Search

Increasing water and power demand in the Middle East requires that desalination plants maximize overall efficiency and operate on the lowest production. Despite the extended pretreatment in the Hamriyah plant, the deteriorating quality of seawater over the last years, the heavy marine biological growth and the extended red tide have imposed serious challenges for seawater reverse osmosis (SWRO) operation. Sharjah Electricity & Water Authority (SEWA) aims to achieve the best long-term performance and reliability to maximize plant availability throughout the year. DuPont™ B-Free™ creates an instant and sustained biostatic environment for the downstream RO operations and is resilient to upstream upsets. This pretreatment will allow water production to be maintained during all regular variations in seawater quality throughout the seasons and in future. A demo unit was installed and commissioned on-site to demonstrate the reduction in fouling potential achieved thanks to DuPont™ B-Free™ pre-treatment technology. This long-term test has shown significant improvements in SWRO operation and the mitigation of biofouling potential. These results are translated into reduced energy consumption, reduced chemical cleaning, and upgraded system reliability. [ABSTRACT FROM AUTHOR]

Satellite ocean color observation has been an effective way to detect red tide in a wide coastal area of many countries. However, red tide water, which has high red and infra-red reflectance, often causes failure in atmospheric correction, making quantification algorithms based on remote sensing reflectance produce large errors. This study proposes a new framework that tackles the difficulties in red tide quantification stemming from atmospheric variability, limited in-situ training data, and image artifacts, through the combined use of radiative simulation, machine learning, and in-situ measurements. The framework was applied to the geostationary ocean color imager (GOCI) to monitor Margalefidinium blooms that are frequent in Korean coasts. The estimation results were validated first quantitatively with independent ship survey data, and then qualitatively with other 3 red tide algorithms. Finally, the operational robustness of the proposed framework was analyzed based on the data acquired in the entire outbreak period in 2018. The results showed that the proposed algorithm produced a high correlation with field data (R2 ∼ 0.89) and high detection rate and low false alarms compared to the other red tide algorithms. The monitoring result for 2018 also demonstrated that the initiation, expansion, peak, and termination of red tide were successfully identified by the satellite data, which coincides with the field survey results provided by the national fishery agency. [ABSTRACT FROM AUTHOR]

The harmful algal bloom (red tides) (HAB) phenomenon is an issue for desalination facilities. This paper reviews the causes and impacts of HABs on desalination plants. Some HABs are linked to the creation of natural pollutants, dissolved oxygen depletion, and other negative consequences. Because desalination facilities are the principal source of freshwater for communities, agriculture, and industry for middle eastern arid nations, the disruption of plant operations by red tide poses a danger to the availability of drinkable water and can constitute an extraordinary HABs impact. Desalination plants are responsible for pollutants added to the Gulf seawater via outfall systems. Consequently, desalination projects must undergo an environmental impact assessment (EIA), considering accepted environmental characteristics and criteria. EIA assesses the potential effects on air, land, and sea water qualities, techniques to mitigate their impact. [ABSTRACT FROM AUTHOR]

The excessive proliferation of the genus Enteromorpha serves as the primary catalyst for the occurrence of red tides. Nonetheless, this genus is abundant in sulfated polysaccharides, phenolic compounds, peptides, and alkaloids, which exhibit remarkable efficacy in antioxidation, anti-inflammation, and immune response modulation. Consequently, Enteromorpha -derived products hold promising application prospects as aquatic feed additives. The primary objective of this study was to evaluate the impact of E. prolifera powder (EPM) and its enzymatic hydrolysate (EPH) on the growth, antioxidant capacity, intestinal morphology, and immunity of juvenile Trachinotus ovatus. Four isonitrogenous and isolipidic diets were formulated with varying levels of Enteromorpha products: 0 % (Control), 0.1 % EPH (EPH0.1), 0.3 % EPH (EPH0.3), and 3 % EPM, and were administered to juvenile T. ovatus for eight weeks. The findings revealed that growth performance in the EPH0.3 and EPM groups surpassed that of the control group, concomitant with increased feed intake and elongated intestinal villi. Notably, Enteromorpha -derived products supplementation significantly bolstered the antioxidant capacity of T. ovatus through activation of the Nrf2-Keap1 signaling pathway, leading to elevations in antioxidant enzymes such as SOD and CAT, as well as T-AOC. Conversely, MDA levels were conspicuously reduced in the Enteromorpha -treated groups. Moreover, Enteromorpha -derived products supplementation exhibited pronounced anti-inflammatory effects, marked by the downregulation of proinflammatory cytokine expression and upregulation of anti-inflammatory cytokines, along with decreased apoptotic gene expression. These observations highlight the potential anti-inflammatory properties of EPM and EPH, which may contribute to the preservation of hepatic tissue health and homeostasis. In summary, the optimal growth performance and antioxidant capacity were achieved with 0.3 % EPH supplementation, indicating the efficacy of this concentration in promoting the overall wellbeing of T. ovatus. Remarkably, the employment of processing methodologies, notably enzymatic hydrolysis, has not only facilitated the manifestation but also potentially augmented the inherent beneficial attributes traditionally ascribed to EPM. Furthermore, this refinement process has enabled a reduction in the inclusion rate of EPM within feed formulations, thereby enhancing cost-effectiveness. Consequently, Enteromorpha-derived products emerge as highly promising candidates for aquatic feed additives, with the potential to mitigate the economic burdens imposed by red tide management strategies. Their utilization represents a strategic approach towards sustainable aquaculture practices. • Dietary Enteromorpha -derived products supplementation notably boosted the growth performance and feed intake of T. ovatus. • Enteromorpha supplements notably enhanced antioxidant defenses in T. ovatus via Nrf2-Keap1 pathway activation. • Enteromorpha supplements reduced inflammation in T. ovatus by modulating cytokines and inhibiting apoptosis. • Enteromorpha products show promise as aquatic feed additives, potentially reducing red tide management costs. [ABSTRACT FROM AUTHOR]

• SSSM was used to prepare highly efficient and eco-safe MC for red tide control. • Targeted elemental activation and functional group shaping were achieved. • The algal removal efficiency of the optimum MC was 90.51 % at 0.15 g/L. • Charge neutralization and sweeping are key mechanisms for algal cell removal. Single source with series modifications (SSSM) is a new method to modify clay surfaces by activating clay mineral resources for harmful algal blooms control. In this study, the optimal preparation conditions for this method were obtained using response surface methodology. Based on the material analysis, an important way to obtain modified clay (MC) with the excellent Prorocentrum donghaiense removal performance was explored and the optimum preparation conditions were as follows: calcination temperature 750 °C, alkali neutralization pH 3.7 and clay supplementation ratio 1.3:1. Under these conditions, the calcination treatment can effectively activate the aluminum element in the clay lattice and obtain the largest amount of highly active Al IV and Al V, which are readily released from the lattice as activated aluminum. When the alkali neutralization pH was adjusted to 3.7, the activated aluminum was hydrolyzed and induced into highly positively charged polyhydroxyaluminum compounds. The supplemented kaolin increased the yield of the MC product by surface convergence of the activated aluminum in the system. As a result, the optimized MC can form large particle size flocs with good regeneration and stability during the algal removal process, which greatly improved its ability to coagulate and sediment algal cells. Overall, the MC prepared by the SSSM method achieved high algal removal efficiency through targeted element activation and functional group shaping. [Display omitted] [ABSTRACT FROM AUTHOR]

Phaeocystis proliferation is a primary instigator of algal blooms, commonly known as red tides, posing a significant threat to marine life and severely disrupting marine ecosystems. Currently, no effective method exists for estimating Phaeocystis density, underscoring an urgent need for preventative measures against Phaeocystis blooms. Given the challenges associated with the varying sizes and frequent overlapping of Phaeocystis colonies, we propose an innovative counting algorithm that leverages feature reconstruction and multispectral generator modules. Utilizing deep learning, our method achieves accurately real-time density estimation and prediction of Phaeocystis colonies. The algorithm operates in two stages: first, a multispectral reconstruction block is trained to function as a multispectral generator; second, spectral and spatial features are integrated to predict density and perform counting. Our approach surpasses existing algorithms in accuracy for Phaeocystis counting and demonstrates the utility of multispectral data in enhancing the neural network's ability to discern targets from their background. [ABSTRACT FROM AUTHOR]

Red tides occurring off the southern coast of Korea impact the marine ecosystem and aquaculture industries. Zooplankton are crucial in the food web, connecting primary producers to higher predators and interact diversely with red tide organisms. This study explores dynamics of the zooplankton community over seven years including three red tide and four non-red tide years in Tongyeong using metabarcoding. In non-red tide years, zooplankton diversity showed typical seasonal patterns, increasing from June to early October. However, during red tide years, diversity remained high, with a shift in species composition-decreased Copepoda and increased Branchiopoda, Echinodermata, Malacostraca, and Annelida. Diversity indices were significantly higher in red tide years across all periods except for the richness in "after" that showed an insignificant higher value. The differences in zooplankton assemblages across periods were influenced by surface temperatures and the density of the red tide-causing alga Margalefidinium polykrikoides. Eight species emerged as indicator species and showed direct correlations with M. polykrikoides and among them, seven species were indicator species for red tide occurrence years. The ecological characteristics of M. polykrikoides blooms and their recurrent occurrences over several decades suggest that zooplankton may adapt to the toxins and use these blooms as spawning cues. Overall, this study provides comprehensive understanding on changes in zooplankton communities during red tide events, offering novel insights into their ecology. [Display omitted] • HABs caused by C. polykrikoides maintain or increase the diversity of zooplankton. • HAB events increase primary production and supply plenty of food to zooplankton. • Increased marine biodiversity suggest adaptation to spawn based on HABs cues. [ABSTRACT FROM AUTHOR]

