXs) known to bioaccumulate in fish, and the ingestion of tropical fish that accumulated CTXs and possibly also maitotoxins (MTXs) can cause ciguatera fish poisoning (CFP) in humans. In Australia, ciguatera poisonings have been reported in tropical parts of Queensland and the Northern Territory. Here, we report for the first time the seasonal abundance (April-May 2012/13) of Gambierdiscus spp. (up to 6565-8255 cells g À1 wet weight algae) from Merimbula and Wagonga Inlets in temperate southern New South Wales, Australia (378 S) at water temperatures of 16.5-17 8C. These are popular shellfish aquaculture and recreational fisheries areas with no reports of ciguatera poisoning. Sequencing of a region of the 28S rRNA gene led to the conclusive identification of Gambierdiscus carpenteri. The cells differed however from the Belize type description, including the absence of a thecal groove, dorsal rostrum and variable hatchet-to rectangular-shaped 2 0 plate, and were morphologically more similar to Gambierdiscus toxicus. To study the dinoflagellate community structure in detail, a pyrosequencing approach based on the 18S rRNA gene was applied, which confirmed the presence of a single Gambierdiscus species only. Neither CTXs nor MTXs were detected in natural bloom material by LC-MS/MS; however, the extracts were found to be toxic via mouse-bioassay, with symptoms suggestive of poisoning by MTX-like compounds. Understanding the abundance of Gambierdiscus populations in areas with no apparent human health impacts is important towards defining the alternate conditions where sparse populations can create ciguatera problems.

Alexandrium catenella (formerly A. tamarense Group 1, or A. fundyense) is the leading cause of paralytic Shellfish Poisoning in North and South America, Europe, Africa, Australia and Asia. The quantification of A.catenella via sxtA, a gene involved in Paralytic Shellfish Toxin synthesis, may be a promising approach, but has not been evaluated in situ on blooms of A. catenella, in which cell abundances may vary from not detectable to in the order of 10 6 cells L −1. in this study, we compared sxtA assay performance to a qPCR assay targeted to a species-specific region of ribosomal DNA (rDNA) and an established fluorescent in situ hybridization (fiSH) microscopy method. passing-Bablok regression analyses revealed the sxtA assay to overestimate abundances when <5 cell equivalents A. catenella DnA were analysed, but otherwise was closer to microscopy estimates than the rDnA assay, which overestimated abundance across the full range of concentrations analysed, indicative of a copy number difference between the bloom population and a culture used for assay calibration a priori. in contrast, the sxtA assay performed more consistently, indicating less copy number variation. the sxtA assay was generally reliable, fast and effective in quantifying A. catenella and was predictive of pSt contamination of shellfish. Saxitoxin (STX) and its many analogues, known as the paralytic shellfish toxins (PSTs), are neurotoxins that can have profound effects on marine food chains 1 and are responsible for causing the syndrome paralytic shellfish poisoning (PSP) in humans. In marine environments, STX-producing phytoplankton comprise ~8 species of the genus Alexandrium, as well as Gymnodinium catenatum and Pyrodinium bahamense 2-6. Because these blooms threaten seafood safety, they are monitored extensively through a variety of frequently labour-intensive methods (reviewed in 7). Quantitative polymerase chain reaction (qPCR) based methods are a compelling alternative to more commonly applied microscopy-based approaches because they are species specific and can be low-cost, especially when integrated with automated DNA extraction and multiplexed with other, similar PCR-based water quality assays. Many previous studies have developed and applied qPCR assays for detection of Alexandrium sp. ribosomal RNA sequences in seawater extracts, targeting A. catenella (=A. fundyense, A. tamarense Group I), A. pacificum (=A. tamarense Group IV), A. minutum, A. ostenfeldii, and A. tamutum (e.g., 8-22). The amplicon targets of these assays have high copy numbers (i.e., commonly >10 5 copies cell −1). None of these assays, however, is able to quantify all PST producing species. In recent years, the identification of the core genes responsible for the PST biosynthesis pathway in Alexandrium spp., Pyrodinium bahamense and Gymnodinium catenatum 23-25 have enabled the detection of genes involved in PST biosynthesis from environmental samples 26. A group of eight genes (sxtA, sxtB, sxtD, sxtG, sxtH or sxtT, sxtI, sxtS, and sxtU) may be directly implicated in PST synthesis in dinoflagellates 27,28 , in particular the synthesis of the parent compound, STX, which is hypothesised to subsequently be modified to form the other PST analogs. sxtA is considered to be the first gene in the PST biosynthetic pathway 27,29. sxtA has four catalytic

