Proteogenomics for Non-model Ocean-Derived Fungi.

Most biological and biomedical experiments are designed and studied using the most common model organisms (MOs) like humans, mice, Escherichia coli, Saccharomyces cerevisiae, Neurospora crassa, worms, fruit flies, zebrafish, and Arabidopsis thaliana. These model organisms have been extensively studied and have a well-established set of genetic, physiological, and other tools available for research. In contrast, non-model organisms (NMOs) are those that are not traditionally used in scientific research and do not have a well-established set of genetic or other biological tools available for their study. The majority of MOs are associated with land habitats but rarely with ocean environments. The ocean forms the largest portion of our planet, yet ocean-derived organisms are the least explored, and these organisms are primarily NMOs. However, these are thrilling living entities, such as ocean-derived fungi (ODF). These ODFs are a diverse group of fungi that live in different ocean sectors, including the ocean, estuaries, and coastal ecosystems. These fungi are found to colonize and adapt to different substrates. They are important decomposers in marine ecosystems, breaking down dead organic matter and recycling nutrients. ODFs have adapted to survive in the unique and challenging conditions of the ocean environment, including high salt concentrations, low nutrient availability, and exposure to waves and currents. ODFs are potent producers of natural compounds with pharmaceutical and industrial applications, such as antibiotics, anticancer agents, antivirals, and enzymes for industrial processes. ODFs are an exciting group of fungi; however, these are the least studied because of the nonavailability of MOs from this group. Hence, there is a massive scope of expanding our current knowledge about ODFs, their genetic traits, potential future drug-producing capabilities, and lifestyle traits.With the advent of next-generation DNA sequencing, there is huge potential for the characterization of the genetic material of ODF as NMOs. Parallel proteomic methods also pose huge potential. A marriage of NGS and proteomic methods generates a new avenue called proteogenomics, which focuses on better annotation of existing genomic data. Both methods are getting cheaper and accessible to the research community for studying the proteogenomics of NMOs. Herein, the proteogenomic protocol development and data analyses are illustrated for the ocean-derived fungus Scopulariopsis brevicaulis.

Thioclava arctica sp. nov. and Zhongshania arctica sp. nov., isolated from the surface sediment of the Arctic Ocean and reclassification of Marortus luteolus Yu et al. 2019 as a later heterotypic synonym of Zhongshania marina On et al. 2019.

Two Gram-stain-negative bacterial strains, 15-R06ZXC-3T and R06B22T, were isolated from the surface sediment of the Arctic Ocean. Phylogenetic analyses based on the 16S rRNA gene and genome sequences indicated that strain 15-R06ZXC-3T belongs to the genus Thioclava, while strain R06B22T belongs to the genus Zhongshania. Strain 15-R06ZXC-3T showed the closest relationship to Thioclava indica DT23-4T. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain 15-R06ZXC-3T and all of the type strains of the genus Thioclava ranged from 20.8 to 30.4% and 79.1 to 85.7%, respectively. Strain R06B22T was most closely related to Zhongshania marina DSW25-10T. The dDDH and ANI values between strain R06B22T and all of the type strains of the genus Zhongshania ranged from 18.6 to 20.4% and 77.5 to 79.4%, respectively. These dDDH and ANI values were all below the standard cutoff criteria for the delineation of bacterial species, indicating that the two strains may represent novel species within their respective genera. Furthermore, their phenotypic and chemotaxonomic characteristics also differentiated them from closely related species. Based on the polyphasic analyses, strains 15-R06ZXC-3T and R06B22T separately represent novel species of the genera Thioclava and Zhongshania, for which the names Thioclava arctica sp. nov. (type strain 15-R06ZXC-3T = MCCC 1A07434T= KCTC 8342T) and Zhongshania arctica sp. nov. (type strain R06B22T = MCCC 1A08273T= KCTC 8343T) are proposed. Additionally, phylogenomic analyses showed that the strain Marortus luteolus ZX-21T was clustered with the strain Z. marina DSW25-10T and all other type strains of the genus Zhongshania. Furthermore, the ANI and dDDH values between strains ZX-21T and DSW25-10T were 97.6% and 78.8±2.5%, respectively, strongly indicating that they represented a single species. Therefore, it is proposed that M. luteolus Yu et al. 2019 be recognized as a later heterotypic synonym of Z. marina On et al. 2019.