[Display omitted] • Glyphosate reduces in-vitro proliferation capacity of manatee T-lymphocytes. • Glyphosate promotes expression of genes associated with acute-phase inflammation. • T-lymphocyte proliferation was reduced in mid-winter compared to early winter. Exposure to contaminants, such as the herbicide glyphosate, can suppress protective immune functions. Glyphosate is the herbicide most used worldwide and has been found in the plasma of more than 50 % of the Florida manatees (Trichechus manatus latirostris) and all-year-round in their aquatic environment. Our objectives were to analyze the consequences of glyphosate exposure on their immune responses via T-lymphocyte proliferation assays and transcriptomics. We isolated peripheral blood mononuclear cells (mainly lymphocytes) of free-ranging manatees and performed T-cell proliferation assays. We used transcriptomics to understand the consequences of glyphosate in vitro exposure. The three doses chosen ranged from environmentally relevant concentrations at 10 to 10,000 µg.L−1 that is considered an environmental contamination scenario. Glyphosate caused a dose-dependent reduction in T-lymphocyte proliferation, with a significant mean reduction of 27.3 % at 10,000 µg.L−1 and up to 51.5 % in some individuals. Additionally, T-lymphocyte proliferation was significantly reduced in mid-winter compared to early winter. Transcriptomic analysis of peripheral blood mononuclear cells indicated that all doses of glyphosate (10, 1,000, and 10,000 µg.L−1) resulted in up-regulation of genes related to acute phase inflammation and inhibition of the T-lymphocyte proliferation pathway. Exposure to this contaminant along with other environmental stressors, such as extreme winters and red tide, might further affect the adaptive immune response of this threatened species. [ABSTRACT FROM AUTHOR]

• Random forest models forecast K. brevis abundance over one- and four-week horizons. • Models were trained on 'live' data to assess performance under realistic conditions. • The one-week and four-week forecasts exhibited 73 % and 84 % accuracy, respectively. • The forecasts correctly predicted bloom onset 80 % and 50 % of the time, respectively. Karenia brevis blooms occur nearly annually along the southwest coast of Florida, and effective mitigation of ecological, public health, and economic impacts requires reliable real-time forecasting. We present two boosted random forest models that predict the weekly maximum K. brevis abundance category across the Greater Charlotte Harbor estuaries over one-week and four-week forecast horizons. The feature set was restricted to data available in near-real time, consistent with adoption of the models as decision-support tools. Features include current and lagged K. brevis abundance statistics, Loop Current position, sea surface temperature, sea level, and riverine discharges and nitrogen concentrations. During cross-validation, the one-week and four-week forecasts exhibited 73 % and 84 % accuracy, respectively, during the 2010–2023 study period. In addition, we assessed the models' reliability in forecasting the onset of 10 bloom events on time or in advance; the one-week and four-week models anticipated the onset eight times and five times, respectively. [ABSTRACT FROM AUTHOR]

Massive harmful algal blooms (HABs) have increased the risk of marine organisms encountering the dinoflagellate toxin, okadaic acid (OA). Strongylocentrotus intermedius , a globally significant benthic aquaculture species, has a large appetite for benthic algae. During red tide events, there is a high risk of red tide toxin accumulation. This study systematically evaluated the potential impact of short-term OA exposure on the behavior and physiological functions of juvenile S. intermedius. From typical (5 μg/L) to extreme OA concentrations (20 μg/L) during HAB outbreaks, OA exposure gradually inhibited a series of tube foot-related behaviors (sheltering, foraging, righting, and tube-foot tenacity). At OA concentrations during HAB outbreaks (5 μg/L), the tube foot function of S. intermedius was progressively inhibited. Further physiological indicator analyses revealed that the activity of antioxidants increased over a short period to prevent damage from reactive oxygen species induced by OA. However, OA ultimately suppressed the immune response of S. intermedius , leading to apoptosis. Although HAB-associated concentrations of OA (5 μg/L) did not induce a continuous increase in the integrated biological response index of S. intermedius , this study speculated that HABs pose a future risk to echinoderm species. Notably, principal component analysis results showed that OA exposure eventually induced significant changes in the production of O2−, malondialdehyde, and total glutathione, as well as in glutathione S-transferase activity and caspase-7, -8, and -9 levels. This study provides preliminary evidence of OA's toxic effects on sea urchins and essential data for urgent risk assessments of algal toxin pollution in aquaculture during HABs. [Display omitted] • OA inhibits tube-foot-related behaviors of S. intermedius. • OA induces oxidative stress. • OA suppresses immune response and activates apoptosis. • High concentrations of OA lead to a continuous increase in the IBR index of S. intermedius. [ABSTRACT FROM AUTHOR]

This study is the first to document an algal bloom caused by Noctiluca scintillans , which was detected using remote sensing techniques and confirmed in the field along the coast of Elba National Park. Noctiluca scintillans is a phytoplankton species that accumulate toxic ammonia that endangers various organisms, including fish, birds, mammals, and human. Therefore, monitoring red tide is essential for water pollution control and management. This study aims to evaluate the potential of the recent launch of the Ocean and Land Color Instrument (OLCI) onboard the Sentinel-3 satellite to identify chlorophyll-a (Chl-a) as a proxy for an algal bloom event and study its impacts on the ecosystem. To fulfill the aim, OLCI images were collected over the study area from the 25th of May to the 13th of June 2017. Satellite images were converted from level 1 to level 2 through radiometric and atmospheric correction, and Chl-a maps were produced from the level 3 data during product development using standard Ocean Color 4 for MERIS (OC4Me) model. The time-series analyses of the Sentinel-3 satellite images indicated that the algal blooms (Red tide) event occurred four days at the studied sites (7th to 10th of June). The current findings reveal a strong relationship between the deterioration in water quality criteria and Noctiluca scintillans cell counts (×104) /L (0.05 > P ≤ 0.01). This study strongly urges routine monitoring of the physicochemical characteristics of coastal waters and using remote sensing techniques for early rid tide detection to control the phenomenon. [ABSTRACT FROM AUTHOR]

Accessing the production value is essential to the selection of suitable sites for aquaculture farms. This study employed a Dynamic Energy Budget (DEB) model and used market-oriented indicators, including shell length, flesh weight, condition index and minimum farming duration, to analyze the suitability for Pacific oyster aquaculture in offshore Shandong, China. Chlorophyll a (Chl-a) concentration, Total Suspended Sediment (TSS) concentration, and Sea Surface Temperature (SST) were extracted by remote sensing and used as forcing variables in the bioenergetic model. Four market-oriented indicators and five zones in the study area were chosen to develop a Suitable Market-Aquaculture site-selection model (SMASM) and estimate the oyster farming suitability. The results demonstrated that Sanggou Bay exhibits high potential for Pacific oyster year-round aquaculture. Eastern Laizhou Bay is suitable for the autumn-spring fattening culture of adult oysters. Laoshan Bay and Changshan Islands are suitable for promoting rapid growth in juvenile oysters. The results of our model were consistent with the oyster production value in Shandong, showing an overall increasing trend except for the anomalous value observed in 2019. Sudden drops in water temperature, red tides, and significant increases in turbidity can exert detrimental effects on oyster production, which has been evidenced to be influenced by Super Typhoon Lekima in 2019. Although this study concentrated on a specific geographical region, the model could be applied to other regions to develop market-oriented suitability management for species and environments worldwide. • Our study develops a Suitable Market-Aquaculture site-selection model (SMASM) for Pacific oyster inShandong coastal area. • Sanggou Bay exhibit the highest potential suitability for Pacific oyster market-oriented farming in Shandong coastal area. • We combine with Super Typhoon Lekima to examine the impact of a tropical storm on Pacific oyster farming. [ABSTRACT FROM AUTHOR]

Achieving high-accuracy real-time recognition of marine red tide algae images is crucial in implementing red tide algae early warning systems. However, due to uneven lighting and the deposition of unknown suspended particles in seawater, real-time collected harmful algal blooms (HABs) microscopic images in marine engineering suffer from poor clarity and blurred cell contours, leading to lower accuracy of current edge detection models for microscopic images. Firstly, to enhance the quality of degraded images in the original HABs dataset, we design an image enhancement algorithm based on underwater image restoration models, which involves precise depth estimation of seawater scenes and fusion of transmission maps. This algorithm effectively eliminates chromatic aberration and enhances image edge details and contrast. Secondly, we propose a deep-learning model based on the VGG16 network. This model integrates multi-scale features through the Spatial Feature Mapping module to improve edge detection accuracy. Experimental results using real-time HABs microscopic image data show that the proposed enhancement method achieves the best results regarding contrast, image enhancement metrics, and clarity gradient. Moreover, the edge detection method achieves an ODS of 0.636 and an OIS of 0.701. The results demonstrate that performing edge detection after the image enhancement preprocess significantly improves detection accuracy. • We propose an encoder-decoder network for extracting multi-scale features. • We propose a spatial feature mapping network that integrates contextual features. • Enhancement method based on precise depth estimation and channel judgment. [ABSTRACT FROM AUTHOR]