Delayed luminescence (DL), also termed delayed fluorescence or delayed light emission, is the phenomenon of long-lived light emission by plants and cyanobacteria after being illuminated with light and put into darkness. Culture growth of three Prorocentrum minimum strains was studied with DL measurements. DL decay kinetics was measured from 1-60 s after a pulse of white light. The strains used were from the Adriatic Sea (PmK), from Chesapeake Bay, USA (D5), and from the Baltic Sea (BAL), cultured at salinity of 32, 16, and 8 (practical salinity scale), respectively. The strains differed in cell size and chlorophyll a content (PmK > D5 > BAL), as well as in DL parameters. The DL results were compared to standard measurements of culture density and carbon content (calculated from biovolumes). DL decay curves had a specific peak, which changed with culture growth and showed more similarities between the strains PmK and D5. The DL intensity increased with cell density and carbon content in a two-stage process, corresponding to the lag and exponential phases of growth. DL intensity was best correlated with carbon content irrespective of strain and is proposed as an estimate of biomass and for differentiating between lag and exponential phases of growth.

20 Several species of the marine diatom Pseudo-nitzschia can produce the neurotoxin domoic 21 acid that is responsible for the seafood-borne illness amnesic shellfish poisoning in humans, 22 marine wildlife mortalities, and prolonged closures of fisheries resulting in economic losses 23 to coastal communities. Since the year 2000, Pseudo-nitzschia species have been monitored 24 in the Pacific Ocean with the Continuous Plankton Recorder (CPR). This study used a 25 combination of scanning electron microscopy with high-throughput and Sanger sequencing of 26 CPR survey samples to compare the diversity of phytoplankton, including Pseudo-nitzschia 27 species, from the north-eastern Pacific Ocean over three climatically different years: 2002, 28 2005, and 2008. Using a Pseudo-nitzschia- specific primer set targeting a 320bp region of the 29 large subunit ribosomal DNA (rDNA), revealed spatially-separated communities of Pseudo- 30 nitszschia . The coastal region was dominated by a diverse a...

Species in the epi-benthic dinoflagellate genus Gambierdiscus produce ciguatoxins (CTXs) and maitotoxins (MTXs), which are among the most potent marine toxins known. Consumption of fish contaminated with sufficient quantities of CTXs causes Ciguatera Fish Poisoning (CFP), the largest cause of non-bacterial food poisoning worldwide. Maitotoxins, which can be found in the digestive system of fish, could also contribute to CFP if such tissues are consumed. Recently, an increasing number of Gambierdiscus species have been identified; yet, little is known about the variation in toxicity among Gambierdiscus strains or species. This study is the first assessment of relative CTX- and MTX-toxicity of Gambierdiscus species from areas as widespread as the North-Eastern Atlantic Ocean, Pacific Ocean and the Mediterranean Sea. A total of 13 strains were screened: (i) seven Pacific strains of G. australes, G. balechii, G. caribaeus, G. carpenteri, G. pacificus, G. scabrosus and one strain of an u...

Functional drivers of phytoplankton that can potentially form harmful algal blooms (HABs) are important to understand given the increased prevalence of anthropogenic modification and pressure on coastal habitats. However, teasing these drivers apart from other influences is problematic in natural systems, while laboratory assessments often fail to replicate relevant natural conditions. One such potential bloom-forming species complex highlighted globally is Mesodinium cf. rubrum, a planktonic ciliate. This species occurs persistently in the Sundays Estuary in South Africa yet has never been observed to "bloom" (> 1,000 cell.ml -1 ). Modified by artificial nutrient-rich baseflow conditions, the Sundays Estuary provides a unique Southern Hemisphere case study to identify the autecological drivers of this ciliate due to artificial seasonally "controlled" abiotic environmental conditions. This study utilised a three-year monitoring dataset (899 samples) to assess the drivers of M. cf. rubrum using a generalised modelling approach. Key abiotic variables that influenced population abundance were season and salinity, with M. cf. rubrum populations peaking in summer and spring and preferring polyhaline salinity regions (>18) with pronounced water column salinity stratification, especially in warmer months. This was reflected in the diel vertical migration (DVM) behaviour of this species, demonstrating its ability to utilise the optimal daylight photosynthetic surface conditions and high-nutrient bottom waters at night. The only phytoplankton groups clearly associated with M. cf. rubrum were Raphidophyceae and Cryptophyceae. Although M. cf. rubrum reflects a niche overlap with the dominant HABforming phytoplankton in the estuary (the raphidophyte, Heterosigma akashiwo), its reduced competitive abilities restrict its abundance. In contrast, the mixotrophic foraging behaviour of M. cf. rubrum exerts a topdown control on cryptophyte prey abundance, yet, the limited availability of these prey resources (mean < 300 cells ml -1 ) seemingly inhibits the formation of red-water accumulations. Hydrodynamic variability is necessary to ensure that no single phytoplankton HAB-forming taxa outcompetes the rest. These results confirm aspects of the autecology of M. cf. rubrum related to salinity associations and DVM behaviour and contribute to a global understanding of managing HABs in estuaries.

