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Harmful cyanobacterial blooms have adversely impacted human and animal health for thousands of years. Recently, the health impacts of harmful cyanobacteria blooms are becoming more frequently detected and reported. However, reports of human and animal illnesses or deaths associated with harmful cyanobacteria blooms tend to be investigated and reported separately. Consequently, professionals working in human or in animal health do not always communicate findings related to these events with one another. Using the One Health concept of integration and collaboration among health disciplines, we systematically review the existing literature to discover where harmful cyanobacteria-associated animal illnesses and deaths have served as sentinel events to warn of potential human health risks. We find that illnesses or deaths among livestock, dogs and fish are all potentially useful as sentinel events for the presence of harmful cyanobacteria that may impact human health. We also describe ways to enhance the value of reports of cyanobacteria-associated illnesses and deaths in animals to protect human health. Efficient monitoring of environmental and animal health in a One Health collaborative framework can provide vital warnings of cyanobacteria-associated human health risks.

Algae and cyanobacteria are present in all aquatic environments. We do not have a good sense of the extent of human and animal exposures to cyanobacteria or their toxins, nor do we understand the public health impacts from acute exposures associated with recreational activities or chronic exposures associated with drinking water. We describe the Harmful Algal Bloom-related Illness Surveillance System (HABISS) and summarize the collected reports describing bloom events and associated adverse human and animal health events. For the period of 2007–2011, Departments of Health and/or Environment from 11 states funded by the National Center for Environmental Health (NCEH), Centers for Disease Control and Prevention contributed reports for 4534 events. For 2007, states contributed 173 reports from historical data. The states participating in the HABISS program built response capacity through targeted public outreach and prevention activities, including supporting routine cyanobacteria monitoring for public recreation waters. During 2007–2010, states used monitoring data to support196 public health advisories or beach closures. The information recorded in HABISS and the application of these data to develop a wide range of public health prevention and response activities indicate that cyanobacteria and algae blooms are an environmental public health issue that needs continuing attention.

Abstract Harmful algal blooms (HABs) have increased throughout the world's coastal oceans during the last century mostly due to water eutrophication and climate change. These blooms are often accompanied by extreme extensive negative impacts to fisheries, coastal resources, public health and local economies. However, limited studies have reported HAB events in Red Sea coastal waters. This article reviews potentially harmful microalgae in the Red Sea, based on available published information during the last 3 decades. Five harmful algal blooms were recorded in the Red Sea; of which 3 blooms are formed by dinoflagellates (Noctiluca scintillans , Pyrodinuium bahamense , Protoperidinium quinquecorne), one by raphidophytes (Heterosigma akashiwo) and one by cyanobacteria (Trichodesmium erythraeum). Additionally, mangrove swamps in the Red Sea were occupied by cyanobacterial mats, which contain microcystin and saxitoxin-producing species. The existing data in this review could be a catalyst for the establishment of monitoring and management program for HABs and their toxins in Red Sea coastal waters. This review also identifies current research gaps and suggests future research directions. Highlights • Potentially harmful algae have become prevalent in the Red Sea coastal waters. • Blooms of toxin-producing species were recorded in coastal waters of some countries. • Cysts of harmful dinoflagellate species in the Red Sea sediments were also presented. • This review will assist Red Sea countries monitor and manage harmful algal blooms. [ABSTRACT FROM AUTHOR]

The diversity of phytoplankton species has become relevant for assessing environmental disturbances in marine habitats because its relationship with harmful algal blooms (HABs). The scientific expedition on board of the R/V Race for Water in August 2017 gave us the opportunity for sampling the phytoplankton off Havana City. The aims were (i) to describe the diversity and composition of phytoplankton testing for differences between coastal and oceanic waters, and (ii) to explore the occurrence of potentially harmful phytoplankton species. Twelve sites were selected between Havana Bay and the entrance of Almendares River. Superficial samples of water were taken with a 20 µm plankton net. We identified 71 phytoplankton species belonging to five taxa: 63 Dinophyta, five Bacillariophyta, one Chlorophyta, one Charophyta and one Cyanobacteria. There were 21 phytoplankton species reported by first time for Cuban waters. The observed richness was statistically the same for both coastal and oceanic sites (44 and 52 species respectively). However, the clustering patterns in the MDS plot indicated different species composition between coastal and oceanic waters. Fifteen recorded species may be involved in HABs: Coscinodiscus spp., Dinophysis caudata, Gambierdiscus sp., Gonyaulax polygramma, Gonyaulax spinifera, Gymnodinium sp. 2, Lingulodinium polyedra, Peridinium quadridentatum, Phalacroma mitra, Phalacroma rotundatum, Prorocentrum cf. compressum, Thalassiosira spp., Tripos fusus, Tripos furca and Trichodesmium thiebautii. The occurrence of these species pointed to the necessity of a monitoring program in waters of Havana City since its large vulnerability to HABs. [ABSTRACT FROM AUTHOR]

In this report, we establish proof-of-principle demonstrating for the first time genetic engineering of a photoautotrophic microorganism for bioremediation of naturally occurring cyanotoxins. In model cyanobacterium Synechocystis sp. PCC 6803 we have heterologously expressed Sphingopyxis sp. USTB-05 microcystinase (MlrA) bearing a 23 amino acid N-terminus secretion peptide from native Synechocystis sp. PCC 6803 PilA ( sll1694 ). The resultant whole cell biocatalyst displayed about 3 times higher activity against microcystin-LR compared to a native MlrA host ( Sphingomonas sp. ACM 3962), normalized for optical density. In addition, MlrA activity was found to be almost entirely located in the cyanobacterial cytosolic fraction, despite the presence of the secretion tag, with crude cellular extracts showing MlrA activity comparable to extracts from MlrA expressing E. coli . Furthermore, despite approximately 9.4-fold higher initial MlrA activity of a whole cell E. coli biocatalyst, utilization of a photoautotrophic chassis resulted in prolonged stability of MlrA activity when cultured under semi-natural conditions (using lake water), with the heterologous MlrA biocatalytic activity of the E. coli culture disappearing after 4 days, while the cyanobacterial host displayed activity (3% of initial activity) after 9 days. In addition, the cyanobacterial cell density was maintained over the duration of this experiment while the cell density of the E. coli culture rapidly declined. Lastly, failure to establish a stable cyanobacterial isolate expressing native MlrA (without the N-terminus tag) via the strong cpcB560 promoter draws attention to the use of peptide tags to positively modulate expression of potentially toxic proteins. [ABSTRACT FROM AUTHOR]

Continued anthropogenic carbon emissions are expected to cause a decline in global average pH of the oceans to a projected value of 7.8 by the end of the century. Understanding how harmful algal bloom (HAB) species will respond to lowered pH levels will be important when predicting future HAB events and their ecological consequences. In this study, we examined how manipulated pH levels affected the growth rate of three strains of Prymnesium parvum from North America, Denmark and Japan. Triplicate strains were grown under pH conditions ranging from 6.6 to 9.1 to simulate plausible future levels. Different tolerances were evident for all strains. Significantly higher growth rates were observed at pH 6.6–8.1 compared to growth rates at pH 8.6–9.1 and a lower pH limit was not observed. The Japanese strain (NIES-1017) had the highest maximum growth rate of 0.39 divisions day −1  at pH 6.6 but a low tolerance (0.22 divisions day −1 ) to high levels (pH 9.1) with growth declining markedly after pH 7.6. The Danish (SCCAP K-0081) and North American (UTEX LB 2797) strains had maximum growth rates of 0.26 and 0.35 divisions day −1 , respectively between pH 6.6–8.1. Compared to the other two strains the Danish strain had a statistically lower growth rate across all pH treatments. Strain differences were either attributed to their provenance or the length of time the strain had been in culture. [ABSTRACT FROM AUTHOR]