• A weak electronegative surface was favorable for P. donghaiense removal. • A hydrophobic surface aggravated the removal difficulty of H. akashiwo. • Strong attractions with MCs led to fast sedimentation of red tide organisms. • Oxidative damage caused by MC facilitated the removal of red tide organisms. In recent years, red tides have increased worldwide in frequency, intensity, involving a higher number of causative species during the events. As the most commonly used method for control of red tides, modified clay (MC) was found to have differential ability to remove various red tide species. However, the underlying mechanisms have not yet been completely elucidated. In this study, the use of MC to remove three typical disaster-causing species, Aureococcus anophagefferens, Prorocentrum donghaiense and Heterosigma akashiwo, was investigated, and differential removal of these species was probed with insights into their biocellular properties and mechanical interactions. The results showed that removal efficiencies of the three species by MC decreased in the order P. donghaiense > A. anophagefferens > H. akashiwo , while the sedimentation rates decreased in the order H. akashiwo > P. donghaiense > A. anophagefferens. Analyses of the cell surface properties and redundancy analysis (RDA) revealed that the highest surface zeta potential of -5.32±0.39 mV made P. donghaiense the most easily removed species; the smallest cell size of 3.30±0.03 μm facilitated the removal of A. anophagefferens ; and the highest hydrophobicity with a H 2 O surface contact angle of 98.50±4.31° made the removal of H. akashiwo difficult. X-ray photoelectron spectroscopy (XPS) data indicated that the electronegativity of P. donghaiense was caused by carboxyl groups and phosphodiester groups, and the hydrophobicity of H. akashiwo was associated with a high C-(C, H) content on the cell surface. According to the extended Derjaguin, Landau, Verwey, and Overbeek (ex-DLVO) theory calculation, differences in the interaction energies between MC and the three red tide species effectively explained their different sedimentation rates. In addition, the degree of oxidative damage caused by MC to the three red tide species differed, which also affected the removal of red tide organisms. [Display omitted] [ABSTRACT FROM AUTHOR]

The eutrophication of water, such as excessive nitrogen and phosphorus, are closely associated with the outbreak of red tide. However, the response of dissolved inorganic phosphorus (DIP) to red tide remained unclear in water. In this study, three species of diatoms capable of causing red tides were cultured in simulated seawater with different concentrations of DIP. The changes of biomass, chlorophyll a concentration and the carbon stable isotope composition of microalgae, the DIP concentration and pH of the culture medium were compared among the experimental groups. In addition, correlation verification was used to test the correlation between the change of DIP concentration and other indicators. The results showed that in the experimental period, the DIP concentration of each experimental group decreased significantly first, and the concentration dropped to less than 40% of the initial level. After that, the pH of the medium, the biomass, chlorophyll a concentration and carbon stable isotope composition of the microalgae showed varying degrees of increase, and then stabilized or decreased. These also marked the outbreak of red tide. Moreover, the correlation test showed that there was a correlation between them and the change of DIP concentration. Therefore, by exploring the relationship between the change of DIP concentration in water and the occurrence of red tide, this study provides a possible direction for the current prediction of red tide, and provides a basis for further investigation of the occurrence mechanism of red tide. [Display omitted] • Outbreak of red tide of different algae species under different eutrophic levels. • The decrease of DIP concentration was earlier than the increase of other indicators of red tide algae. • The outbreak of red tide resulted in the accumulation of 13C in red tide algae. [ABSTRACT FROM AUTHOR]

• Resting cysts of E. voratum were identified in sediments via multi-approaches. • E. voratum produced asexual resting cysts in laboratory-reared clonal cultures. • Cysts stored for six months germinated and displayed internal development processes. Coral reef ecosystems are the most productive and biodiverse marine ecosystems, with their productivity levels highly dependent on the symbiotic dinoflagellates belonging to the family Symbiodiniaceae. As a unique life history strategy, resting cyst production is of great significance in the ecology of many dinoflagellate species, those HABs-causing species in particular, however, there has been no confirmative evidence for the resting cyst production in any species of the family Symbiodiniaceae. Based on morphological and life history observations of cultures in the laboratory and morpho-molecular detections of cysts from the marine sediments via fluorescence in situ hybridization (FISH), cyst photography, and subsequent singe-cyst PCR sequencing, here we provide evidences for the asexual production of resting cysts by Effrenium voratum , the free-living, red tide-forming, and the type species of the genus Effrenium in Symbiodiniaceae. The evidences from the marine sediments were obtained through a sequential detections: Firstly, E. voratum amplicon sequence variants (ASVs) were detected in the cyst assemblages that were concentrated with the sodium polytungstate (SPT) method from the sediments collected from different regions of China Seas by high-throughput next generation sequencing (NGS); Secondly, the presence of E. voratum in the sediments was detected by PCR using the species-specific primers for the DNA directly extracted from sediment; Thirdly, E. voratum cysts were confirmed by a combined approach of FISH using the species-specific probes, light microscopic (LM) photography of the FISH-positive cysts, and a subsequent single-cyst PCR sequencing for the FISH-positive and photographed cysts. The evidences from the laboratory-reared clonal cultures of E. voratum include that: 1) numerous cysts formed in the two clonal cultures and exhibited a spherical shape, a smooth surface, absence of ornaments, and a large red accumulation body; 2) cysts could maintain morphologically intact for a storage of two weeks to six months at 4 °C in darkness and of which 76–92 % successfully germinated through an internal development processes within a time period of 3–21 days after being transferred back to the normal culturing conditions; 3) two or four germlings were released from each cyst through the cryptopylic archeopyle in all cysts with continuous observations of germination processes; and 4) while neither sexual mating of gametes nor planozygote (cells with two longitudinal flagella) were observed, the haploidy of cysts was proven with flow cytometric measurements and direct LM measurements of fluorescence from cells stained with either propidium iodide (PI) or DAPI, which together suggest that the cysts were formed asexually. All evidences led to a conclusion that E. voratum is capable of producing asexual resting cysts, although its sexuality cannot be completely excluded, which guarantees a more intensive investigation. This work fills a gap in the knowledge about the life cycle, particularly the potential of resting cyst formation, of the species in Symbiodiniaceae, a group of dinoflagellates having unique life forms and vital significance in the ecology of coral reefs, and may provide novel insights into understanding the recovery mechanisms of coral reefs destructed by the global climate change and suggest various forms of resting cysts in the cyst assemblages of dinoflagellates observed in the field sediments, including HABs-causing species. [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]

The characteristics and influencing factors of phytoplankton assemblages were analyzed in July (rainy season) and November (dry season) 2022 in the Qiongzhou Strait, China. A total of 68 species of phytoplankton belonging to 33 genera and 3 phyla were recorded. Diatom was the most dominant group. The broad-temperature widespread species were the most abundant. The dominant species in the rainy season were Skeletonema costatum , S. tropicum , Chaetoceros preseudocurvisetus and Thalassionema nitzschioides while those in the dry season were T. frauenfeldii , T. nitzschioides and Coscinodiscus granii. Phytoplankton cell abundance was significantly positively correlated with nitrite and total nitrogen concentrations, and negatively correlated with temperature and pH. Red tide algae occurred with high frequency. All sites were at eutrophic level except for 3 sites in the rainy season, which were at mesotrophic level. Therefore, there is a potential risk of red tides in the Qiongzhou Strait, which requires long-term monitoring and precautions. • Nutrient Quality Index was higher in the nearshore that that in the offshore. • Red tides species were dominant in both rainy and dry seasons. • Most of the sites of the Qiongzhou Strait were at eutrophication level. • The Qiongzhou Strait has a potential risk of red tides and requires precautions. [ABSTRACT FROM AUTHOR]

• Diatoms were more dominant group in PRE sampling sites in wet (73.5%) and dry (99.5%) season. • Melosira granulata in, Bellerochea malleus and Skeletonema costatum were placed in top of the cluster group distinctively. • The phytoplankton abundance and community composition was more crucially influenced by depth, salinity and silicate concentration. Monitoring the primary producer diversity is crucial in understanding ecosystems balance, as imbalanced nutrients richness and diversity may induce red tide situations. The present study deals with evaluating the impact of hydrological factors regulating the dynamics of phytoplankton communities and the influence of chemical parameters on phytoplankton growth in Pearl River Estuary (PRE). During wet season (April), around 50 different species of phytoplankton were identified at 14 different sampling sites including 24 diatoms, 9 dinoflagellates, 10 green algae and 6 cyanobacterial species respectively. The diatom Melosira granulate was the dominant species at most of the sampling sites. Phytoplankton surveys during the dry season (November) showed Bellerochea malleus and Skeletonema costatum species as dominant at most of the sampling locations. Silicate (SiO 3) distribution was one of the reason for the abundance of diatoms in west shoal sites. The concentration of nutrients and hydrological factors like water depth and salinity strongly supported phytoplankton growth. In addition, PRE west and middle shoal sites showed evidence of rich phytoplankton diversity when compared to east shoal and channel sites. The Non-metric Multidimensional Scaling (NMDS) analysis and cluster grouping analysis demonstrated the uniqueness of plankton species diversity at PRE west and east shoal sites. The results of Canonical Correspondence Analysis (CCA) suggested that diversity of phytoplankton communities was significantly influenced by environmental factors such as salinity, depth and SiO 3 concentration. From these results, one may conclude that salinity with SiO 3 distribution plays a crucial role in PRE phytoplankton community composition assisting in maintaining healthy intertidal ecosystem. [ABSTRACT FROM AUTHOR]

