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Harmful blooms of the toxic dinoflagellate Ostreopsis cf. ovata have been a recurrent phenomenon along the Mediterranean coasts in the last decades. Since first recorded, there has been a widespread belief that the extension of this dinoflagellate, well-known in tropical areas, to higher latitudes was due to global warming and the general rise of seawater temperature. Blooms of O. cf. ovata along the Conero Riviera (northern Adriatic Sea) occur between the end of the summer and the beginning of the autumn since 2006. The Ostreopsis cf. ovata abundances collected from its first record to today were analysed to better define the interannual trend of this phenomenon and its possible linking to certain climate change predictors. A significant increasing trend in the magnitude of Ostreopsis phenomenon was observed up to year 2012, then a stabilization at relatively low values was observed. This trend does not follow the incessant increase in water temperature observed during the last three decades in the Adriatic Sea, but rather recalls patterns seen in invasive species, although the provenience of O. cf. ovata in the Mediterranean Sea is still unresolved. Even if the Ostreopsis bloom in this area seems to slightly lessen in the last decade, Ostreopsis abundances still reach values of up to 103 cells cm−2 which could be harmful to human health. [ABSTRACT FROM AUTHOR]

Ocean warming and acidification may significantly alter the distribution and intensity of harmful algal blooms as well as their effects on marine food webs. Estimating such effects rely, in part, on understanding the physiological response of individual algal species to controlled laboratory simulations of climate change conditions. Here we report the physiological response of the harmful dinoflagellate Karlodinium veneficum to the combined effects of elevated temperature and CO2 (29°C/1000 ppm CO2). We first examined these effects by comparing ambient control (25°C/441 ppm CO2) and elevated conditions under short-term (~20 generations) growth. Next, we compared the short-term elevated condition to a longer-term (~200 generations) growth scenario under the same elevated temperature and CO2. Under the short-term elevated conditions, K. veneficum growth declined, cell toxicity increased, and saturated and mono-unsaturated fatty acid (FA) composition varied significantly from ambient conditions. Meanwhile, after ~ 200 generations of growth under elevated temperature and CO2, K. veneficum carbon assimilation, growth, and cell toxicity were significantly higher than the short-term elevated treatment. Further, while total saturated FA declined, essential fatty acids increased and likely represented an adaptive temporal response to long-term exposure to high temperature and CO2. Such shifts in FA profiles and cell toxicity may possibly alter K. veneficum nutritional quality as prey and its mixotrophic behavior, thereby affecting the energy and mass transfer through the marine food webs as well as bloom dynamics. [ABSTRACT FROM AUTHOR]

In the autumn of 2021, a large-scale harmful algal bloom (HAB) emerged along the southeast coast of Hokkaido, Japan, and this was predominantly composed of the dinoflagellate Karenia selliformis. The emergence of K. selliformis-dominated HABs was the first observation in Japan; therefore, no previous reports exist on the impact of HABs on zooplankton in the region. This study investigated the effects of K. selliformis on the survival of copepods'a critical component of the zooplankton community. The results indicated that the survival rates of all six copepod species examined were markedly reduced, particularly at elevated K. selliformis concentrations or during extended exposure. The copepod survival rate decline occurred even in the absence of direct contact or ingestion of K. selliformis, thus implying that K. selliformis may excrete harmful substances extracellularly. Feeding experiments revealed that Neocalanus plumchrus consumes K. selliformis cells; however, the ingestion rate diminished with increased concentrations of K. selliformis cells. The results suggest that larger copepods with smaller surface-to-volume ratios may possess greater resilience to the harmful substances compared to smaller species. Further, the HAB in southeast Hokkaido likely exerted deleterious effects on lower trophic levels within the marine ecosystem by disrupting copepod survival and feeding activity. [ABSTRACT FROM AUTHOR]

Hatcheries nationwide suffer from unexplained acute production failures, termed crashes. The microbiota of oysters relates to larval health with previous studies showing that some bacterial species have positive and others negative effects on oyster health. To investigate microbial correlates of crashes, we collected samples from every batch of oyster larvae (Crassostrea virginica) produced by the Horn Point Laboratory Oyster Hatchery since 2021 and analyzed the microbiota of 15 of those batches over their duration in the hatchery, from age of 3 to 5 days until either harvest or complete die off of the batch. Across events, die-offs generally became evident at or after six days of age. We found that the microbiota of oyster larvae appears to respond to die-off events with crashed batches having fundamentally different microbiota than good batches at age 7 to 9 and 9 to 12 days. Crashed batches were often taken over by microeukaryotes and bacterial taxa from the Protobacteria and Bacteroidetes phyla. However, this presumably opportunistic community differed between batches. Observed Vibrio species level groups did not appear to be oyster pathogens and appeared to respond to, rather than precede, crashes. The microbiota of 3 to 5 day old larvae were statistically related to whether a die-off occurred later in the larval batches’ life, only when the taxa were first agglomerated to family level. The detection of two microbial species not previously known to associate with oysters, along with an increased presence of Dinophyceae, predominantly the toxin-producing Gyrodinium jinhaense, in 3 to 5 day old oyster larvae was statistically linked with subsequent batch crashes. This study suggests that the health of larval oysters shapes their microbiome. Conversely, it provides hints that the microbiome of larvae, and perhaps harmful algae, may drive hatchery crashes.

The Continuous Plankton Recorder (CPR) survey is a valuable resource for mapping changes in plankton distribution and understanding harmful algal ecology because of its breadth and longevity. Preservation methods with formalin degrade DNA, making it difficult to use as a molecular tool for archived marine samples. DNA was extracted from CPR samples immediately after collection, seven months later and after nine years of storage from a cruise track along the Iberian Peninsula. PCR reactions performed from the nine-year timepoint were hybridized to probes in an electrochemical biosensor and compared to results obtained from RT-PCR performed at two earlier time points. The successful identification of Pseudo-nitzschia spp., Prorocentrum lima, Alexandrium minutum, Alexandrium ostenfeldii, Gambierdiscus spp. and Coolia spp. was documented. The biosensor analysis outperformed RT-PCR, allowing us to document certain tropical toxic dinoflagellates, viz., Gambierdiscus and Coolia, that produce human ciguatoxins and Coolia toxins, respectively. These non-native algal toxins can accumulate, pervade the food web and negatively impact human food security. This supports the northerly movement of microalgae with climate change in offshore Iberian peninsular waters. This study highlights biosensors as a cost-effective tool for the offshore monitoring of HAB species and advances molecular technologies for long-term CPR datasets that have limited records of harmful algae. DNA from formalin-preserved CPR samples is degraded, so the use of a short, multiprobe biosensor can augment historical plankton records with contemporary methods that also capture infrequently occurring benthic taxa carried in surface waters. The integration of probe-based biosensor technologies offers a promising avenue for exploring plankton dynamics in response to environmental changes.

The Continuous Plankton Recorder (CPR) survey is a valuable resource for mapping changes in plankton distribution and understanding harmful algal ecology because of its breadth and longevity. Preservation methods with formalin degrade DNA, making it difficult to use as a molecular tool for archived marine samples. DNA was extracted from CPR samples immediately after collection, seven months later and after nine years of storage from a cruise track along the Iberian Peninsula. PCR reactions performed from the nine-year timepoint were hybridized to probes in an electrochemical biosensor and compared to results obtained from RT-PCR performed at two earlier time points. The successful identification of Pseudo-nitzschia spp., Prorocentrum lima, Alexandrium minutum, Alexandrium ostenfeldii, Gambierdiscus spp. and Coolia spp. was documented. The biosensor analysis outperformed RT-PCR, allowing us to document certain tropical toxic dinoflagellates, viz., Gambierdiscus and Coolia, that produce human ciguatoxins and Coolia toxins, respectively. These non-native algal toxins can accumulate, pervade the food web and negatively impact human food security. This supports the northerly movement of microalgae with climate change in offshore Iberian peninsular waters. This study highlights biosensors as a cost-effective tool for the offshore monitoring of HAB species and advances molecular technologies for long-term CPR datasets that have limited records of harmful algae. DNA from formalin-preserved CPR samples is degraded, so the use of a short, multiprobe biosensor can augment historical plankton records with contemporary methods that also capture infrequently occurring benthic taxa carried in surface waters. The integration of probe-based biosensor technologies offers a promising avenue for exploring plankton dynamics in response to environmental changes. [ABSTRACT FROM AUTHOR]