Toxic cyanobacterial blooms are a water quality issue worldwide whose incidence and severity are predicted to increase due to climate change and eutrophication. Argentina is not an exception to this trend, since those massive proliferations have increased in the last two decades as a consequence of water quality changes due to human activities. This work presents a thorough search and analysis of published literature on the occurrence of cyanobacterial blooms and cyanotoxins in Argentina. We retrieved 241 bloom events (1944–2014) covering 63 impacted water bodies, used either for recreational activities and/or drinking water supply. The highest incidence was concentrated in the central and eastern areas of the country (Chaco-Pampean Plain and Peripampean Sierras), the most densely populated regions, also highly impacted by agro-industrial activities. Intense blooms of Microcystis, Dolichospermum and Cylindrospermopsis species represent a potential hazard for both human beings and wild–life through oral ingestion and/or direct contact, although quantitative and systematic registers to estimate the extent of occurrence are still missing. Elevated microcystins concentrations, together with the presence of blooms of potential saxitoxin or anatoxin-a producers emphasize the need to increase monitoring of these toxins in drinking water supplies and recreational areas. The data presented are valuable for promoting the generation and implementation of guideline values and risk management frameworks at a national and regional scale. [ABSTRACT FROM AUTHOR]

The present paper reports on the phenomenon of pinkish-red discoloration of the nearshore water of Puri, Odisha on 12th May 2016. Many local newspapers covered this event, as Puri city is a major tourist and pilgrimage place on the east coast of India. Field observations were carried out in order to provide a scientific basis to the event and to elicit possible causes of this discoloration. Taxonomic analysis of the phytoplankton samples revealed the dominance of red colored dinoflagellate species Gonyaulax polygramma, contributing 90% to total phytoplankton population. The localized concentration of G. polygramma was responsible for the pinkish-red discoloration of nearshore water. The exact factor that lay behind the genesis of this bloom could not be delineated due to the short period of its persistence. But two factors - upwelling and anthropogenic nutrient influx - can be viewed as the main cause for this ephemeral bloom. Non-hypoxic conditions in the coastal water following the ephemeral bloom event indicated no significant risk of ecological deterioration to the ambient medium. [ABSTRACT FROM AUTHOR]

This paper describes the adoption and validation of two innovative methods for the automated count of Ostreopsis spp. concentration in sea water: a molecular assay based on RT-qPCR and an opto-electronic device implementing automatic recognition algorithms. The proposed approaches were tested on samples coming from different locations along the Mediterranean Sea and compared with the standard counting method based on microscopy observation by a taxonomy expert. The results demonstrate the effectiveness of both automatic approaches which provide a valuable tool, mostly cost and time effective, for the establishment of wide pan-Mediterranean monitoring strategies of Ostreopsis spp. blooms. Moreover, the two automatic methods demonstrated the ability to discriminate for the presence of a different but similar species, O. fattorussoi , for which new species-specific qPCR primers were developed. [ABSTRACT FROM AUTHOR]

We developed a new assay method, which combines loop-mediated isothermal amplification (LAMP) with a chromatographic lateral flow dipstick (LFD) for the rapid and special detection of the diatom Skeletonema costatum . Four groups of LAMP primers were derived from a conserved DNA sequence unique to S. costatum . The amplifications were carried out at 61, 63, and 65 °C for 60 min in various combinations by the quantitative PCR thermal cycler to confirm optimal primers and reaction temperature. The LAMP-LFD detection limit was 0.94 pg/μL of S. costatum genomic DNA and was 100 times more sensitive than conventional PCR. The LAMP-LFD method had high specificity and accurately identified S. costatum algal isolates, but not other algal isolates. The new LAMP-LFD assay can be used as a reliable and easy method to detect S. costatum. [ABSTRACT FROM AUTHOR]

Phytoplankton abundance in relation to some physicochemical characters of the costal water of Arabian Gulf (Saudi Arabia) was studied for one year. The sampling program included 15 locations in Dammam, Saihat, Al-Qatif, Al-Awamia and Safwa. Water samples were analyzed monthly for these parameters; temperature, pH, salinity, dissolved oxygen, nitrite, nitrate, ammonia, carbon dioxide, total chloride, reactive orthophosphate and total phosphorus and alkalinity, also phytoplankton communities were identified and Chlorophyll a was estimated. The results showed that, the high phytoplankton density attaining the maximum (190.3 × 10 4 /m 3 ) during May and June, and the minimum (10.4 × 10 4 /m 3 ) during November and December. Forty Five species belonging to 5 phytoplankton groups were recorded. Bacillariophyceae was the first dominant group forming 48% of the total phytoplankton communities (23 species). The dominant species of Bacillariophyceae were Pleurosigma strigosum , Pleurosigma elongatum , Lyrella clavata , Rhizosolenia shrubsolei , Cylindrotheca closterium , Nitzschia panduriform , Nitzschia longissimia , Amphora sp and Stephanopyxis . Dinophyceae was the second dominant group and formed 31% of the total phytoplankton communities (10 species); the dominant species were Ceratium fusus , Heterosigma sp , Ceratium furca , Prorocentrum triestium , Protoperidinium sp , Gyrodinium spirale , Noctiluca scintillans and Scrippsiella trochoidea . Cyanophyceae formed 13% (5 species) where Nostoc sp , Oscillatoria and Merismopedia sp were the dominant species. Chlorophyceae had 8% (6 species); Scendesmus sp ., Chlorella sp ., Chlamydomonas sp ., Dunaliella salina and Nannochloropsis sp were the dominant species. The Euglinophyceae was rare only one species ( Euglina sp ). The relationship was positive between the phytoplankton, chlorophyll a and carbon dioxide while negative amongst dissolved oxygen and total nitrogen. This research indicated that the relation between water quality and phytoplankton organisms at the coast of Arabian Gulf (Saudi Arabia) was extremely overlapping and interdependent; any changes in the one component may significantly affect those of the other components. [ABSTRACT FROM AUTHOR]

Microcystin (MC) is a cyanobacteria-produced liver toxin that has been found in fish from Lake Erie, sometimes in excess of World Health Organization (WHO) guidelines for safe consumption. Even so, few studies have quantified MCs in Lake Erie fishes, and these studies have drawn different conclusions concerning the risk that fish consumption poses to public health. To address this gap in knowledge, we used Enzyme-Linked Immunosorbant Assay (ELISA) to evaluate the MC concentration in muscle tissue from three commonly harvested fish in Lake Erie: walleye ( Sander vitreus , n = 29); yellow perch ( Perca flavescens , n = 52); and white perch ( Morone americana , n = 55), collected during summer 2013. Satellite remote sensing was used to compare MC concentrations in fish tissue to bloom conditions in Lake Erie at the time of harvest. We found a significant difference among mean MC concentrations in walleye (71 ng MC/g wet weight), white perch (37 ng MC/g), and yellow perch (8.1 ng MC/g). In addition, MC levels in white perch appeared to depend on local bloom conditions. While few of the fish collected contained MC in excess of WHO guidelines, our results indicate that more toxic blooms could increase MC in fish to levels that pose a greater risk to public health. [ABSTRACT FROM AUTHOR]