Arid countries throughout the world are massively reliant on seawater desalination for their supply of drinking and municipal water. Harmful algal bloom (HABs), frequently referred to as ‘red tides’ due to their vibrant colors are predicted to grow in recurrence and distribution in the coming years where numerous desalination facilities will become increasingly susceptible to damage or shutdown during HAB events. Such a phenomenon, one of the operational challenges facing the industry, can cause significant operational issues that result in increased chemical consumption, increased membrane fouling rates, and in extreme cases, a plant to be taken off-line due to the high biomass of microalgae and a variety of substances that some of these algae produce. Hence, understanding the HABs’ nature, their challenges, and ways in which they can be monitored, treated, and mitigated will allow engineers and operators to address HAB hazards and maintain the integrity of new and existing desalination facilities. [ABSTRACT FROM AUTHOR]

Red tide, one of the major ecological disasters in the world, exerts great impact on the marine environment. The ocean color satellite data with low spatial resolution and high spectral resolution is often used for red tide detection, but is insufficient for the fine-scale red tide detection due to its coarse spatial resolution. To address this problem, a new red tide detection method based on pseudo hue angle (PHA-RI) for high spatial resolution broad band satellite data is proposed in this paper. Different from the standard International Commission on Illumination (CIE) system, the false-color bands of near infrared (NIR), red and green are used to calculate the CIE tristimulus X, Y, Z, instead of the true-color bands of red, green and blue. With this method, the red tide can be easily differentiated from non-red tide water, and the distinction between red tide and non-red tide water is doubled compared to that of true-color bands composite. Experiment results show that the PHA-RI method can effectively detect red tide, with an averaged overall accuracy, F1-score and precision of 92%, 0.92 and 0.92 respectively. Compared with the traditional machine learning method support vector machine (SVM) and spectral index algorithm Gaofen-1 (GF-1) red tide detection index (GF-RI), the proposed algorithm has obvious advantages in red tide detection, especially for the strip distributed red tide. Besides, the proposed algorithm has good applicability, and it is proved to be suitable for the detection of red tides with different dominant species including Noctiluca scintillans , Skeletonema costatum and Heterosigma akashiide. Also, it is applicable to different broad band sensors, such as Chinese satellites GF-1 Wide Field of View (WFV), Haiyang 1D (HY-1D) Coastal Zone Imager (CZI), Sentinel-2 MultiSpectral Instrument (MSI) and Landsat 8 Operational Land Imager (OLI). The application experiment indicates that the proposed algorithm is effective in red tide detection, and it can successfully detect fine-scale red tide events, which have not been detected by Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua due to its coarse spatial resolution. The results also shows the advantages of high spatial resolution satellites in fine-scale red tide detection. This work provides a method for red tide detection using high spatial resolution broad band satellite data. [ABSTRACT FROM AUTHOR]

Qarun Lake is a unique saline basin. Its phytoplankton species abundance and dynamics in relation to the Red Tide phenomenon is the focus of this study. Samples were collected from May 2015 to April 2016 in twelve successive cruises. Phytoplankton productivity attained the highest level on July with the bloom of Dinophyceae, while showing negative correlation with water transparency (r = −0.72) and positive correlation with DO (r = 0.84). The causative species was Gymnodinium lantzschii. Another incident of Dinophyceae bloom was observed in March when chlorophyll a recorded 158.4 mgm−3, chl. b was (92.7 mgm−3 and chl. c was 160 mgm−3. The causative species were Prorocentrum aporum and Prorocentrum micans and the lake's water turned to red color; the "Red Tide phenomenon". Chlorella vulgaris bloom was recorded for the first time in the lake on August at site (4) with green water discoloration. The water temperature of the lake was one of the main phytoplankton bloom's drivers as the dominant species grew and flourished within a narrow range of temperature (30.4–34.9 °C). The results showed that there were strong correlations between carbonate, bicarbonate, DO and nutrients indicating that the dinoflagellate bloom was due to the high eutrophication of the lake. Finally, the Red tide phenomenon may influence the lake fisheries causing significant economic loss. [ABSTRACT FROM AUTHOR]

Polyaluminum chloride modified clay (PAC-MC) is a safe and efficient red tide control agent that has been studied and applied worldwide. Although it is well known that the distribution of hydrolytic aluminum species in PAC affects its flocculation, little is known about the influence of particulars aluminum species on the microalgae removal efficiency of PAC-MC; this lack of knowledge creates a bottleneck in the development of more efficient MCs based on aluminum salts. The ferron method was used in this study to quantitatively analyze the distributions of and variations in different hydrolytic aluminum species during the process of microalgae removal by PAC-MC. The results showed that Al a , which made up 5%–20% of the total aluminum, and Al p , which made up 15%–55% of the total aluminum, significantly affected microalgae removal, with Pearson's correlation coefficients of 0.83 and 0.89, respectively. Most of the aluminum in the PAC-MC sank rapidly into the sediments, but the rate and velocity of settlement were affected by the dose of modified clay. The optimal dose of PAC-MC for precipitating microalgae was determined based on its aluminum profile. These results provide guidance for the precise application of PAC-MC in the control of harmful algal blooms. [Display omitted] [ABSTRACT FROM AUTHOR]

Phosphorus (P) is an essential nutrient for algal growth in nearshore ecosystems. In recent years, there has been a shift in nutrient dynamics in nearshore areas, leading to an exacerbation of P limitation, although the underlying mechanisms remain unclear. This study analyzed the P species and budget in the Bohai Sea (BS) from 2011 to 2020, aiming to explore the intrinsic mechanisms of P limitation in the BS. The results show that the main external source of P in the BS was river transport (89%), and the primary fate of P was burial (96%) into the sediment. Due to excessive nitrogen (N) input and biological processes in the BS, the P budget in the BS is unbalanced, resulting in an increase in the N/P ratio, particularly in nearshore areas. Nearshore areas typically have lower concentrations of dissolved inorganic P (DIP) in the water and higher concentrations of reactive P (Reac-P) in the sediments. This pattern is particularly evident in Bohai Bay and the northwest nearshore region, where harmful algal blooms occur frequently. To cope with enhanced P limitation, the biologically driven P regeneration and cycling processes within the BS are accelerated. From 2011 to 2020, the concentration of DIP in the BS during autumn increased, while the content of Reac-P in sediments slightly decreased. Historical data indicate that P depletion in the BS is intensifying and expanding, primarily due to N enrichment and algal production. N enrichment alters the structure and composition of primary production, potentially exacerbating P depletion in the BS. Excessive N may have significant impacts on the P pool, potentially influencing the stability of future coastal ecosystems. Note: Stock is P storage in the seawaters, τP is the P residence time. [Display omitted] • River export to BS has high and increasing N:P in past 5 decades. • P burial in sediments exceeds P inputs, causing further P depletion. • Reactive P is the major source of DIP. • Red tides occur in regions with high reactive P concentrations. [ABSTRACT FROM AUTHOR]

Red tide is a marine phenomenon caused by the excessive growth of microscopic algae in the ocean. This study aims to analyze the development trends of red tides in the past 20 years and the dynamic external causes that induce red tides based on existing satellite remote sensing and numerical simulation data. And the changes in dominant species of red tides in different seasons are analyzed. The results show significant temperature fluctuations within the week before the red tide occurs, with an average increase of 1.42 °C. In contrast, the change in salinity is relatively small. Meanwhile, ocean fronts are areas in the ocean where different water masses meet and form boundaries. The average strength of ocean fronts increased by 3.7%, indicating enhanced ocean mixing over a short period of time. Under the combined influence of these factors, the probability of a red tide outbreak in the East China Sea increases rapidly. Therefore, this study has important reference value for further research on the causes of red tides and their response to ocean dynamic changes. • Study analyzes 20-year trend of red tides and their dynamic causes. • Before a red tide, average temperature rises by 1.42 °C; salinity changes little. • Increased ocean front strength by 3.7% boosts East China Sea red tide risk. [ABSTRACT FROM AUTHOR]

Accurately classifying harmful algal blooms (HABs) is crucial in red tide warning. However, the current automatic recognition system for real-time HABs image classification has a low accuracy rate of only about 70% and a high computational complexity. To address these issues, we propose a Weighted Feature Fusion of Dual Attention Convolutional Neural Network and Transformer Encoder Module (WFTC) for Ocean HABs Image Classification. First, we design an image enhancement algorithm specifically for HABs images, which significantly improves the quality of real-time dynamic sampling data by enhancing contrast, edges, and texture features. Second, the transformer encoder module is utilized as the first branch of WFTC to generate a feature vector representation with global semantic information. Then, we combine the attention mechanism with the convolutional neural network as the second branch of WFTC, which is used to emphasize the main feature information of HABs. Finally, the extracted features are weighted fusion by combining the characteristics of the transformer encoder module and dual-attention convolutional neural network. The experimental results using real-world data from HABs in the Chinese nearshore waters in 2020 demonstrate that compared with other classification networks, the proposed WFTC method achieves the highest accuracy rate of 87% and competitive results in terms of stability and convergence. [ABSTRACT FROM AUTHOR]