Phylogenetic and molecular characteristics of two Aphanizomenon strains from the Curonian Lagoon, Southeastern Baltic Sea and their biological activities.

Polyphasic approach has become a generally accepted method for the classification of cyanobacteria. In this study, we present a detailed characterisation of two strains, KUCC C1 and KUCC C2, isolated from the Curonian Lagoon and classified to the Aphanizomenon genus. Despite phylogenetic similarity, the strains differ with respect to morphology, ultrastructure characteristics, and the metabolite profile. In the KUCC C1 extract, three unknown peptides and eight anabaenopeptins were detected, while KUCC C2 produced one unknown peptide and one aeruginosin. In both strains, a total of eleven pigments were detected. The production of myxoxantophyll, chlorophyll-a, chlorophylide-a, and zeaxanthin was higher in KUCC C2 than in KUCC C1. Extracts from both strains of Aphanizomenon also had different effects in antibacterial, anticancer and enzyme inhibition assays. Comprehensive analyses of Aphanizomenon strains performed in this study showed significant diversity between the isolates from the same bloom sample. These differences should be considered when exploring the ecological significance and biotechnological potential of a given population.

Geographic distribution of modern dinoflagellate cysts in surface sediments of the Arabian Sea: significance of taxa and morphometry as potential ecological indicators.

Studies on dinoflagellate cysts in the Arabian Sea (AS) are limited to the coastal waters, but no information from the deeper depths. The dinoflagellate cyst assemblages in surface sediment samples (0-2 cm) from the deeper depths (up to ~ 4500 m) of central (oxygen minimum zone (OMZ)) and southeastern (oligotrophic) AS revealed that the relatively good numbers of cyst concentrations reach deeper depths of OMZ (3505 m) and oligotrophic (4368 m) regions, but the former harbored more cyst concentrations than the latter. The cyst concentration and species count (including HAB species) recorded here are lower compared to the eastern (EAS) and western (WAS) AS, but the autotrophic cyst dominance (74-83%) at deeper depths is in contrast with the heterotrophic dominance in coastal AS. Of the recorded 41 cyst species (belonging to 18 genera), four species (cyst of Cladopyxis sp., Operculodinium janduchenei, Stelladinium bifurcatum, and Protoperidinium monospinum) from the deepest part of oligotrophic AS form the first report. In contrast, Spiniferites and Lingulodinium cysts were common occurrences. Taxonomic comparison with literature revealed (i) the prevalence of more cosmopolitan species (32 species) which could be due to the prevalence of large and small-scale lateral transport of cysts in oligotrophic regions followed by OMZ and coastal regions, respectively, and (ii) very few region-specific species, i.e., cyst of Protoperidinium latissimum, Lejeunecysta sabrina, cyst of Protoperidinium denticulatum in EAS and Impagidinium patulum, and I. strialatum, in WAS. Interestingly, variability in the morphometry was evident between the coastal and open oceans in some cosmopolitan cysts, e.g., Operculodinium centrocarpum and Lingulodinium machaerophorum. These findings from the less studied pelagic regions will contribute to the growing knowledge of dinoflagellate cyst distribution patterns and highlight the significance of cyst taxa and morphology as potential ecological indicators for AS.

Ploidy levels in diverse picocyanobacteria from the Baltic Sea.