Excessive algae growth can lead to negative consequences for ecosystem function, economic opportunity, and human and animal health. Due to the cost‐effectiveness and temporal availability of satellite imagery, remote sensing has become a powerful tool for water quality monitoring. The use of remotely sensed products to monitor water quality related to algae and cyanobacteria productivity during a bloom event may help inform management strategies for inland waters. To evaluate the ability of satellite imagery to monitor algae pigments and dissolved oxygen conditions in a small inland lake, chlorophyll‐a, phycocyanin, and dissolved oxygen concentrations are measured using a YSI EXO2 sonde during Sentinel‐2 and Sentinel‐3 overpasses from 2019 to 2022 on Lake Mendota, WI. Machine learning methods are implemented with existing algorithms to model chlorophyll‐a, phycocyanin, and Pc:Chla. A novel machine learning‐based dissolved oxygen modeling approach is developed using algae pigment concentrations as predictors. Best model results based on Sentinel‐2 (Sentinel‐3) imagery achieved R2 scores of 0.47 (0.42) for chlorophyll‐a, 0.69 (0.22) for phycocyanin, and 0.70 (0.41) for Pc:Chla. Dissolved oxygen models achieved an R2 of 0.68 (0.36) when applied to Sentinel‐2 (Sentinel‐3) imagery, and Pc:Chla is found to be the most important predictive feature. Random forest models are better suited to water quality estimations in this system given built in methods for feature selection and a relatively small data set. Use of these approaches for estimation of Pc:Chla and dissolved oxygen can increase the water quality information extracted from satellite imagery and improve characterization of algae conditions among inland waters. Plain Language Summary: Agricultural runoff and wastewater discharge has fueled nutrient pollution in Lake Mendota over the last century. As a result, algae blooms have become a common summertime occurrence on Lake Mendota. Algae blooms are often made up of different algae species. Green algae are typically harmless, but cyanobacteria (blue‐green algae) can produce a range of toxins harmful to human and animal health. The ability to discriminate between cyanobacteria and green algae during a bloom may be useful for lake managers and public health officials in making decisions about closing waterfront areas and communicating with the public. In recent years, satellite imagery has become a powerful tool for monitoring water quality. In this study, we build models that use imagery from two satellites to estimate the abundance of cyanobacteria versus green algae in Lake Mendota. We also find that our algae estimates can be used to model dissolved oxygen, an important water quality indicator that cannot be directly measured from satellite imagery. The methods presented for satellite‐based monitoring of algae pigments, the Pc:Chla ratio, and dissolved oxygen has the potential to increase the water quality information extracted from satellite imagery, better characterize algae blooms, and inform management strategies for Lake Mendota. Key Points: Chlorophyll‐a and phycocyanin are sampled from 2019 to 2022 on Lake Mendota, WISentinel‐2 and Sentinel‐3 are used to model chlorophyll‐a, phycocyanin, and Pc:ChlaA model based in situ data allows for satellite‐based estimates of dissolved oxygen [ABSTRACT FROM AUTHOR]

Phytoplankton and other protists in the 3 µmto 50 µmsize fraction are grazed on by zooplankton and form the base of Arctic marine food webs essential for local indigenous communities. Anthropogenic climate change is increasing stratification over much of the Arctic Ocean and surrounding seas, but the influence of stratification on protist communities in more coastal regions along Eastern Hudson Bay, Hudson Strait and Ungava Bay is little known. We used 18S rRNA and rDNA amplicon sequencing during two consecutive summers (2017 and 2018) and detailed water column properties to compare the 3 µm to 50 µm protist communities under contrasting stratification regimes in the Eastern Hudson Bay Complex. We found that the surface mixed layer in Eastern Hudson Bay, which is under the influence of river runoff, was strongly stratified and dominated by mixotrophic and bacterivorous taxa, mostly the dinoflagellates Heterocapsa rotundata and Gymnodiniales spp., and a more diatom-dominated community at the Subsurface Chlorophyll Maximum (SCM), which persisted in deeper colder and more saline water. The massive sequencing effort retrieved seven putative toxic algae from the upper warmer waters of eastern Hudson Bay. These included Pseudo-nitzschia spp. and potentially harmful dinoflagellates, most notably Alexandrium sp. The persistent weaker stratification conditions in Hudson Strait and Ungava Bay in summer favored a different diatom community, dominated by Chaetoceros spp. and Thalassiosira spp., and small photosynthetic flagellates including Phaeocystis pouchetii and Micromonas polaris. As freshwater input increases and stratification intensifies in the Arctic, our findings suggest the summer dinoflagellate-based community seen in coastal Hudson Bay may also be favored in other regions receiving increased river runoff. These conditions could also favor harmful algal events. The Hudson Strait and Ungava Bay protist communities were found nearer the surface and consisted of diverse species able to profit from ongoing nutrient input due to tidal mixing. These results suggest greater resilience in this and other tidally influenced coastal Arctic Bays lacking larger rivers inputs. [ABSTRACT FROM AUTHOR]

Various harmful microalgae coexist in the marine environment, seriously affecting the survival of aquatic animals, the sustainable development of fisheries, and pose a great threat to the safety of aquatic food. Consequently, monitoring these harmful microalgae in the marine aquaculture environment is an urgent issue that needs to be addressed. This paper focused on developing a multiplex polymerase chain reaction (MPCR) assay for the simultaneous detection of representative harmful microalgae commonly distributed in the aquaculture environment along the Chinese coast, including Karenia mikimotoi, Alexandrium tamarense, Chattonella marina, Prorocentrum minimum and Heterosigma akashiwo. First, the internal transcribed spacer and large subunit rDNA of target algal species were selected as target for the design of MPCR primers, the specificity of which was subsequently verified. Next, the MPCR system was established and the reaction conditions were optimized, including primer concentration, dNTP concentration, Mg2+ concentration, the concentration of Taq DNA polymerase, and annealing temperature. Specificity test showed that the established MPCR did not cross-react with all of the control algal species and thus can be used for specific detection of target algal species. The sensitivity test showed that the established MPCR could still detect all of the target algae when the concentration of genomic DNA was as low as 1 ng µL–1. Moreover, the MPCR could still detect K. mikimotoi when the concentration of genomic DNA was as low as 1 pg µL–1. The stability test indicated that the performance of the developed MPCR was not affected by the interfering algal species. In addition, the practicality of the established MPCR assay was evaluated using spiked water samples. The tests with the spiked samples indicated that the detection limit of MPCR for the all of the target algal species was approximately 4 cells mL−1, which can meet the requirement for the warning of HABs caused by them. In conclusion, the MPCR assay established here is characterized with strong specificity and good stability and is expected to be promising for daily monitoring of harmful microalgae in the aquaculture environment as an important alternative to traditional morphology-based methods. [ABSTRACT FROM AUTHOR]

Ammonium and polyamines are essential nitrogen metabolites in all living organisms. Crosstalk between ammonium and polyamines through their metabolic pathways has been demonstrated in plants and animals, while no research has been directed to explore this relationship in algae or to investigate the underlying molecular mechanisms. Previous research demonstrated that high concentrations of ammonium and putrescine were among the active substances in bacteria-derived algicide targeting dinoflagellates, suggesting that the biochemical inter-connection and/or interaction of these nitrogen compounds play an essential role in controlling these ecologically important algal species. In this research, putrescine, ammonium, or a combination of putrescine and ammonium was added to cultures of three dinoflagellate species to explore their effects. The results demonstrated the dose-dependent and species-specific synergistic effects of putrescine and ammonium on these species. To further explore the molecular mechanisms behind the synergistic effects, transcriptome analysis was conducted on dinoflagellate Karlodinium veneficum treated with putrescine or ammonium vs. a combination of putrescine and ammonium. The results suggested that the synergistic effects of putrescine and ammonium disrupted polyamine homeostasis and reduced ammonium tolerance, which may have contributed to the cell death of K. veneficum. There was also transcriptomic evidence of damage to chloroplasts and impaired photosynthesis of K. veneficum. This research illustrates the molecular mechanisms underlying the synergistic effects of the major nitrogen metabolites, ammonium and putrescine, in dinoflagellates and provides direction for future studies on polyamine biology in algal species. [ABSTRACT FROM AUTHOR]

In the framework of benthic harmful algal bloom monitoring, the most common sampling strategy is based on the collection of macroalgae, and the abundance of epiphytic microalgae are mainly expressed as cells g−1 macroalgal fresh weight (fw). However, this methodology has some inherent problems, due to (i) the thallus-specific weights that markedly differ among algal species, (ii) the thallus architecture, and (iii) the production of allelopathic compounds that affects the epiphyte abundances among macroalgae, irrespective of the available colonizable surface. This study proposes a method to compare the abundances of Ostreopsis cf. ovata cells on different substrata, using a conversion factor that converts the abundances expressed as cells g−1 fw (or dry weight) to cells cm−2. Expressing abundances in terms of cells cm−2, the abundances can be compared (i) among different macroalgal species and (ii) between macroalgae and other substrata (such as rocks, pebbles, or shellfish shells). We also propose to normalize abundances when different macroalgae are sampled throughout the bloom period, considering the different epiphyte loads of different macroalgal species regardless of the available surface area. [ABSTRACT FROM AUTHOR]

