Species-specific transparent exopolymer particle (TEP) during three harmful algal blooms (2022-2024) in an upwelling-influenced coastal bay.

Abstract Marine pollution threatens ocean ecosystems and human health through eutrophication, bioaccumulation, and habitat degradation. This article discusses chemical contaminants, nutrient pollution and eutrophication, marine debris, ocean noise pollution, global and regional hotspots of ocean pollution, the impact of pollution on marine biodiversity, mitigation strategies and global effects, restoration and cleanup efforts, and challenges and future outlooks in marine pollution. The excess nutrient levels disturb ecological balances, cause harmful algal blooms, and threaten biodiversity and coastal economies. While plastic pollution has received widespread attention, marine debris also includes non-plastic materials such as metal, glass, rubber, and textiles. Ocean noise pollution, primarily from shipping, seismic exploration, and military sonar, significantly disrupts marine ecosystems by interfering with the communication, navigation, and behavioral patterns of marine species. The buildup of plastic gyres such as the Great Pacific Garbage Patch is a key contributor to global ocean pollution. Remote polar regions can also show significant accumulation of pollutants due to long-distance marine and atmospheric transportation. Multi-faceted and integrated approaches, such as global regulatory frameworks, technological innovation, waste management improvement, and public engagement, are required to decrease ocean pollution. The growing awareness of marine pollution, especially for plastic debris, has fueled the pick-up trash before it disperses into the open ocean. Meanwhile, ecosystem restoration, ranging from mangrove replanting to coral reef rehabilitation, is crucial in rebuilding degraded marine habitats and promoting resilience to subsequent environmental and climatic pressures.

Role of 222 nm UV irradiation in triggering trichloronitromethane formation in algal organic matter.

Integrating multi-stage interventions for harmful algal blooms effective management.

Coastal eutrophication and freshwater inputs drive acidification in the Indian River Lagoon, Florida.

Wind-driven shear stress on sediment phosphorus release: Implications for water quality, and harmful algal blooms in a shallow estuary.

Rapid elimination of harmful cyanobacteria via synergistic effects of photo-oxidation and flocculation.

Characteristics of benthic toxic dinoflagellate communities within three coastal regions of the Great Barrier Reef, Australia.

River mouth nitrogen: phosphorus: silicon (N:P:Si) stoichiometry can predict marine eutrophication potential. Furthermore, deviations from Redfield molar N: P:Si = 16:1:20 ratios can offer insight into limiting nutrients and risks for harmful algal blooms (HAB). Here, we present N:P:Si stoichiometry based on total P, dissolved inorganic N and dissolved Si for 88 coastal river mouths in Norway, Sweden and Finland between 2017 and 2024. Rivers ranged from ultra-oligotrophic to hyper-eutrophic. N and P concentrations increased from north to south, with no latitudinal Si gradient. Most rivers were either P or jointly NP depleted relative to Si, with no overall evidence of Si depletion. However, there was some evidence of seasonal Si depletion. We show how using multi-element approaches, e.g., the Index of Coastal Eutrophication Potential (ICEP) can help to guide management actions. Specifically, Using Si depletion relative to N and P concentrations as an indicator of HAB potential may offer a means to identify catchments where nutrient load reductions can have the largest benefit on marine ecosystem health. Such multi-element approaches can complement single nutrient assessments based on, e.g., the Carlson Trophic Status Index or Water Framework Directive status class assessments.

Macro- and microalgae are primary producers in coastal ecosystems, and the former harbor diverse microbes. During our investigation of the fungi associated with estuarine macroalgae, Trichoderma spp. appeared predominant as epiphytes and exhibited no host affiliation. Furthermore, a dual culture of algicolous T. virens and T. longibrachiatum led to the production of 21 metabolites, including eight new terpenoids (1-3, 5-7, 11, and 12) and three new alkaloids (14, 15, and 21), identified by combined spectroscopic data. The terpenoids comprise four frameworks, especially the unusual eudesmane (3 and 4) in Trichoderma and the rare 6/7 fused ring system (11-13) in nature. Compounds 1, 3, and 4 feature characteristic halogenations, while 14 and 15 represent the first two hydroxylated derivatives at C-3 of gliotoxin. HPLC analysis revealed that 1, 3, 9-12, 14-16, and 21 were induced by the coculture. Among them, iodine-bearing terpenoid 3 was evaluated as the most broad-spectrum algicide against representative microalgae, which could cause harmful algal blooms. However, it only weakly inhibited the microalgae that can be used as bait in aquaculture and the zooplankton tested. This metabolite may be developed as a promising modulator of coastal microalgal communities.

The cyanobacterial genus Microcystis is globally distributed and known for its ability to produce microcystins, a structurally diverse group of cyanotoxins. However, the biosynthetic capacity of Microcystis is vast; its diverse genomes contain a variety of biosynthetic gene clusters (BGCs) encoding the synthesis of metabolites that may be toxic, have important ecological function, or have applications for biotechnology or drug discovery. Recent studies illustrate that these BGCs vary significantly across Microcystis strains, can be highly expressed in environmental conditions, and may play key roles in cellular physiology, grazer deterrence, and microbial interactions. However, many of these BGCs and metabolites remain poorly characterized or completely uncharacterized, having been identified only through genome sequencing or mass spectrometry, respectively, leaving no knowledge of their structure, bioactivity, or physiological or ecological functions. Here, we synthesize the current body of knowledge regarding the secondary metabolism of Microcystis in terms of genetic and chemical diversity, potential drivers of synthesis, and physiological and ecological functions. This review highlights the need for further research to characterize the largely unexplored genetic and chemical diversity of Microcystis in communities in the environment and discusses the challenges and opportunities of integrating high-throughput multiomic approaches to link uncharacterized gene clusters with their corresponding metabolites. Microcystis will continue to be a rich source for secondary metabolite research as its genetic and chemical potential likely plays a critical role in the persistence and observed dynamics of harmful algal blooms and may harbor uncharacterized toxins and metabolites.