In nature, the number of genome or chromosome copies within cells (ploidy) can vary between species and environmental conditions, potentially influencing how organisms adapt to changing environments. Although ploidy levels cannot be easily determined by standard genome sequencing, understanding ploidy is crucial for the quantitative interpretation of molecular data. Cyanobacteria are known to contain haploid, oligoploid, and polyploid species. The smallest cyanobacteria, picocyanobacteria (less than 2 µm in diameter), have a widespread distribution ranging from marine to freshwater environments, contributing significantly to global primary production. In this study, we determined the ploidy level of genetically and physiologically diverse brackish picocyanobacteria isolated from the Baltic Sea using a qPCR assay targeting the rbcL gene. The strains contained one to four genome copies per cell. The ploidy level was not linked with phylogeny based on the identity of the 16S rRNA gene. The variation of ploidy among the brackish strains was lower compared to what has been reported for freshwater strains and was more similar to what has been reported for marine strains. The potential ecological advantage of polyploidy among picocyanobacteria has yet to be described. Our study highlights the importance of considering ploidy to interpret the abundance and adaptation of brackish picocyanobacteria.

Study on the variation patterns of sea surface oil spill characteristics based on GNSS-R under different wind speeds.

Marine oil spills severely pollute marine environments, making rapid and accurate detection crucial. However, current Global Navigation Satellite System-Reflectometry (GNSS-R) oil spill detection studies overlook the impact of sea wind, leading to false or missed detections. This study simulates the mean square slope (MSS), scattering coefficient, coherent power, and delay-Doppler map (DDM), and explores the impact of sea wind on GNSS-R oil spill detection parameters. Results indicate that at wind speeds ≤3 m/s, the differences in MSS and scattering coefficient between oil and water are minimal, but become significant at speeds >3 m/s. Oil-covered sea surfaces exhibit unusually high coherent power and DDM in spill zones compared to clean surfaces, with both metrics decreasing as wind speed rises. Finally, using Cyclone Global Navigation Satellite System (CYGNSS) data, this study validated the reliability of GNSS-R oil spill parameter variation patterns derived from simulation data, providing references for oil spill detection research.

Assessing the impact of simulated ocean acidification on the photodegradation of selected microplastics.

This study investigated the impact of ocean acidification on the photodegradation of three microplastics (MPs): polypropylene (PP), expanded polystyrene (EPS), and ethylene-vinyl acetate (EVA), under accelerated UV radiation at three pH levels (i.e., 8.1, 7.8, and 7.5), simulating marine conditions. The acidification system simulated current and projected future environmental conditions. As expected, an increase in partial pressure of CO2, total inorganic carbon, bicarbonate ion, and CO2 resulted in more acidic pH levels, with the reverse being true for the carbonate ion. Structural changes of MPs were evaluated, revealing that all weathered samples underwent higher degradation rate compared to the virgin samples. The oxidation state and crystallinity of PP and EVA MPs were higher in samples exposed to the lowest pH, whereas no significant increase in the degradation rate of EPS samples was observed. Saltwater acidification in this study contributed to enhance the photo-oxidation of MPs depending on their polymeric composition.

Distribution characteristics and ecological risk analysis of microplastics in sediments and effluents related to offshore oil and gas activities in the Bohai Sea, China.

Oil and gas activities are sources of marine microplastics (MPs) but have received less attention globally. This study assessed the distribution characteristics and ecological risks of MPs in 31 sediment samples and effluent samples of 5 oil and gas platforms related to offshore oil and gas activities in the Bohai Sea. The results showed that the mean abundance of MPs in sediment, produced water, and domestic sewage was 205.7 ± 151.5 items/kg d.w., 18 ± 11 items/L, and 26 ± 39 items/L, respectively. The MPs in sediments and effluents were dominated by transparent, rayon, and fibers <1 mm. Oil and gas activities may influence the abundance of MPs in the sediments. The sediments in the area were at a low level of risk, but some samples exhibited indexes beyond low levels. The mass of MPs carried by the effluents from oil and gas platforms in the Bohai Sea was less than that of other sources.

Preservation of Organic Carbon Associated with Iron on Continental Shelves Influenced by Hydrodynamic Processes.