Globally aquatic ecosystems are reportedly overwhelmed by algal blooms due to excessive deposition of nutrients which ultimately cause hypoxia, leading to massive fish death. This study aimed at assessing the relationship between algae contents and dissolved oxygen (DO) in Lake Babati which is threatened by anthropogenic activities, whereas Lake Eyasi was used as a control. Algae contents (chlorophyll a), DO and surface water temperature were measured using standard methods. Results revealed that the mean algae content was significantly higher (4.47±0.88 mg/L) in Lake Babati than in Lake Eyasi (1.6±0.45 mg/L) (P < 0.05) and was beyond the standard permissible levels for domestic water supply and healthy ecosystem. Conversely, DO was significantly lower in Lake Babati than in Lake Eyasi (P < 0.05). There was no significant difference in water temperature in the two lakes (P > 0.05). Furthermore, there was an inverse relationship between algae content and DO in Lakes Eyasi and Babati (r = -0.88 and r = -0.30, respectively) suggesting that algal bloom is partly responsible for lowering DO. Responsible authorities are advised to enforce management policies and regulations to control unsustainable activities around these lakes that contribute to nutrient loading resulting into overgrowth of algae. [ABSTRACT FROM AUTHOR]

Ocean warming and acidification may significantly alter the distribution and intensity of harmful algal blooms as well as their effects on marine food webs. Estimating such effects rely, in part, on understanding the physiological response of individual algal species to controlled laboratory simulations of climate change conditions. Here we report the physiological response of the harmful dinoflagellate Karlodinium veneficum to the combined effects of elevated temperature and CO2 (29°C/1000 ppm CO2). We first examined these effects by comparing ambient control (25°C/441 ppm CO2) and elevated conditions under short-term (~20 generations) growth. Next, we compared the short-term elevated condition to a longer-term (~200 generations) growth scenario under the same elevated temperature and CO2. Under the short-term elevated conditions, K. veneficum growth declined, cell toxicity increased, and saturated and mono-unsaturated fatty acid (FA) composition varied significantly from ambient conditions. Meanwhile, after ~ 200 generations of growth under elevated temperature and CO2, K. veneficum carbon assimilation, growth, and cell toxicity were significantly higher than the short-term elevated treatment. Further, while total saturated FA declined, essential fatty acids increased and likely represented an adaptive temporal response to long-term exposure to high temperature and CO2. Such shifts in FA profiles and cell toxicity may possibly alter K. veneficum nutritional quality as prey and its mixotrophic behavior, thereby affecting the energy and mass transfer through the marine food webs as well as bloom dynamics.

We have developed probabilistic models to estimate the likelihood of harmful algae presence and outbreaks along the Norwegian coast, which can help optimization of the national monitoring program and the planning of mitigation actions. We employ support vector machines to calibrate probabilistic models for estimating the presence and harmful abundance (HA) of eight toxic algae found along the Norwegian coast, including Alexandrium spp., Alexandrium tamarense, Dinophysis acuta, Dinophysis acuminata, Dinophysis norvegica, Pseudo-nitzschia spp., Protoceratium reticulatum, and Azadinium spinosum. The inputs are sea surface temperature, photosynthetically active radiation, mixed layer depth, and sea surface salinity. The probabilistic models are trained with data from 2006 to 2013 and tested with data from 2014 to 2019. The presence models demonstrate good statistical performance across all taxa, with R (observed presence frequency vs. predicted probability) ranging from 0.69 to 0.98 and root mean squared error ranging from 0.84% to 7.84%. Predicting the probability of HA is more challenging, and the HA models only reach skill with four taxa (Alexandrium spp., A. tamarense, D. acuta, and A. spinosum). There are large differences in seasonal and geographical variability and sensitivity to the model input of different taxa, which are presented and discussed. The models estimate geographical regions and periods with relatively higher risk of toxic species presence and HA, and might optimize the harmful algae monitoring. The method can be extended to other regions as it relies only on remote sensing and model data as input and running national programs of toxic algae monitoring.

Phytoplankton and other protists in the 3 µm to 50 µm size fraction are grazed on by zooplankton and form the base of Arctic marine food webs essential for local indigenous communities. Anthropogenic climate change is increasing stratification over much of the Arctic Ocean and surrounding seas, but the influence of stratification on protist communities in more coastal regions along Eastern Hudson Bay, Hudson Strait and Ungava Bay is little known. We used 18S rRNA and rDNA amplicon sequencing during two consecutive summers (2017 and 2018) and detailed water column properties to compare the 3 µm to 50 µm protist communities under contrasting stratification regimes in the Eastern Hudson Bay Complex. We found that the surface mixed layer in Eastern Hudson Bay, which is under the influence of river runoff, was strongly stratified and dominated by mixotrophic and bacterivorous taxa, mostly the dinoflagellates Heterocapsa rotundata and Gymnodiniales spp., and a more diatom-dominated community at the Subsurface Chlorophyll Maximum (SCM), which persisted in deeper colder and more saline water. The massive sequencing effort retrieved seven putative toxic algae from the upper warmer waters of eastern Hudson Bay. These included Pseudo-nitzschia spp. and potentially harmful dinoflagellates, most notably Alexandrium sp. The persistent weaker stratification conditions in Hudson Strait and Ungava Bay in summer favored a different diatom community, dominated by Chaetoceros spp. and Thalassiosira spp., and small photosynthetic flagellates including Phaeocystis pouchetii and Micromonas polaris. As freshwater input increases and stratification intensifies in the Arctic, our findings suggest the summer dinoflagellate-based community seen in coastal Hudson Bay may also be favored in other regions receiving increased river runoff. These conditions could also favor harmful algal events. The Hudson Strait and Ungava Bay protist communities were found nearer the surface and consisted of diverse species able to profit from ongoing nutrient input due to tidal mixing. These results suggest greater resilience in this and other tidally influenced coastal Arctic Bays lacking larger rivers inputs.

Benthic dinoflagellates of the Coolia genus have been associated with cytotoxicity and lethal and sublethal effects on marine species. This study aimed to assess the harmful effects of C. cf. canariensis phylogroup II (PII) and C. malayensis strains through bioassays. Experimental exposures (24, 48, and 72 h) of Artemia salina nauplii to Coolia species (330–54,531 cells mL−1) were performed independently. When a concentration-dependent response was achieved, additional experiments were carried out to evaluate the cell-free medium toxicity. The two Coolia species were harmful to Artemia nauplii, inducing significant mortality and sublethal responses. Coolia cf. canariensis PII was the most toxic species, inducing significant lethality at lower concentrations and shorter exposure times, followed by C. malayensis. Only the survival curves achieved after 24 and 48 h of exposure to C. cf. canariensis PII fitted to a concentration–response curve with valid LC50s of 18,064 and 19,968 cells mL−1, respectively. Moreover, extracellular compounds (i.e., culture filtrates) of C. cf. canariensis PII induced significant mortality to nauplii after 48 and 72 h. The toxicity of C. cf. canariensis PII was demonstrated for the first time using bioassays, and it was surprisingly higher than that of the C. malayensis strain, which was previously demonstrated to induce biological activity at the cellular and subcellular levels. Our findings highlight the harmful and lethal effects induced by Coolia cells and the importance of bioassays for toxicity assessments.

Introduction: Histamine-mediated angioedema is a potentially life-threatening reaction following exposures that incite mast cell activation. In Florida, red tides are a frequent phenomenon caused by overgrowth of the harmful algae species Karenia brevis, which contain environmentally detrimental brevetoxins. Even in low concentrations, brevetoxins can cause disease in humans through inducing histamine release. We report the first documented case of angioedema associated with red tide exposure.Case Report: A 52-year-old-male presented with severe angioedema encompassing both lips within a few hours after exposure to red tide algae. Other symptoms included voice changes and difficulty swallowing. Laboratory findings revealed complement factors that were within reference range, which ruled out a bradykinin-mediated pathology and supported the diagnosis of histaminergic angioedema. Symptoms resolved after 24 hours in the intensive care unit under management with epinephrine, diphenhydramine, methylprednisolone, and famotidine.Conclusion: In coastal regions, red tide algae should be recognized as a rare cause of acute angioedema. Emergency management of histamine-mediated angioedema should focus on preventing respiratory compromise with frequent airway monitoring and treatment with steroids, antihistamines, and epinephrine.