• Growth rate r , carrying capacity K , and competition coefficient α were quantified. • Difference in initial cell density affects α-optimization. • r, K , and α explain the superiority of Chattonella spp. and Heterosigma akashiwo. • α is discussed based on exploitation, interference, and pre-emptive competitions. • α may relate to the competition for comfortable space. Phytoplankton growth can cause red tide, lowering water quality and damaging fisheries. The simple Lotka–Volterra model (LV model), estimating the population changes in different species, is often used to analyze the growth and competition of causative species. However, the LV model has not been sufficiently applied to examining the actual occurrence and development of red tides in the field. Therefore, the mechanism of seasonal dominant species replacement and applicability of the LV model were studied to analyze the competition between the harmful raphidophytes Chattonella marina and Heterosigma akashiwo. Sensitivity analysis was performed, and optimization method of competition coefficient (α) was discussed by comparison with measured data from culture experiments. We found that it is crucial to evaluate in advance the initial cell density conditions under which the population size changes concerning α (the order of root mean squared logarithmic error ≥ 10−2). Using this as a reference, we pointed that the initial cell density difference between the two species in co-culture experiments should be as large as possible. In addition, simulation analysis using the model revealed that growth rate (r) and carrying capacity (K) determine H. akashiwo dominance in spring, and the increase in α due to rising temperatures causes C. marina dominance in summer. Comparing α of C. marina with α of C. antiqua cited from a previous study found that the formation of red tides of C. marina less than that of C. antiqua can be explained by α that is 0.42 times smaller than α of C. antiqua. Moreover, the increase in α with increasing temperature is related to the physiological and ecological characteristics of C. marina , which is more likely to dominate the space suitable for growth with temperature rise. We consider that investigations of α, in particular, contributes to modeling various competition and more improving accuracy in analyses. These results provide valuable scientific findings on the occurrence and development of red tide flagellates and their analytical method. [Display omitted] [ABSTRACT FROM AUTHOR]

In 1997, the inner part of Isahaya Bay on the west coast of the Ariake Sea was separated from the sea by dikes, leading to the formation of a freshwater reservoir. Since the Isahaya Reclamation Project began in the 1990s, red tides have become more common in the bay. Studies suggested that a non-negligible amount of NH 4 + was regenerated from organic matter decomposition in the turbid water drained from the reservoir into the bay, and this drainage water might be an important source of NH 4 + for red tides in the bay. Although labile organic matter in the turbid water might also originate from resuspended sediments in the reservoir induced by the drainage process, the potential for the resuspended sedimentary organic matter to serve as an NH 4 + source has never been evaluated. In this study, we found that sediments near the drainage gates on the dike in the reservoir contained high levels of amino acids and NH 4 +. In addition, the NH 4 + concentrations were positively correlated with amino acids concentrations. This result can be explained by increasing NH 4 + production according to labile organic nitrogen accumulation in the sediments near the dike. The result of our study suggests that the sediment resuspension near the dike induced by drainage might be a source of bioavailable nitrogen for Isahaya Bay. [ABSTRACT FROM AUTHOR]

Harmful Algal Blooms (HAB) pose significant challenges to fisheries management and food and water security. The onset of a HAB is notoriously difficult to predict. Traditional methods of algal species identification under a microscope are also laborious and time consuming. A real-time system for identification and concentration measurement of algal bloom species has been developed at a marine fish culture zone (FCZ) in the subtropical coastal waters of Hong Kong. The system is based on analysis of high frequency algal cell images obtained from an underwater Imaging FlowCytobot (IFCB) deployed on the fish farm. An explainable supervised machine learning technique has been successfuly developed. The algal species classifier is trained by presenting a wide range of extracted image features to a random forest algorithm. An optimized set of 25 features is identified by a recursive feature elimination technique. The random forest (RF) classifier can identify 15 target HAB classes with an overall out-of-bag accuracy of 94.2%, with individual F 1 score ranging from 0.8 to 1.0. The classifier performs equally well as a Convolution Neural Network (CNN) developed using transfer learning techniques. Based on the classifier, an automated real-time species identification and cell counting protocol has been developed, with a response time of 10 min after data collection. This work represents the first successful attempt of continuous algal species monitoring by IFCB and artificial intelligence (AI) – based detection of HAB in subtropical coastal waters. [ABSTRACT FROM AUTHOR]

A self-similar nonlinear analytic solution is derived for a case of isolated deep flow over broad sloping topography. The solution takes the form of an arctangent function and physically manifests as a compressing jet (narrowing and intensifying) with Ekman pumping controlling the interface evolution. Notably, this jet travels in the direction with shallow water to the left, which is in contrast to the expected flow direction of topographic Rossby wave propagation (shallow water to the right). Such deep flows are not accessible via satellite observations and play an important role ocean-coastal ocean connectivity. Examples of deep flows over broad shelves include the South Atlantic Bight and West Florida Shelf, where deep upwelling is thought to influence the generation of red tides, local ecosystems, and deep carbon sequestration. Relevance of the analytic solution to the South Atlantic Bight circulation is provided. [ABSTRACT FROM AUTHOR]

• MC II removed K. brevis cells but was less effective at toxin removal than expected. • MC II removed dissolved and particulate phosphorus from the water column. • MC II significantly reduced pH and alkalinity over the 72-hour observation period. • Lethal and sublethal measures in animals were unaffected by MC II treatment. • Effectiveness of MC II may be impacted by factors affecting particle collision. Modified clay compounds are used globally as a method of controlling harmful algal blooms, and their use is currently under consideration to control Karenia brevis blooms in Florida, USA. In 1400 L mesocosm tanks, chemical dynamics and lethal and sublethal impacts of MC II, a polyaluminum chloride (PAC)-modified kaolinite clay, were evaluated over 72 h on a benthic community representative of Sarasota Bay, which included blue crab (Callinectes sapidus), sea urchin (Lytechinus variegatus), and hard clam (Mercenaria campechiensis). In this experiment, MC II was dosed at 0.2 g L -1 to treat bloom-level densities of K. brevis at 1 × 106 cells L -1. Cell removal in MC II-treated tanks was 57% after 8 h and 95% after 48 h. In the water column, brevetoxin analogs BTx-1 and BTx-2 were found to be significantly higher in untreated tanks at 24 and 48 h, while in MC II-treated tanks, BTx-3 was found to be higher at 48 h and BTx-B5 was found to be higher at 24 and 48 h. In MC II floc, we found no significant differences in BTx-1 or BTx-2 between treatments for any time point, while BTx-3 was found to be significantly higher in the MC II-treated tanks at 48 and 72 h, and BTx-B5 was higher in MC II-treated tanks at 24 and 72 h. Among various chemical dynamics observed, it was notable that dissolved phosphorus was consistently significantly lower in MC II tanks after 2 h, and that turbidity in MC II tanks returned to control levels 48 h after treatment. Dissolved inorganic carbon and total seawater alkalinity were significantly reduced in MC II tanks, and partial pressure of CO 2 (p CO 2) was significantly higher in the MC II-only treatment after 2 h. In MC II floc, particulate phosphorus was found to be significantly higher in MC II tanks after 24 h. In animals, lethal and sublethal responses to MC II-treated K. brevis did not differ from untreated K. brevis for either of our three species at any time point, suggesting MC II treatment at this dosage has negligible impacts to these species within 72 h of exposure. These results appear promising in terms of the environmental safety of MC II as a potential bloom control option, and we recommend scaling up MC II experiments to field trials in order to gain deeper understanding of MC II performance and dynamics in natural waters. [ABSTRACT FROM AUTHOR]

This paper revealed the spatial and temporal distribution characteristics of Chinese marine environmental quality and driving factors during 2003–2021. [Display omitted] • Spatial distribution: South China Sea > East China Sea > Yellow Sea > Bohai Sea. • Shanghai, Zhejiang, Fujian and Hainan maintain high-pollution-low-investment model. • Jiangsu maintains low-pollution-low-investment model. • Typical correlation between Environmental Quality and Socioeconomic is 0.960. • GOP and Per Capita GDP show significant correlation with excellent water quality. As land and sea integration continues to accelerate, it will inevitably have an effect on the marine ecological environment. However, the study on spatial and temporal distribution characteristics of Chinese marine environmental quality and its driving factors was lacking. This paper employs Regression Analysis, Spearman Correlation Analysis, Canonical Correlation Analysis, Boston Consulting Group Matrix and Environmental Kuznets Curve to examine the spatial–temporal distribution characteristics and correlation factors of Chinese jurisdictional sea areas environmental quality. The environmental quality of the waters under China's jurisdiction improved on average from 2003 to 2021, the area of sea with excellent water quality increased by 7.21 × 104 km2. The spatial distribution showed "South superior, North inferior" trend. The accumulated red tide area is 2.01 × 105 km2, and the green tide has the average maximum area of distribution is 3.13 × 104 km2. The marine dumping area's volume of waste has a three stages of slow rise (2003–2007), steady (2008–2014) and rapid rise (2015–2021). The average percentage of seawater bathing areas with good water quality is 82.10 %. Urban Environmental Infrastructure Investment and Urban Drainage Construction Investments are positively correlated with excellent water quality and negatively correlated with light-sewage water quality. The typical correlation for the group "Environmental Quality/Environmental Governance" is 0.911, and the strongest correlation is between excellent water quality and urban drainage construction investment. The typical correlation coefficient for the "Environmental Quality/Socioeconomic" group is 0.960, and the strongest correlation is between excellent water quality and per capita GDP. The Gross Ocean Product, Per Capita GDP, Proportion of Non-agricultural Industries, Year-end Resident Population, and excellent water quality are positively correlated whereas light-sewage water quality is negatively correlated. Liaoning, Tianjin, Shandong and Guangdong shift from high-pollution-low-investment to low-pollution-low-investment model. Shanghai, Zhejiang, Fujian and Hainan maintain high-pollution-low-investment model, Hainan maintains high-pollution-high-investment model. Jiangsu maintains low-pollution-low-investment model. Hebei and Guangxi shift from low-pollution-low-investment to low-pollution-high-investment model. Liaoning, Hebei, Tianjin, Shandong, Guangxi and Shanghai show inverted "N" shape, Jiangsu shows positive "N" shape, Zhejiang and Fujian show monotonic decline shape, Guangdong and Hainan show positive "U" shape. The results could provide valuable suggestions for coastal provinces to accomplish economic development and environmental improvement, which to prevent the old way of "pollution first and treatment later". [ABSTRACT FROM AUTHOR]