Understanding the environmental fate of organic carbon associated with iron (OC-Fe) is critically important for investigating OC preservation in aquatic systems. Here, we first investigate 13C and 14C isotopes of OC-Fe within grain size-fractionated sediments retrieved from the East China Sea and estimate their sources and reactivities of OC-Fe through isotope-mixing models and thermal pyrolysis approaches in order to reveal the fate of OC-Fe on continental shelves influenced by hydrodynamic processes. Our results show that the OC-Fe proportion in total OC (fOC-Fe) in the sortable silt fractions (20-63 µm) is the highest among three grain size fractions, likely suggesting that hydrodynamics may enhance the iron protection on OC. In addition, Δ14COC-Fe values fall within the range of from -358.73 to -64.03‰, and both Δ14COC-Fe values and ancient OC-Fe% exhibit strong positive linear relationships with fOC-Fe. This emphasized that the hydrodynamic processes may cause the ancient OC to be tightly associated with Fe, accompanying OC-Fe aging. Our findings shed new light on the preservation of OC-Fe in marginal seas to advance the recognition of carbon "rusty sinks" in seafloor sediments.

Immunomodulatory Compounds from the Sea: From the Origins to a Modern Marine Pharmacopoeia.

From sea shores to the abysses of the deep ocean, marine ecosystems have provided humanity with valuable medicinal resources. The use of marine organisms is discussed in ancient pharmacopoeias of different times and geographic regions and is still deeply rooted in traditional medicine. Thanks to present-day, large-scale bioprospecting and rigorous screening for bioactive metabolites, the ocean is coming back as an untapped resource of natural compounds with therapeutic potential. This renewed interest in marine drugs is propelled by a burgeoning research field investigating the molecular mechanisms by which newly identified compounds intervene in the pathophysiology of human diseases. Of great clinical relevance are molecules endowed with anti-inflammatory and immunomodulatory properties with emerging applications in the management of chronic inflammatory disorders, autoimmune diseases, and cancer. Here, we review the historical development of marine pharmacology in the Eastern and Western worlds and describe the status of marine drug discovery. Finally, we discuss the importance of conducting sustainable exploitation of marine resources through biotechnology.

Review of the sources and behaviors of plutonium isotopes in the atmosphere and ocean.

Plutonium, as well as fission products such as 137Cs, had been released into the earth environment in 1945 after the first atmospheric nuclear explosion of plutonium bomb in the desert of New Mexico (USA, July 16) and later over Nagasaki (August 9), followed then by many other explosions. Thus, plutonium cycling in the atmosphere and ocean has become a major public concern as a result of the radiological and chemical toxicity of plutonium. However, plutonium isotopes and 137Cs are important transient tracers of biogeochemical and physical processes in the environment, respectively. In this review, we show that both physical and chemical approaches are needed to comprehensively understand the behaviors of plutonium in the atmosphere and ocean. In the atmosphere, plutonium and 137Cs attach with aerosols; thus, plutonium moves according to physical and chemical processes in connection with aerosols; however, since plutonium is a chemically reactive element, its behavior in an aqueous environment is more complicated, because biogeochemical regulatory factors, in addition to geophysical regulatory factors, must be considered. Meanwhile, 137Cs is chemically inert in aqueous environments. Therefore, the biogeochemical characteristics of plutonium can be elucidated through a comparison with those of 137Cs, which show conservative properties and moves according to physical processes. Finally, we suggest that monitoring of both plutonium and 137Cs can help elucidate geophysical and biogeochemical changes from climate changes.

Forecasting of compound ocean-fluvial floods using machine learning.