Harmful algal blooms (HABs) in coastal British Columbia (BC), Canada, negatively impact the salmon aquaculture industry. One disease of interest to salmon aquaculture is Net Pen Liver Disease (NPLD), which induces severe liver damage and is believed to be caused by the exposure to microcystins (MCs). To address the lack of information about algal toxins in BC marine environments and the risk they pose, this study investigated the presence of MCs and other toxins at aquaculture sites. Sampling was carried out using discrete water samples and Solid Phase Adsorption Toxin Tracking (SPATT) samplers from 2017–2019. All 283 SPATT samples and all 81 water samples tested positive for MCs. Testing for okadaic acid (OA) and domoic acid (DA) occurred in 66 and 43 samples, respectively, and all samples were positive for the toxin tested. Testing for dinophysistoxin-1 (DTX-1) (20 samples), pectenotoxin-2 (PTX-2) (20 samples), and yessotoxin (YTX) (17 samples) revealed that all samples were positive for the tested toxins. This study revealed the presence of multiple co-occurring toxins in BC's coastal waters and the levels detected in this study were below the regulatory limits for health and recreational use. This study expands our limited knowledge of algal toxins in coastal BC and shows that further studies are needed to understand the risks they pose to marine fisheries and ecosystems. [ABSTRACT FROM AUTHOR]

Benthic dinoflagellates of the Coolia genus have been associated with cytotoxicity and lethal and sublethal effects on marine species. This study aimed to assess the harmful effects of C. cf. canariensis phylogroup II (PII) and C. malayensis strains through bioassays. Experimental exposures (24, 48, and 72 h) of Artemia salina nauplii to Coolia species (330–54,531 cells mL−1) were performed independently. When a concentration-dependent response was achieved, additional experiments were carried out to evaluate the cell-free medium toxicity. The two Coolia species were harmful to Artemia nauplii, inducing significant mortality and sublethal responses. Coolia cf. canariensis PII was the most toxic species, inducing significant lethality at lower concentrations and shorter exposure times, followed by C. malayensis. Only the survival curves achieved after 24 and 48 h of exposure to C. cf. canariensis PII fitted to a concentration–response curve with valid LC50s of 18,064 and 19,968 cells mL−1, respectively. Moreover, extracellular compounds (i.e., culture filtrates) of C. cf. canariensis PII induced significant mortality to nauplii after 48 and 72 h. The toxicity of C. cf. canariensis PII was demonstrated for the first time using bioassays, and it was surprisingly higher than that of the C. malayensis strain, which was previously demonstrated to induce biological activity at the cellular and subcellular levels. Our findings highlight the harmful and lethal effects induced by Coolia cells and the importance of bioassays for toxicity assessments. [ABSTRACT FROM AUTHOR]

The port ecosystems are prone to deterioration due to the maritime and coastal activities and as a major source of the country's economy need efficient management. Phytoplankton communities can serve as reliable indicators of the prevailing environmental conditions due to their short life cycles. Seasonal sampling was conducted at 26 stations from October 2014 to February 2016 at Kandla port situated in a creek, along the west coast of India. The post-monsoon and monsoon water temperatures were higher (30 °C) whereas pre-monsoon were lower (21 °C). The salinity varied from polyhaline (18–30; monsoon) to euhaline (30 to 45; non-monsoon). The strong currents, high tidal activity, shallow depth areas, and the creek backwater systems make this ecosystem well-mixed and turbid. The annual average trophic index (TRIX) scores indicated very good water quality and low eutrophication, except during pre-monsoon (2.3 ± 0.7 to 4.1 ± 0.2). Based on the cell size, the phytoplankton community was classified into two main groups, i.e., nano-microphytoplankton, which comprised forty-seven species (represented by diatoms, dinoflagellates, and silicoflagellates) and picophytoplankton including two groups (picocyanophytes and picoeukaryotes). The diatoms and picophytoplankton dominated the total biomass and cell abundance, respectively. Only the picophytoplankton exhibited significant seasonal variations in cell abundance and carbon biomass. The lowest monsoon phytoplankton abundance coincided with high turbidity and vice versa during the post-monsoon. The hypersaline pre-monsoon environment with lower annual temperature, relatively lower turbid waters, and increased nutrients favoured higher diatom diversity. These conditions also supported potentially harmful Gymnodinium sp. and bloom-forming Tripos furca and Pyrophacus sp. Overall, ten non-toxic but bloom-forming species were observed. The study provides insights into the phytoplankton community's response to environmental conditions that can have repercussions on the ecosystem's functioning. [ABSTRACT FROM AUTHOR]

The planktonic diatom genus Pseudo-nitzschia contains several genetically closely related species that can produce domoic acid, a potent neurotoxin known to cause amnesic shellfish poisoning (ASP). An early identification and an adequate monitoring of the potential toxic Pseudo-nitzschia spp. are necessary. However, effective monitoring programs are time consuming due, in some cases, to the cell morphology similarities among species, determined with light microscopy, that can result in insufficient data to give a definitive species and toxins attribution. In this paper, Whole-Cell Fluorescent In Situ Hybridization (WC-FISH) has been evaluated as a powerful tool to detect and enumerate harmful cryptic and/or pseudo-cryptic Pseudo-nitzschia spp. collected in the Gulf of Naples. Fluorescently labelled probes directed against the ribosomal RNA (rRNA) of the 28S large subunit (LSU) were used. In particular, five probes detecting four cryptic species of Pseudo-nitzschia delicatissima complex and one specific for Pseudo-nitzschia multistriata gave good results for the molecular identification of potentially toxic target species in natural samples. Finally, we can state that the WC-FISH method, to identify Pseudo-nitzschia species, is faster and more cost-effective if compared with other rDNA-based methods. [ABSTRACT FROM AUTHOR]

The evaluation of water quality is commonly conducted by measuring physicochemical parameters. However, to enable identification of water quality changes of aquatic ecosystems, such as lakes, requires long time series data sampling. In this study, we performed water quality assessments by utilising the presence of potential harmful algae presence in Lake Ranu Grati, Indonesia. We conducted water sampling to evaluate 13 water quality parameters (in-situ and ex-situ) and identified the phytoplankton community structure of the lake at seven sampling sites from December 2018 to February 2019. To assess the water quality of the lake, we used two approaches. First, calculated the classical water quality index using the STORET method. Second, identified the potential harmful algae from the phytoplankton community structure of Lake Ranu Grati, and then determined the water quality factors related to its occurrence using canonical correspondence analysis. The results showed that water quality condition of Lake Ranu Grati was optimum except for COD, BOD and ammonia. The STORET index also classified the seven sites in Lake Ranu Grati as lightly polluted and moderately polluted. Considering the presence of potentially harmful algae from the Cyanophyta and Euglenophyta divisions, it was suggested that Sites 6 and 7 were the most polluted areas of Lake Ranu Grati, which corresponded to the high concentration of COD and BOD. This finding indicates that agricultural and aquaculture activities around the lake need to be controlled to maintain the sustainability of the water quality condition of Lake Ranu Grati.

Molecular-based approaches for harmful algal bloom species, which can be difficult to identify by light microscopy, are important tools for detecting and predicting the blooms. In this study, 84 samples from Aotearoa/New Zealand coastal waters that contained Azadinium-like cells were analysed using an Amphidomataceae real-time PCR assay. Nineteen samples were positive, and 24 Azadinium-like clonal isolates were established from these samples. Subsequently, only five isolates from one sampling point were positive using the real-time PCR assay. Four of the five isolates were genetically identified as Amphidoma languida and one as Azadinium dalianense. The field samples were analysed retrospectively using the species-specific real-time PCR assays; Am. languida was detected from the temperate areas, while Az. poporum and Az. spinosum were detected at one site. Two representative strains of each species were analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), including Am. languida, which is known as toxic in the previous studies, but neither produced the currently monitored azaspiracids (AZAs). These two newly recorded species for New Zealand are important findings. The results highlight the need for more information on the spatio-temporal variations of potentially toxic Amphidomataceae species and the risk of AZAs in New Zealand coastal waters. [ABSTRACT FROM AUTHOR]

Gorney RM, June SG, Stainbrook KM, Smith AJ. 2023. Detections of cyanobacteria harmful algal blooms (cynanoHABs) in New York State, United States (2012–2020). Lake Reserv Manage. 39:21–36. Patterns in frequency, intensity, and duration of cyanobacteria harmful algal blooms (cyanoHABs) were evaluated in New York State from 2012 to 2020. The dataset included information from formal monitoring efforts, beach closures, and public reports. The total dataset included more than 24,000 records from 655 waterbodies and included cyanoHAB reports from 477 lakes. Nearly half of those lakes (49.6%) had only 1 year in which a cyanoHAB was documented. Less than 1% (6 lakes) had cyanoHABs documented in every year of the study. We noted a significant increase in the number of cyanoHABs reports each year (P < 0.001), but not an overall increase in intensity, based on evaluation of chlorophyll levels in mid-lake samples collected on a routine basis. The analysis indicated that cyanoHABs duration did not lengthen over the study period, based on beach closure data captured on a daily observation basis. This study addresses the limitations of monitoring data for analysis of patterns in cyanoHABs, based on the structure of the programs and frequency of observations. We provide retrospective feedback on the design of monitoring programs to improve future data collection and our ability to evaluate cyanoHABs in a wide range of waterbodies. [ABSTRACT FROM AUTHOR]