A bloom of the fish-killing haptophyte Chrysochromulina leadbeateri in northern Norway during May and June 2019 was the most harmful algal event ever recorded in the region, causing massive mortalities of farmed salmon. Accordingly, oceanographic and biodiversity aspects of the bloom were studied in unprecedented detail, based on metabarcoding and physico-chemical and biotic factors related with the dynamics and distribution of the bloom. Light-and electron-microscopical observations of nanoplankton samples from diverse locations confirmed that C. leadbeateri was dominant in the bloom and the primary cause of associated fish mortalities. Cell counts by light microscopy and flow cytometry were obtained throughout the regional bloom within and adjacent to five fjord systems. Metabarcoding sequences of the V4 region of the 18S rRNA gene from field material collected during the bloom and a cultured isolate from offshore of Tromsøy island confirmed the species identification. Sequences from three genetic markers (18S, 28S rRNA gene and ITS region) verified the close if not identical genetic similarity to C. leadbeateri from a previous massive fish-killing bloom in 1991 in northern Norway. The distribution and cell abundance of C. leadbeateri and related Chrysochromulina species in the recent incident were tracked by integrating observations from metabarcoding sequences of the V4 region of the 18S rRNA gene. Metabarcoding revealed at least 14 distinct Chrysochromulina variants, including putative cryptic species. C. leadbeateri was by far the most abundant of these species, but with high intraspecific genetic variability. Highest cell abundance of up to 2.7 × 10 7 cells L -1 of C. leadbeateri was found in Balsfjorden; the high cell densities were associated with stratification near the pycnocline (at ca. 12 m depth) within the fjord. The cell abundance of C. leadbeateri showed positive correlations with temperature, negative correlation with salinity, and a slightly positive correlation with ambient phosphate and nitrate concentrations. The spatio-temporal succession of the C. leadbeateri bloom suggests independent initiation from existing pre-bloom populations in local zones, perhaps sustained and supplemented over time by northeastward advection of the bloom from the fjords.

The productive but highly exposed coastline of the southern Benguela eastern boundary upwelling system offers limited natural environment for aquaculture. Saldanha Bay located on the west coast of South Africa is one of the few embayments on the coastline that provides a productive and relatively sheltered environment suitable for the cultivation of shellfish. Consequently, bivalve culture in South Africa is centered in Saldanha Bay and is presently targeted for expansion. Pseudo-nitzschia blooms including toxin-producing species are shown to contribute significantly to the phytoplankton of Saldanha Bay specifically in spring and summer. Their dominance at this time of the year, when upwelling is strongest, fits the ecological profile of Pseudo-nitzschia occurring during periods of high turbulence and nutrients. Multiple Pseudo-nitzschia blooms were sampled under varying environmental conditions and the strength of the relationship between Pseudo-nitzschia cell abundance and particulate domoic acid (pDA) content, reflecting bloom toxicity, varied greatly. This variability is the result of the combined influence of species and strain composition of the Pseudo-nitzschia assemblage and the effect of environmental conditions on toxin production. Elevated levels of pDA were associated with higher concentrations of cells of the P. seriata complex differentiated by frustule width (>3 µm). P. australis was identified as a toxin-producing species and a prominent member of the P. seriata complex. Low DA levels in shellfish in Saldanha Bay are considered a function of low cellular domoic acid (cDA). Silicate limitation has emerged as an important factor inducing DA production in Pseudo-nitzschia species. The high ratio of silicate to nitrate in Saldanha Bay provides a plausible explanation for the low toxin content of Pseudo-nitzschia blooms in the bay and the consequent low risk posed by these blooms to the aquaculture sector.