Alexandrium leei and Alexandrium catenella are noxious dinoflagellates that form red tides but the two species differ substantially in optimal growth conditions. For formation of blooms in natural environments, A. leei favors moderate temperatures (around 20 °C) while A. catenella favors much lower temperatures (around 10 °C). We examined the effects of temperature and light on cell proliferation and photosynthesis in cell cultures of the two species. Under light at 100 μmol photons m−2 s−1, the growth rate of both species was highest at 20 °C. At 25 °C, A. leei continued to proliferate but A. catenella did not survive. Conversely, at lower temperatures, namely, 12 °C and 15 °C, the growth rate of A. leei was very low while that of A. catenella remained high. The net photosynthetic activity, as determined in terms of oxygen evolution, was highest at 20 °C in A. leei. By contrast, it was highest at 15 °C in A. catenella. Illumination of cells with strong light at 1000 μmol photons m−2 s−1 decreased the activity of photosystem II (PSII), as determined in terms of Fv/Fm, in both species. In A. leei , the activity of PSII declined more rapidly at 12 °C and 15 °C than at 20 °C and 25 °C under strong light. In A. catenella , the activity of PSII declined more rapidly at 20 °C than at 12 °C and 15 °C. Thus, A. catenella appeared to be more resistant to photoinhibition of PSII at low temperatures than A. leei. In addition, the ability to repair photodamaged PSII at 12 °C and 15 °C was greater in A. catenella than that in A. leei. Thus, the tolerance of PSII to strong light and low temperatures might determine the range of temperatures that supports the formation of blooms of the two Alexandrium species. • Two noxious Alexandrium species differ with respect to the sensitivity of PSII to photoinhibition. • Photoinhibition of PSII in A. leei is resistant to higher temperatures. • Photoinhibition of PSII in A. catenella is resistant to lower temperatures. • Tolerance of PSII to photoinhibition affects the temperature for cell proliferation. [ABSTRACT FROM AUTHOR]

Moina mongolica and Daphniopsis tibetana are typical saline Cladocera in China that are characterized by a wide salinity range, rapid reproduction, and high-density culture. In this paper, the characteristics and life history of M. mongolica and D. tibetana are reviewed. The application of these two species of Cladocera to ecotoxicology in recent years is also summarized from the aspects of environmental factors and environmental pollutants, including ultraviolet B radiation, temperature, salinity, alkalinity, pH, heavy metals, harmful red tide, pesticides, and persistent organic pollutants. Additionally, the toxicity sensitivity of saline Cladocera in different reproductive statuses and inter-generational embryos is discussed. Finally, the need to enhance knowledge of the molecular genomics, population dynamics, and strategies for protection of saline Cladocera, along with the need for establishment of estuarine and marine environmental monitoring standards are discussed. Overall, this review highlights the potential for using these Cladocera species as indicator organisms for estuarine and marine ecotoxicology studies. • Moina mongolica and Daphniopsis tibetana had been domesticated in seawater. • They had been applied to the ecotoxicological researches for over 30 years. • This review highlights the potential for them for seawater ecotoxicology. [ABSTRACT FROM AUTHOR]

• Environmental toxins may cause biliary atresia. • Red tide is caused by overwhelming algal blooms (Karenia brevis). • Red tide is debilitating to marine wildlife. • Gestational exposure to K. brevis was not associated with biliary atresia. The study objective was to evaluate the association between Karenia brevis (K. brevis) exposure during pregnancy and the prevalence of biliary atresia (BA) in offspring. This was a hospital-based, case-control study in which cases were infants diagnosed with BA at Johns Hopkins All Children's Hospital from October 2001 to December 2019. Cases were matched 1:4 by age to controls who were randomly selected from a pool of healthy infants hospitalized during the study period for common pediatric diagnoses. Infants were excluded if they had congenital anomalies and/or were non-Florida residents. Gestational K. brevis exposure levels (cells/liter) were determined from Florida Fish and Wildlife Conservation Commission exposure data at 10- and 50 mile radii from the mother's zip code of residence. Multivariable conditional logistic regression determined odds of BA in offspring in relation to maternal gestational K. brevis exposure adjusted for infant sex, race/ethnicity, coastal residence, and seasonality. Of 38 cases and 152 controls, no significant inter-group differences were observed for infant race/ethnicity, season of birth, or coastal residence. Median gestational exposure at the 10 mile radius was 0 cells/liter in both groups. A greater proportion of cases had no gestational K. brevis exposure (63.2 %, n = 24) in comparison to controls (37.5 %, n = 57; p =.04) at a 10 mile radius. At a 50 mile radius, cases had a peak median exposure at 6 months of gestation compared to controls' peak at 9 months. After adjustment for sex, seasonality, race/ethnicity, and coastal residence, there was no significant association between BA and maximum K. brevis exposure per trimester of pregnancy observed at a 10- or 50 mile radius. In this matched case-control study, we observed no association between gestational K. brevis (cells/liter) exposure at a 10- or 50 mile radius from maternal zip code of residence and BA in offspring. [ABSTRACT FROM AUTHOR]

• Use a difference-in-differences model to estimate healthcare visits due to HABs. • HABs cause an increase of 23.67 healthcare admissions per zip code per month, a 2934 % increase over baseline. • Data used are finer geographic granularity and additionally add outpatient visits compared to prior research. Harmful algal blooms (HABs) have been found to cause increases in healthcare visits for a variety of illnesses to humans if exposure and contact is sufficient. We use a more comprehensive dataset than previously implemented in prior literature to better isolate visits by healthcare facility type and proximity to bloom. Using a difference-in-differences model, our results suggest HABs cause an increase of 23.67 healthcare admissions per zip code per month across four HAB-related diagnoses. This impact is a 3,000% increase over baseline non-bloom times and an increase in monthly healthcare costs of about $250,000 for the entire impacted area. Our data include inpatient non-emergency and outpatient healthcare visits, which account for over 60% of all HAB-related healthcare visits, meaning that prior literature that has not measured those facilities has greatly underestimated HAB health impacts. [ABSTRACT FROM AUTHOR]

• Summer and fall Karenia populations have been observed along the Delmarva Peninsula since 2007. • K. mikimotoi and K. papilionacea blooms (105 cells L −1) contained other Karenia spp. (103-104 cells L −1). • The first record of a Karenia bloom in Chesapeake Bay was made in late summer/early autumn of 2017. A bloom of Karenia papilionacea that occurred along the Delaware coast in late summer of 2007 was the first Karenia bloom reported on the Delmarva Peninsula (Delaware, Maryland, and Virginia, USA). Limited spatial and temporal monitoring conducted by state agencies and citizen science groups since 2007 have documented that several Karenia species are an annual component of the coastal phytoplankton community along the Delmarva Peninsula, often present at background to low concentrations (100 to 10,000 cells L −1). Blooms of Karenia (> 105 cells L −1) occurred in 2010, 2016, 2018, and 2019 in different areas along the Delmarva Peninsula coast. In late summer and early autumn of 2017, the lower Chesapeake Bay experienced a K. papilionacea bloom, the first recorded in Bay waters. Blooms typically occurred summer into autumn but were not monospecific; rather, they were dominated by either K. mikimotoi or K. papilionacea , with K. selliformis, K. brevis -like cells, and an undescribed Karenia species also present. Cell concentrations during these mid-Atlantic Karenia spp. blooms equalled concentrations reported for other Karenia blooms. However, the negative impacts to environmental and human health often associated with Karenia red tides were not observed. The data compiled here report on the presence of multiple Karenia species in coastal waters of the Delmarva Peninsula detected through routine monitoring and opportunistic sampling conducted between 2007 and 2022, as well as findings from research cruises undertaken in 2018 and 2019. These data should be used as a baseline for future phytoplankton community analyses supporting coastal HAB monitoring programs. [ABSTRACT FROM AUTHOR]

• The bloom of Noctiluca alters its associated bacterial community carbon utilization. • Ammonium is an important nitrogen source for Noctiluca -associated bacteria. • Noctiluca bloom enriches Vibrio anguillarum , posing threat to marine life. • Enrichment of V. anguillarum at the bloom stage may be due to increase of glucose. Noctiluca scintillans (red) is a widely distributed heterotrophic dinoflagellate and a prominent red tide forming species. This study investigated the effects of Noctiluca blooms on marine microbial diversity and functionality using multi-omics approaches. Our findings revealed significant differences in the community composition of Noctiluca -associated bacteria compared to those associated with autotrophic plankton and free-living bacteria in the surrounding seawater. The dominant bacterial groups within the Noctiluca -associated community shifted at various bloom stages, which could be attributed to changes in prey composition of Noctiluca. During the non-bloom stage, Burkholderiaceae, Carnobacteriaceae, and Pseudomonadaceae dominated the community, while Vibrionaceae became dominant during the bloom stage, and Saprospiraceae, Crocinitomicaceae, and Pirellulaceae thrived during the post-bloom stage. Compared to the non-bloom stage, Noctiluca -associated bacterial community at the bloom stage exhibited significant down-regulation of genes related to complex carbohydrate metabolism, while up-regulation of genes related to glucose transportation and utilization. Furthermore, we identified Vibrio anguillarum , a potential pathogenic bacterium to marine fish, as a major component of the Vibrionaceae family during the bloom stage. The occurrence of V. anguillarum associated with Noctiluca blooms may be attributed to the increased availability of its preferred carbon sources and its high capabilities in glucose transportation, motility and chemotaxis. Moreover, the presence of Vibrio infection genes (hap, hlyA, rtxA) encoding vibriolysin, hemolysin, and RTX (Repeats-in-toxin) toxin in the V. anguillarum genome, with the hap gene showing high expression levels during Noctiluca blooms, indicates an elevated risk of infection. This study underscores the unique composition of the bacterial community associated with red tide forming heterotrophic dinoflagellates and suggests that Noctiluca cells may serve as reservoirs and vectors for pathogenic bacteria, potentially posing a threat to fish-farming and the health of other marine organisms. [Display omitted] [ABSTRACT FROM AUTHOR]