Plankton monitoring by microscopy offers a long-term ecological perspective of plankton communities, but detection approaches are uniquely biased. Genetic identification of marine plankton has become standard but is still not used in routine monitoring. This study assesses the value that genetic methods bring to microscopic and flow cytometry monitoring methods in the Western (English) Channel. An 18S high throughput sequencing (HTS) diversity survey of plankton taxa was performed on samples collected from an automated Water and Microplankton Sampler (WaMS) deployed on the Continuous Plankton Recorder platform (CPR) from 2011–2012. This survey detected contrasting but complementary taxa assemblages to that of microscopic surveys, mostly composed of smaller or naked or thin-walled plankton taxa, with most phytoplankton being under 10 µm infrequently recorded by other surveys. Most genetically-detected taxa in the survey were mixotrophic or heterotrophic. In comparison with microscopic phytoplankton counts from the CPR survey and Western Channel Observatory station L4, only 8–12 taxonomic families were common to all three surveys, most of them dinoflagellates, with a bias towards larger diatoms and dinoflagellate taxa in microscopy surveys. Additional quantitative real-time PCR detection of two potentially harmful taxa, the pelagophyte, Aureococcus anophagefferens and four Pseudo-nitzschia from 2011–2013. This revealed that growth of A. anophagefferens was elevated in the summer of 2011, whilst the appearance of Pseudo-nitzschia delicatissima in February of that year contrasted with it's timing at a coastal station. Smaller phytoplankton measured by flow cytometry had distinct seasonality and abundance in the mid-Atlantic compared to coastal regions reflecting distinct conditions. [ABSTRACT FROM AUTHOR]

Based on biological traits, the ecological quality status under the pressure of two harmful algal bloom (HAB) species was evaluated using functional units (FUs) of periphytic protozoan communities. Five treatments with different concentrations of Alexandrium tamarense and Gymnodinium catenatum, i.e., 100, 102, 103, 104, and 105 cells ml−1, were used. A total of 20 FUs were identified from 25 test protozoan species. Among these FUs, vagile algivores with large sizes showed a decreasing trend (i.e., in diversity and abundance) with increasing concentrations of algae, while vagile bacterivores and non-selectives with small sizes dominated at concentrations of 104 cells ml−1 of both algal species. Ellipse tests on pair-wise functional distinctness indices revealed a significant departure of test protozoan communities from an expected functional distinctness breadth when algal concentrations exceeded 104 cells ml−1. Based on these findings, it was concluded that FUs of periphytic protozoa may be a useful tool for evaluating the effects of HABs on ecological quality status in marine ecosystems. [ABSTRACT FROM AUTHOR]

Some strains of the dinoflagellate species Prorocentrum hoffmannianum show contrasting ability to produce diarrhetic shellfish poisoning (DSP) toxins. We previously compared the okadaic acid (OA) production level between a highly toxic strain (CCMP2804) and a non-toxic strain (CCMP683) of P. hoffmannianum and revealed that the cellular concentration of OA in CCMP2804 would increase significantly under the depletion of phosphate. To understand the molecular mechanisms, here, we compared and analyzed the proteome changes of both strains growing under normal condition and at phosphate depletion using two-dimensional gel electrophoresis (2-DE). There were 41 and 33 differential protein spots observed under normal condition and phosphate depletion, respectively, of which most were upregulated in CCMP2804 and 22 were common to both conditions. Due to the lack of matched peptide mass fingerprints in the database, de novo peptide sequencing was applied to identify the differentially expressed proteins. Of those upregulated spots in CCMP2804, nearly 60% were identified as peridinin-chlorophyll a-binding protein (PCP), an important light-harvesting protein for photosynthesis in dinoflagellates. We postulated that the high expression of PCP encourages the production of DSP toxins by enhancing the yields of raw materials such as acetate, glycolate and glycine. Other possible mechanisms of toxicity related to PCP might be through triggering the transcription of non-ribosomal peptide synthetase/polyketide synthase genes and the transportation of dinophysistoxin-4 from chloroplast to vacuoles. [ABSTRACT FROM AUTHOR]

Subtropical lakes remain understudied by comparison to lakes in temperate and tropical regions when considering environmental factors impacting cyanobacterial harmful algal bloom (CyanoHAB) propagation and success. Central Texas, USA, exhibited an extended, severe drought from 2010 to 2015. Phytoplankton data from Lake Buchanan, a large reservoir on the Colorado River, displayed rapid shifts in the community during this period as the reservoir transitioned to more eutrophic conditions. This study serves to assess the likelihood of CyanoHABs considering this recent transition in trophic status and determine factors promoting success of potentially harmful species. Routine monitoring was performed every other month, including measurements of environmental parameters, nutrients, as well as the identification of phytoplankton using DNA barcoding and cell counts. DNA sequencing analysis confirmed the presence of multiple known bloom-forming cyanobacteria. Potential producers of saxitoxins Planktothrix, Aphanizomenon/Chrysosporum, and Raphidiopsis thrived in drought conditions, whereas Limnothrix and Pseudanabaena performed better during non-drought conditions. Following the drought period, Chrysosporum ovalisporum, Phormidium tenue, and Planktothrix sp. were still present along with other potentially harmful species; however, the community had shifted to predominantly diatoms comprised of Fragilaria and Lindavia. These results suggest the drought conditions, i.e., increased conductivity, temperature, and nutrient loads, likely influenced the success of potentially toxic cyanobacteria. The success of these taxa contributed to eutrophication and subsequent decline in diversity. Subtropical lakes should therefore be monitored more closely during extended drought periods, as the risks associated with eutrophication and CyanoHABs are predicted to be significantly higher. [ABSTRACT FROM AUTHOR]

A harmful algal bloom occurred in late spring 2019 across multiple, interconnected fjords and bays in northern Norway. The event was caused by the haptophyte Chrysochromulina leadbeateri and led to severe fish mortality at several salmon aquaculture facilities. This study reports on the spatial and temporal succession dynamics of the holistic marine microbiome associated with this bloom by relating all detectable 18S and 16S rRNA gene amplicon sequence variants to the relative abundance of the C. leadbeateri focal taxon. A k-medoid clustering enabled inferences on how the causative focal taxon cobloomed with diverse groups of bacteria and microeukaryotes. These coblooming patterns showed high temporal variability and were distinct between two geographically separated time series stations during the regional harmful algal bloom. The distinct blooming patterns observed with respect to each station were poorly connected to environmental conditions, suggesting that other factors, such as biological interactions, may be at least as important in shaping the dynamics of this type of harmful algal bloom. A deeper understanding of microbiome succession patterns during these rare but destructive events will help guide future efforts to forecast deviations from the natural bloom cycles of the northern Norwegian coastal marine ecosystems that are home to intensive aquaculture activities. [ABSTRACT FROM AUTHOR]

In Asia, four harmful raphidophyte species, Chattonella malayana, C. marina, C. subsalsa, and C. tenuiplastida, coexist in the tropical waters but only C. marina was detected in temperate waters. This occurrence pattern pointed to a potentially distinct ecophysiological niche occupancy and possible species dispersion. The growth physiology of these species isolated from tropical Southeast Asia was investigated using unialgal cultures in ten temperatures (13.0–35.5°C) and five salinities (15–35) to better understand the factors driving their distribution. The highest maximum specific growth rates were observed in C. subsalsa (0.65 ± 0.01 d-1), followed by C. malayana (0.47 ± 0.03 d-1), C. marina (0.45 ± 0.02 d-1), and C. tenuiplastida (0.39 ± 0.01 d-1). Their optimal temperatures were 28.0, 30.5, 25.5, and 30.5°C, respectively, of which C. marina preferred colder water. C. subsalsa exhibited a wider growth temperature range (20.5–35.5°C), followed by C. marina (20.5–30.5°C), C. tenuiplastida (23.0–33.0°C), and C. malayana (25.5–33.0°C). Optimal salinities were similar between C. subsalsa and C. malayana (30), and between C. marina and C. tenuiplastida (25), but C. subsalsa and C. marina exhibited a similar growth salinity range of 15–35, while C. malayana and C. tenuiplastida was 20–35. High values of Fv/Fm were observed in C. subsalsa and C. marina (> 0.5) in all tested conditions, but Fv/Fm of C. malayana and C. tenuiplastida were significantly lower at 20.5°C. All four species achieved a maximum cell density of > 104 cells mL-1 in their optimal conditions. Optimal temperatures in C. subsalsa and C. marina were identical to previous reports. The high adaptability of C. subsalsa in various temperatures and salinities suggests its high competitiveness and bloom potential. The high adaptability of C. marina in colder waters compared to other species likely contributes to its wide distribution in the temperate Asian waters. The narrow temperature window of C. malayana and C. tenuiplastida suggests their endemicity and limited distribution in the tropical waters. This study provides evidence about the occurrences and bloom potential of Chattonella spp. in Asia, but the endemicity versus dispersion issue remains unresolved.