Pseudo-nitzschia is a diatom genus capable of producing the neurotoxin domoic acid (DA), which has been related to mortalities of marine vertebrates, and the amnesic shellfish poisoning (ASP) in human consumers of contaminated bivalves. This study reports DA production among Pseudo-nitzschia strains isolated from shellfish farming areas in southern Brazil. Twenty-seven cultures of potentially toxigenic Pseudo-nitzschia species were established. Growth, stepped-chain formation, and DA production were evaluated in static, intermittently illuminated (12:12 photoperiod) batch cultures for 12 selected strains, and under continuous light and/or turbulence for a single Pseudo-nitzschia calliantha strain. Growth rate ranged from 0.16 to 0.39 day among the 12 strains. Only P. calliantha and P. cf. multiseries yielded detectable levels of intracellular DA, reaching up to 0.054 fg cell in late exponential and 0.15 pg cell in early stationary phase, respectively. Continuous light impaired cell growth, and turbulence enhanced step-chain formation by threefold during exponential growth phase, but no DA production was detected under both conditions. The effect of turbulence on chain formation should be further evaluated in the field, once particle size is expected to affect the ingestion of toxic cells and thus toxin accumulation by certain DA vectors. The low cell toxicity revealed herein under laboratory conditions is in accordance with the low frequency of DA contamination episodes in south Brazilian waters. Nevertheless, monitoring of Pseudo-nitzschia abundance and DA presence in farming areas is continuously required to assure the quality of local shellfish products. [ABSTRACT FROM AUTHOR]

Intense blooms of the toxic dinoflagellate Ostreopsis have been a recurrent phenomenon along several Mediterranean coasts. Blooms have been associated with noxious effects on human health and mortality of marine organisms, due to the production of palytoxin-like compounds. We analyzed the toxin concentrations throughout an O. cf. ovata bloom to highlight their relationships with environmental parameters in the Conero Riviera, northern Adriatic Sea. High temperature and balanced nutrient conditions were the optimal environmental conditions to start and sustain blooms as well as to maximize toxin production. Ostreopsis showed a gradual decrease of toxin content throughout the bloom ascribed to the occurring of the same non-optimal conditions that led to the bloom decline. Moreover, our results suggest that toxin fraction released during bloom could be higher than that released in batch culture. Results from this study pointed out that the first bloom phase is potentially the most dangerous to human health. [ABSTRACT FROM AUTHOR]

The Penobscot River Estuary is an important system for diadromous fish in the Northeast United States of American (USA), in part because it is home to the largest remnant population of Atlantic salmon, Salmo salar , in the country. Little is known about the chemical and biological characteristics of seston in the Penobscot River Estuary. This study used estuarine transects to characterize the seston during the spring when river discharge is high and diadromous fish migration peaks in the Penobscot River Estuary. To characterize the seston, samples were taken in spring 2015 for phytoplankton identification, total suspended matter (TSM), percent organic TSM, chlorophyll a , particle size (2 μm-180 μm), particulate carbon and nitrogen concentrations, and stable carbon and nitrogen isotopes. The estuarine profiles indicate that TSM behaved non-conservatively with a net gain in the estuary. As phytoplankton constituted only 1/1000 of the particles, the non-conservative behavior of TSM observed in the estuary was most likely not attributable to phytoplankton. Particulate carbon and nitrogen ratios and stable isotope signals indicate a strong terrestrial, allochthonous signal. The seston in the Penobscot River Estuary was dominated by non-detrital particles. During a short, two-week time period, Heterosigma akashiwo, a phytoplankton species toxic to finfish, also was detected in the estuary. A limited number of fish samples, taken after the 2015 Penobscot River Estuary bloom of H. akashiwo, indicated frequent pathological gill damage. The composition of seston, along with ichthyotoxic algae, suggest the need for further research into possible effects upon resident and migratory fish in the Penobscot River Estuary. [ABSTRACT FROM AUTHOR]

Ostreopsis blooms regularly occur in many Mediterranean coastal areas in late summer-autumn. In the northern Adriatic Sea, Ostreopsis blooms affect diatom-dominated microphytobenthic communities. In this study, the effects of the filtrates of some diatom species, both benthic ( Tabularia affinis , Proschkinia complanatoides and Navicula sp.) and planktonic ( Thalassiosira sp. and Skeletonema marinoi ) on cell morphology, cytological features and growth of O . cf. ovata were investigated. Our results showed a marked decrease of O . cf. ovata growth when cells were exposed to all diatom filtrates tested. The highest inhibitions were observed for exposures to P. complanatoides and Navicula sp. filtrates (92.5% and 80%, respectively) and increased with the age of diatom culture. Moreover, a clear DNA degradation and abnormal forms of O. cf. ovata cells (83.8% of the total) were found at the highest concentrations using Navicula sp. filtrate after 10 days of the inoculum. [ABSTRACT FROM AUTHOR]

In order to assess the effects of Fe-enrichment on the growth and domoic acid (DA) production of the toxigenic diatom Pseudo-nitzschia multiseries, static cultures that received the addition of different iron (Fe) concentrations were maintained for 30 days. Intra- and extracellular DA concentrations were evaluated over time, and growth and chain-formation were compared to those of non-toxic diatoms, Bacillaria sp. Growth rates of P. multiseries (μ = 0.45-0.73 d-1) were similar among cultures containing different Fe concentrations. Likewise, the similar incidence and length of P. multiseries stepped cell chains (usually 2-4; up to 8-cell long) among the treatments reinforces that the cultures were not growth-inhibited under any condition tested, suggesting an efficient Fe acquisition mechanism. Moreover, DA concentrations were significantly higher under the highest Fe concentration, indicating that Fe is required for toxin synthesis. Bacillaria sp. reached comparable growth rates under the same Fe concentrations, except when the dissolved cell contents from a P. multiseries culture was added. The 50-70% reduction in cell density and 70-90% decrease in total chlorophyll-a content of Bacillaria sp. at early stationary growth phase indicates, for the first time, an allelopathic effect of undetermined compounds released by Pseudo-nitzschia to another diatom species. [ABSTRACT FROM AUTHOR]

In subtropical coastal waters around Hong Kong, dissolved oxygen (DO) can undergo significant diurnal changes (up to 40%–50% saturation) during algal blooms. The carbon to chlorophyll- a ratio (CCHL) – a key parameter in water quality models – is variable and depends on factors that include light intensity and temperature. Despite numerous laboratory and field investigations, the prediction of CCHL and DO during high productivity conditions remains a difficult problem; the CCHL during algal blooms has also not been measured. The phytoplankton and DO dynamics are studied in a semi-enclosed tidal inlet using a submerged Imaging FlowCytobot (IFCB) together with a real-time water quality monitoring system. A diurnal pattern of algal abundance is observed with peaks around 4pm. Based on carbon estimates from the bio-volumes of the algal images and direct measurements of chlorophyll- a , the CCHL ratio is monitored continuously during an algal bloom event. The CCHL is found to vary significantly over a bloom cycle—in the range of 10 to several hundred and generally much greater than the constant values (in the order of 10) assumed in industry standard water quality models. A first order theoretical estimate of the CCHL as a function of algal growth rate and light saturation intensity is supported by field data. Using a simple oxygen budget model, the diurnal DO changes during an algal bloom can be satisfactorily predicted by integrating IFCB data with water quality data. The findings help to improve environmental and ecosystem modeling and mariculture management. • Real time observation of algal blooms and DO dynamics in sub-tropical waters. • Integration of field imaging flow cytometry with water quality monitoring. • First high frequency field measurements of carbon to chlorophyll ratio (CCHL). • Field validation of CCHL model to predict diurnal change of DO. • Simple DO model that benefits ecosystem modeling and fisheries management. [ABSTRACT FROM AUTHOR]