The marine dinoflagellate Alexandrium Halim represents perhaps the most significant and intensively studied genus with respect to species diversity, life history strategies, toxigenicity, biogeographical distribution, and global magnitude and consequences harmful algal blooms (HABs). The socioeconomic impacts, environmental and human health risks, and mitigation strategies for toxigenic Alexandrium blooms have also been explored in recent years. Human adaptive actions based on future scenarios of bloom dynamics and shifts in biogeographical distribution under climate-change parameters remain under development and not yet implemented on a regional scale. In the CoCliME (Co-development of climate services for adaptation to changing marine ecosystems) project these issues were addressed with respect to past, current and anticipated future status of key HAB genera and expected benefits of enhanced monitoring. Data on the distribution and frequency of Alexandrium blooms related to paralytic shellfish toxin (PST) events from key CoCliME Case Study areas, comprising the North Sea and adjacent Kattegat-Skagerrak, Norwegian Sea, and Baltic Sea, and eastern North Atlantic marginal seas, were evaluated in a contemporary and historical context over the past several decades. The first evidence of possible biogeographical expansion of Alexandrium taxa into eastern Arctic gateways was provided from DNA barcoding signatures. Various key climate change indicators, such as salinity, temperature, and water-column stratification, relevant to Alexandrium bloom initiation and development were identified. The possible influence of changing variables on bloom dynamics, magnitude, frequency and spatial and temporal distribution were interpreted in the context of regional ocean climate models. These climate change impact indicators may play key roles in selecting for the occurrence and diversity of Alexandrium species within the broader microeukaryote communities. For example, shifts to higher temperature and lower salinity regimes predicted for the southern North Sea indicate the potential for increased Alexandrium blooms, currently absent from this area. Ecological and socioeconomic impacts of Alexandrium blooms and effects on fisheries and aquaculture resources and coastal ecosystem function are evaluated, and, where feasible, effective adaptation strategies are proposed herein as emerging climate services.

El análisis morfométrico de deslizamientos submarinos en el talud continental del margen convergente del Norte de Ecuador -Sur de Colombia provee perspectivas al respecto de riesgos naturales, incluyendo la localización de movimientos en masa, tamaño de rupturas y control de la localización. Datos batimétricos y sísmicos adquiridos en el 2005 revelan tres distintos tipos de deslizamientos submarinos potencialmente tsunamigénicos: 1) El borde del margen erosivo está caracterizada por tres escarpes semi-circulares de 5-6 Km de ancho y hasta 1500 m de alto, localmente por un área de escarpes lineales de 35 Km de largo que resultan de la imbricación de rupturas sucesivas; 2) paredes de cañones que están afectadas por cinco escarpes de hasta 500 m de alto, 3) el frente de la deformación exhibe un área potencialmente desestabilizada de 50x20 Km caracterizada por una intensa fracturación. Todas estas formas están controladas por tectónica activa. La pendiente muy abrupta es un parámetro clave que facilita el inicio de ruptura en ésta para los dos primeros tipos, y está asociada con 1) subducción de montes submarinos, 2) subsidencia relacionada con una erosión basal de la placa superior, y 3) levantamiento a lo largo de estructuras tectónicas activas. Observando el tercer tipo, el área de desestabilización esta influenciada por una intensa fracturación en la vecindad de una falla en rama (splay fault).

Harmful algal blooms (HABs) have affected salmon farms in Chile since the early 1970&#39;s, causing massive losses in fish. Two large HABs occurred in 2002 and 2009, during which Alexandrium catenella blooms killed tons of salmon over an extended geographic area in southern Chile. At the beginning of 2016, high and persistent densities of Pseudochattonella cf. verruculosa and A. catenella were detected in the estuarine and marine ecosystems of southern Chile. Mortality for this latter event reached 27 million salmon and trout (i.e. 39,000 tons). Unfortunately, the threshold concentrations of algae that could be harmful to the health of farmed salmon in southern Chile have not yet been quantified. Here, to protect fish farms from HABs, critical concentration levels, i.e. thresholds at which the behavior of farmed Salmo salar is affected by harmful algae were quantified using generalized linear mixed models (GLMM). An extensive database from southern Chile covering the period from 198...

Zooplankton responses to toxic algae are highly variable, even towards taxonomically closely related species or different strains of the same species. Here, the individual level feeding behavior of a copepod, Temora longicornis, was examined which offered 4 similarly sized strains of toxic dinoflagellate Alexandrium spp. and a non-toxic control strain of the dinoflagellate Protoceratium reticulatum. The strains varied in their cellular toxin concentration and composition and in lytic activity. High-speed video observations revealed four distinctly different strain-specific feeding responses of the copepod during 4 h incubations: (i) the 'normal' feeding behavior, in which the feeding appendages were beating almost constantly to produce a feeding current and most (90%) of the captured algae were ingested; (ii) the beating activity of the feeding appendages was reduced by ca. 80% during the initial 60 min of exposure, after which very few algae were captured and ingested; (iii) capture and ingestion rates remained high, but ingested cells were regurgitated; and (iv) the copepod continued beating its appendages and captured cells at a high rate, but after 60 min, most captured cells were rejected. The various prey aversion responses observed may have very different implications to the prey and their ability to form blooms: consumed but regurgitated cells are dead, captured but rejected cells survive and may give the prey a competitive advantage, while reduced feeding activity of the grazer may be equally beneficial to the prey and its competitors. These behaviors were not related to lytic activity or overall paralytic shellfish toxins (PSTs) content and composition and suggest that other cues are responsible for the responses.