Toxic algae and their toxins represent an emerging public health issue, particularly due to global warming. The toxicological mechanisms of neurotoxic phycotoxins and their human health effects have been widely described (paralytic, neurological, amnesic, and ciguateric toxins). Food poisoning by bivalve shellfish (mussels, oysters…) can cause serious or even fatal neurological disorders, as bivalves accumulate toxins by feeding on harmful algae. However, retrospective study of human shellfish poisoning highlighted the difficulties in identifying cases related to neurotoxic phycotoxins by gathering clinical and biological diagnostic confirmations on the one hand, as well as environmental contaminations on the other. To improve the collection of shellfish poisoning data, the French Agency for Food, Environmental and Occupational Health and Safety (ANSES), French Poison Control Centers (PCCs), the French Research Institute for Exploitation of the Sea (Ifremer) and the French Defense Procurement Agency (DGA) have developed a prospective surveillance of neurotoxins from algal origin that combines monitoring of poisoning cases (clinical monitoring), of harmful algae and their toxins in shellfish production areas (environmental monitoring), as well as of toxins levels in seafood leftovers and in biological samples from poisoned subjects. This original clinical and environmental monitoring will allow us to have a more complete view of phycotoxin human exposures that are underreported, and to implement measures to protect consumers.

To assist the researches of toxic and harmful algae and provide government workers with judgment basis for decision-making related events, we established a biological information management system for toxic and harmful algae in China's offshore to assist relevant research. In this study, Karenia mikimotoi was studied as a typical toxic and harmful algae species, and the basic biological information and biogeographic distribution information of K. mikimotoi were systematically studied and collected. In the part of basic biological information, the name, toxin, and molecular characteristic sequence of K. mikimotoi were sorted out by literature searching and website browsing. Through experimental means, the relevant information of morphological identification, pigment composition, and lipid composition were obtained. In the part of biogeographic distribution information, this study sorted out the information of K. mikimotoi, analyzed the characteristics of its occurrence, and completed the standardized construction of biogeographic distribution information. Through the collation of basic biological information and biogeographic distribution information of K. mikimotoi, the standardization of related information was completed, which provided template and method reference for information collection of other toxic and harmful algae species, which was beneficial to the database analysis and design. [ABSTRACT FROM AUTHOR]

The "harmful algae and algal toxins in coastal waters of China: investigation and database" project (HAATC) is funded (US$2.3 million) by the Ministry of Science and Technology of China for 60 months starting on the 1st Jan 2019. Since the 1990s, national projects and other related work have greatly improved harmful algal bloom (HAB) research in China. However, the existing research on HABs is often limited to specific sea areas or specific algal bloom disasters, which is insufficient for understanding the long-term evolution of HAB occurrence under the influence of intensified human activity and global change. The HAATC project intends to determine the overall distribution of marine harmful microalgae and macroalgae, and marine algal toxins (in phytoplankton and shellfish) through a large-scale investigation in the coastal waters of China and continuous investigation in key sea areas. It also aims to observe biotic and abiotic processes during harmful red tides and green tides, and establish an open database and query platform of HABs in China. The research consortium, led by chief scientist Prof. Tian YAN, includes approximately 100 scientists and students. More than 2 years of work have shown the increased distribution of HAB species (including cysts) and algal toxins in China's coastal waters, the increased occurrence of macroalgae blooms (mainly by Ulva prolifera and Sargassum horneri) in the Southern Yellow Sea, increased amount of causative species being identified due to the use of molecular technologies in taxonomy, and new records of algal toxins such as azaspiracid, cycloimines and neurotoxins β-N-methylamino-l-alanine have been detected, which complicates the research in algal toxins and toxicology. Eventually, the project will provide systematic basic data and techniques for the rapid and accurate identification of harmful algae species to support the research, monitoring, and control of harmful algal blooms, as well as seafood safety management in China. [ABSTRACT FROM AUTHOR]

Intense blooms of the toxic dinoflagellate Ostreopsis producing palytoxin (PlTX) analogs, mainly ovatoxins (OVTXs), have been a recurrent phenomenon along several Mediterranean coasts. Although there is evidence of seafood contamination by these toxins, the dynamics of their bioaccumulation during Ostreopsis blooms is not yet clear. Toxin concentrations in wild mussels at two sites in the Conero Riviera, along the northern Adriatic Sea (Portonovo and Passetto), were analyzed from August to October 2021, throughout an Ostreopsis cf. ovata bloom, to investigate their relationships with the bloom pattern and abundances. Contaminated mussels showed the typical toxin profile dominated by OVTX-a and -b, with levels lower than the threshold considered unsafe for human consumption (30 µg PlTX-equivalent kg−1 soft tissue). The toxin content reached 36.4 µg PlTX kg−1 soft tissue only in a single sampling date. A clear correlation between the bioaccumulation of OVTXs in mussels and the abundance of Ostreopsis was observed. Our results highlighted, however, that bioaccumulation in the mussels is not affected merely by the abundance of toxic microalgae, since higher toxin levels were recorded at Portonovo, where the cell abundances were lower than at Passetto. The results from this study indicate that the Italian guidelines for the management of Ostreopsis blooms in bathing waters are also useful in managing the risks of human intoxication through ingestion, as mussel contamination was detected only during the alert phase (10,000–30,000 cells L−1). [ABSTRACT FROM AUTHOR]

Worldwide used glyphosate-based organophosphorus herbicides may be potential phosphorus sources for phytoplankton in coastal waters. In this study, the changes in growth, fluorescent and cytometric parameters of the potentially toxic dinophytic algae Prorocentrum cordatum under the influence of glyphosate of different concentrations were investigated. The effect of glyphosate on the growth dynamics of P. cordatum under conditions of availability and deficiency of inorganic phosphorus in the medium is estimated. Results showed that P. cordatum could grow due to glyphosate as the only source of phosphorus. The final density of the culture was higher than that of the control (without glyphosate) by 22–136% depending on the applied herbicide concentration. Glyphosate stimulated the growth of microalgae, which was observed in increasing the efficiency of the photosynthetic apparatus of cells and their enzymatic (esterase) activity. P. cordatum used glyphosate as a source of phosphorus only when there was a deficiency in inorganic phosphorus, but it was also susceptible to the herbicide when there was inorganic phosphorus present in the medium. An increase of glyphosate concentration in coastal waters may lead to a change in the species structure of natural biocenoses and increase in the number of potentially harmful species. • Glyphosate stimulates the growth of P. cordatum. • P. cordatum can grow due to glyphosate as the only source of phosphorus. • P. cordatum consumes glyphosate only when there is a deficiency of inorganic phosphorus. • Glyphosate can lead to a change in the species structure of natural biocenoses. [ABSTRACT FROM AUTHOR]

Although microalgae typically serve as prey for jellyfish ephyrae in marine food webs, this study investigated the potential of harmful microalgae to produce detrimental effects on the moon jellyfish Aurelia aurita. Understanding the biological interactions between Aurelia and microalgal species is crucial, particularly considering their common co-occurrence in coastal waters worldwide. We examined the effects of 11 protist strains, comprising seven species of harmful microalgae and two non-toxic microalgae, on A. aurita ephyrae. The rhythmic pulsation behavior of A. aurita was significantly suppressed when exposed to the raphidophytes Heterosigma akashiwo and Chattonella marina var. ovata and the dinoflagellates Amphidinium carterae , Coolia canariensis , and Pfiesteria piscicida. Notably, the media filtrates of all H. akashiwo strains and C. marina var. ovata killed ephyrae, implying a possible extracellular release of chemicals. This study discovered novel interactions between microalgae and jellyfish ephyrae, implying that harmful algal blooms may suppress mass occurrences of Aurelia medusae. • This study explored the effects of harmful microalgae on moon jellyfish (Aurelia aurita) ephyrae. • Harmful microalgae significantly suppressed the rhythmic pulsation of A. aurita ephyrae through diverse mechanisms. • Harmful algal blooms could suppress large populations of A. aurita medusae by negatively affecting their ephyrae. [ABSTRACT FROM AUTHOR]

Invasive species that outcompete endemic ones and toxic harmful algae that cause algal blooms threaten marine resources like fisheries, aquaculture, and even tourism. Environmental DNA (eDNA) metabarcoding can help as a method for early alert. In this study, we have analyzed communities inhabiting six lagoons within the Gulf of Lion (northwest Mediterranean Sea) with spatial protection as RAMSAR and Natura 2000 sites. Employing the COI gene as the only metabarcode, we found 15 genera that have caused recognized algal bloom outbreaks in the studied lagoons since 2000. In addition, seven alien invasive species that can pose risks to the rich marine resources of the zone and lagoons were also found. The results found from eDNA are consistent with events of toxic algae blooms before and after the sampling moment and with reported occurrences of the invasive species in nearby Mediterranean areas. Multivariate multiple analysis showed the importance of anthropic pressure in the abundance of these nuisance species. Mitigation actions and routine eDNA metabarcoding in zones of special interest like these fragile French Mediterranean lagoons are recommended for early alert of nuisance species in order to plan timely management actions. • Mediterranean lagoons are threatened due to anthropogenic activities. • Anthropogenic pressures are significantly and positively associated with nuisance species. • eDNA metabarcoding is a useful tool to early detect nuisance species in Mediterranean lagoons. • Management actions should be taken to detect and control nuisance species before they become established. [ABSTRACT FROM AUTHOR]