Background Dinoflagellate cysts (i.e., dinocysts) are biologically and ecologically important as they can help dinoflagellate species survive harsh environments, facilitate their dispersal and serve as seeds for harmful algal blooms. In addition, dinocysts derived from some species can produce more toxins than vegetative forms, largely affecting species through their food webs and even human health. Consequently, accurate identification of dinocysts represents the first crucial step in many ecological studies. As dinocysts have limited or even no available taxonomic keys, molecular methods have become the first priority for dinocyst identification. However, molecular identification of dinocysts, particularly when using single cells, poses technical challenges. The most serious is the low success rate of PCR, especially for heterotrophic species. Methods In this study, we aim to improve the success rate of single dinocyst identification for the chosen dinocyst species (Gonyaulax spinifera, Polykrikos kofoidii, Lingulodinium polyedrum, Pyrophacus steinii, Protoperidinium leonis and Protoperidinium oblongum) distributed in the South China Sea. We worked on two major technical issues: cleaning possible PCR inhibitors attached on the cyst surface and designing new dinoflagellate-specific PCR primers to improve the success of PCR amplification. Results For the cleaning of single dinocysts separated from marine sediments, we used ultrasonic wave-based cleaning and optimized cleaning parameters. Our results showed that the optimized ultrasonic wave-based cleaning method largely improved the identification success rate and accuracy of both molecular and morphological identifications. For the molecular identification with the newly designed dinoflagellate-specific primers (18S634F-18S634R), the success ratio was as high as 86.7% for single dinocysts across multiple taxa when using the optimized ultrasonic wave-based cleaning method, and much higher than that (16.7%) based on traditional micropipette-based cleaning. Discussion The technically simple but robust method improved on in this study is expected to serve as a powerful tool in deep understanding of population dynamics of dinocysts and the causes and consequences of potential negative effects caused by dinocysts.

The coast of Alexandria has been subjected to successive engineering alterations since 1998. Such alterations have affected the topography of the coast as well as the water quality, the phytoplankton productivity and diversity. In 1998 protective wave breakers were built in order to reduce erosion and create new beaches. This resulted in the formation of relatively large semi-closed, shallow lagoons. Due to their shallow depth and the partial stagnation of their waters, these lagoons became a suitable environment for algal blooms. Corrective measures were then taken around 2010 to reduce the harmful effects caused by the previous coastal modifications. The phytoplankton composition and its standing crop became totally different during the two periods. The most important bloom was caused by Micromonas pusilla forming a heavy green tide accompanied by a bloom of Peridinium quinquecorne. Although there were no fish or invertebrate mortality, this bloom caused economic losses to internal tourism. In the absence of any Environmental Assessment, the coastal engineering works increased the harmful algal blooms in Alexandria coastal waters, even after corrective steps were taken to mitigate the harmful effects.

The distribution and abundance of epiphytic and planktonic Coolia monotis Meunier along the Alexandria coast were studied through five annual cycles; from summer 2005 to summer 2010 at four sites: Abu Qir Beach, Stanly, Eastern Harbour and Mex Beach. The morphology of C. monotis was characterised by noticeable small size specimens in the E.H., the D.V. diameter is not exceeding 20 μm and width between 10 and 15 μm. On the other hand, the epiphytic specimens showed a normal cell size. The species was most abundant as planktonic form in the E.H., reaching 15.2 × 103 cell l−1 during summer 2010. The epiphytic forms showed lower density, with a maximum of 454 cell g−1 fwm during autumn 2005, 2006 and summer from 2007 to 2010. The fluctuations of cell abundance of C. monotis showed a significant negative correlation with salinity and a weak positive correlation with temperature. This study represents the first report of Coolia monotis Meunier in the Egyptian Mediterranean waters.

In order to control the cyanobacterial blooms in eutrophic water, an Ag/AgCl@ZIF-8 floating coating was prepared by a dip-coating method with a sponge, innovatively employed as a carrier for the removal of algae in natural water samples. The as-prepared photocatalyst was characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (SEM). The effects of this Ag/AgCl@ZIF-8 coating on algal removal and phytoplankton community structure in natural water samples with cyanobacterial blooms were investigated under sunlight. Results showed that Ag/AgCl@ZIF-8 distributed uniformly on the surface of the coating with good stability and algae removal efficiency in water bodies. After 6 h of exposure under sunlight, the chlorophyll a in the natural water samples was degraded by 99.9%, the densities of Microcystis aeruginosa were reduced by 92.6% and the densities and biomass of the other algae decreased by about 80%. Meanwhile, the content of colored dissolved organic matter (CDOM) in the samples was decreased, effectively controlling the cyanobacterial blooms. It was found that O2•− played the main role in the photocatalytic inactivation. In conclusion, the Ag/AgCl@ZIF-8 coating has a promising application potential for the removal of harmful cyanobacteria, and provides a new idea for the control of cyanobacterial blooms in water bodies.

The identification of a new suite of toxins, called azaspiracids (AZA), as the cause of human illnesses after the consumption of shellfish from the Irish west coast in 1995, resulted in interest in understanding the global distribution of these toxins and of species of the small dinoflagellate genus Azadinium , known to produce them. Clonal isolates of four species of Azadinium, A. poporum, A. cuneatum, A. obesum and A. dalianense were obtained from incubated sediment samples collected from Puget Sound, Washington State in 2016. These Azadinium species were identified using morphological characteristics confirmed by molecular phylogeny. Whereas AZA could not be detected in any strains of A. obesum, A. cuneatum and A. dalianense , all four strains of A. poporum produced a new azaspiracid toxin, based on LC–MS analysis, named AZA-59. The presence of AZA-59 was confirmed at low levels in situ using a solid phase resin deployed at several stations along the coastlines of Puget Sound. Using a combination of molecular methods for species detection and solid phase resin deployment to target shellfish monitoring of toxin at high-risk sites, the risk of azaspiracid shellfish poisoning can be minimized. [ABSTRACT FROM AUTHOR]

Concern regarding Benthic Harmful Algal Blooms (BHABs) is increasing since some harmful benthic species have been identified in new areas. In the Mediterranean basin, the most common harmful benthic microalgae are Ostreopsis cf. ovata and Prorocentrum lima, which produce palytoxin-like compounds and okadaic acid respectively, and the need to implement monitoring activities has increased. However, a general agreement on appropriate strategies (e.g. sampling season, definition of alarm thresholds, etc.) is still lagging behind, especially for P. lima, whose proliferation dynamics are still poorly known. [ABSTRACT FROM AUTHOR]