Harmful algal blooms (HABs), varying in intensity and causative species, have historically occurred throughout the Chesapeake Bay, U.S.; however, phycotoxin data are sparse. The spatiotemporal distribution of phycotoxins was investigated using solid-phase adsorption toxin tracking (SPATT) across 12 shallow, nearshore sites within the lower Chesapeake Bay and Virginia's coastal bays over one year (2017)(2018). Eight toxins, azaspiracid-1 (AZA1), azaspiracid-2 (AZA2), microcystin-LR (MC-LR), domoic acid (DA), okadaic acid (OA), dinophysistoxin-1 (DTX1), pectenotoxin-2 (PTX2), and goniodomin A (GDA) were detected in SPATT extracts. Temporally, phycotoxins were always present in the region, with at least one phycotoxin group (i.e., consisting of OA and DTX1) detected at every time point. Co-occurrence of phycotoxins was also common; two or more toxin groups were observed in 76% of the samples analyzed. Toxin maximums: 0.03 ng AZA2/g resin/day, 0.25 ng DA/ g resin/day, 15 ng DTX1/g resin/day, 61 ng OA/g resin/day, 72 ng PTX2/g resin/day, and 102,050 ng GDA/g resin/day were seasonal, with peaks occurring in summer and fall. Spatially, the southern tributary and coastal bay regions harbored the highest amount of total phycotoxins on SPATT over the year, and the former contained the greatest diversity of phycotoxins. The novel detection of AZAs in the region, before a causative species has been identified, supports the use of SPATT as an explorative tool in respect to emerging threats. The lack of karlotoxin in SPATT extracts, but detection of Karlodinium veneficum by microscopy, however, emphasizes that this tool should be considered complementary to, but not a replacement for, more traditional HAB management and monitoring methods.

One of the key tasks in the project MIDTAL (MIcroarrays for the Detection of Toxic ALgae) is to demonstrate the applicability of microarrays to monitor harmful algae across a broad range of ecological niches and toxic species responsible for harmful algal events. Water samples are collected from a series of sites used in national phytoplankton and biotoxin monitoring programmes across Europe. The samples are filtered; the rRNA is extracted, labelled with a fluorescent dye and applied to a microarray chip. The signal intensity from >120 probes previously spotted on the chip is measured and analysed. Preliminary results comparing microarray signal intensities with actual field counts are presented.

Benthic dinoflagellates of the toxigenic genus Coolia Meunier (Dinophyceae) are known to have a global distribution in both tropical and temperate waters. The type species, C. monotis, has been reported from the Mediterranean Sea, the NE Atlantic and from Rhode Island, USA in the NW Atlantic, whereas other species in the genus have been reported from tropical locations. Coolia cells were observed in algal drift samples collected at seven sites in Nova Scotia, Canada. Clonal isolates were established from four of these locations and identified with light and scanning electron microscopy, then confirmed with genetic sequencing to be C. monotis. This is the first record of this species in Nova Scotia. The isolates were established and incubated at 18 C under a 14:10 L:D photoperiod with an approximate photon flux density of 50-60 mmol m À2 s À1. Growth experiments using an isolate from Johnston Harbour (CMJH) were carried out at temperatures ranging from 5 to 30 C under the same photoperiod with an approximate photon flux density of 45-50 mmol m À2 s À1. Cells tolerated temperatures from 5 to 25 C with optimum growth and mucilage aggregate production between 15 and 20 C. Methanol extracts of this isolate examined by Liquid Chromatography-Mass Spectrometry (LC-MS) did not show the presence of the previously reported cooliatoxin. Toxic effects were assayed using two zebrafish bioassays, the Fish Embryo Toxicity (FET) assay and the General Behaviour and Toxicity (GBT) assay. The results of this study demonstrate a lack of toxicity in C. monotis from Nova Scotia, as has been reported for other geneticallyconfirmed isolates of this species. Conditions in which cell growth that could potentially degrade water quality and provide substrate and dispersal mechanisms for other harmful microorganisms via mucilage production are indicated.