Gymnodinium catenatum is a dinoflagellate known to cause paralytic shellfish poisoning (PSP), commonly associated with human muscular paralysis, neurological symptoms, and, in extreme cases, death. In the present work, we developed a real-time PCR-based assay for the rapid detection of the toxic microalgal species, G. catenatum, in environmental bivalve mollusc samples as well as seawater samples. G. catenatum-specific primers and probe were designed on the ITS1-5.8S-ITS2 rDNA region. Hydrolysis probe qPCR assay was optimized. ITS1-5.8S-ITS2 rDNA region copy numbers per G. catenatum cell genome were estimated to be 122.73 ± 5.54 copies/cell, allowing cell quantification. The application of the optimized qPCR assay for G. catenatum detection and quantification in field samples has been conducted, revealing high sensitivity (detection of around 1.3105 cells/L of seawater samples. Thus, the designed hydrolysis probe qPCR assay could be considered an efficient tool for phytoplankton monitoring whilst ensuring accuracy and sensitivity and providing cost and time savings. [ABSTRACT FROM AUTHOR]

Simple Summary: Harmful algae are those which release toxins to the aquatic ecosystems. Excessive growth of these algae can kill fish, create anoxia, impede aquaculture activities and contaminate aquatic food. Therefore, it is important to investigate their occurrence, diversity and abundance in pond aquaculture systems. In this study, we have identified 81 genera of harmful algae from 30 coastal homestead ponds mainly consisting of Microcystis spp. (30.14%) and Actinoptycus spp. (18.32%). Based on taxonomic classes, the community assemblage was dominated by Cyanophyceae, Chlorophyceae and Bacillariophyceae. Statistical analyses demonstrated that that dissolved oxygen, nitrates, phosphates, sulphates, salinity and transparency influence the abundance of identified algal genera. Algae are the naturally produced food for fish in any aquatic ecosystem and an indicator of a productive pond. However, excess abundance of harmful algae can have detrimental effects on fish health. In this study, the algal communities of 30 coastal homestead fish ponds were investigated to identify the diversity, assemblage and controlling environmental variables of harmful algae from a tropical coastal area. The findings showed that 81 of the 89 genera of identified algae were harmful, with the majority of them being in the classes of Cyanophyceae (50.81%), Chlorophyceae (23.75%), Bacillariophyceae (9.5%), and Euglenophyceae (8.47%). Microcystis spp. alone contributed 28.24% to the total abundance of harmful algae. Significant differences (p < 0.05) in algal abundance were found among the ponds with the highest abundance (470 ± 141.74 × 103 cells L−1) at pond (S25) near agricultural fields and the lowest abundance (109.33 ± 46.91 × 103 cells L−1) at pond (S14) which was lacking sufficient sunlight and nutrients. Diversity indices, e.g., dominance (D), evenness (J′), richness (d) and Shannon diversity index (H′) ranged from 0.17 to 0.44, 0.23 to 0.6, 0.35 to 2.23 and 0.7 to 1.79, respectively, indicating a moderate range of diversity and community stability. Community composition analysis showed the assemblage was dominated by Cyanophyceae, Chlorophyceae and Bacillariophyceae, whereas, multivariate cluster analyses (CA) identified 11 major clusters. To identify the factors controlling their distribution or community assemblages, eight environmental variables (temperature, pH, dissolved oxygen (DO), salinity, transparency, nitrates, phosphates and sulphate) were measured. ANOVA analysis showed that the variables significantly differed (p < 0.05) among the ponds, and canonical correspondence analysis (CCA) demonstrated that DO, nitrates, phosphates, sulphates, salinity and transparency have the most impact on the abundance of algal genera. In addition, analyses with Pearson's correlation coefficient showed that the abundance of total algae, diversity and community were mainly governed by phosphates and sulphates. These results can be used to identify and control these toxic algal groups in the local aquaculture sector. [ABSTRACT FROM AUTHOR]

Prevalent interactions among marine phytoplankton triggered by long-range climatic stressors are well-known environmental disturbers of community structure. Dynamic response of phytoplankton physiology is likely to come from interspecies interactions rather than direct climatic effect on single species. However, studies on enigmatic interactions among interspecies, which are induced by bioactive extracellular compounds (BECs), especially between related harmful algae sharing similar shellfish toxins, are scarce. Here, we investigated how BECs provoke the interactions between two notorious algae, Alexandrium minutum and Gymnodinium catenatum, which have similar paralytic shellfish toxin (PST) profiles. Using techniques including electron microscopy and transcriptome analysis, marked disruptions in G. catenatum intracellular microenvironment were observed under BECs pressure, encompassing thylakoid membrane deformations, pyrenoid matrix shrinkage and starch sheaths disappearance. In addition, the upregulation of gene clusters responsible for photosystem-I Lhca1/4 and Rubisco were determined, leading to weaken photon captures and CO 2 assimilation. The redistribution of lipids and proteins occurred at the subcellular level based on in situ focal plane array FTIR imaging approved the damages. Our findings illuminated an intense but underestimated interspecies interaction triggered by BECs, which is responsible for dysregulating photosynthesis and organelle function in inferior algae and may potentially account for fitness alteration in phytoplankton community., (© 2024 John Wiley & Sons Ltd.)

Harmful algal blooms (HABs) in coastal British Columbia (BC), Canada, negatively impact the salmon aquaculture industry. One disease of interest to salmon aquaculture is Net Pen Liver Disease (NPLD), which induces severe liver damage and is believed to be caused by the exposure to microcystins (MCs). To address the lack of information about algal toxins in BC marine environments and the risk they pose, this study investigated the presence of MCs and other toxins at aquaculture sites. Sampling was carried out using discrete water samples and Solid Phase Adsorption Toxin Tracking (SPATT) samplers from 2017–2019. All 283 SPATT samples and all 81 water samples tested positive for MCs. Testing for okadaic acid (OA) and domoic acid (DA) occurred in 66 and 43 samples, respectively, and all samples were positive for the toxin tested. Testing for dinophysistoxin-1 (DTX-1) (20 samples), pectenotoxin-2 (PTX-2) (20 samples), and yessotoxin (YTX) (17 samples) revealed that all samples were positive for the tested toxins. This study revealed the presence of multiple co-occurring toxins in BC’s coastal waters and the levels detected in this study were below the regulatory limits for health and recreational use. This study expands our limited knowledge of algal toxins in coastal BC and shows that further studies are needed to understand the risks they pose to marine fisheries and ecosystems.

The planktonic diatom genus Pseudo-nitzschia contains several genetically closely related species that can produce domoic acid, a potent neurotoxin known to cause amnesic shellfish poisoning (ASP). An early identification and an adequate monitoring of the potential toxic Pseudo-nitzschia spp. are necessary. However, effective monitoring programs are time consuming due, in some cases, to the cell morphology similarities among species, determined with light microscopy, that can result in insufficient data to give a definitive species and toxins attribution. In this paper, Whole-Cell Fluorescent In Situ Hybridization (WC-FISH) has been evaluated as a powerful tool to detect and enumerate harmful cryptic and/or pseudo-cryptic Pseudo-nitzschia spp. collected in the Gulf of Naples. Fluorescently labelled probes directed against the ribosomal RNA (rRNA) of the 28S large subunit (LSU) were used. In particular, five probes detecting four cryptic species of Pseudo-nitzschia delicatissima complex and one specific for Pseudo-nitzschia multistriata gave good results for the molecular identification of potentially toxic target species in natural samples. Finally, we can state that the WC-FISH method, to identify Pseudo-nitzschia species, is faster and more cost-effective if compared with other rDNA-based methods.