This study investigated the genetic diversity of phytoplankton communities in six shallow lagoons located on the French coast of the northwestern Mediterranean Sea that represented a trophic gradient ranging from oligotrophic to hypereutrophic. The phytoplankton communities were sampled once a month from spring (May) to the beginning of autumn (September/early October) in 2012 and fractionated by size. Metabarcodes were generated from cDNAs by targeting the D1-D2 region of the 28S rRNA gene and pyrosequenced using Roche 454 technology. Examination of the annotated barcodes revealed harmful algal species not previously documented in these lagoons. Three ichthyotoxic species belonging to Pfiesteriaceae were detected: Luciella masanensis was relatively widespread and abundant in many samples, whereas Pfiesteria piscicida and Stoeckeria changwonensis were found as single barcode sequences. Furthermore, a phylogenetic analysis of barcodes annotated as belonging to Pfiesteriaceae suggested the existence of two previously undescribed clades. The other toxic or potentially harmful dinoflagellates detected through rare barcodes were Dinophysis acuminata , Vulcanodinium rugosum , Alexandrium andersonii and A. ostenfeldii . The two most abundant dinoflagellate taxa were Gymnodinium litoralis and Akashiwo sanguinea with respect to sequence numbers. Four diatom species from the genus Pseudo-nitzschia that potentially produce domoic acid were identified ( P. galaxiae , P. delicatissima , P. brasiliana and P. calliantha ). These observations are discussed in terms of the literature and monitoring records related to the identified taxa in this Mediterranean area. [ABSTRACT FROM AUTHOR]

Exposure of the toxin-producing dinoflagellate Alexandrium catenella ( A. catenella ) was previously demonstrated to cause apoptosis of hemocytes in the oyster species Crassostrea gigas . In this work, a coumarin-labeled saxitoxin appeared to spread throughout the cytoplasm of the hemocytes. PSTs, including saxitoxin, were also shown to be directly responsible for inducing apoptosis in hemocytes, a process dependent on caspase activation and independent of reactive oxygen species (ROS) production. A series of in vitro labelling and microscopy experiments revealed that STX and analogs there of induced nuclear condensation, phosphatidylserine exposure, membrane permeability, and DNA fragmentation of hemocytes. Unlike in vertebrates, gonyautoxin-5 (GTX5), which is present in high concentrations in A. catenella , was found to be more toxic than saxitoxin (STX) to oyster immune cells. Altogether, results show that PSTs produced by toxic dinoflagellates enter the cytoplasm and induce apoptosis of oyster immune cells through a caspase-dependent pathway. Because of the central role of hemocytes in mollusc immune defense, PST-induced death of hemocytes could negatively affect resistance of bivalve molluscs to microbial infection. [ABSTRACT FROM AUTHOR]

The potentially toxic, invasive cyanobacterium Cylindrospermopsis raciborskii, originating from sub-tropical regions, has spread into temperate climate zones in almost all continents. Potential factors in its success are temperature, light and nutrient levels. Grazing losses through zooplankton have been measured in the laboratory but are typically not regarded as a factor in (failed) invasion success. In some potentially suitable lakes, C. raciborskii has never been found, although it is present in water bodies close by. Therefore, we tested the invasive potential of three different isolates introduced into natural plankton communities using laboratory mesocosm experiments under three grazing levels: ambient zooplankton densities, removal of large species using 100 µm mesh and a ca. doubling of large species. Three C. raciborskii isolates originating from the same geographic region (North-East Germany) were added separately to the four replicates of each treatment and kept in semi-continuous cultures for 21 days. Two isolates disappeared from the mesocosms and were also not viable in filtered lake water indicating that the lake water itself or the switch from culture medium to lake water led to the decay of the inoculated C. raciborskii. Only one out of the three isolates persisted in the plankton communities at a rather low level and only in the treatment without larger zooplankton. This result demonstrates that under potentially suitable environmental conditions, top-down control from zooplankton might hamper the establishment of C. raciborskii. Non-metric multidimensional scaling showed distinct variation in resident phytoplankton communities between the different grazing levels, thus differential grazing impact shaped the resident community in different ways allowing C. raciborskii only to invade under competitive (= low grazing pressure) conditions. Furthermore, even after invasion failure, the temporary presence of C. raciborskii influenced the phytoplankton community. [ABSTRACT FROM AUTHOR]

RNA interference is a powerful method to inhibit specific gene expression. Recently, silencing target genes by feeding has been successfully carried out in nematodes, insects, and small aquatic organisms. A non-invasive feeding-based RNA interference is reported here for the first time in a mollusk bivalve, the pacific oyster Crassostrea gigas. In this Trojan horse strategy, the unicellular alga Heterocapsa triquetra is the food supply used as a vector to feed oysters with Escherichia coli strain HT115 engineered to express the double-stranded RNA targeting gene. To test the efficacy of the method, the Clock gene, a central gene of the circadian clock, was targeted for knockout. Results demonstrated specific and systemic efficiency of the Trojan horse strategy in reducing Clock mRNA abundance. Consequences of Clock disruption were observed in Clock-related genes ( Bmal, Tim1, Per, Cry1, Cry2, Rev.- erb, and Ror) and triploid oysters were more sensitive than diploid to the interference. This non-invasive approach shows an involvement of the circadian clock in oyster bioaccumulation of toxins produced by the harmful alga Alexandrium minutum. [ABSTRACT FROM AUTHOR]

Salinity (5–30) effects on golden alga growth were determined at a standard laboratory temperature (22 °C) and one associated with natural blooms (13 °C). Inoculum-size effects were determined over a wide size range (100–100,000 cells ml −1 ). A strain widely distributed in the USA, UTEX-2797 was the primary study subject but another of limited distribution, UTEX-995 was used to evaluate growth responses in relation to genetic background. Variables examined were exponential growth rate ( r ), maximum cell density (max-D) and, when inoculum size was held constant (100 cells ml −1 ), density at onset of exponential growth (early-D). In UTEX-2797, max-D increased as salinity increased from 5 to ∼10–15 and declined thereafter regardless of temperature but r remained generally stable and only declined at salinity of 25–30. In addition, max-D correlated positively with r and early-D, the latter also being numerically highest at salinity of 15. In UTEX-995, max-D and r responded similarly to changes in salinity − they remained stable at salinity of 5–10 and 5–15, respectively, and declined at higher salinity. Also, max-D correlated with r but not early-D. Inoculum size positively and negatively influenced max-D and r , respectively, in both strains and these effects were significant even when the absolute size difference was small (100 versus 1000 cells ml −1 ). When cultured under similar conditions, UTEX-2797 grew faster and to much higher density than UTEX-995. In conclusion, (1) UTEX-2797’s superior growth performance may explain its relatively wide distribution in the USA, (2) the biphasic growth response of UTEX-2797 to salinity variation, with peak abundance at salinity of 10–15, generally mirrors golden alga abundance-salinity associations in US inland waters, and (3) early cell density – whether artificially manipulated or naturally attained – can influence UTEX-2797 bloom potential. [ABSTRACT FROM AUTHOR]