Phosphorus-doped yolk-shell carbon nanocages derived from metal-organic frameworks for enhanced magnetic solid-phase extraction of brevetoxins in seawater.

Excess inorganic phosphate is a leading cause of eutrophication in aquatic ecosystems, contributing to harmful algal blooms, oxygen depletion, and an overall decline in the water quality. Accurate determination of the phosphate is essential for effective water quality monitoring and environmental management. Traditional methods involve multiple reagents, incubation steps, and long assay times, making them labor-intensive and impractical for large-scale monitoring. Here, we report a simple spectroscopic assay for determining phosphate in eutrophic waters using the unique reactivity and fast proton-coupled electron transfer (PCET) kinetics of quinhydrone (QH) for phosphate. The detection mechanism, supported by density functional theory calculations, involves PCET and hydrogen bonding between QH and dihydrogen phosphate, forming a stable hydrogen-bonded complex (QH-H2PO4-), triggering π → π* transitions and an immediate color change from light yellow to dark brown. The method achieves a low limit of detection (374 nM), a broad linear range (1-350 μM), and selectivity over common interferences, with a total analysis time of 30 s. When applied to phosphate measurements in eutrophic lake water, it demonstrates robust performance in excellent agreement with standard approaches while offering superior speed and simplicity. Requiring only one reagent, no incubation steps, and operating efficiently across a broad pH range (4-9), the method holds promise as an easy-to-use tool for the rapid monitoring of phosphate and nutrient pollution in water systems.

Harmful algal blooms (HABs) pose escalating ecological, economic, and public health threats across global aquatic ecosystems. This study presents a comprehensive bibliometric analysis of the research landscape at the intersection of sensor technologies and artificial intelligence for HAB monitoring. Using 1278 peer-reviewed publications (2005-2024) retrieved from the Web of Science Core Collection and analyzed via CiteSpace, we explored publication trends, collaboration networks, keyword evolution, and citation bursts. The results reveal exponential growth in research output since 2019, with the USA and China leading in productivity and international collaboration. Thematic evolution has shifted from marine-focused remote sensing to AI-driven freshwater monitoring, emphasizing real-time sensing, multi-source data fusion, and early warning systems. Despite technical progress, key challenges persist, including data heterogeneity, limited model interpretability, and poor cross-regional transferability. This study outlines strategic directions-such as digital twin construction, physics-informed AI, and transfer learning-to guide the development of scalable, explainable, and climate-aware monitoring systems. By mapping the intellectual structure and emerging frontiers of this field, our findings provide a foundation for interdisciplinary innovation and evidence-based environmental governance.

High-throughput phytoplankton monitoring and screening of harmful and bloom-forming algae in coastal waters with updated functional screening database.

Harmful algal blooms (HABs) are an escalating global threat to aquatic ecosystems, reducing biodiversity, degrading water quality, and compromising human health. Climate-driven warming and excessive nutrient inputs are key drivers of HABs in global lakes. However, as nutrient reduction strategies gain traction, the relative contributions of rising water temperatures and nutrient enrichment remain unclear. Here, we compiled a dataset spanning 40 years from 156 lakes worldwide and analyzed the nonlinear response relationship between chlorophyll-a (Chl-a) and water temperature using a combination of empirical mode decomposition (EMD) and a random forest (RF) model. EMD demonstrated strong adaptability in extracting long-term stable signals from non-stationary records, revealing that over 40% of the lakes are eutrophic, with substantial spatial heterogeneity in HAB intensity; mean Chl-a concentrations reached as high as 26 μg L-1 in tropical regions. As warming continues, water temperature emerges as a progressively stronger driver of HABs, surpassing the influences of nutrient availability and stoichiometric balance. Rising water temperatures diminish the reliance of HABs on nutrient availability, while the nitrogen-to-phosphorus ratio consistently explains variation in Chl-a concentrations throughout the warming process. Furthermore, RF-based scenario projections indicate that under current warming and nutrient scenarios, the mean annual Chl-a concentrations of global lakes are projected to rise to 17.7 μg L-1 under RCP 4.5 and 18.4 μg L-1 under RCP 8.5 by the end of the 21st century. These findings highlight the urgent need to incorporate temperature effects into lake HAB management strategies.

Bifunctional fungi trade off denitrification and algicidal performance to inhibit algal growth and control algal bloom: Denitrification-algicidal interactions, organic matter dynamics, and raw water treatment.

Urban eutrophication enhances domoic acid production by Pseudo-nitzschia in the Southern California Bight.

A digital PCR assay for the dabA gene involved in domoic acid biosynthesis by Pseudo-nitzschia spp.

Spatiotemporal variations of epimicroplastic harmful algae and their driving factors in four semi-enclosed bays of China.