Flood modelling and forecasting can enhance our understanding of flood mechanisms and facilitate effective management of flood risk. Conventional flood hazard and risk assessments usually consider one driver at a time, whether it is ocean, fluvial or pluvial, without considering the compound nature of flood events. In this paper, we developed a novel approach for modelling and forecasting compound coastal-fluvial floods using a two-step framework. In step one, a hydrodynamic model is used to simulate floodwater propagation; while in step two, machine learning (ML) models are used to generate flood forecasts. The architecture of hydrodynamic-ML forecasting system incorporates a hydrodynamic model covering a specific domain, with individual ML models trained for each pixel. In total 7 ML models including: Support Vector Regression (SVR), Support Vector Machine (SVM), Radial Basis Function (RBF), Linear Regression (LR), Gaussian Process Regression (GPR), Decision Tree (DT), and Artificial Neural Network (ANN) were applied in this study. Forecasting compound floods is achieved using two sets of inputs: timeseries of river discharges in the upstream fluvial section and downstream ocean water levels in the coastal areas. The accuracy of the flood forecasting system is demonstrated for Cork City, Ireland; and modelling performance was evaluated using several statistical tools. Results show that the proposed models can provide reliable estimates of flood inundation and associated water depths. Overall, the RBF model exhibits the best performance. Despite the complexity of compound multi-driver floods, this study shows that the coupled hydrodynamic-ML approach can forecast coastal-fluvial flood with limited hydraulic and hydrological input data. This system overcomes the limitations of traditional hydrodynamic model-based systems where trade-offs between the always competing numerical model accuracy and computational time prohibit the model to be used for short-term flood forecasting. Once trained, the ML component of the coupled system can perform flood forecasting in near real-time, potentially integrating into a flood early warning system. Accurate flood forecasting has a wide range of positive societal impacts, including improved flood preparedness, increased confidence, better resource allocation, reduced flood damage, and potentially even flood prevention.

Driving mechanisms for the adaptation and degradation of petroleum hydrocarbons by native microbiota from seas prone to oil spills.

Offshore waters have a high incidence of oil pollution, which poses an elevated risk of ecological damage. The microbial community composition and metabolic mechanisms influenced by petroleum hydrocarbons vary across different marine regions. However, research on metabolic strategies for in-situ petroleum degradation and pollution adaptation remains in its nascent stages. This study combines metagenomic techniques with gas chromatography-mass spectrometry (GC-MS) analysis. The data show that the genera Pseudoalteromonas, Hellea, Lentisphaera, and Polaribacter exhibit significant oil-degradation capacity, and that the exertion of their degradation capacity is correlated with nutrient and oil pollution stimuli. Furthermore, tmoA, badA, phdF, nahAc, and fadA were found to be the key genes involved in the degradation of benzene, polycyclic aromatic hydrocarbons, and their intermediates. Key genes (INSR, SLC2A1, and ORC1) regulate microbial adaptation to oil-contaminated seawater, activating oil degradation processes. This process enhances the biological activity of microbial communities and accounts for the geographical variation in their compositional structure. Our results enrich the gene pool for oil pollution adaptation and degradation and provide an application basis for optimizing bioremediation intervention strategies.

Spatiotemporal variations and risk assessment of estrogens in the water of the southern Bohai Sea: A comprehensive investigation spanning three years.

The ubiquitous and adverse effects of estrogens have aroused global concerns. Natural and synthetic estrogens in 255 water samples from the southern Bohai Sea were analyzed over three years. Total estrogen concentrations were 11.0-268 ng/L in river water and 1.98-99.7 ng/L in seawater, with bisphenol A (BPA) and 17α-ethynylestradiol (EE2) being the predominant estrogens, respectively. Estrogen showed the highest concentrations in summer 2018, followed by spring 2021 and spring 2019, which was consistent with the higher estrogen flux from rivers during summer. Higher estrogen concentrations in 2021 than in 2019 were driven by the higher level of BPA, an additive used in personal protective equipment. Estrogen exhibited higher concentrations in the southern coast of the Yellow River Delta and the northeastern coast of Laizhou bay due to the riverine input and aquaculture. Estrogens could disturb the normal endocrine activities of organisms and edict high ecological risks (90th simulated RQT > 1.0) to aquatic organisms, especially to fish. EE2 was the main contributor of estrogenic potency and ecological risk, which requires special concern. This is the first comprehensive study of estrogen spatiotemporal variations and risks in the Bohai Sea, providing insights into the environmental behavior of estrogens in coastal regions.