We present the first comprehensive taxonomic and environmental study of dinoflagellate cysts in 185 surface sediment samples from the Black Sea Corridor (BSC) which is a series of marine basins extending from the Aegean to the Aral Seas (including Marmara, Black, Azov and Caspian Seas). For decades, these low-salinity, semi-enclosed or endorheic basins have experienced large-scale changes because of intensive agriculture and industrialisation, with consequent eutrophication and increased algal blooms. The BSC atlas data provide a baseline for improved understanding of linkages between surface water conditions and dinoflagellate cyst (dinocyst) distribution, diversity and morphological variations. By cross-reference to dinocyst occurrences in sediment cores with radiocarbon ages covering the past c. 11,700 years, the history of recent biodiversity changes can be evaluated. The seabed cyst samples integrate seasonal and multi-year data which are not usually captured by plankton samples, and the cyst composition can point to presence of previously unrecorded motile dinoflagellate species in the BSC. Results show the presence of at least 71 dinocyst taxa of which 36% can be related to motile stages recorded in the plankton. Comparison with sediment core records shows that five new taxa appear to have entered or re-entered the region over the past century. Statistical analysis of the atlas data reveals the presence of four ecological assemblages which are primarily correlated with seasonal and annual surface water salinity and temperature; correlation with phosphate, nitrate and silicate nutrients, chlorophyll- a and bottom water oxygen is less clear but may be important for some taxa. Biodiversity indices reveal strong west − east biogeographical differences among the basins that reflect the different histories of Mediterranean versus Ponto-Caspian connections. The atlas data provide a standardised taxonomy and regional database for interpreting downcore cyst variations in terms of quantitative oceanographic changes. The atlas also provides a baseline for monitoring further changes in the BSC dinocysts that may accompany the accelerating development of the region. [ABSTRACT FROM AUTHOR]

The genus Prymnesium includes several species that produce toxins with cytotoxic, ichthyotoxic, neurotoxic and haemolytic activity. Bloom episodes of Prymnesium species have been reported from several parts of the world (North America, Europe, Africa, Asia and Australia), especially from temperate and subtropical regions and most of them from brackish waters. Blooms cause great economic losses to aquaculture and fisheries around the world. The ichthyotoxic and allelopathic effects of Prymnesium have been linked to the presence of Haemolysin 1, Prymnesins 1 and 2 and, more recently, fatty acids and fatty acid amides. The toxicology of this genus with regard to different growth conditions such as light, nutrients and other parameters has been well documented. It is unknown, however, whether different species and strains from the Prymnesium genus all produce the same types and level of toxins. In this study, we have determined the haemolytic activity of eight different strains from the genus Prymnesium in both exponential and stationary phases of growth. We have also evaluated the efficiency of the extraction solvent. [ABSTRACT FROM PUBLISHER]

Paralytic shellfish toxins (PST) were detected in abalone ( Haliotis rubra ) in April 2011 in south-east Tasmania, Australia, during a dinoflagellate bloom of Gymnodinium catenatum . This led to restrictions on abalone harvesting and triggered continued PST monitoring by Ultra Performance Liquid Chromatography (UPLC-FLD) of abalone and mussels ( Mytilus galloprovincialis ), and concurrent phytoplankton monitoring, between 2011 and 2013. PST up to 2437 μg STX eq kg −1 (three times the bivalve regulatory limit) were confirmed in abalone viscera, with toxicity up to 586 μg STX eq kg −1 in the muscular foot (mainly doSTX and minor proportions of STX and dcSTX). Mussels accumulated PST at a faster rate than abalone which suggests they can serve as sentinels of PST accumulation to inform abalone risk management protocols. Three lines of evidence for G . catenatum as the source of PST in abalone were established: (1) PST in abalone tissues increased and declined in association with dinoflagellate blooms; (2) G . catenatum DNA was detected by real-time PCR in abalone digestive tracts; and (3) the PST analogues (toxin profile) observed in both abalone viscera and mussels were similar suggesting a common PST source. This is the first time a conclusive linkage between the occurrence of PST in abalone and a dinoflagellate source has been demonstrated. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a loop-mediated isothermal amplification (LAMP) combined with a chromatographic lateral flow dipstick (LFD) assay to rapidly and specifically detect the Karlodinium veneficum ITS gene. Four groups of LAMP primers were specially designed to target the K. veneficum ITS gene. The LAMP-LFD detection limit was 7.4 pg/μL (approximately 6.5 cells/mL) of K. veneficum genomic DNA and was 10 times more sensitive than standard PCR. The LAMP-LFD method exhibited high specificity and accurately identified K. veneficum algal isolates, but not other algal isolates. To test the assay’s accuracy, samples from positive results were further analyzed by sequencing and phylogenetic analysis, all of which were identified as K. veneficum. Over all, the LAMP-LFD assay established in this paper can be used as a reliable and simple method to detect the K. veneficum. [ABSTRACT FROM AUTHOR]

Kongsfjorden (Spitsbergen, Svalbard) is an inlet treated as a model site for studies on the impact of climate change in the Arctic due to its hydrological features. In this research, seven-days monitoring was carried out to evaluate the effects of hydrological variability on phytoplankton biomass and diversity in the late summer period. Temperature, salinity, nutrients, total suspended matter, phytoplankton abundance and biomass were determined for each sample. The thermo-haline properties of the column water seemed to affect phytoplankton communities. Their abundances and biomass were correlated with the amount of the total suspended matter. Moreover, species composition and biomass dramatically changed throughout the study period. Cold-water and Atlantic species were replaced by temperatewarm water dinoflagellates, including harmful species. An increase in phytoplankton biomass as well as the presence of dinoflagellate aggregations, mainly composed of Prorocentrum cf. gracile, were detected. This kind of algal accumulation is a new phenomenon in the Arctic and was probably related to the mobilization of sediment-rich glacial meltwaters. These findings, even if preliminary, suggest the need to study how additional biomass pulses and the increase of harmful species may alter the food web structure and the biogeochemical cycles, leading to major ecosystem changes. [ABSTRACT FROM AUTHOR]

Phycotoxins, which are produced by harmful microalgae and bioaccumulate in the marine food web, are of growing concern for Australia. These harmful algae pose a threat to ecosystem and human health, as well as constraining the progress of aquaculture, one of the fastest growing food sectors in the world. With better monitoring, advanced analytical skills and an increase in microalgal expertise, many phycotoxins have been identified in Australian coastal waters in recent years. The most concerning of these toxins are ciguatoxin, paralytic shellfish toxins, okadaic acid and domoic acid, with palytoxin and karlotoxin increasing in significance. The potential for tetrodotoxin, maitotoxin and palytoxin to contaminate seafood is also of concern, warranting future investigation. The largest and most significant toxic bloom in Tasmania in 2012 resulted in an estimated total economic loss of ~AUD$23M, indicating that there is an imperative to improve toxin and organism detection methods, clarify the toxin profiles of species of phytoplankton and carry out both intra- and inter-species toxicity comparisons. Future work also includes the application of rapid, real-time molecular assays for the detection of harmful species and toxin genes. This information, in conjunction with a better understanding of the life histories and ecology of harmful bloom species, may lead to more appropriate management of environmental, health and economic resources. [ABSTRACT FROM AUTHOR]