The crisis in small-scale fisheries (SSFs) is worsened by weak governance structures, requiring urgent transformation. Participatory arrangements like co-management offer potential to enhance resilience in these social-ecological systems. However, the performance of collaborative governance modes must be evaluated to support institutional learning, refine governance structures, and ensure the legitimacy of transformative changes. In Uruguay, Local Fishery Councils (LFCs) were institutionalized a decade ago to involve fishers in managing and governing SSFs. This study assesses the LFC for the yellow clam SSF using three approaches: analysis of LFC meeting minutes, compilation of stakeholder perceptions, and analysis of social networks. The study found a decline in session frequency due to limited resources caused by the termination of an externally funded project. Performance indicators from the minutes identified recurring concerns on assessment, governance, and management, and issues related to monitoring, control, and surveillance. The influence of markets and the impact of red tides on fisheries performance were also brought up. Stakeholders perceived successful management solutions achieved through collaborative efforts, supporting co-management and resource recovery progress. However, social network analysis revealed communication patterns marked by core-periphery structure, showing partial disconnection and reluctance of the coastal marine authority to engage in inter-institutional collaboration. Despite challenges from climate change and markets, the LFC played a crucial role in co-creating solutions, empowering fishers with new skills and knowledge. Findings stress the importance of collaborative governance in promoting sustainable management and supporting institutional learning for transformative change in SSFs. • Governance transformation into co-management is assessed in a small-scale fishery. • Mixed methods using content analysis of minutes and structured interviews. • Participatory management led to success, optimism, and support for co-management. • Challenges in sustaining governance infrastructure hinder effective management. • Social network analysis suggests that engaging peripheral actors enhances governance. [ABSTRACT FROM AUTHOR]

Anchialine caves are common in Mediterranean karstic shorelines and elsewhere, delivering point-source fresh groundwater and nutrients to the coastal ocean. Here, we first quantified submarine groundwater discharge (SGD) in a typical karstic system (Zaton Bay, Croatia) receiving groundwater from anchialine caves using a radon (222Rn) mass balance model. We then combine our new observations with the literature to provide a Mediterranean-scale estimate of karstic fresh SGD nutrient fluxes. We found that SGD and related nutrient fluxes in the upper brackish layer were much higher than those in the underlying layer in Zaton Bay. In the upper brackish layer, both SGD (m d−1) and associated nutrient fluxes (mmol m−2 d−1) in the wet season (SGD: 0.29–0.40; DIN: 52; DIP: 0.27) were significantly higher than those in the dry season (SGD: 0.15; DIN: 22; DIP: 0.08). Red tides were observed in the wet season but not in the dry season. Nutrient budgets imply that SGD accounted for >98% of the total dissolved inorganic nitrogen (DIN) and phosphorous (DIP) sources into Zaton Bay. These large SGD nutrient fluxes with high N/P ratios (190–320) likely trigger and sustain red tide outbreaks. Combining our results with 30 previous studies in the region revealed that point-source DIN and DIP fluxes via karstic fresh SGD may account for 8–31% and 1–4%, respectively, of riverine inputs in the Mediterranean Sea. Overall, we demonstrate the importance of karstic SGD as a source of new nutrients with high N/P ratios to the Mediterranean Sea and emphasize how SGD lagging precipitation can drive red tide outbreaks. [ABSTRACT FROM AUTHOR]

The nutrient regime has changed significantly in the Bohai Sea (BS) during the past six decades because of anthropogenic perturbations. Specifically, the concentration of DIN increased by about 7-fold from the end of the 1950s to the mid-2010s, while DIP and DSi concentrations decreased from the end of the 1950s to the beginning of the 1990s, and have since increased again. Unsynchronized changes in nutrient levels have led to changes in the nutrients structure, which has caused a series of ecological effects. Phytoplankton biomass increased by 6-fold from the 1960s to the mid-2010s. Additionally, phytoplankton composition shifted from a diatom-dominated to a dinoflagellate-dominated system, and the dominant species of macrozoobenthos changed. Red tides rarely occurred before the 1980s, but have occurred periodically and frequently since the 1990s. Finally, the BS ecosystem has shifted from an N-limited oligotrophic state before the 1990s to a potentially P-limited eutrophic state. • Dissolved inorganic nitrogen increased by 7-fold over the past 60 years in Bohai Sea • Dissolved inorganic phosphorus, dissolved silica decreased first and then increased • Phytoplankton biomass increased by 6-fold and the dominant species changed • Bohai Sea shifted from N-limited oligotrophic state to P-limited eutrophic state [ABSTRACT FROM AUTHOR]

• P was the limiting during transitional period. • Dynamics of DON and DOP were affected by impoundment. • TPP and BSi were highly retained in the TGR. • Algal bloom likely occurred in TGR and estuary since 2003, but frequency and area of red tides in ECS dramatically decreased. 2009 ∼ 2010 was a critical period for the Three Gorges Reservoir (TGR) transition from staged impoundment to full operation. This study reports on the composition of nutrients in the whole Changjiang and retention effect of the reservoir during the transitional period, and the potential impact of the reservoir impoundment on the eutrophication of the TGR and estuary. Water samples were collected in the mainstream and tributaries of Changjiang from August to October 2009 and June 2010 to analyze the concentrations of dissolved and particulate nutrients, and suspended particulate matter (SPM). The Changjiang was enriched with dissolved inorganic nitrogen (DIN), dissolved silicate (DSi) and SPM, but depleted in PO 4 3− and biogenic silica (BSi), with higher DIN:PO 4 3− and DSi:PO 4 3− ratios. DIN and PO 4 3− concentrations were lower in the Jinshajiang, but increased in the Mid-downstream of the Changjiang due to high human activities and nutrients import from major tributaries. DSi concentration varied little along the Changjiang, and was relatively low in the TGR. Particulate inorganic phosphorus (PIP), total particulate phosphorus (TPP) and BSi concentrations were very high in the Jinshajiang, and then dramatically decreased with the SPM in the TGR. The northern tributaries contributed more nutrients to the Changjiang than the southern tributaries. Depending on the nutrients input-output mass balance model, the retention of nutrients in the TGR were higher for TPP and BSi, lower for dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP). Total dissolved nitrogen (TDN), total phosphorus (TP) and DSi retained in the reservoir accounted for 15%, 12% and 1%, respectively of the TDN, TP and DSi fluxes in the Datong station near the estuary. Historical data showed that the impoundment of the TGD greatly contributed to the eutrophication of the reservoir and estuary. Since 2003, algal blooms were likely to occur in the TGR, estuary and adjacent seas, but the outbreak frequency and area of red tides in the East China Sea (ECS) dramatically decreased. Therefore, further study is required to estimate the response of estuarine ecosystem on the dispatching mode of the TGR. [ABSTRACT FROM AUTHOR]

• Red seabream showed similar survival rates upon C. polykrikoides exposure under LD conditions. • C. polykrikoides significantly inhibited the opercular respiratory rate of red seabream. • C. polykrikoides induced an array of GSH-mediated antioxidant defense responses. • Sublethal concentrations of C. polykrikoides modulated DNA stability in red seabream gill tissues. The ichthyotoxic Cochlodinium polykrikoides is one of the most harmful bloom-forming dinoflagellates. In the present study, the economically important red seabream Pagrus major was exposed to sublethal concentrations of C. polykrikoides (i.e., 1,000 and 3,000 cells mL−1) for 24 h, and the antioxidant defense system and DNA damage dose-specific responses were analyzed during the exposure and additional depuration period (2 h) in the gill tissue. No significant ichthyotoxicity was observed under different light and dark conditions, while significantly lower levels of opercular respiratory rate were measured in the C. polykrikoides -exposed red seabream. Intracellular malondialdehyde (MDA) content increased significantly in the 3,000 cells-exposed gill tissues at 24 h and the increased level was maintained during depuration. Intracellular glutathione (GSH) levels were significantly depleted following exposure to 3,000 cells mL-1 of C. polykrikoides , but the levels increased significantly in the depuration phase. Overall, significantly higher activity of antioxidant defense system enzymes such as catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), and glutathione peroxidase (GPx) were observed in the 3,000 cells mL−1-exposed gill tissues at 24 h and during depuration. Analysis of the two reliable DNA damage parameters, Olive tail moment and percent tail DNA, showed significantly elevated levels of DNA damage in the 1,000 and 3,000 cells mL−1-exposed gill tissue. Increases in the activity of the antioxidant defense system and DNA damage may be one of the major mechanisms mediating C. polykrikoides- induced devastation in aquaculture and fisheries. [ABSTRACT FROM AUTHOR]