Exploring the roles of ribosomal peptides in prokaryote-phage interactions through deep learning-enabled metagenome mining.

BACKGROUND: Microbial secondary metabolites play a crucial role in the intricate interactions within the natural environment. Among these metabolites, ribosomally synthesized and post-translationally modified peptides (RiPPs) are becoming a promising source of therapeutic agents due to their structural diversity and functional versatility. However, their biosynthetic capacity and ecological functions remain largely underexplored. RESULTS: Here, we aim to explore the biosynthetic profile of RiPPs and their potential roles in the interactions between microbes and viruses in the ocean, which encompasses a vast diversity of unique biomes that are rich in interactions and remains chemically underexplored. We first developed TrRiPP to identify RiPPs from ocean metagenomes, a deep learning method that detects RiPP precursors in a hallmark gene-independent manner to overcome the limitations of classic methods in processing highly fragmented metagenomic data. Applying this method to metagenomes from the global ocean microbiome, we uncover a diverse array of previously uncharacterized putative RiPP families with great novelty and diversity. Through correlation analysis based on metatranscriptomic data, we observed a high prevalence of antiphage defense-related and phage-related protein families that were co-expressed with RiPP families. Based on this putative association between RiPPs and phage infection, we constructed an Ocean Virus Database (OVD) and established a RiPP-involving host-phage interaction network through host prediction and co-expression analysis, revealing complex connectivities linking RiPP-encoding prokaryotes, RiPP families, viral protein families, and phages. These findings highlight the potential of RiPP families involved in prokaryote-phage interactions and coevolution, providing insights into their ecological functions in the ocean microbiome. CONCLUSIONS: This study provides a systematic investigation of the biosynthetic potential of RiPPs from the ocean microbiome at a global scale, shedding light on the essential insights into the ecological functions of RiPPs in prokaryote-phage interactions through the integration of deep learning approaches, metatranscriptomic data, and host-phage connectivity. This study serves as a valuable example of exploring the ecological functions of bacterial secondary metabolites, particularly their associations with unexplored microbial interactions. Video Abstract.

Synergistic innovations enabled the radiation of anglerfishes in the deep open ocean.

Major ecological transitions are thought to fuel diversification, but whether they are contingent on the evolution of certain traits called key innovations1 is unclear. Key innovations are routinely invoked to explain how lineages rapidly exploit new ecological opportunities.1,2,3 However, investigations of key innovations often focus on single traits rather than considering trait combinations that collectively produce effects of interest.4 Here, we investigate the evolution of synergistic trait interactions in anglerfishes, which include one of the most species-rich vertebrate clades in the bathypelagic, or "midnight," zone of the deep sea: Ceratioidea.5 Ceratioids are the only vertebrates that possess sexual parasitism, wherein males temporarily attach or permanently fuse to females to mate.6,7 We show that the rapid transition of ancestrally benthic anglerfishes into pelagic habitats occurred during a period of major global warming 50-35 million years ago.8,9 This transition coincided with the origins of sexual parasitism, which is thought to increase the probability of successful reproduction once a mate is found in the midnight zone, Earth's largest habitat.5,6,7 Our reconstruction of the evolutionary history of anglerfishes and the loss of immune genes support that permanently fusing clades have convergently degenerated their adaptive immunity. We find that degenerate adaptive immune genes and sexual body size dimorphism, both variably present in anglerfishes outside the ceratioid radiation, likely promoted their transition into the bathypelagic zone. These results show how traits from separate physiological, morphological, and reproductive systems can interact synergistically to drive major transitions and subsequent diversification in novel environments.

The Ocean's Pharmacy: Health Discoveries in Marine Algae.