Harmful algal blooms (HABs) have frequently occurred worldwide, causing marine ecosystems and human health risks. As an advanced and green oxidation technology, photocatalysis has potential to remove red tide algae using solar energy. Herein, in this work, Z-scheme photocatalysts of Ag 3 PO 4 /g-C 3 N 4 (APCN) floating foam with different mass ratios were fabricated for the algae inactivation. Under visible light irradiation, the 0.10APCN (0.10 mM AgNO 3) composite photocatalyst could cause 91.8% of the loss in Karenia mikimotoi (K. mikimotoi) cell viability following 24 h and the removal rate of algae could reach to 86% after five successive cycles. The underlying mechanism of photocatalytic inactivation of harmful algae is proposed in this system. The photosynthetic efficiency of harmful algae is inhibited with the decrease of photosynthetic pigments, which are inactivated by the high levels of reactive oxygen species (ROS) (superoxide radical •O 2 − and hydroxyl radical •OH) produced in Z-scheme photocatalytic system of the Ag 3 PO 4 /g-C 3 N 4 heterojunction under visible light. Meanwhile, the activities of antioxidant enzymes (i.e. POD, APX and SOD) are up-regulating with the overproduction of ROS going into the algae, causing the cytotoxicity and apoptosis of algae. This work not only reveals the mechanisms of photocatalytic inactivation of harmful algae, but also guides the design the construction of high active composite photocatalysts, and thus provides theoretical and practical significance for highly efficient and recyclable prospect of controlling of harmful algae. [Display omitted] • A floating Z-scheme heterojunction of Ag 3 PO 4 /g-C 3 N 4 was successfully constructed. • The APCN photocatalyst exhibits an algae inactivation rate of 92% within 24 h. • The floating photocatalyst can be easily collected for further use than traditional powder photocatalysts. • The APCN photocatalyst exhibits that the removal rate of algae could reach to 86% after five consecutive recycles. [ABSTRACT FROM AUTHOR]

Rotifers have great potential in controlling the harmful algae Phaeocystis blooms that frequently occur in coastal waters. To evaluate the effects of harmful algae on the key life-history traits of rotifer in eliminating Phaeocystis and reveal the underlying mechanism of these effects, we fed Brachionus plicatilis with Chlorella vulgaris and Phaeocystis globosa respectively, recorded the key life-history traits, and conducted transcriptomic analysis. Results showed that the rotifers feeding on P. globosa significantly decreased total offspring but obviously prolonged lifespan compared to those feeding on C. vulgaris , indicating that there was a trade-off between the reproduction and lifespan of rotifers feeding on algae with different nutrient contents. Nevertheless, rotifers can completely eliminate the population of P. globosa. The changes in the reproduction and lifespan of rotifers are highly correlated with algal key nutrition and the expression of some related genes. Transcriptomic analysis showed that the changes in the key life history traits of rotifers feeding on harmful algae are determined by regulating the expression of some key genes involved in the pathways of carbohydrate digestion and absorption, glycolysis, gluconeogenesis, unsaturated fatty acid biosynthesis, and environmental stress. Understanding the trade-off of the key life history traits of zooplankton in eliminating harmful algae from the underlying mechanism helps improve their application for controlling harmful algae. [Display omitted] • Rotifers can completely eliminate the population of harmful algae Phaeocystis. • Reproduction decreases but lifespan prolongs when rotifer feeds on Phaeocystis. • Changes in key traits of rotifer are highly correlated with algal key nutrition. • Trade-off between reproduction and lifespan of rotifer is regulated by some pathways. • Related pathways involve energy metabolism, glycolysis, and fatty acid biosynthesis. [ABSTRACT FROM AUTHOR]

As the start of the supply chain for the aquaculture industry, hatcheries are a crucial component in the success of oyster and northern quahog (hard clam) aquaculture on the East Coast of the US. Intermittent failures in hatchery production slow industry growth and reduce profits. To begin investigations into the possible role of algal toxins in hatchery production failure, post-treatment hatchery water from one research and four commercial hatcheries in lower Chesapeake Bay, USA, was sampled for (1) toxin presence and (2) harmful algal bloom (HAB) cell enumeration. Overall, seven toxin classes, likely produced by six different HAB species, were detected in post-treatment hatchery water, despite a lack of visually identifiable HAB cells within the facility. Toxins detected include pectenotoxin-2, goniodomin A, karlotoxin-1 and karlotoxin-3, okadaic acid and dinophysistoxin-1, azaspiracid-1 and azaspiracid-2, brevetoxin-2, and microcystin-LR. In a second, more targeted study, two batches of source water were followed and sampled at each step of a water-treatment process in the VIMS Aquaculture Genetics and Breeding Technology Center research hatchery in Gloucester Point, Virginia, USA. Two treatment steps showed particular promise for decreasing the concentrations of the three toxins detected in the source water, 24-h circulation through sand filters and activated charcoal filtration. Toxin concentrations of pectenotoxin-2, 3.53 ± 0.56 pg mL−1, okadaic acid, 6.14 ± 0.69 pg mL−1, and dinophysistoxin-1, 1.88 ± 0.0 pg mL−1, were low in the source water. The sand filtration step decreased these concentrations by 49–62%. Activated charcoal filtration subsequently brought the concentrations down to <0.5 pg mL−1, successfully removing another 87–99% of toxins from incoming water. With toxin breakthrough now documented in commercial hatchery facilities during non-bloom conditions, future studies are needed to investigate breakthrough and water-treatment options during more-intense bloom conditions, as well as the potential interactions of algal toxins with other stressors in a potentially multifactorial etiology underlying hatchery production failures. • Breakthrough of HAB toxins and cells (DNA) into commercial shellfish hatcheries. • Hatchery water-treatment process reduced toxin concentrations. • Sand filtration reduced toxins by 49–62%. • Charcoal filtration reduced toxins by 87–99%. [ABSTRACT FROM AUTHOR]

The new benthic toxic dinoflagellate, Ostreopsis fattorussoi sp. nov., is described from the Eastern Mediterranean Sea, Lebanon and Cyprus coasts, and is supported by morphological and molecular data. The plate formula, Po, 3′, 7″, 6c, 7s, 5‴, 2′′′′, is typical for the Ostreopsis genus. It differs from all other Ostreopsis species in that (i) the curved suture between plates 1′ and 3′ makes them approximately hexagonal, (ii) the 1′ plate lies in the left half of the epitheca and is obliquely orientated leading to a characteristic shape of plate 6″. The round thecal pores are bigger than the other two Mediterranean species ( O. cf. ovata and O. cf. siamensis). O. fattorussoi is among the smallest species of the genus ( DV: 60.07 ± 5.63 μm, AP: 25.66 ± 2.97 μm, W: 39.81 ± 5.05 μm) along with O. ovata. Phylogenetic analyses based on the LSU and internal transcribed spacer rDNA shows that O. fattorussoi belongs to the Atlantic/Mediterranean Ostreopsis spp. clade separated from the other Ostreopsis species. Ostreopsis fattorussoi produces OVTX-a and structural isomers OVTX-d and -e, O. cf. ovata is the only other species of this genus known to produce these toxins. The Lebanese O. fattorussoi did not produce the new palytoxin-like compounds (ovatoxin-i, ovatoxin-j1, ovatoxin-j2, and ovatoxin-k) that were previously found in O. fattorussoi from Cyprus. The toxin content was in the range of 0.28-0.94 pg · cell−1. On the Lebanon coast, O. fattorussoi was recorded throughout the year 2015 (temperature range 18°C-31.5°C), with peaks in June and August. [ABSTRACT FROM AUTHOR]