Allelopathy between algae is an ecological strategy that can facilitate or inhibit the occurrence of algal blooms. The role of allelopathic effects of marine microalgae Cylindrotheca closterium in other phytoplankton population dynamics are still limited. In the current study, the effects of cell-free filtrates of diatom Cylindrotheca closterium on two common dinoflagellate s (Prorocentrum donghaiense and Prorocentrum cordatum), a chrysophyceae (Isochrysis galbana) and a diatom (Chaetoceros curvisetus) were investigated within controlled laboratory experiments. It was observed that the growth of P. donghaiense was significantly suppressed and approximately 80% cells disappeared after 8-d exposure, while the other three algae was less sensitive. P. donghaiense was very sensitive to the exudates of C. closterium from the stationary phase by comparing various percentage (10, 30, 50, 70 and 100%) of filtrates. In addition, the allelopathic effects of extracellular compounds of C. closterium extracted by three different organic solvents (ethyl acetate, chloroform and petroleum ether) on P. donghaiense were explored by determining cell density, chlorophyll content and maximum photosystem II (PSII) quantum yield (F v /F m). It was found that the compounds extracted by ethyl acetate and chloroform appeared to exhibit less toxicity on P. donghaiense than that of petroleum ether. The present results indicated that the allelochemicals released by C. closterium might be concentrated effectively in the petroleum ether extraction phase, which provided a new perspective for controlling the red tides of P. donghaiense in the East China Sea by means of the ecological inhibitors extracted. • The effects of C. closterium filtrates on P. donghaiense , P. cordatum , I. galbana and C. curvisetus were investigated. • P. donghaiense was more sensitive to C. closterium filtrates than other three algae. • Extracellular compounds of C. closterium were concentrated effectively in petroleum ether extraction phase. • Petroleum ether extracts of C. closterium filtrates decreased the chlorophyll content and F v /F m of P. donghaiense. [ABSTRACT FROM AUTHOR]

High incident rates of red tide have occurred off the coast of the Changjiang (Yangtze) River Estuary in summer, resulting from a magnified population growth discharging substantial nutrient loads into this vicinity. The presence of elevated Chlorophyll-a concentrations (≥36.3 μg/l), low suspended sediment concentrations in surface and mid-layers (<10 mg/l), a strong saline front and surface water temperature gradient, veering surface winds, and a bimodal shape to the Changjiang Diluted Water (CDW) revealed two red tide patches appearing between August 6–13, 2010. Two distinguishable hydrodynamic driving mechanisms, connected to these incidents, are diagnosed. Field observations and numerical simulations determined a red tide patch in the northeastern offshore area is caused by a northeast transport of the CDW truncated by a northwest intrusion of the Taiwan Warm Current (TWC) as winds deviated. Red tide occurrence in the southern nearshore area originated from a plume front where CDW interfaces with the TWC. • Hydrodynamic environment variability determines the pattern of red tide incidents. • Southeast winds >8 m/s correlates with detachment event's timing and red tide events. • Plume front created by current mixing and presence of coastal upwelling region. • Light intensity and nutrient loads yield chlorophyll- a concentrations to >20 μg/l. [ABSTRACT FROM AUTHOR]

• Karenia brevis exposure had lethal and sublethal impacts on stage-1 stone crab larvae. • Larval survivorship was reduced at medium and high concentrations of K. brevis. • Larval vertical swimming was altered following K. brevis exposure. The dinoflagellate Karenia brevis causes harmful algal blooms commonly referred to as red tides that are prevalent along Florida's gulf coast. Severe blooms often cause fish kills, turbid water, and hypoxic events all of which can negatively impact local fisheries. The stone crab, Menippe mercenaria, is a ˜$25 million per year fishery that occurs primarily along Florida's gulf coast. On the west Florida shelf, red tides occur from fall through spring, although severe blooms can occur during the summer. During the summer, stone crabs are reproductive and release larvae that are transported offshore where K. brevis blooms originate. This study determined the effects of K. brevis exposure on the survivorship, vertical swimming behavior, and oxygen consumption of stage-1 larval stone crabs. Survivorship was determined by exposing larvae to high (> 1 × 106 cells L−1) and medium (˜1 × 105 cells L−1) K. brevis concentrations for 96-hrs and were compared to controls that had no algae present. Larval swimming behavior (i.e., geotaxis) and oxygen consumption were monitored after 6-hr exposure to K. brevis. After 96-hrs of exposure, mortality was 100% and 30% for larvae in the high and medium concentrations of K. brevis , respectively, relative to the control. Larval swimming behavior was reversed in the K. brevis treatment; however oxygen consumption rates did not differ among treatments. These results suggest that severe blooms during the summer may reduce larval supply and serve as a potential bottleneck for new individuals recruiting into the fishery in years following a K. brevis bloom. [ABSTRACT FROM AUTHOR]

• Genetic relatedness of Japanese and global A. ostefeldii isolates was investigated. • Western Japanese isolates group with isolates from low-saline and shallow areas. • Northern Japanese isolates form a separate group explained by geographic isolation. • Low genetic diversity of western Japanese population implies a recent introduction. • Bloom in a shallow coastal lagoon in western Japan after a change in salinity. In recent years, blooms of toxic Alexandrium ostenfeldii strains have been reported from around the world. In 2013, the species formed a red tide in a shallow lagoon in western Japan, which was the first report of the species in the area. To investigate the genetic relatedness of Japanese A. ostenfeldii and global isolates, the full-length SSU, ITS and LSU sequences were determined, and phylogenetic analyses were conducted for isolates from western and northern Japan and from the Baltic Sea. Genotyping and microsatellite sequence comparison were performed to estimate the divergence and connectivity between the populations from western Japan and the Baltic Sea. In all phylogenetic analyses, the isolates from western Japan grouped together with global isolates from shallow and low saline areas, such as the Baltic Sea, estuaries on the east coast of U.S.A. and from the Bohai Sea, China. In contrast, the isolates from northern Japan formed a well-supported separate group in the ITS and LSU phylogenies, indicating differentiation between the Japanese populations. This was further supported by the notable differentiation between the sequences of western and northern Japanese isolates, whereas the lowest differentiation was found between the western Japanese and Chinese isolates. Microsatellite genotyping revealed low genetic diversity in the western Japanese population, possibly explained by a recent introduction to the lagoon from where it was detected. The red tide recorded in the shallow lagoon followed notable changes in the salinity of the waterbody and phytoplankton composition, potentially facilitating the bloom of A. ostenfeldii. [ABSTRACT FROM AUTHOR]

Highlights • Brevetoxins are produced by the marine harmful alga, Karenia brevis (K. brevis); and humans can be exposed to these toxins through a variety of pathways, including inhalation of aerosols and consumption of toxin-contaminated seafood; • Neurological illnesses may also be associated with human exposures to brevetoxins, but to date there has been little research on this specific effect; • During K. brevis blooms in nearby coastal waters, significant increases in visits to emergency departments by older coastal residents (≥55 years) were found specifically for the primary diagnosis of headache (ICD-9 784.0); • In previous studies, older coastal residents were also at increased risk for respiratory illnesses associated with K. brevis blooms; • Preventive measures designed to reduce and limit human exposures to brevetoxins are recommended; and healthcare providers should be instructed to consider brevetoxin exposures and resultant neurological illness as possible diagnoses. Abstract Human respiratory and gastrointestinal illnesses can result from exposures to brevetoxins originating from coastal Florida red tide blooms, comprising the marine alga Karenia brevis (K. brevis). Only limited research on the extent of human health risks and illness costs due to K. brevis blooms has been undertaken to date. Because brevetoxins are known neurotoxins that are able to cross the blood-brain barrier, it is possible that exposure to brevetoxins may be associated with neurological illnesses. This study explored whether K. brevis blooms may be associated with increases in the numbers of emergency department visits for neurological illness. An exposure-response framework was applied to test the effects of K. brevis blooms on human health, using secondary data from diverse sources. After controlling for resident population, seasonal and annual effects, significant increases in emergency department visits were found specifically for headache (ICD-9 784.0) as a primary diagnosis during proximate coastal K. brevis blooms. In particular, an increased risk for older residents (≥55 years) was identified in the coastal communities of six southwest Florida counties during K. brevis bloom events. The incidence of headache associated with K. brevis blooms showed a small but increasing association with K. brevis cell densities. Rough estimates of the costs of this illness were developed for hypothetical bloom occurrences. [ABSTRACT FROM AUTHOR]

[Display omitted] • MoS 2 @ZIF-67/TiO 2 was prepared by simple hydrothermal synthesis. • MoS 2 @ZIF-67/TiO 2 showed excellent efficiency in algae deactivation. • Photosynthetic, metabolism and antioxidant system of algal cells were destroyed. Water eutrophication led to the occurrence of harmful algal blooms (HABs) with the increase of urban sewage and industrial wastewater. As a periodic ecological disaster, it caused serious harm to the ecological environment (including the destruction of the food chain and the death of animals, etc.) and human health. Karenia mikimotoi (K. mikimotoi) was a kind of common algae that caused red tides, and it could produce harmful toxins. Therefore, a composite photocatalyst MoS 2 @ZIF-67/TiO 2 (MZ/T) for the inactivation of K. mikimotoi was synthesized by a simple and easy-to-operate hydrothermal synthesis method. The MoS 2 @ZIF-67 nanoflowers were attached by the grainy TiO 2. The composite photocatalyst MZ/T showed excellent photocatalytic performance, and the inactivation efficiency of MZ/T was up to 97.2 % in 4 h and 99.45 % in 12 h. The composite photocatalyst MZ/T could inactivate algal cells by destroying cell membrane structure, reducing chlorophyll content, soluble protein content. This study would provide a novel photocatalyst for water treatment of HABs. [ABSTRACT FROM AUTHOR]