Non-communicable diseases (NCDs) represent a global health challenge, constituting a major cause of mortality and disease burden in the 21st century. Addressing the prevention and management of NCDs is crucial for improving global public health, emphasizing the need for comprehensive strategies, early interventions, and innovative therapeutic approaches to mitigate their far-reaching consequences. Marine organisms, mainly algae, produce diverse marine natural products with significant therapeutic potential. Harnessing the largely untapped potential of algae could revolutionize drug development and contribute to combating NCDs, marking a crucial step toward natural and targeted therapeutic approaches. This review examines bioactive extracts, compounds, and commercial products derived from macro- and microalgae, exploring their protective properties against oxidative stress, inflammation, cardiovascular, gastrointestinal, metabolic diseases, and cancer across in vitro, cell-based, in vivo, and clinical studies. Most research focuses on macroalgae, demonstrating antioxidant, anti-inflammatory, cardioprotective, gut health modulation, metabolic health promotion, and anti-cancer effects. Microalgae products also exhibit anti-inflammatory, cardioprotective, and anti-cancer properties. Although studies mainly investigated extracts and fractions, isolated compounds from algae have also been explored. Notably, polysaccharides, phlorotannins, carotenoids, and terpenes emerge as prominent compounds, collectively representing 42.4% of the investigated compounds.

Preliminary investigation on the causes of red tides in Qinhuangdao coastal areas in 2022.

To explore the causes of red tides in Qinhuangdao coastal water, we conducted surveys on both water quality and red tides during April to September of 2022 and analyzed the relationships between main environmental factors and red tide organisms through the factor analysis and canonical correspondence analysis. The results showed that there were eight red tides along the coast of Qinhuangdao in 2022, with a cumulative blooming area of 716.1 km2. The red tides could be divided into three kinds based on the major blooming organisms and occurrence time, Noctiluca scintillans bloom, diatom-euglena (Skeletonema costatum, Eutreptiella gymnastica, Pseudo-nitzschia spp.) bloom, and dinoflagellate (Scrippsiella trochoidea and Ceratium furca) bloom. Seasonal factor played roles mainly during July to September, while inorganic nutrients including nitrogen and phosphorus influenced the blooms mainly in April and July. The canonical correspondence analysis suggested that N. scintillans preferred low temperature, and often bloomed with high concentrations of ammonium nitrogen and dissolved inorganic phosphorus. S. costatum, E. gymnastica, and Pseudo-nitzschia spp. could tolerate broad ranges of various environmental factors, but favored high temperature and nitrogen-rich seawater. C. furca and S. trochoidea had higher survival rate and competitiveness in phosphate-poor waters. Combined the results from both analyses, we concluded that the causes for the three kinds of red tide processes in Qinhuangdao coastal areas in 2022 were different. Adequate diet algae and appropriate water temperature were important factors triggering and maintaining the N. scintillans bloom. Suitable temperature, salinity and eutrophication were the main reasons for the diatom-euglena bloom. The abundant nutrients and seawater disturbance promoted the germination of S. trochoidea cysts, while phosphorus limitation caused the blooming organism switched to C. furca and maintained the bloom hereafter.

From the Caribbean to the Arctic, the most abundant microplastic particles in the ocean have escaped detection.

Comprehensive methodologies for monitoring microplastics (MPs) in the ocean are critical for accurately assessing abundances across a broad size spectrum, and to document distributions, sources, sinks, temporal trends, and exposure risks for organisms. Discrete 0.5-L water samples from the northeastern-coast of Venezuela (NECV), Pacific-Arctic Ocean (PAO), and Gulf Stream Current (GSC) were analyzed by Raman microspectroscopy to detect MPs not captured by net-tow surveys. Equivalent spherical diameters (ESD) of most MPs were <5 µm, accounting for 68, 83, 86 % of total inventories in NECV, GSC, PAO samples. We did not observe a single MP particle >53 µm ESD. Abundances of MPs in the 0.5-200 µm size fraction were 5-6 orders of magnitude higher than previous surveys that were almost exclusively based on net tow collections of MPs > 300 µm ESD. Abundances of MPs in NECV samples were ~10-fold higher than those from PAO and GSC. The most abundant polymers were polypropylene (PP), polystyrene (PS) and polyethylene terephthalate (PET), consistent with composition of plastic waste generated globally.