The dinoflagellate Karlodinium and the diatom Pseudo-nitzschia are bloom-forming genera frequently present in Alfacs Bay. Both microalgae are associated with toxic events. Therefore, understanding their population dynamics and predict their occurrence in short-term is crucial for an optimal management of toxic events for the local shellfish production and ecosystem managers. Artificial neural networks have been successfully used to model the complex nonlinear dynamics of phytoplankton. In this study, this approach was applied to predict absence-presence and abundance of Karlodinium and Pseudo-nitzschia microalgae in Alfacs Bay (NW Mediterranean) using biological and/or environmental variables. Neural Interpretation Diagram (NID) and Connection Weight Approach (CWA) methodologies were applied to obtain ecological information from the models. The dataset used was long-term (1990–2015) time series of environmental and phytoplankton variables from different monitoring stations established in Alfacs Bay (Ebre Delta), meteorological data and Ebre River flow rates. Several models were presented. The best ones were achieved for one-week ahead procedures performed with environmental and biological variables using all the available data. A sensitivity analysis showed the larger the data set used, the better the models obtained. However, Karlodinium absence-presence models developed with five years of data present high accuracy. The size of the neural networks denotes complex relationships between environmental and phytoplankton variables. The environmental variables had stronger influence on the abundance models while biological variables had more importance in the absence-presence models. These results highlight a complex ecosystem in Alfacs Bay involving anthropogenic, climatic and hydrologic factors forcing phytoplankton dynamics. In addition, a change in the ecosystem dynamics regarding Karlodinium is detected. The configuration and the accuracy achieved with the models allow their use in different real-world applications as automated systems and/or monitoring programs. [ABSTRACT FROM AUTHOR]

Harmful algal blooms (HABs) and marine pathogens – like Vibrio spp. – are increasingly common due to climate change. These stressors affect the growth, viability and development of bivalve larvae. Little is known, however, about the potential for interactions between these two concurrent stressors. While some mixed exposures have been performed with adult bivalves, no such work has been done with larvae which are generally more sensitive. This study examines whether dinoflagellates and bacteria may interactively affect the viability and immunological resilience of blue mussel Mytilus edulis larvae. Embryos were exposed to environmentally relevant concentrations (100, 500, 2500 & 12,500 cells ml −1 ) of a dinoflagellate ( Alexandrium minutum , Alexandrium ostenfeldii , Karenia mikimotoi , Protoceratium reticulatum , Prorocentrum cordatum , P. lima or P. micans ), a known pathogen ( Vibrio coralliilyticus/neptunius -like isolate or Vibrio splendidus ; 10 5 CFU ml −1 ), or both. After five days of exposure, significant (p < 0.05) adverse effects on larval viability and larval development were found for all dinoflagellates (except P. cordatum ) and V. splendidus . Yet, despite the individual effect of each stressor, no significant interactions were found between the pathogens and harmful algae. The larval viability and the phenoloxidase innate immune system responded independently to each stressor. This independence may be related to a differential timing of the effects of HABs and pathogens. [ABSTRACT FROM AUTHOR]

Diatoms have been shown to produce and release a wide range of secondary metabolites that mediate interactions between individuals of different species. Among these compounds, different types of fatty acid derived long-chained polyunsaturated aldehydes (PUAs) have been related to multiple functions such as intra- or interspecific signals and adverse effect on the reproduction of marine organisms. Several studies have reported changes on growth, cell membrane permeability, flow cytometric properties and cell morphology in phytoplankton organisms exposed to PUAs, but little information is available on the effect of these compounds on benthic microalgae. Ostreopsis cf. ovata is a toxic benthic dinoflagellate which causes massive blooms along the Mediterranean coasts typically during the late summer period. In this study the effects of three toxic PUAs known to be produced by several algae (2 E ,4 E -decadienal, 2 E ,4 E -octadienal and 2 E ,4 E -heptadienal) on the growth, cytological features and cell morphology of O. cf. ovata were investigated. Our results show a clear decrease of O . cf. ovata growth with longer-chain molecules than with shorter-chain ones, confirmed also by EC 50 values calculated at 48 h for 2 E ,4 E -decadienal and 2 E ,4 E -octadienal (6.6 ± 1.5, 17.9 ± 2.6 μmol L −1 respectively) and at 72 h for 2 E ,4 E -heptadienal (18.4 ± 0.7 μmol L −1 ). Moreover, morphological analysis highlighted up to 79% of abnormal forms of O. cf. ovata at the highest concentrations of 2 E ,4 E -decadienal tested (9, 18 and 36 μmol L −1 ), a gradual DNA degradation and an increase of lipid droplets with all tested PUAs. Further studies are needed to better clarify the interactions between diatoms and O . cf. ovata , especially on bloom-forming dynamics. [ABSTRACT FROM AUTHOR]

The two most toxic Gambierdiscus species identified from the Caribbean are G. excentricus and G. silvae. These species are the primary causes of ciguatera fish poisoning and likely contribute disproportionately to the toxicity of marine food webs. While Gambierdiscus species are difficult to distinguish using light or scanning electron microscopy, reliable species-specific molecular identification methods have been developed and used successfully to identify a number of other Gambierdiscus species. Corresponding speciesspecific assays are not yet available for G. excentricus and G. silvae, which imposes limitations on species identification and related ecological studies. The following note describes species-specific polymerase chain reaction assays for G. excentricus and G. silvae that can be used for these purposes. [ABSTRACT FROM AUTHOR]

The genus Ostreopsis includes species largely distributed from tropical to temperate marine areas worldwide. Among the nine species of the genus, O. siamensis, O. mascarenensis, O. lenticularis and O. cf. ovata can produce toxins of the palytoxin group. In the last decade Ostreopsis cf. ovata and O. cf. siamensis originated intense blooms in all the rocky Mediterranean Sea coastal areas, typically during summer-late summer. The correct identification of Ostreopsis species in field samples is often problematic as Ostreopsis species are morphologically plastic and hardly discriminable under light microscopy and, therefore, molecular analyses are required. Ostreopsis blooms are often associated with noxious effects on health of both humans and benthic marine organisms mainly carried by aerosol and direct contact with seawater. Environmental factors have been shown to affect toxin content of Ostreopsis which generally produces more toxins per cell when growing under suboptimal conditions. O. cf. ovata is able to produce both temporary and resting cysts. In particular, the resting cysts are able to germinate in laboratory conditions for as long as 5 months after their formation at 25°C, but not at 21°C; the presence of a temperature threshold affecting cyst germination in the laboratory suggests that temperature represents a key factor for Ostreopsis cf. ovata bloom onset in natural environments as well. Several studies conducted to assess the role of abiotic factors (mainly hydrodynamics, water temperature and nutrients) on the bloom dynamics, revealed that the synergic effects of hydrodynamics, temperature and N:P ratios would lead the Ostreopsis blooms in temperate areas. Ostreopsis abundances showed a significant decrease with depth, likely related to light availability, although there are conflicting data about the relationship between light intensity and Ostreopsis growth in experimental conditions. The relationship between Ostreopsis blooms and salinity is not completely clear, complicated by the influence of high nutrient levels often associated to low salinity waters. Finally, Ostreopsis colonize a variety of substrata, although living substrata seems to allow lower concentration of epibionts than any other substrate, probably due to the production of some allelopathic compounds.