As the eutrophication of natural water bodies becomes more and more serious, the frequency of outbreaks of harmful algal blooms (HABs) mainly formed by harmful algae also increases. HABs have become a global ecological problem that poses a serious threat to human health and food safety. Therefore, it is extremely important to establish methods that can rapidly detect harmful algal species for early warning of HABs. The traditional morphology-based identification method is inefficient and inaccurate. In recent years, the rapid development of molecular biology techniques has provided new ideas for the detection of harmful algae and has become a research hotspot. The current molecular detection methods for harmful algal species mainly include fluorescence in situ hybridization, sandwich hybridization, and quantitative PCR (qPCR), but all of these methods can only detect single harmful algal species at a time. The establishment of methods for the simultaneous detection of multiple harmful algal species has become a new trend in the development of molecular detection technology because various harmful algal species may coexist in the natural water environment. The established molecular techniques for multiple detections of harmful algae mainly include gene chip, multiplex PCR, multiplex qPCR, massively parallel sequencing, antibody chip, and multiple isothermal amplification. This review mainly focuses on the principles, advantages and disadvantages, application progress, and application prospects of these multiple detection technologies, aiming at providing effective references not only for the fisheries but also for economic activities, environment, and human health. [ABSTRACT FROM AUTHOR]

This study aimed to test the effects of rainfall-driven nutrient loading on the microphytoplankton dynamics in the shallow water at Trou aux Biches lagoon on the northwest coast of Mauritius. Changes in density, diversity and estimated productivity of microphytoplankton were monitored in three zones—coast, lagoon and reef—during two rainfall periods of 4 and 3 days' duration, respectively, in March–April 2017. The average nutrient loading from terrestrial runoff was 15.5% and the salinity decreased by 2.5%. Following the two rainfall events, a 3-fold increase in total microphytoplankton density (TMPD), with a dominance of diatoms, was noted within a week at the coast and lagoon, while it remained relatively unchanged at the reef. These changes in microphytoplankton densities were concomitant with adequate levels of silicate (>2 µM) and high nitrate:silicate ratios (2.84–6.93). During this study, the numbers of genera of diatoms, dinoflagellates and cyanobacteria observed were 28, 12 and 3, respectively. The Shannon–Wiener, equitability and evenness indices showed high diversity values for diatoms and cyanobacteria prior to the rainfall events and for dinoflagellates after the events. The chlorophyll a content, relative electron transport rate, and estimated productivity of microphytoplankton increased during and after the rainy periods. TMPD and chlorophyll a were correlated significantly and positively with nutrients, salinity and temperature. Toxic algal species such as the dinoflagellates Alexandrium, Dinophysis and Tripos were recorded, although not in bloom densities. These findings indicate that rainfall-driven nutrient loading led to an increase in microphytoplankton density and estimated productivity, and a change in its diversity. [ABSTRACT FROM AUTHOR]

Margalefidinium polykrikoides blooms resulted in massive fish mortality in many countries around the world. The prevalence of booms is believed to be associated with the eutrophication of the coastal area. Therefore, this study aims to determine the effects of different nitrogen (N) and phosphorus (P) concentrations on the growth of M. polykrikoides. Experiments were conducted on M. polykrikoides isolated from the affected area by exposing the cell to various N and P ratio: seawater without the addition of N and P (SW), equal N:P ratio (NP), trial ratio of N and P (TR), F/2 medium (+NP), deficient N (–N), and deficient P (–P). The experiments were carried out in triplicates for 20 d in similar environmental conditions with the determination of density, specific growth rate, and cell size during the study period. Furthermore, nutrient concentrations nitrite+nitrate (NO2 –+NO3 –), phosphate (PO4 3–), and ammonia (NH4 +) were measured initially in the medium and both nutrients and chlorophyll were determined at the end of the experiment. The results revealed that M. polykrikoides grew in all the experiments, but the growth patterns differed between the treatments. The highest specific growth rate (0.1901 ± 0.017 d–1) with the highest cell density (1709 ± 68.21 cells mL–1) with a long chain of cells was observed in TR during the exponential phase. However, cell size was significantly smaller in SW compared to other nutrient conditions during the exponential phase. This study shows that M. polykrikoides a flexible species in nutrient uptake, thus allowing the species to survive in different nutrient conditions. The understanding of this bloom mechanism is important in monitoring and management of this harmful species, particularly in Sabah coastal waters. [ABSTRACT FROM AUTHOR]

In the last decade, there has been a steady stream of information on the methods and techniques available for detecting harmful algae species. The conventional approaches to identify harmful algal bloom (HAB), such as microscopy and molecular biological methods are mainly laboratory-based and require long assay times, skilled manpower, and pre-enrichment of samples involving various pre-experimental preparations. As an alternative, biosensors with a simple and rapid detection strategy could be an improvement over conventional methods for the detection of toxic algae species. Moreover, recent biosensors that involve the use of nanomaterials to detect HAB are showing further enhanced detection limits with a broader linear range. The improvement is attributed to nanomaterials' high surface area to volume ratio, excellent biological compatibility with biomolecules, and being capable of amplifying the electrochemical signal. Hence, this review presents the potential usage of biosensors over conventional methods to detect HABs. The methods reported for the detection of harmful algae species, ranging from conventional detection methods to current biosensor approaches will be discussed, along with their respective advantages and drawbacks to indicate the future prospects of biosensor technology for HAB event management. [ABSTRACT FROM AUTHOR]

Harmful algal bloom (HAB) species Alexandrium catenella and Dinophysis acuminata are associated with paralytic shellfish poisoning (PSP) and diarrhetic shellfish poisoning (DSP) in humans, respectively. While PSP and DSP have been studied extensively, less is known about the effects of these HAB species or their associated toxins on shellfish. This study investigated A. catenella and D. acuminata toxicity in a larval oyster (Crassostrea virginica) bioassay. Larval activity and mortality were examined through 96-h laboratory exposures to live HAB cells (10–1000 cells/mL), cell lysates (1000 cells/mL equivalents), and purified toxins (10,000 cells/mL equivalents). Exposure to 1000 cells/mL live or lysed D. acuminata caused larval mortality (21.9 ± 7.0%, 10.2 ± 4.0%, respectively) while exposure to any tested cell concentration of live A. catenella, but not lysate, caused swimming arrest and/or mortality in >50% of larvae. Exposure to high concentrations of saxitoxin (STX) or okadaic acid (OA), toxins traditionally associated with PSP and DSP, respectively, had no effect on larval activity or mortality. In contrast, pectenotoxin-2 (PTX2) caused rapid larval mortality (49.6 ± 5.8% by 48 h) and completely immobilized larval oysters. The results indicate that the toxic effects of A. catenella and D. acuminata on shellfish are not linked to the primary toxins associated with PSP and DSP in humans, and that PTX2 is acutely toxic to larval oysters. [ABSTRACT FROM AUTHOR]

Amphidinium species are amongst the most abundant benthic dinoflagellates in marine intertidal sandy ecosystems. Some of them are able to produce a variety of bioactive compounds that can have both harmful effects and pharmaceutical potentials. The diversity of Amphidinium in shallow waters along the Chinese coast was investigated by isolating single cells from sand, coral, and macroalgal samples collected from 2012 to 2020. Their morphologies were subjected to examination using light microscopy (LM) and scanning electron microscopy (SEM). A total of 74 Amphidinium strains were morphologically identified, belonging to 11 species: A. carterae, A. gibbosum, A. operculatum, A. massartii, A. cf. massartii, A. fijiensis, A. pseudomassartii, A. steinii, A. thermaeum, A. theodori, A. tomasii, as well as an undefined species. The last seven species have not been previously reported in Chinese waters. Amphidinium carterae subclades I, II, and IV were found in the South China Sea, while subclade III was only found in the Yellow Sea. Threadlike body scales were observed on the surface of subclades III and V, supporting the idea that A. carterae might contain several different species. Large subunit ribosomal RNA (LSU rRNA) sequences-based phylogeny revealed two groups (Groups I and II) within Amphidinium, which is consistent with the relative position of sulcus (in touch with cingulum or not). In addition, large differences in morphology and molecular phylogeny between A. operculatum (the type species of Amphidinium) and other species, suggest that a subdivision of Amphidinium might be needed. The pigment profiles of all available strains were analyzed by high performance liquid chromatography (HPLC). Eleven pigments, including peridinin, diadinoxanthin, diatoxanthin, pheophorbide (and pheophorbide a), antheraxanthin, β-carotene, and four different chlorophylls were detected. The high pheophorbide/pheophorbide a ratio in Amphidinium implies that it may be a good candidate as a natural source of photosensitizers, a well-known anticancer drug. [ABSTRACT FROM AUTHOR]

The southern part of the Okhotsk Sea off Hokkaido has rich fishery resources supported by high primary production. The phytoplankton community has been described by several studies based on size-fractionated chlorophyll a concentration and primary production; however, the details of the species composition of nano- and micro-protist communities have not been well investigated. We evaluated the spatial distribution and relationship with hydrography of nano- and micro-protist communities in the southern region of the Okhotsk Sea off Hokkaido during the summer of 2019. Forty-two species of diatoms from 19 genera, dinoflagellates from 7 genera, tintinnid ciliates, oligotrich ciliates, and 1 genus of silicoflagellates were identified. Their spatial distribution showed distinct differences among the taxa. Cluster analysis based on the protist cell density identified six groups with geographically well-distinguished distributions. Diatom-dominant communities were distributed in the Cold Water Belt and Soya warm current along the coastal area of Hokkaido. Nanoflagellate-dominated communities were distributed in the offshore area. Some harmful species of diatoms (Pseudonitzschia pseudodelicatissima) and dinoflagellates (Alexandrium spp.) were dominant in the Cold Water Belt off Wakkanai. We suggest that the upwelling of cold water could increase the abundance of harmful species, with immanent negative impacts on marine ecosystems or fishery resources. In summary, the species composition and abundance of the summer protist community was strongly related to different water masses in the southern part of the Okhotsk Sea off Hokkaido. [ABSTRACT FROM AUTHOR]